Issued May 10, 1909.
I S. DEPARTMENT OF AGRICULTURE.
BUREAU OF CHEMISTRY BULLETIN No. 125.
U. \V. WILKV, CUIKK of BUREAU.
THE CANNING OF PEAS,
BASED ON FACTOR? INSI'KiTInN AND
BXPERIMBNTAL DATA.
A. W. lilTTI
WASHINGTON:
GOVERNMENT Pit IN TIM, OFFICE,
19<
LETTER OF TRANSMITTAL
U. S. DEPARTMENT or AGRICULTURE,
BUREAU OF CHEMISTRY,
Washington, D. C., March 1, 1909.
SIR: I have the honor to submit herewith for your consideration
and approval a manuscript on " The Canning of Peas." This in-
dustry has grown to very large proportions in the United States, and
it is thought that the results of the investigations made by Inspector
Bitting, as based on a year's inspection and experimentation, while
not final in some particulars will yet be of interest and utility to the
manufacturer as suggesting methods for a more economical treat-
ment of the raw material and better sanitary conditions in the
factory. The bulletin will also be of interest to the consumer in
indicating the method of preparation of an article of diet which has
come so generally into deserved favor in this country. I recommend
that this report be published as Bulletin 125 of the Bureau of
Chemistry.
Respectfully, H. W. WILEY.
Chief.
Hon. JAMES WILSON,
Secretary of Agriculture.
2
CONTENTS
rical note >
Tin- jea
Origin and charartt risti.^
1 '.,.! value 7
Geographical distri hi it ion
Production of peas especially for canning S
Tiinr and manner of harvesting. . . 9
;! \aluatioii of cn.p . ... 10
y ojKrationH . 11
Vininf or tfafHhing . 11
\Va.-liin- 12
i::
ft r mze 17
Hand picking ...... M
Blanching 19
Filling the cans.... 21
|Mition of liquor i'4
Proceemng . . ...._' I
Cooling the tini.-hrd pr.Mhirt 27
Examination of commercial canne<l |>eai*.. . 27
i-'C
!'> i-roducte ...
ILLUSTRATION-
FKI. 1 Hauling peas at a Wisconsin pea-canning factory 10
2. Interior of cannery showing squirrel cages for waxhinu JK-HM and the
brine tanks where they are graded according to quality 13
3. Testing the peas in a salt solution for quality 14
4. Separation of three grades of peas by suspension in salt solutions 15
5. A modern sanitary {tea-canning plant 17
6. A battery of filling machines j-j
3
THE CANNING OF PEAS.
HISTORICAL NOTE.
rdiiiir t<> tin' early accounts of the art of canning, peas were
aiuonir the lir-t vegetable- in I,,' pre-erved in this manner, and later
the\ IIIIOIIL' tin- Iir-t tn enter the can nod -goods trade. Pea
canning may l.r -aid. theref,.re. in !. as old as the canning industry.
At lir-t i In- |>mre-- wa- u-ed only to preserve such choice fruits and
were m-t diflicult to keep in the fresh state, as the cost
I' glass bntile^ and earl henu a re jar- prevented their use for cheaper
pn>diiei~. At'icr the inxention of the tin can, as the cost was less-
I, pea- bream ie of the im>-t iin|)ortaiit articles packed. The
'aiming indu-try began in thi> country in Baltimore during the
Fifth-. Th( an immediate demand for the product, and conse-
quently -nine parking wa- done at nearly every factory. The peas
were in n\\n garden f;i>hion and picked and podded by hand; but the
laU.r ir(|uii-ed \\a- so ui ai that the output was small and the price
high. The method- u-rd did not differ in any essential detail from
tho-' followed in preparing fre-h pea- in the kitchen. The demand
continued to inerra-e. Imt the total output of all the early factories
would not equal that of one >mall modern plant.
The tii--t lalor--a\ ing device of importance in pea canning was the
pnddinir machine invented l>y Madame Faure in France in 1883.
Tin- machine was de-cribed in La Nature. Paris, April, 1885, and
a tran-lat ion. with illu-t rat ion-, appeared in the Scientific Ameri-
can June ;. L885. The invention was practically duplicated in
thi> country in 1880. By means of the podding machine one person
could do the work of a hundred or more in removing the peas from
I he pods. thu> making possible the canning of much greater quanti-
tie-. The American podding machine was improved, and in 189:5
it wa- patented as a vining machine. After this invention it was
no longer ne< -e ary to pick the pods from the vines in the field; the
plant- could be mowed, hauled in by wagon, and the peas separated
from the pod and vine at one operation. The whole pea-canning
industry wa> ehaiiged by this invention. Practically all of the peas
canned in thi- country are passed through these vining machines, so
that their use has virtually changed the growing of peas in small
patches market -garden fashion, with hundreds of persons going
5
THE CANNING OF PEAS.
over the vines and picking the pods to the cultivating of large
fields which are cut by a machine. The< viner occupies the same
relation to hand picking in the pea-canning industry that the
thrashing machine does to the flail in the thrashing of wheat.
Pea canning is one of the most important lines of the canning
industry, being third in order of output, tomatoes and corn being,
respectively, first and second, although peas are second in point of
value. The pea pack for 1907 is estimated at 6,505,961 cases, valued
at $14,650,000, the largest amount ever packed in one season. Accord-
ing to the statistics given by The Canner and Dried Fruit Packer of
December 26, 1907, the production of peas in the different States
during 1907 was as follows:
Peas canned during 1901, &// State*.
Cases.
California 90,450
Colorado, Idaho, Utah, and
Oregon- _ 193,018
Delaware.. 141,046
Illinois 216,508
Indiana 826,500
Iowa 50,000
Kansas 11, 589
Maryland 568,393
Michigan 595,088
Cases.
Minnesota 25, 750
New Jersey 153, 564
New York 1,659,944
Ohio 101,521
Pennsylvania 80,373
Virginia 15, 486
Wisconsin ___ 1,773,599
Other States __ 3,132
Total United States__ 6, 505, 961
THE PEA.
ORIGIN AND CHARACTERISTICS.
The pea belongs to the LeguminosaB, an order of plants which is of
great economical value, as many of its members yield foods, drugs,
dyes, and valuable woods. Chief among their products are peas,
beans, lentils, peanuts, tamarinds, licorice, senna, gum tragacanth, gum
arable, logwood, indigo, rosewood, locust, and Brazil wood.
The origin of the pea is unknown, but it is supposed to have been
carried to Europe by the Aryans at a remote period. The field pea,
Pwiun <irr<<iise, is found wild in Italy, but the garden pea, Pixum
sativum, grows only under cultivation, so far as known. In Queen
Elizabeth's time peas were occasionally brought from Holland and
considered " a dainty dish for ladies, they came so far and cost so
dear." The taste for green peas became fashionable after the Restora-
tion in 1660, and their culture was given much attention, later becom-
ing so general as to be one of the most important field crops. Garden
peas were considered a delicacy, and the French gave considerable
attention to their culture and canning, and through selection they
developed varieties yielding tender small peas of fine flavor. The
pea was brought to Xorth America by European colonists, and grown
in kitchen and market gardens.
T1IK PEA.
FOOD VAI.l I .
Of .ill vegetable- known the legumes are the richest in respect to
their nitrngenou- content. Knight going so far as to claim that they
will lie found e<jual to meat in nutritive powers for active open-air
worker^. Statement- of thi> nature are not true of . green peas, but
apply to the matiiiv seeds only. The following analyses show the
Ita obtained on the mature pea. and al-o on the green pea before
and after .-anniiiir.
It* of nnaluxtx nf / <tx.
IM: \s
Chun h
Water.
Protein.
Kiit.
Starch,
elc.
Cellu-
lose.
Ash.
/Vrrm/.
PcrcfnL
24.60
/' / .- .'/'.
1.00
'
62.00
Per cent.
I'n- ri nt.
2.00
B i"
tt 8 :
.80
1.7'.'
J. 10
51.30
68.24
58.70
6L78
6.50
5.45
3.50
3.90
3.00
2.65
2.10
3.11
J;RKKN IM: \s
AU-1 .
7.00
0.50
/16.90
1 00
-, .
3.87
. 1 ''
13.30
1*68
.78
. \N\I:I. ri \s
- . :n
3. .'.7
0.20
7.79
1.18
1.10
1.11
- Al. ..il.l anil Ituhriili. IH.-t in Il.-alth and Uis.-jisi-. p. !M. 11)05.
F.M.,1. |,
Food ami its I'utu)
1 anil Hi.-l,-ti.-x. ,, 1.17. l^si
Isaml Th.-lr A.liilt-rai i..n. pp. -js. ::i::. 1D(7.
t Including n-ll'.
According to the-e figure-, the average amount of protein in the dry
i- _'}.<'.> per cent, in the green peas :>.[[ per cent, and in the
canned petfi 8.59 p-r cent, indicating that the canned peas lost some
protein during the preliminary treatment. Leach states that 2.03
per cent of the protein of the pea i- >olul>le in water, and 10 per cent
in -alt -olution. The-e ti-itre- were evidently for the mature pea.
Church -late- that the predominating protein in leguminous plants
appears to l>e more -oluhle and more easily digested in the green than
in the mature -eed. In the preparation of peas for canning, they
pa-> through a washer, where they arc -prinkled with cold water, and
then go to the pic-king tables, still wet, and after this into the
blancher containing hot water. The length of time that the peas are
in the \va-her varies in the factories, while the time they remain in
the blancher depend- upon the grade and size of the. peas, varying
8 THE CANNING OF PEAS.
from one to twelve minutes. After leaving the blanchers. the peas
are placed in the cans as quickly as the machines will work, and the
brine is filled in at the same time. From the treatment it is apparent
that the peas may lose some protein before entering the cans, and that
more may dissolve in the brine afW they are in the cans. A part of
the loss of protein in canning is, however, more apparent than real,
a- the peas take up water in blanching and processing, thus increas-
ing their total weight, which only seemingly reduces the proportion
of protein.
The liquor from peas which had been canned in water, and also
liquor from peas canned in brine, were tested for protein. While
thi' ivartion> with the water extract indicated distinct traces of pro-
tein, those with the brine were much more pronounced. Some of the
canners advise the use of the original pea liquor in the preparation of
the peas for the table, supposedly with the object of utilizing the
extracted foods. Usually the liquor is discarded as being somewhat
objectionable in odor.
GEOGRAPHICAL DISTRIBUTION.
While the growing of peas is not limited to any one particular part
of the United States, they are grown with the greatest success where
the spring is a little slow in changing from cool to warm weather.
The northeastern and north central parts of the country grow most
of the peas, Wisconsin leading in their production, closely followed
by' New York. These two States produce almost one-half of the
entire pea pack of the country. Indiana. Michigan, Maryland, Illi-
nois. New Jersey. Delaware, Ohio, California. Pennsylvania, Iowa,
Minnesota. Virginia, and Kansas follow in order. Peas are also
being packed in Colorado, Idaho, Utah, and Oregon, but they can
not l>e grown in the Southern States nor in many places in the Central
and Western States in competition with those grown near the Lakes.
as the period of harvesting is too brief and other hazards of the crop
are too great. Pea packing is rapidly increasing in Wisconsin and
Michigan, because of favorable climatic conditions for production.
PRODUCTION OF PEAS ESPECIALLY FOB CANNING.
It is said that the different seed firms list about 300 varieties of
garden peas, or at least give that many names. The varieties used
by most canneiv are Alaska and Little Gem for the early or smooth
varieties, and Horseford's Market-Garden, Admirals, and Advancers
for the late or wrinkled varieties. The smooth varieties are not
as sweet as the wrinkled.
It would seem as though much improvement might be made in
peas through breeding and selection for increased sugar content, fine
TIM I. AND MANNER OF HARVESTING.
texture, plea-ing flavor-, and smaller peas. These are qualities es-
pecially .-ought 1)\ tin- trade. To simulate a greater sugar content,
i! i- added to the liquor, but the other requirements can only be
obtained by proper growth. The possibility of developing a plant
with greater resistance to climatic changes, especially heat, and of
lengthen iu: tin- -ea-on of development :uv also worthy of special
Ly-
nn AND MANNER OF HARVESTING.
In Indiana. Illhioi>. Ohio, and State- of similar climatic condi-
tion- the period of harve-ting f or the factory is less than twenty
day-, .mil -eed will not inatmv to advantage on account of weevils.
In Michigan and Wi-eon.-in the harvest period is from six to eight
week-, and the -red readily mature-. Ninety per cent of all the pea
for planting i~ produced in northern Michigan. The irrigation
ems in Colorado and Ctah have opened up possibilities in pea
growing, the extent of \\hich i- not known at this time.
for Inirri-xtinti /<*/* fur n snicx nf
IMC.
State.
Date.
California.
1
N.-u York .
June 15 to Aug 1
.1 inn- 1" to V UK !'
Ohio
.1 uiu' 1 to July 10
1 to Jtuir^iO
'11
June 10 to July 30
Illinoifl
Jiliu- 1
l'-p.n*vl Viitiia
June 1 to July 1
JlllH- "' t" JuiV 10
Ctnh
June 10 to July 15
-ilv 1
::iia
May 20 to June 10
Michigan
.hllic \'> In Aug. 10
'UMIl . .
June 15 to Aug. 10
,
i t<> I M!\ :5
A longer hanv-tinir period in the Northern States is possible be-
successive plant ing- ean \H- made of the same varieties as well
a- of t-arly and late vai'ietie-. In the more southern areas the crops
are too liable to mature at one tiim late-sown peas as early as the
firM -own thei-rl\ o\-ren>wding the factory.
Pea- were formerly gathered by hand. Five pods usually form
upon each vine, and the lowe-t is only about 10 inches above the
ground. Tin- part of the work was. therefore, very slow and labo-
riou>. and required an amount of help available to but few factories.
At pre-cnt there i- only one large factory known to the writer em-
ploying hand labor in the picking of the peas. It requires about
tun thousand pickers to keep a large factory in operation, and adds
i of about !.." to "2 cent- to each can.
The method in general use is to cut the vines with a mowing ma-
chine, or. if any are exceptionally erect, to use the self-rake reaper.
If the mowing machine be used, then it must be followed immediately
by men with fork- to bunch the peas in order to prevent trampling
by the hor-e-. and to put them in condition for easy loading. Within
77893 Bull. 12509 2
10
THE CANNING OF PEAS.
the past year or two special attachments have been devised to be con-
nected to the mowing machine for the purpose of bunching and
delivering to one side. The cutting is usually done early in the morn-
ing, and only such part of the field is cut as can be delivered promptly
to the viner. The object is to prevent any heating of the vines or
any drying. The vines are loaded upon wagons, like hay, and hauled
to the vining machines.
GRADING AND VALUATION OF CROP.
The basis on which peas are paid for varies greatly at the different
factories. Many pay a flat price so much per bushel or hundred
pounds of shelled peas. When this plan is pursued it is advantageous
to the factor}' to insist on the peas being delivered as } 7 oung as it is
possible to use them in order to get the maximum amount of small
FIG. 1. Hauling peas at a Wisconsin pea-canning factory.
pi-as, but it is to the farmer's advantage to delay hauling them in
order to get an increase in growth and weight. Such a method is
not fair to either factory or producer, neither is it fair to the different
producers, one with a first-class load and another with an overripe
load.
A second method is to have a scale of prices for two or three grades
of peas. The rating of any given load is made by an expert and is
a matter of judgment. The appearance of the vines, the size of the
peas, the hardness to the sense of touch when squeezed between the
fingers, and sometimes the taste are the factors which guide in the
derision. Such a method is manifestly better than a flat rate of so
much per bushel, but it is not nearly so accurate as could be desired
and is also subject to personal bias.
A third method is to pay two or more prices, according to the
percentage of peas of a given size. A half-gallon measure of peas
FACTORY OPERATIONS. H
is taken out of a given load and poured into a box having a bottom
perforated with No. :i holes. If, as the result of shaking, one-half or
more of the peas pass through the sieve the highest price is paid; if
tea than one-half of the peas pass through the sieve and they are
fairly soft the second price is paid; if the peas be overripe or hard
tin- lowc-t price i- paid. This method is used by a number of fac-
torie- and. although not perfect, is an improvement over the other two.
A fourth method i- to take a sample from each load during the
thrashing and run it through the grader. The sample usually
weigh- 1" pound-, and the screens in the grader correspond to those
u-ed in tin- faetory. The weights of the five grades are taken sepa-
rately and the price i- eMabli.-hed upon the percentage of the different
Bizefl of peas. Some faetorir- modify this procedure slightly by
rating Nos. 1 and -J together and Nos. I and 5 together, thus making
three grade- in tfUA ifl the la-i- for payment. The greater the per-
centage of tin- -mallei- sixes of pea-, the higher the price paid for a
l>u-hel. Thi- method Beemfl the fairest of those now in general use.
The fifth method for payment i- la>ed upon quality, rather than
upon -i/.e. M in three of the methods de.-eribed, in which it is
a umed that -mall DM If a-- ociated with immaturity and tender-
iimption whicli '.- not a I way- in accordance with facts.
Large peas may le a- -oft and lender as the small ones, and small
pea- may he a- hard a- tho-- that are overripe. This method con-
eists in taking a fe\ rin a- a -ample from each load, shelling the
pea- and placing them in a cylinder which has a perforated bottom
and i- -u-peiided in a -alt -olution. If the pea- are young and tender
a large percentage will lloat in a weak hrine. If they are older or
second grade they will sink in a light solution, but will float in a
heavier one. If old, hard, or overripe they will sink in the heavier
-olution. The den-ity of the-e -ohiiions is varied within narrow
limit- for the early and late varietie- of peas, and is discussed in
more detail under grading in the factory (page 13).
Thi- method i- expedition-, and experience has shown that it is as
nearly accurate in pi-act ice a- the fourth method of grading based on
size. The ideal grading -ystem -hould be based on a combination of
size and weight.
FACTORY OPERATIONS.
viMM. oi: i ii HASH i N(;.
The -epa ration of the peas from the pods and vines is accom-
plished by a -ingle operation. The viner is an ingenious though
-imple piece of mechani-m. consisting of an outer cylinder having
torations of such size that peas will pass readily through, but
which will retain the pods and vines, and an inner cylinder upon
12 THE CANNING OF PEAS.
which there are paddles or beaters. The outer cylinder is made to
revolve slowly in one direction and the inner one at a high rate of
d in the opposite direction. The vines are fed in at one end of the
cylinder and are carried up by the slower-moving outer cylinder
until they fall off, and in so doing strike the paddles upon the rap-
idly revolving inner cylinder. The impact of the paddle causes the
pod to break open and the peas to be thrown out. The proces> is
repeated again and again as the vines work from one end of the
cylinder to the other. The peas are discharged through the perfora-
lions of the outer cylinder and the vines at the opposite end. The
work is done thoroughly and the peas are not bruised or crushed by
the operation, as might be expected. As a further aid in separating
the smaller bits of stems, leaves, etc., the peas fall from the cylinder
upon a moving web placed at such an angle that the peas will readily
roll down into the receiver, while the flat leaves and other particles
which will not roll will be carried off.
The vining machines are supplied to the different factories upon a
royalty basis, the charge being 3 cents per dozen cans for all shelled
peas put up at the factory. These machines are large and, as a rule,
an- .-et in batteries at the factory instead of being taken to the fields.
A few of the very large factories have established vining stations at
varying distances from the factory and bring in the shelled pea> by
wagon, automobile, or rail. This practice requires rapid handling, as
the peas will heat much more quickly after than before being shelled.
A large saving in fhe hauling of vines is effected, and the injury to the
pea* is probably not greater than would occur in letting the vines wait.
These viners were formerly fed by hand, but recently a mechanical
feeder has been devised so that the vines are pitched off the load and
the machine completes the work. An automatic weighing device has
a No been added to take the place of the pea collector and weigher,
and conveyors are used to carry all vines to the stack or silos so that
the actual hand work is reduced to a minimum.
Shelled peas which are hauled to the factory must be kept in thin
layers rather than in bulk. The best carrier seems to be a box about
inches deep having a raised wire bottom made like that of a berry
box. The layer of peas is only about 4 inches thick and is well ven-
tilated. The boxes or crates, no matter how constructed, must be
-terilized with steam and rinsed with scalding water each day or they
will become infected with germs which will cause spoilage.
WASHING.
The first operation through which the peas pass after being
weighed from the viner is that of washing. This is accomplished in
what is known as the squirrel c:>ge. which is a wire cylinder about 3
feet in diameter and 12 feet long. The cylinder is set on a slight in-
FACTORY OPERATIONS.
13
dine M> that when the peas are admitted at one end they will tend to
roll to tin- other ;i> tin- cylinder revolves. On the inside is a perfo-
rated pipe that sprays a stream of water upon the peas, which insures
their heini: ^ell wa-hed provided the spray has some force. When
the \\eather i- vrry warm and the peas accumulate more rapidly than
thev can be passed through the filler, it may be necessary to wash
the -helled pea- in cold water every few hours in order to prevent
fermentation. The washing should be thorough not only to remove
all dirt. l>iit al-o the mucoii- -nh-tance, thus insuring a clearer liquor.
tiir. _'. i
_. Interior >f mnn.T.v showing s.|tiirn>l cajri-s for washing peas and the brine tanks
wh>r> t!-y art- trruded according to quality.
, i:\DlXt; FOK QUALITY.
After the peM IKI-S throurh the wa>her, they should be graded ac-
cordinir to the .leirree of maturity or hardness. This is accomplished
1\ pa^ini: them through tanks containing salt solutions of different
den.-itir-. It has been found that the young tender peas will float in
a -alt solution somewhat heavier than water and those more mature
will -ink. while the very mature peas will sink in a heavy salt solu-
tion. Pea-, therefore, may be sorted very readily into different grades
according to their density by using different strengths of salt water.
In practice three -rrades have been made. The first grade consists of
all j>ea> which will float in a solution having a specific gravity of
1.040. The second grade consists of those peas which will sink in a
14 THE CANNING OF PEAS.
solution of this density but which will float in a solution having a
specific gravity of 1.070. The third grade consists of the peas which
will sink in the latter solution. Figures 3 and 4 show how the three
grades of peas are separated by this means. A machine has been de-
vised to remove the peas from the top and bottom of these solutions
so that their separation is automatic and continuous.
The principle involved in the separation of peas into grades for
quality is not new, having long been applied to the selection of seeds.
Fie. 3. Testing the peas in a salt solution for quality.
It was tried for grading peas for several years without success, be-
cause solutions having the proper density were not obtained and the
necessary working apparatus was not available. On May 27, 1894, a
patent was granted on a device for grading peas, which has since
been improved so as to work very well.
The grading of peas for quality is as sharp and clear as that for
size. The lightest weight peas are the finest, being even in quality,
succulent, and tender. The heaviest peas are the poorest, being
uneven in quality, hard, overripe, and of bad color. The middle-
FACTORY OPERATIONS.
15
weight peas are good, but harder than the first grade, of darker color,
and not so uniform. These differences are most apparent before the
canning is done, though they are readily distinguishable in the can,
and also show on chemical examination.
In any load of peas there must be some plants more mature than
other-, ami a- a conMM|iience. xrnie hard peas will be mixed with the
tender ones. Every effort is made to cut the peas at nearly the same
of maturity, but no field will ripen perfectly evenly. If the
Fi.;. 4. Separation >f three grades of peas by suspension in salt solutions:
() Weak Mil l-rin.- isp. irr. 1.O40) : (61 strong salt brine (sp. gr. 1.070 .
peas be produce,! by a hundred farmers, the differences will be accen-
tuated. In localities where the peas mature slowly, the differences
will l,r less marked than where they mature rapidly. Under any
condition-- theiv will be some differences in quality, and under un-
favorable conditions the percentage of poor peas may be very high.
Separation for quality is so well effected by the specific gravity grader
that it undoubtedly will receive a recognition equal to that given the
machine.
16
THE CANNING OF PEAS.
According to an Indiana factory, in which the quality system of
grading has-been developed, peas rated good and poor upon the
wagon gave the following results after passing through the grader.
Quality gmtlinti <-"iiij><ir< d with iragon tests.
Qtade.
Rated Rated
good on poor on
wagon. wagon.
1906.
Fir^t
Per cent.
60.60
20.75
18.65
51.10
28.85
20.06
28
43
30
Per cent.
40.20
20.59
39. 21
26.35
37.76
35.89
85
34
81
Third
1907.
First
Third
1908.
First
Third
" Whole crop rated by grader in this year.
Had the specific-gravity system not been in use the output of first-
class peas would have been much smaller and that of second and third
grades correspondingly increased. The trade permits a small per-
centage of hard and off-size peas in the first grade, but with this
system these " off " peas are very few. The characteristics of the dif-
ferent grades will be considered again under the finished product.
A chemical examination of peas graded for quality as well as for
size gave results as shown in the following table :
Chemical examination of peas graded for size and quality.
[Analyses made in the Division of Foods, Bureau of Chemistry.]
Grade.
Total
solids.
Ash.
Crude
protein.
Crude
fiber.
Pento-
sans.
Starch.
Sucrose.
Reducing
sugar.
Undeter-
mined.
Petite pois:
First
14 23
1 03
3 44
1 68
75
5 57
7
00
1 04
Second . .
Third
18.80
18 44
.78
82
4.19
4 41
1.84
2 28
.92
94
8.53
8 53
.93
817
.00
00
.61
357
Sifted:
First.
22 06
36
5 31
2 21
96
10 23
987
00
1 012
Second ..
Third
24.32
11 11
.04
.37
5.69
5 63
2.05
2 18
1.01
1 50
11.52
13 52
.57
48
.00
00
2.44
3 06
Marrowfat:
First
22 22
02
5 13
2 18
98
10 48
94
00
1 49
Second
Third
24. 10
2" 15
.30
2 03
6.69
5 94
2l 55
2 00
1. 55
1 27
8.77
i2 91
.636
OKI
.00
00
2.604
2 639 1
The table shows more total solids and higher protein and starch
content in the third-grade goods. This might be expected, as the
third grade represents the more mature product. If canned peas
were purchased for their nutritive properties only, then the third
IORY OPERATIONS.
17
grade would IK- the preferable one to buy, but they are usually se-
lected for their delicacy and flavor, which are found in the highest
degree in the youn<re-t and tenderest peas, or the first grade.
(;1L\I)IN(; FOIl SIXK.
The grading for -i/.e i- a very -imple matter. The peas are passed
over sieves, <>r int a revolving cylinder having four sections with
perforation- of diil'eivnt sizes. The perforations in the first sieve or
lection measure nine thirty-seconds of an inch in diameter. The
which pa through this -i/.e opening are known as No. 1, or
!'i'. ' A in. .. I. in -;iMit:ir\ p.-a canning plant. The large cylinders on the right are the
graders for siz.- i:.-l..w th.-m and .-xtending out into the room are the picking belts.
On the left are the cylinder blanchers. The roof shows the sawtooth lighting system,
and the floor Is of concrete for flushing.
" petit- pois." The next >ize of perforation is ten thirty-seconds of
an inch in diameter, ami the peas passing through are known as No.
-2. "extra -if ted," or "extra fins." The third size of perforation is
eleven thirty-seconds of an inch, and the peas which pass through
are known a> No. ''>. "sifted," or u fins." The last size is twelve
thirty-second- of an inch, and the peas which pass through are
known a> No. 4, or "early June" peas. The peas which are too
large to pa through this sieve go over the end and are known as
No. :.. or " marrowfat-." Some packers add one more sieve for late
1-ea-. with perforations thirteen thirty-seconds of an inch in diameter
for the No. :>. and those which pass over this sieve are called No. 6,
18 THE CANNING OF PEAS.
or " telephone peas." The sizes of these perforations are standard
and in general use. Some packers have attempted to make sizes of
their own by reaming out the holes, while others do not use all four
sieves, but group two sizes together; and some peas are ungraded.
These sizes are so nearly standard for all pea packing that they
should be adhered to in the labeling. The term " early June " peas
as now used applies to a certain size and not to the season at which
the peas are picked, and the size larger, or " marrowfat," should not
be labeled " early June." " Extra early June " or " May pickings "
is not a proper designation for sifted peas. It is evident that the
standard terms used to designate size should be employed in labeling
if the proper meaning is to be conveyed to the purchaser. Com-
mercially, almost any size of pea may be found to be selling as " early
June " in the cheaper grades. The more expensive peas are usually
sold true to name, though it is not unusual to get smaller peas in the
high grades than is indicated upon the label. The terms " early
June," " May pickings," " extra early June," and others of that char-
acter could be advantageously supplanted by names more distinc-
tive of size, as the present terms conflict with the requirements of the
food and drugs act as to labeling, unless the product be actually
packed at the time indicated.
The percentage of peas which go into the different sizes will vary
considerably with the time of harvesting, the variety, and the season.
One of the large factories furnishes the following figures upon the
crops for 1906 and 1907 :
Percentage of different sizes in the crops of two years.
Size.
1906.
1907.
1. Petits pois
Per cent.
4 00
Per cent.
1 60
2. Extra sifted . . .
7 50
]2 20
3. Sifted
30 30
34 70
4. Early June .
50 20
28 10
5. Marrowfat
8 00
17 40
It is not known how these figures will compare with the grading
for the entire country, as this is a matter which canners do not make
public.
HAND PICKING.
After the peas have been graded into sizes they are usually run in
thin layers over slowly moving belts, so that pieces of foreign ma-
terial, broken, fully matured, and defective peas may be seen easily
and removed. Low-grade peas are not so carefully picked over.
In the section of the country where Canada thistles are abundant,
their separation is a difficult problem, as the thistle top is about the
FACTORY OPERATIONS. 19
SMI in ' BUM M the pea, and only the very large ones are removed by
the graders. During the last season experiments were made in
removing the thistle tops by the specific gravity system, and it was
found that more than 90 per cent of them would float in a light brine
(having a den-ity of 1.020), while only a small percentage of the
pea- limited in sueh a solution. It is evident, therefore, that instead
of employing hundred- of girls to perform this work, more than 90
pei- cent of the to| could 1 >e collected in less than 10 per cent of the
peas. The reduction of the tedious hand labor by such a method
i- apparent. Tin-,- testa \\ere made too near the close of the season
to be completed. lmt -uilicient work was done to demonstrate the
correct iie-- of the principle. The work can also be very materially
reduced ly -eparating the thi-ile- from the vines at the vining
machine.
r.i. \M HI\<..
There are two object- in blanching peas: (1) To remove the mu-
cou- -ul>-tance i'mm the mitsidc and a part of the green coloring
matter. BO U to ha\ a dear liquor in the can; and (2) to drive water
into the pen- >o that all will be tender.
In the young, juicy pea. the \\ater content is at its maximum, so
that the cleaning of the -urface i- all that is necessary. The time
required I'm- blanehing i- from one-half to one minute for No. 1 and
\". _', or "petit- poi-" and "extra -ifted:" one and a half minutes
for No. 8, or " aifted ; " two minntei for No. -t, or " early June; " and
t\\o and one-half minute- for No. :>. or "marrowfat" peas. To get
the hc-i molts, petfl which are very old and hard will need a blanch
approximately the times as long as young peas of the corresponding
grade, while tho-e in the intermediate stages will require a blanch
proportional to their development.
It i- evident, therefore, that among peas that are good, but un-
graded M to quality, there will be a greater or les^ number which
will be hard because of under blanching, and some above size because
of -welling during the blanching and after processing. There is no
part of the work of canning peas which requires so much judgment
;i- that of blanching if the best quality of goods is to be obtained.
Much of the very cheap goods upon the market are made so because
of following -rule of thumb" methods in this department. The
division of peas into grades for quality as w^ell as for size will
simplify -omewhat the problem as to the length of time that blanch-
ing should be continued, but not to the point of making the position
of blancher one of secondary importance in the canning factory.
Experiments were made to determine the effect of varying periods
of blanching on the different >i/es and grades of peas and the influ-
ence exerted on -welling, tenderness, color of the liquor, and fill of
20 THE CAN XING OF PEAS.
the can. While the primary object was to determine the relation of
blanching to spoilage, the secondary effect on the commercial grading
was evident.
Young peas will stand either a long or short blanch better than
old ones. The effect upon the increase in size was determined by
running the peas over the same size screens before and after blanch-
ing, and noting the percentage which did not pass through. It was
found that after a ten-minute blanch the percentage which showed
an increase in size was as follows :
Percentage of />e* increased in size by blanching for ten minutes.
size of peas.
Grade 1.
Grade 2.
Grade 3.
Petits pois
Per cent.
28
Per cent.
45
Percent.
82
Sifted
26
42
56
Marrowfat...
2-1
42
68
The increase in size was much greater in grades 2 and 3 than in
grade 1. The experiments with the one-minute blanch and the five-
minute blanch were not made upon complete sets, but the results
obtained indicated a similar change, though it was less marked.
The peas were filled into the can so as to give a uniform weight,
and water was added without salt or sugar, to give a total of G60
grams. After processing it was found that of those given the short
blanch, the peas in grade 1 had taken up but little of the liquor, and
those in grades 2 and 3, particularly the latter, had taken up so much
of the water as to leave an insufficient amount to cover the peas in
the can.
The appearance of the liquor was best on grade 1 for the one-minute
blanch, and good for the five-minute and ten-minute blanches; on
grade 2 it was best for the five-minute blanch, and on grade 3 best
for the ten-minute blanch. The liquor on grade 1 was clear, on grade
2, cloudy but thin, and on grade 3, thick and starchy. The peas in
grade 3 for the one-minute blanch had formed a solid mass with the
liquor so that half of the peas would not fall out when the can was
inverted.
Tender peas which are over-blanched, soften, break open, and dis-
charge free starch grains so as to make a muddy liquor, and if in
great excess, the liquor in the bottom of the can becomes pasty. Old
peas which are under-blanched remain hard and unpalatable after
processing, or, if given a hard process, they will take up all the liquor
in the can and become a more or less thickened mass. Such peas never
have clear liquor. If the tender and hard peas be mixed, and the
blanching be set for the young peas, the older ones are not well done ;
FACTORY OPERATIONS. 21
it -et for the older {MM*, the tender ones are overdone. It follows,
therefore, that to ^et irood results requires much judgment, and a
-\ iein of blanching te-ts could possibly be worked out to advantage.
The operation of blanching peas is of comparatively recent intro-
duction in the pea-packing process and at first was thought to be an
unnece-sary -tep. When the liquor was unattractive, the peas were
placed in 1 oo-e hair- or perforated buckets and suspended in hot
water for a -hort time, after which the water was drained off. From
tin- practice the operation of blanching developed, and at present a
numher of Uanchini: device- are on the market. Those seen in opera-
tion are of t\\o type-. In the older one the peas are held in a wire
l.a-ket \\hich i- -u-pended in a trough of hot water. The trough is
usually long, and mechanical device- are arranged to carry the baskets
tliroiiirh at -uch a -peed a- will insure their boing given a certain
lenirth of time I'm* the different sizes. These tanks vary from 20 to 80
h. The -econd type of hlaiichcr is that of the continuous
wa-her. A cylinder i- made to revolve in a shallow tank of water
and if run n n -peed, the pea- will he delivered at the oppo-
-iie end in a given time. Sume of these cylinders are sectioned in
order to have .-leaner \\ah-r a- the blanching progresses. The hot
water i- admitted at one end and the wa-ie ex-apes from the opposite
rnd. The ra\\ pea- and the water enter opposite ends of the trough
>o that the clean pea- d<> not conu' in contact with the dirty water.
From a -anitaix -tandpoini. thi> i> the better type of apparatus,
though in practice, the trough blanchers are probably the more
.omieal. but not so cleanly.
I II I !\. I 111. AN-.
When the pea- leave the l.lancher. they are sometimes washed, and
thi- i- de-nable in order to in>ure a clear liquor, especially if the peas
ha\e heen blanched in wire !>a-ket- -us|)ende<l in a tank of water.
The pea- are tilled into the cans by special machines, although in
very -mail fadone- tin- may be done by hand. The modern machines
do the work with a fair degree of accuracy, insuring a uniform quan-
tity in each can. then adding liquor to fill, so that the caps will just
n. Figure r, -hows a battery of filling machines into which the
are delivered directly from the blanchers.
,11 is -aid to be wel'l tilled when the contents are within three-
eighth- inch of the cap and the peas are just covered with liquor.
Peas of excellent quality when covered to too great a depth with
liquor deteriorate in appearance as can be determined by inserting
a >piMiu and raiding the peas gently but without appreciably dis-
turbing the liquor. ( )n the other hand, if there is not sufficient liquor
to cover the pea-, they are not generally attractive, and if very short
22
THE CANNING OF PEAS.
on liquor, they become pasty. It is important, therefore, to use just
enough liquor to cover the peas.
The No. 2 can generally used is popularly supposed to mean a,
2-pound can, and is often so billed and referred to in market reports,
but it does not hold 2 pounds and should be given its proper desig-
nation. The average fill of a can is such that after processing there
will be 14 ounces of peas (400 grams) and 7 ounces (200 grams) of
liquor. The can weighs 100 grams, making a total of 700 grams or
25 ounces. Any very marked deviation from these figures in the
direction of reducing the proportion of peas would evidently be an
FIG. 6. A battery of filling machines.
adulteration with water, while any considerable increase in the pro-
portion of peas would result in dryness. 'Cans containing only 11
or 12 ounces of peas are evidently short weight, though a customer
can not reasonably demand more than 15 ounces as a maximum and
expect a good appearance.
A can of marrowfat or telephone peas will not weigh as much by
about three-fourths ounce (20 grams) as a can of the smaller-sized
peas if the fill be the same. The u sifted " pea, or Xo. 3 size, is the
heaviest in the commercial grading. The " extra sifted " and the
" petits pois " are the most expensive to the canner. and the tendency
is to cut slightly in the weight, usually about three- fourths of an
FACTORY OPERATIONS.
23
ounce, although it is not uncommon to get cans from 1J to 2 ounces
.-.hurt on peas and correspondingly overweight on liquor.
The amount of peas put in a can will depend upon the grade, the
time given in- the blanch, and the length of the process. The better
the grade of pea the greater the quantity which will go into the can,
and these will IK least affected by either blanching or processing,
while the poorest irrade of peas is affected the most. In filling a
can with good peas, an allowance of less than one-fourth of the space
in the can is made for swelling as a result of processing, and for poor
peas an allowance of more than one-half is made, so that the volume
of pea- n-ed in the former ca~e is about three-fourths, and in the latter
about one-half the volume required in the finished product.
i:\prriniriits made to determine the increase in the weight of peas
at the re-ult of proce ini_ r -howed that, given the same process, the
lirM oi- best grade increased from 8 to 11 per cent, the second or
intermediate L'rade from Hi to 21 per cent, and the third grade from
_'l to 83 p'-r cent. There \va- al-o -ome variation in the increase in
\\einfht with the ditlerent sixes of peas, the " petits pois " showing
the ^reate-t increase in I he poon-t grade. These experiments were
limited to the conditions present somewhat late in the season and are
not complete. I. ut only indicative in a general way of the changes
which take place.
The follo\\ in;: taMe. ba-ed on the examination of a number of cans
filled and brined by machine. -lm\v^ approximately the character of
the changes, -ome \ ariation in the liirni'e- being due to the use of vol-
ume instead of \\eiijlit as the unit in filling:
KffiVt <>f />/'orr //;/ nn tin v/: '// diffrmit f/nnlcx of l>CdS.
rrrns pois .NO. i.
Grade.
Total
weight.
(MUM
Weight (granw).
Character of
brine.
Condition of JX-HS.
Size a-fter process-
ing.
Can.
Brim-.
Peas.
Grains un-
changed.
Grams in-
creased.
FiiM..
><,, M.I .
Thin!....
MO
m
675
100
100
100
230
206
155
860
HI
420
Clear
Vino
215
IfiO
120
145
210
300
Cloudy Fair ,
Thick Poor
KXTKA SIFTED Oil "EXTRA FINS I NO. 1
.'XI
100
215
375
Clean
320
55
Thin]
M
m
100
100
HB
160
SS5
420
Very cloudy . .
Thick
Somewhat sticky ...
Dark, poor
115
115
270
305
SIFTED OR "FINS" (NO. 3)
Mfl
100
rMV)
390
Clear
dean 335
55
-
690
100
196
395
Cloudy
Poor and cloudy 205
190
Third
ij-&
41ft
Peas sticky | 185
225
24
THE CANNING OF PEAS.
of processing on the .v/:r of different
EARLY .Tr.NK (NO.
of prf/.v Continued.
Gnulf.
Total
weight,
grams.
Weight (grams).
Character of
brine.
Condition of peas.
Size after process-
ing.
Can.
Brine.
Peas.
Grains un-
changed.
Grams in-
c reused.
Fir-t
Thin!.."."
690
100
100
100
205
185
175
385
395
400
PI par
Clean
295
276
170
90
120
320
Thick
Verv stickv
\ery sticky...
Adherent . .
MARROWFAT (NO. 5)
hirst
*>i)0
Poor
Third....
665
100
Starchy!
Verv poor
:
COMPOSITION OF IJQUOR.
The liquor used on peas is usually composed of water, salt, and
sugar. At one time saccharin was used by many packers instead of
sugar, but this practice has been almost entirely discontinued. The
proportion of salt and sugar used varies greatly with the different
packers. The lowest amounts given were 2 pounds of salt and 2
pounds of sugar to 100 gallons of water. The largest quantities used
were 40 pounds of sugar and 16 pounds of salt per 100 gallons, while
the average seems to be about 10 pounds of salt and 10 of sugar per
100 gallons of water. There is undoubtedly a tendency to reduce
the amount of sugar used, and a few canners have left out both salt
and sugar in some lots of peas to determine whether there is a marker
for an unseasoned product. The heavy sirups are used in the fancy
and extra fancy brands of goods, the amount of sugar added to the
sirup being often the only difference between the " superlatively
good " and the " best." A fairly sweet sirup is sometimes used to
give a weak, insipid, sugarless pea some semblance of quality, also
to make the smooth pea as sweet as the sweet wrinkled variety.
Analyses a of 35 brands of peas purchased in the open market show
the sugar content of the liquor to vary between 0.46 and 4.17 per cent.
the average being 2.62 per cent. More sugar is found in eastern than
in western packed peas, and in the domestic than in the foreign peas.
PROCESSING.
After being filled the can is passed through the wiping machine, the
cap is put on and soldered in the automatic capper, the tipping fol-
lows, and then comes the final inspection in the water bath for leaks.
At one factory the can> were passed through an exhauster for the
double purpose of heating them uniformly and of driving off a cer-
tain characteristic odor which is objectionable.
" Analyses ir.a<l,> by G. Spitzer. Indiana Agricultural Experiment Station.
FACTulJY OPERATIONS. 25
IVa- are processed in retorts under pressure, or in a solution of
a calcium -alt. in order to secure a temperature above that of boiling
water. The germ- which arc found upon and associated with the pea
can not In- killed at hulling temperature unless it is continued for such
a length of time a.- to ruin the peas. The spores of these germs are
Mippo-ed to re-i-t any temperature below 240 F. for twenty minutes.
The time ami temperature nece.-.-ary to sterilize peas can not be given
with certainty becaii-e of the variation in factory practice and con-
dition- which mu-i be taken into account. If all factories handled
their material promptly after being cut in the field, allowed no ds-
lay-, Mich a- .-landing on wagon- up in piles to ferment, washed the
peas w'H M -""ii J- thra-hed. graded them equally well, blanched
them according '" their need-, -irnped and filled the cans the same,
tipped tin- can- at the -ame temperature, and brought them to the
pn.ce-> tank under like condition-, it would be possible to develop
a proce which might In- sale for nearly all localities. Such ideal
lition- :nv not to be found in practice, and hence it is that one
factor] will employ a proce of _'!<> F. for twenty minutes and do
it successfully, while another mu-t double the time before being
nahly MIC.-. I'M! in pi-eventing -poilage.
The duration of the proc. -hould be considered as the length of
time during \\ h *D are Milunitted to a cooking temperature,
and not the length of time they are in the retort. If a retort be filled
with en m-. it will take a few minutes for the steam or water
to OOme I" a fairly -tationary temperature. When steam is used most
factories allow from llmv to live minutes to bring up the tempera-
ture, and v. hen water i- n-ed from right to ten minutes. This prac-
i- often followed too do-elv. not taking into account the fact that
B peafl are tilled and tipped while at a temperature of 180 F. and
,,tl,,. r - : it inn \'. In the he-t of the hundred canning factories in-
ird the mo-t careful attention was given to time and tempera-
ture of processing. The temperature wa- rai-ed gradually, continued
uniformly, and -hut oil -lowly. The circulation stopcocks were
opened and .-lo-d to in-ure a positive temperature at all points, and
the valve- adju-ted to meet any -light change above or below.
For many year- the details of the process were considered a factory
Bt, and' that feeling ha- not wholly passed away. It is evident
thai mod cannen allow a good margin of safety to prevent spoilage.
The majority follow the rules indicated by general practice and make
little attempt to vary them for particular conditions so as to get the
U-t |M> ible re-lilts.
The proce- iriven to peas varies considerably in factory practice,
tin* h,we>t temperature being 230 F. for from twenty-five to thirty
minute.-. The rule, however, is to accept 240 F. as the proper
temperature and to vary the time from twenty-five to forty minutes.
There are a few who use the short period, but most packers consider
26 THE CANMNO OF PEAS.
it unsafe. The majority are processing from thirty to thirty- five
minutes for jreshly thrashed, tender peas ; .from thirty-five to forty
minutes for peas allowed to stand overnight in the vines, and forty-
iive minutes at 245 for very old hard peas. As peas are unlike corn
and pastv products, and the heat penetrates easily and quickly, it
would seem as though these periods give a large margin of safety.
The writer processed good peas for ten minutes and for fifteen
minutes at 240 for the purpose of getting spoilage, but got none.
Poor peas were processed at 240 for twenty, twenty-five, thirty,
thirty-five, fifty, and fifty-five minutes with a like result. Although
the-e experiments in getting spoilage gave only negative results, no
t;: toi v is advised to use such a short process.
There was an incidental factor brought out in these experiments
which is of some importance to the canners ; that is, the effect of length
<>t' process upon the liquor content of a can. The peas used in this
experiment were of rather poor grade, hard, and starchy, but not
worse than may be seen in thousands of cans of standard peas upon
the market. The effect of long processing is to cause a gradual de-
crease in the amount of free liquor in the can and to cause the peas
to become sticky and adherent. This effect is shown in the following
table :
Effect of rnridtioii in time of itrorntxinu on llqunr content of ctin.
Grams of liquor in cans proressi'd for
Grade of peas.
20
25
30
3o
50
66
minutes.
minutes.
minutes.
minutes.
minutes.
minutes.
Marrowfat . .
i
215
21
1QQ
165
70
165
140
12fi
11C
I'.-tits {mis
ITO
1 Tfl
The peas were sufficiently cooked in twenty-five minutes, and at
each succeeding step they became thicker and stickier. The contents
of the cans processed for fifty and fifty-five minutes adhered so
closely that only part would fall from the inverted can. The time
given to processing should be sufficient only to sterilize, and the
processor should use judgment in every case, giving the shortest time
which will be safe and cause the least injury to the goods. The bet-
ter grade of peas will suffer less injury from long or high process
than the poorer grades.
There is some controversy among pea packers as to the best form
of heat for obtaining the most attractive product. Some process in
dry steam, some in water given the desired temperature, and others
in the calcium bath. The advocates of the water process claim that
they secure a clearer liquor and a brighter can. Experiments were
made to determine this point, but it was impossible to distinguish
cans processed in dry steam slowly heated in the retort from those
i:\AMINATlON ol COMMERCIAL CANNED PEAS. 27
proce-.-ed in water. Can- heated gradually that is, by turning the
-team on -lowly -o that it required ten minutes to heat the retort
ha vi- a dearer liquor than when the steam is turned on suddenly at
full pressure The very quick heating injures the peas in contact
with the can and al-o causes a hlackening inside of the can. As the
Calcium system i> maintained at a high heat, the effect upon the peas
i- more like that of the quick, dry .-team than of the water process.
Sterili/atinn can he accomplished with equal certainty by any one
of the three method-, the choice depending upon the relative economy
and the ellect Upon the goods.
l.!\<. Till I IN IMI1 I) I'KolM OT,
-hould be well . -ooled a- -non a- the process is completed.
Merili/atioii i- accomplished by a certain degree of heat applied for
.1 irm-n time. Kai-mg or prolonging the temperature beyond that
060668*1*3 for Men li/.at ion doe- no more in preventing spoilage, but
dOQfl break do\\n th.- pe i eater or le degree and injures their
appearance in the can. The pea-, therefore, should be cooled at
nnce to a fairly low temperature in order to get the best results. A
companion ,,f the conient- of half a do/en well cooled cans with a
like number not c..o|ed will demonstrate conclusively the inferiority
of the latti-r.
There ire -ome packer-, who turn water into the retort as soon as
the -team i- turned oil. and thus get the be.-t results, but at a large
If the j.ea- be lifted nut of the retort and placed at once in the
cooling tank or under a >prinkler. the cost of cooling will be much
lo\\er and the re-ult- nearly a- good. It is desirable that the peas
should be cooled to loo or lower if practicable. If the cans are only
-lightly cooled and are built up in large, solid stacks, those in the
center will hold their heat for week-, if the cans are not well cooled
they -hoiild be placed in rick-, with .-pace- between to facilitate cool-
ing. ()!;.- ,{' the d.^irable re.-ult- of quick cooling is that the leaks
arc found more quickly. The condensing of (he steam causes a
\aciium pre ure of from < to 1-J pounds. When there are tip, seam,
<r cap leak-, the tendency will be to cause prompt suction of air and
infection of the good-. The -wells will occur in a few days and can
be removed promptly.
EXAMINATION OF COMMERCIAL CANNED PEAS.
I'-M- were purcha-ed from 15 groceries, representing 135 brands,
1*J.~ of which were of domestic production and 10 were imported.
With the exception of 5 brands, the domestic peas were put up in
standard No. _' can-. The average weight of a can of peas was found
to be :.. -ram- ( -J.V2 ounces) ; the can, 103 grams (3.66 ounces) ; the
p-a-. after the liquor was allowed to drain through a sieve for one
minute. .'JlU <rrams (14 ounces), and the liquor. 208 grams (7.5
28 THE CANNING OF PEAS.
ounces). The variation in the total weight was between 650 and 735
grams; the can between !>:> and 110 grams; the peas between 301 and
005 grams ; and the liquor between and 300 grams.
In the experimental work it was determined that a well-filled can
should have 400 grams of peas ard 200 grams of liquor, and the
average for the commercial brands is essentially the same. When a
can contains less than 385 grams, it is usually a slack fill, unless it
contains marrowfat or telephone peas; if it contains more than 415
grams, the peas will be overcrowded or the liquor will be poor. If
ihe>e figures are accepted as a fair standard, 30 per cent of the cans
were >liort weight on fill of peas and 20 per cent contained an over-
weight of peas.
The peas were graded for size by shaking them through sieves con-
taining >tamlard-sized holes; 74 per cent were found to be true to
the label; 17.3 per cent were found to be larger than represented; and
8.7 per cent were smaller than was claimed.
The peas were also tested for quality by suspending a sample in
a salt solution having a specific gravity of 1.075. Peas of known
quality before being canned were used as a standard, and it was found
that first-class tender peas would float in such a solution, while the
poorei, hard peas would sink. Assuming such a test to be fair for
quality, it was found that 53 per cent were true to the label; 41.7 per-
cent below the grade claimed; and 5.3 per cent above the grade
claimed.
These figures are not at all surprising. The high-grade and higher-
priced goods are usually what they purport to be, or better, and the
poor goods are offered as being of a high quality. Peas which are
manifestly too poor to be sold as coming from a factory without im-
pairing its reputation are sold under other guises, but with labels
claiming high quality. " Telephone " and "marrowfat" peas are
generally sold as " early June " peas. From 8 to 16 per cent of the
pack consist of these large peas, but they are seldom found on the
grocer's shelves. In the high-class peas the " sifted *' peas are sold
a> "early June" and the "extra sifted" as "sifted" peas. The
lack of uniform grading and the use of individual names accounts in
some measure for the present condition in the trade. The fact that
no method of grading peas for quality at the factory has come into
general use also explains in a measure the lack of a standard for the
canned article. This condition will probably change within the next
fevr year>. The nutritive property of the peas, whether of one size
or another, or one degree of tenderness or another of hardness, is not
brought into question; but trade and custom have established that
young tender peas of a certain size should be so designated, and that
the inferior, hard, overripe article should not be confused with them.
A comparison of the peas packed in 1908 though a poor year
with peas of the same brand of previous years shows a marked im-
SPOILAGE. 29
provement in the latest pack. A comparison of the domestic pack
with thr foreign brands of the same grade and price is decidedly in
fa\or of the home-grown in evenness of size, tenderness, and flavor.
The foreign pea i- of a brighter green color, due to using a copper
>alt. Tin- foreign peas are also misbranded in some cases as to size
and quality.
SPOILAGE.
The -poilaire in canned peas may bo classified under three heads:
( 1 ) That due to Irak- in the can; (2) to insufficient processing; and
to -poila.ire prior to the canning.
The spoilage due to leak- i- largely a matter of carelessness in in-
-peetiun. The manufacturers of can- allow two cans per thousand
for defect- in material or imperfect union on the side, top, or bottom
Tin- appear- to be an ample allowance, as some of the
larjj '.tries tind less than one "spoil" per thousand due to
-uch caii-e-. Tip leak- and cap leak- are much more common than
end oi- -ide leak-, t liese being due to incompetent workers and lax
in-peetion. ( 'ap ami tip leak- become mo-t numerous when long runs
made and the workmen become tired. When night runs are made,
the greater number of leak- are found to occur in cans handled in the
early morning.
Leak- max be found later in good- kept in a damp warehouse. The
tin may be more or teeB broken where the bend is made on the ends,
and an e\ce of moi-tmv may caii-e it to rust through along the
edge-. The HIM ing may be very -low. but it will gradually affect a
considerable pen vntage of can-. Spoilage due to leaks usually occurs
early much of it within twenty-four hours and, as a rule, there
T6 -e\eral form- of bacteria pre-eut. among which there are nearly
alway- some that will cau.-e -welling. A leak may not be apparent
without a careful in-pection: the hole may be so small as to be
plugged by a piece of ti ue. or the swelling of the can may produce
-uch a -train a- to prevent the escape of gas or contents. By cutting
the can and tearing the -earns, the points at which the solder failed to
may be detected.
- spoiled owing to insufficient processing are generally classed
U " -\\ell-" and "sour-." Formerly spoilage of this character was
a -erioii- matter, but the discovery of the cause'and the means of
prevention ha- decrea-ed the loss from this source. At first No. 2
can- were boiled in open kettles from one to three hours, and the
losses wen- not considered large, although the percentage would prob-
ably be considered high at this time. Later the processing was done
in a retort at a higher temperature than that of boiling water, in
order to reduce the time. The practice at many of the factories was
to give a temperature, of 230 F. for from ten to fifteen minutes. Swells
and -our peas resulted, and the cause was not understood. In 1895
30 THE CANNING OF PEAS.
Russell investigated the cau^e of swells in peas and, finding them
to be due to-bacterial infection as a result -of insufficient processing,
he recommended that the process be changed from ten and eleven
minutes at 230 F. to fifteen minutes at 242 F. The losses from
-\vells at this higher temperature were very small, and consequently
this temperature was recommended to the Wisconsin packers.
In 1896 Prescott and Underwood b began the study of swelled and
sour corn and later turned their attention to sour peas. In February.
1901, they presented a paper before the American Canners' Associa-
tion on the cause of sour peas, and from their experiments determined
that the cause was underprocessing. As a result of these investiga-
tions, the} r recommended a process at 240 F. for thirty-five minutes
or 236 F. for forty minutes. The experiments reported at that time
became the basis of the process for a very large part of the pea
canning.
Harding and Xicholson, c of the Xew York experiment station,
studied the swelling of peas, and gave a detailed description of the
organism to which it was ascribed. The} 1 found that a process at
240 F. for thirty minutes was effective in preventing swells, and
made such a recommendation for the prevention of losses. Other
writers have advocated a longer process at this temperature or a
higher temperature in order to prevent spoilage, and many factories
have adopted a heavier process some to the extent of greatly over-
cooking their goods.
The writer processed a series of experimental goods for the purpose
of studying the various forms of spoilage, but with negative results.
All cans processed for fifteen minutes cr more at 240 F. were sterile,
and those processed at a lower temperature and for a shorter time
usually had a mixed infection. The resulting spoilage was so much
less than that given by other writers and generally found in practice
that it would seem unwise to make recommendations based upon one
year's work.
The spoilage occurring before the peas enter the can is due to allow-
ing them to stand in piles, on the wagons or after thrashing, until
they heat and start fermentation. If the peas are kept moving from
the vine to. the can, the spoilage from this source is very small. If
hulled and thoroughly washed in cold water at short periods, they
may be kept for some time without appreciable spoilage. Peas held
on the vines longer than they should be, through accidents or over-
crowding, will not deteriorate to such an extent as to become unfit
for use if the vines are kept loose and the peas are well washed as
soon as hulled. The pods may become wet and even sticky before the
" Wisconsin Agr. E.\i>. Sta. Rep., 1895, pp. 227-231.
1 Prescott, S. C., and Underwood. L. M., Technology Quarterly, 1898, 11 : <>.
c New York Agr. Exper. Sta., Geneva, 1903, Bui. 249.
SPOILAGE. 31
peas sour. Thorough washing :m d extra blanching are necessary, and
if properly conducted no change in acidity or in other characteristics
will he apparent, save a -lightly cloudier liquor. Such peas lose some
of their natural sweetness, becau>e the .-ugar undergoes a change while
.-landing: they an- not, therefore lir.-t grade, but neither are they
^pniled or unfit for u-e if rightly handled.
The nerd for prompt handling of the peas after they have been cut
i-> >ho\vn in tin- change in the pea, as well as in the infection which
caii-e- -poilagc. Tin- experiment- made to determine these points
were conducted when the weather \\a- fairly cool and favorable to
tin- miming of pea-, and do not repre-ent either extreme. A quantity
of vine> equivalent to one- fourth of a wagon load was piled and
allowed to -tand for :','. hour-, -ample- Ixjing taken at intervals and
.-aimed without the addition of -alt or sugar. A quantity of shelled
pea- ua- al.-o allotted to -land, -anipled at intervals, and canned
U in the prerediiii: , ;,.,.. Tflstfl were then made to determine the rela-
iirar content, ttith the fnllnxvinir results:
Kff- ' ' li-ttinii IH-HM xhtml 1,'fnn
mining.
Per cent
of siiKur.
//
Aftrr nitlii:
h:
-,
i
{o
2.19
1.66
1.24
.90
2-1
Tin- p<-a- taken fmm the vine- at different times showed no constant
change in the -ugar content. Tin* vines soured slightly, but the ap-
pea ranee of the pea- remained unchanged. An increase in the cloudi-
neflfi of the !i|uor wa- ol-,-rved asthe time after cutting was prolonged.
The -helled pea- -ho\\ a gradual and continuous decrease in the
-uirar content a- the time increa.-ed. Those -landing for eighteen
hour> were -lightly -ourel. \\hile those standing for twenty-four
hour- were de<-ide(lly -our. The.-e experiments, though planned
with -pecial reference to -tudie- in spoilage, show the necessity for
prompt handling t<> in-ure the highest grade product. One of the
effect- of -landing is to cause the peas of the first grade to change
so as to deteriorate to second or even third grade. This is demon-
-t rated both l>y the specific gravity test and by the swelling after
blanching and processing.
The experiments to determine the influence of delay between the
time of cutting the peas and canning them showed so much less effect
than i- irrnerally a umed in factory practice that the work should
be repeated under less favorable conditions before drawing general
32
THE CANNING OF PEAS.
BY-PRODUCTS.
The pea vines are a waste or by-product at many factories. Some
pay to have them taken away, some pile them up to rot for fertilizers,
some dump them upon the land, others make them into silage, and
still others convert them into hay. In general the value of the pea
vine for food is only slightly appreciated. The silage can be made
cither in the silo or by piling in a large stack and rolling well. The
latter method is economical, as the expense of a special building is
obviated and, if well done, the losses upon the sides and top are not
great. Analyses made by W. J. Jones, jr., Indiana state chemist,
on stacked pea-vine and sweet-corn silage gave the following results :
1 //r////.vr.v of jicu-rhic rt/?/7 xwcct-coni x
Determinations.
Pea-vine silage.
Sweet-corn silage.
Moist
sample.
basfs.
Moist
sample.
Dry
basis.
M .Mure at 100 C -
Per cent. Per cent.
77.49
Percent.
81.621
Percent.
Crude protein
3.566
.839
6.556
8. 70S
2.582
16.027
3.777
29.466
39. 134
11.602
1.507
.334
5.665
9.865
1.011
8.214
1.816
30.822
53.658
5. 503
Ether extract (crude fat)
Crude fiber
\itrogeu-free extract
i^h
These samples were taken in May from stack silage which had
been put up the previous year. A comparison of the analysis of the
pea-vine silage with that of the sweet corn shows the former to be
much the richer in protein. A comparison with regular corn silage
is also favorable to the pea silage. If $2.50 a ton is accepted as
the value of regular corn silage, the pea-vine product should be worth
more. A sample of good pea-vine hay was also analyzed and gave a
value between that of clover and timothy. Stock relish both the
silage and the hay.
of itrn-rinr ///.
Determination.
Moist sam-
ple.
Calculated
a* dry
matter.
Determination.
Moist sam-
pie.
Calculated
as drv
matter.
Moisture
7.120
Per cent.
Fat
Per cent.
1 7^0
Per cent.
1 852
Crude protein
9 760
10 50)
Fiber
23 290
>-, (jy.j
Nitrogen-free extract
51.304
55.239
Ash
6 800
7 _'2r>
These analyses indicate that the by-product has a food value too
great to be ignored, and that an effort should be made to transport
the vines to the factory in good condition in order to get the best re-
sults from them.
14 DAY USE
RETURN TO DESK FROM WHICH BORROWED
] LOAN DEPT.
This book is due on the last date stamped below, or
on the date to which renewed.
Renewed books are subject to immediate recall.
14 DAY USE
RETURN TO DESK FROM WHICH BORROWED
LOAN DEPT. 1
RENEWALS ONLY TEL. NO. 642-3405
This book is due on the last date stamped below, or
on the date to which renewed.
Renewed books are subject to immediate recall.
J/W 2 1 70
fft
HtTURNE
\QV27
DEC 3 1996
CIRCULATION DEPT.
LD21A-60m-6,'69
(J9096slO)476-A-32
General Library
University of California
Berkeley
YD I82V5
U. C. BERKELEY LIBRARIES
\*
