Dehydration of Canadian Fruits
By
F. E. ATKINSON
Dominion Experimental Station
Summerland, B.C.
DOMINION EXPERIMENTAL FARMS
E. S. ARCHIBALD, B.A., B.S.A., LL.D., D.Sc, Director
I*!
Agriculture Canadian Agriculture Library
Canada Bibliotheque canadienne de I'agriculture
Ottawa K1 A 0C5
DOMINION OF CANADA
DEPARTMENT OF AGRICULTURE
BULLETIN No. 151— NEW SERIES
630.4
C212
B 151
U.S.
1931
c. 3
Published by direction of the Hon. Robert Weir, Minister of Agriculture,
Ottawa, 1931
d
PERSONNEL
Director, E. S. Archibald, B.A., B.S.A., LL.D., D.Sc.
Dominion Field Husbandman E. S. Hopkins, B.S.A., MJS.
Dominion Chemist Frank T. Shutt, M.A., D.Sc.
Dominion Horticulturist W. T. Macoun, DJ3c.
Dominion Cerealist L. H. Newman, BJ3.A.
Dominion Botanist H. T. Giissow, LL.D.
Dominion Animal Husbandman
Dominion Forage Crop Specialist
Dominion Poultry Husbandman F. C. Elford.
Chief, Tobacco Division N. T. Nelson, B.S.A., MJ3.,
Ph.D.
Dominion Apiarist C. B. Gooderham, BJ3 A.
Dominion Bacteriologist Grant Lochhead, Ph JD.
Chief, Division of Extension and Publicity F. C. Nunnick, B.S.A.
Chief Supervisor of Illustration Stations J. C. Moynan, B.S.A.
Economic Fibre Specialist R. J. Hutchinson.
ALBERTA
Superintendent, Experimental Station, Lacombe, Alta., F. H. Reed, B.S.A.
Superintendent, Experimental Station, Lethbridge, Alta., W. H. Fairfield, M.Sc, LL.D.
Superintendent, Experimental Sub-station, Beaverlodge, Alta., W. D. Albright.
Superintendent, Experimental Substation, Fort Vermilion, Alta., Robt. Jones.
BRITISH COLUMBIA
Superintendent, Experimental Farm, Agassiz, B.C., W. H. Hicks, B.S.A.
Superintendent, Experimental Station, Summerland, B.C., W. T. Turner, B.S.A.
Superintendent, Experimental Station, Invermere, B.C., R. G. Newton, B.S.A.
Superintendent, Experimental Station, Sidney, B.C., E. M. Straight, B.S.A.
MANITOBA
Superintendent, Experimental Farm, Brandon, Man., M. J. Tinline, B.SA.
Superintendent, Experimental Station, Morden, Man., W. R. Leslie, B.S.A.
SASKATCHEWAN
Superintendent, Experimental Farm, Indian Head, Sask., W. H. Gibson, B.S.A.
Superintendent, Experimental Station, Rosthern, Sask., W. A. Munro, B.A., BJ3.A
Superintendent, Experimental Station, Scott, Sask., G. D. Matthews, B.S.A.
Superintendent, Experimental Station, Swift Current, Sask., J. G. Taggart, B.S.A.
NEW BRUNSWICK
Superintendent, Experimental Station, Fredericton, N.B., C. F. Bailey, B.S.A.
NOVA SCOTIA
Superintendent, Experimental Farm, Nappan, NJ3., W. W. Baird, B.S.A.
Superintendent, Experimental Station, Kemtville, N.S., W. S. Blair, D.Sc.
PRINCE EDWARD ISLAND
Superintendent, Experimental Station, Charlottetown, P.E.I., J. A. Clark, B.S.A., D.Sc
ONTARIO
Central Experimental Farm, Ottawa, Ont.
Superintendent, Experimental Station, Kapuskasing, Ont., S. Ballantyne.
Superintendent, Experimental Station, Harrow, Omt., H. F. Murwin, B.S.A.
QUEBEC
Superintendent, Experimental Station, Cap Rouge, Que., G. A. Langelier, D.ScA.
Superintendent, Experimental Station, Lennoxville, Que., J. A. McClary.
Superintendent, Experimental Station, Ste. Anne de la Pocatiere, Que., J. A. Ste. Marie, B.S.A.
Superintendent, Experimental Station, La Ferme, Que., P. Fortier, Agr.
Superintendent, Experimental Station, Farnham, Que., R. Bordeleau, BS.A.
Superintendent, Experimental Station, L'Assomption, Que., J. E. Montreuil, B.S.A.
TABLE OF CONTENTS
Page
Introduction 3
Quality of fruits for dehydration 3
Size 3
Maturity 5
Apricots 5
Prunes 5
Loganberries 5
Condition 5
Principles of dehydration 5
Dehydration of apples 5
Opportunities for dehydrating apples in Canada 5
Quality must be improved 6
Washing of apples 6
Grading 6
Paring machines 6
Traying and sulphuring 6
Operation of dehydrating 6
Curing 7
Grades of dehydrated apples 7
Apple dehydration projects in progress 9
Dehydrating domestic and C Grade cookers for export 9
Cost of marketing domestic or C Grade cookers 9
Cost of marketing 100 pounds of C Grade British Columbia cookers on the British
market 9
Cost of dehydrating 100 pounds of C Grade British Columbia apples and delivering
same on British market 10
Transportation costs of dehydrated versus canned apples 10
Dehydrated versus evaporated apples 11
Dehydration of prunes 11
Lye dipping 11
Operations in dehydration of prunes 11
Curing and packing 12
Prune dehydration projects in progress 12
Variety tests 12
Dehydration of apricots 12
Cutting 12
Traying 13
Sulphur chambers 13
Sulphuring 13
Operations in dehydration of apricots 13
Processing 13
Apricots, dehydration and sun drying 13
Experiments in progress 13
Minimum sulphur for dehydrated apricots 14
Sun drying for colour 14
Costs of production 14
Dehydration of peaches 14
Principles of dehydrator construction 16
Materials 17
Temperature control apparatus 19
Dehydration equipment 19
Plant arrangement 20
Dominion of Canada
DEPARTMENT OF AGRICULTURE
Bulletin No. 151 — New Sehies
29475—1
Digitized by the Internet Archive
in 2013
http://archive.org/details/dehydrationofcan151atki
DEHYDRATION OF CANADIAN FRUITS
The immensity of the Canadian market for dehydrated fruits may bo
emphasized by the fact that for the three fiscal years ending March, 1929, the
average annual importation of dried fruit amounted to 88,798,477 pounds1.
The f.o.b. shipping point cost of this fruit plus duty was $7,394,895. Over a
fifth of this amount or $1,514,012 was paid for dried prunes and apricots, two
fruits that are being grown in the Dominion. The Dehydration Committee2
has carried on experiments to determine the suitability of the varieties of these
fruits grown in Canada for dehydration as well as extensive experiments with
dehydrated apples. The results of these experiments together with outlines of
commercial processes are given in this bulletin. The dehydration investigation
has been carried on in a commercial plant at Grimsby, Ont., and in a semi-
commercial plant originally located in Penticton, B.C., but now under the
supervision of the Dominion Experimental Station, Summerland, B.C. Smaller
experimental dehydrators have also been built at the Experimental Station at
Saanichton, B.C., at the Central Experimental Farm, Ottawa, and at Kent-
ville, N.S.
QUALITY OF FRUIT FOR DEHYDRATION
It is regrettable that growers in general feel that fruit which is worthless
for fresh fruit shipment is quite suitable for the manufacture of fruit products.
This is contrary to the actual situation and it is hoped that growers and ship-
pers will give this point more consideration than in the immediate past.
Size
As fruit intended for dehydration is usually cut in half, in sectors, or sliced,
it is quite imperative that it be of reasonable size in order to make a good appear-
ing product. Small fruit is an economic curse to dehydrators due to the higher
cost of preparation and the higher percentage of low-grade waste. These facts
are amply illustrated in the following tables, the figures of which were com-
piled from data obtained in the Government plant at Grimsby, Ontario, during
the 1929 season.
HOW SMALL SIZES INCREASE THE PERCENTAGE OF SKINS AND CORES
Variety
Greening
Greening
Greening
Baldwin.
Baldwin.
Baldwin.
Size
2§+
21-2*
2-2£
2*+
2|-2§
2-2£
Fresh
weight
lb.
40,366
41,558
28,870
28,843
38,643
19,547
Peeled
weight
lb.
24,854
23,418
15,618
18,420
20,969
10,502
Per cent
of fresh
weight
61-57
56-35
54-10
63-86
54-26
53-72
Dry
weight
lb.
5,057
5,130
3,760
3,866
4,878
2,522
Weight
of skins
and
lb.
11,115
14,624
11,052
8,839
12,675
7,518
Per cent
of fresh
weight
27-51
35-20
38-28
30-64
35 13
38-46
1 These figures were compiled from "Commerce of Canada" for the years ending March 31,
1927, 1928 and 1929.
2 The "Dehydration Committee" was appointed in May. 1923, and is as follows: —
E. S. Archibald, B.A., B.S.A., L.L.D., D.Sc, Director of Experimental Farms, Chairman.
Geo. E. Mcintosh, Dominion Fruit Commissioner, Vice-president.
C. S. McGillivray, Chief Canning Inspector. Fruit Branch, Secretary.
F. T. Shutt, M.A., D.Sc, F.I.C., Dominion Chemist.
W. T. Macoun, D.Sc, Dominion Horticulturist.
29475—2
Although the peeled weight percentage of the fresh weight does not decrease
appreciably between the 2 to 2^-inch and 2J to 2:i-inch sizes, yet the grades
for these sizes vary considerably. In the following table showing the grading
of the above lots the total absence of Fancy quality in the 2 to 2J-inch size is
directly due to size as outlined on page 8.
Horticultural building on the Dominion Experimental Station, Summerland, B.C.
Dehydration investigation is carried on in the left wing.
HOW SMALL SIZES LOWER THE GRADE
Variety
Size
Fancy
Choice
Standard
quality
Baldwin
in.
2\
24-2|
2-2£
2\
2I-2J
2-2*
%
100
100
%
%
Baldwin
Baldwin
100
Greening
100
100
Greening
Greening
94-93
507
The average dry weight percentage of the fresh weight was 12-55 per cent
for Greenings and 13-06 per cent for Baldwins. No outstanding differences in
yield were found with Russet, Spy, Cranberry Pippin and Blenheim.
HOW SMALL SIZES DOUBLE THE PEELING COST
An average ton of 2-inch apples contains 16, 318 fruits
21-inch " 13,035 "
2|-inch " 8,859 "
The same facts are relatively true in the case of prunes and apricots. An
average price for dried prunes of 30/40 classification, f.o.b. packing house, often
being three times that of 80/90's.
Maturity
Apples. — The most desirable dehydrated apples are made from fruit that
is in prime condition for eating. Accordingly this product when dehydrated
makes sauce or pies equal to that made from apples in autumn months. Apples
dehydrated when too green are quite astringent, and a disadvantage from the
standpoint of economy is the fact that immature fruit has a tremendous dry
away. Apples dehydrated when over mature are flat in taste and more likely to
contain rot.
Apricots. — Apricots for dehydrating are left on the tree until the latest
time when they can be picked, pitted and placed on the trays without mushing.
It is very desirable that full colour and flavour be developed in the fruit before
it is picked.
Prunes. — Wherever possible prunes are allowed to drop on the ground.
In the Okanagan Valley of British Columbia the fruit on odd trees begins to
drop towards the end of September, but the main crop does not commence to
drop freely until the early part of October. A good quality of dehydrated
prunes can be made only from fully mature fruit.
Loganberries. — Loganberries are picked sufficiently firm to enable them to
be hauled to the dehydrator, sorted, and trayed without mushing. Over-ripe
berries also bleed badly during the dehydrating with a resultant large loss of
juice. On the other hand care must be exercised to prevent the pickers from
harvesting the fruit too green as this dehydrates to a poor product and has a
much higher dry away.
Condition
It is wise to watch very closely for rots and other disease marks in fresh
fruit bought for dehydrating. A rigid inspection should be maintained to safe-
guard against such disorders appearing in the prepared product.
PRINCIPLES OF DEHYDRATION
The three factors in the process of dehydration are heat, recirculation and
humidity. The heat is required to activate the water contained in the fruit in
order to change it to a vapour form. The function of the recirculation of the
air is to carry this vapour away from 'the fruit, and as the air would eventually
become saturated with moisture, a small amount of dry air is taken into the
dehydrator while a like portion of moist air is given off. A definite humidity
for each fruit is maintained to prevent a rapid drying of the outer cells of the
skin with consequent "case hardening." If this condition occurs it is difficult
to extract the water from the fruit as there are no openings in the skin by which
it can escape. The speed of dehydrating depends on the relationship of these
factors to one another. For instance, high temperature with poor circulation
would not be better than a low temperature with high circulation. The need
of humidity will depend on the type of fruit being dehydrated.
DEHYDRATION OF APPLES
Opportunities for Dehydrating of Apples in Canada
Canada now supplies the home market for dried apples, and during years
of good crops exports nearly 2,000,000 pounds. On the other hand the United
States besides supplying their domestic market, have doubled their exports since
1922.2 In that year the United States exported 17,391,339 pounds of dried
1 Statistics in "Commerce of Canada" show an importation of dried apples from the United
States of from one to two million pounds annually. However, this is really apple pomace for
the jam plants, and sells for about three cents a pound.
2 These figures were compiled from "Foreign Commerce and Navigation of the United
States" for the years 1922-1928.
29475—2*
apples valued at $2,210,233. In 1928 they exported 35,068,394 pounds with a
value of $4,144,533. Canada produces thousands of tons of apples annually
that are unfit for fresh fruit shipment but suitable for dehydration.
Quality must be improved
Quantity rather than quality production has had its obvious effect on the
market for dehydrated apples. Although with modern equipment the dehydra-
tion of appleis can be very largely a mechanical process, careful personal inspec-
tion is still of first importance. The building of larger markets will be achieved,
to a large extent, through improvement in quality of .the produce. Machine
industry is quite desirable from the standpoint of economical and uniform pro-
duction, but when used in the preparation of fruit it must have adequate per-
sonal supervision.
Washing Fruit
In general, apples for dehydrating are not washed before being treated
although this is a very desirable practice. Where washing is included it m the
first operation in the preparation.
Grading
From the wTasher the applies are conveyed to the grader where they are
graded into lots according to their diameter. Apples smaller than 2 inches in
diameter are either made into chop or returned to the grower. The sizes of 2
to 2J inches, 2\ to 2J inches, etc., are conveyed to peelers.
Paring Machines
Several types of paring machines are on the market, which peel, core and
cut the apple into sectors. These then pass on an inspection belt before a row
of women who pick off culls or pieces which need additional workmanship.
Besides the machine mentioned above, there are many simpler types which pare,
core and slice, or do a part of these tasks.
Modern plants are also equipped with "seed cellers" to remove the last
fragments of the core. This operation is done after the apples are peeled and
cored and before they are cut.
Traying and Sulphuring
The peeled and cored fruit is spread on trays at the rate of about 2 pounds
to the square foot. The loaded trays are placed on a small car, on which they
may be easily transported, and when a full carload is prepared, the car and fruit
is placed in a sulphur chamber. Here the fruit is exposed to sulphur fumes for
20 to 35 minutes. In small plants where the preparation is slow and where
browning may be excessive, the fruit is sometimes dipped in a dilute salt solution
(2 to 5 per cent). If this practice is followed the sulphuring period may be
reduced to 15 or 20 minutes. Apples are often sliced before sulphuring but the
former method is gaining in popularity.
Operation of Dehydrating
Upon removal from the sulphur chamber, the car and its load is placed in
the cooler end of the dehydrator. Here the temperature will approximate 125°
to 130° F. with a relative humidity of 5 to 10 per cent. In the hot end of the
tunnel the temperature will be about 30 degrees higher. The car of prepared
fruit progresses through the tunnel, the actual time for the dehydrating varying
with the type and efficiency of the dehydrator. Although the "Meat and Canned
Foods Act" allows a moisture content of 25 per cent, it has been found through
experiments at Grimsby that 22-5 per cent moisture is a safer content to dry
to as the remaining 2-5 per cent may be considered as a surety to prevent exceed-
ing the tolerance. There is also the ever present possibility of shrinkage where
the moisture content is high, resulting in complaints from the trade.
Curing
After the fruit has been removed from the dehydrator and has cooled, it is
dumped from the trays into curing bins. These are often arranged so that the
fruit can be mechanically turned every second day for six days by having several
floors (one above the other) on hinges. During a "turning" the fruit falls from
one floor to the next. The fruit is moved in this manner, or turned with a shovel,
to prevent heating and consequent spoilage. By turning the fruit, the curing
is encouraged which results in all pieces being of equal moisture content.
Pease apple paring machine.
Grade*
The requirements of the various grades of dehvdrated apples, as outlined in
" The Meat and Canned Foods Act," 1929, pages 29, 30 and 31, are as fol-
lows:—
'•' Fancy Quality Dehydrated Apples " (slices and rings) shall be packed from sound,
firm ripe apples not less than 2\ inches in diameter which have been properly peeled, cored
and trimmed, and when prepared, are free from worm holes, scab, etc. The finished stock
shall be 90 per cent whole rings, 90 per cent free of pieces of skin and core, 70 per cent
uniform in size and not more than 5 per cent shall pass through a screen 1-inch square
openings. The colour of the product shall be as white as the natural colour of the fruit
8
used in the manufacture and shall not vary more than 10 per cent. Only one variety of
apples shall be used in this grade and the name of that variety shall be shown on the label,
carton, container or other lithograph design in type reasonably proportionate to the size of
the other printing on the label, etc., but in no instance shall it be less than f of an inch
in height. No smoke odour or other defects will be permitted.
" Choice Quality 'Dehydrated Apples " (slices and rings) shall be packed from sound,
firm, ripe apples not less than 2 inches in diameter which have been properly peeled, cored
and trimmed, and when prepared, are free from worm holes, scab, etc. The finished stock
shall be 80 per cent whole rings, 80 per cent free of pieces of skin and core, reasonably
uniform in size and not more than 5 per cent shall pass through a screen f inch square
openings. The colour of the product shall be as white as the natural colour of the fruit used
in the manufacture, and shall not vary more than 20 per cent. Only apples of similar varieties
shall be used in this grade and the name of that variety shall be shown on the label, carton,
container or other lithograph design in type reasonably proportionate to the size of the other
printing on the label, etc., but in no instance shall it be less than | of an inch in height. No
smoke odour or other defects will be permitted.
" Standard Quality Dehydrated Apples " (slices and rings) shall be packed from sound,
firm, ripe apples which have been properly peeled, cored and trimmed, and when prepared
are free from worm holes, scab, etc. The finished stock shall be 60 per cent whole rings,
70 per cent free of pieces of skin and core, reasonably uniform in size and not more than
10 per cent shall pass through a screen i inch square openings. The colour of the product
shall be as white as the natural colour of the fruit used in the manufacture and shall not
vary more than 50 per cent. No smoke odour or other defects will be permitted.
" Second Quality Dehydrated Apples " (slices and rings) may be packed from apples
from which all decomposed, bruised or other objectionable portions have been removed. The
fruit shall be properly peeled, cored and trimmed but need not necessarily be uniform in
size, colour or variety. The slices shall be 50 per cent free from skin or core and not more
than 5 per cent shall pass through a screen I inch square openings.
" Fancy Quality Dehydrated Apples " (quarters, sixths and eighths) shall be packed
from sound, firm, ripe apples not less than 21 inches in diameter, which have been properly
peeled, cored and trimmed, and when prepared, are free from worm holes, scab, etc. The
finished stock shall be 90 per cent free of pieces of skin and core, 80 per cent uniform in
size and not more than 5 per cent shall pass through a screen |- inch square openings. The
colour of the product shall be as white as the natural colour of the fruit used in the manu-
facture and shall not vary more than 10 per cent. Only one variety of apples shall be used
in this grade and the name of that variety shall be shown on the label, carton, container
or other lithograph design in type reasonably proportionate to the size of the other printing
on the label, etc., but in no instance shall it be less than f of an inch in height. No smoke
odour or other defects will be permitted.
" Choice Quality Dehydrated Apples " (quarters, sixths and eighths) shall be packed
from sound, firm, ripe apples not less than 2 inches in diameter which have been properly
peeled, cored and trimmed, and when prepared are free from worm holes, scab, etc. The
finished stock shall be 80 per cent of pieces of skin and core, 70 per cent uniform in size and
not more than 10 per cent shall pass through a screen i inch square openings. The colour
of the product shall be as white as the natural colour of the fruit used in the manufacture
and shall not vary more than 20 per cent. Only apples of similar varieties shall be used in
this grade and the name of that variety shall be shown on the label, carton, container or
other lithograph design in type reasonably proportionate to the size of the other printing
on the label, etc., but in no instance shall it be less than -f of an inch in height. No smoke
odour or other defects will be permitted.
" Standard Quality Dehydrated Apples " (quarters, sixths and eighths) shall be packed
from sound, firm, ripe apples, which have been properly peeled, cored and trimmed, and
when prepared are free from worm holes, scab, etc. The finished stock shall be 70 per cent
free of pieces of skin and core, reasonably uniform in size and not more than 20 per cent
shall pass through a screen i inch square openings. The colour of the product shall be as
white as the natural colour of the fruit used in the manufacture and shall not vary more
than 50 per cent. No smoke odour or other defects will be permitted.
" Second Quality Dehydrated Apples " (quarters, sixths and eighths) may be packed
from apples from which all decomposed, bruised or other objectionable portions have been
removed. The fruit shall be properly peeled, cored and trimmed, but need not necessarily
be uniform in size, colour or variety. The pieces shall be 50 per cent free from skin or core
and not more than 50 per cent shall pass through a screen i inch square openings.
Note: In the foregoing definitions the term " White as the natural colour of the fruit
used " shall not be deemed to apply to unbleached quarters, sixths and eighths.
APPLE DEHYDRATION PROJECTS IN PROGRESS
Dehydrating Domestic and C Grade Cookers for Export
Besides endeavouring to utilize the actual cull apples, the Dehydration
Committee has been experimenting with a product made from fruit that would
normally be shipped as " Domestic " or C grade cookers. One hundred and
twenty-three tons were dehydrated in the Grimsby plant during the 1929 sea-
son. In the preparation, this fruit was peeled, cored and cut into longitudinal
sectors. These sectors were then placed on trays, sulphured and dehydrated.
The advantages of processing this grade of cooking apples in this man-
ner for the domestic or export market may be outlined as follows: —
1. The cost of transportation is reduced approximately seven-eighths.
2. The apples have the same nutritive value during spring months as in
fall when dehydrated.
3. Packing and storage costs are reduced.
4. Only the flesh of the apple is transported.
5. The peeling, slicing and coring is done by machinery before dehydrating,
and is much cheaper than the hand operations of the bakery.
6. The product can be stored for a much longer period than the fresh fruit.
7. It is very easily refreshened and made ready for use.
8. The sectors give the body of the pie the same appearance as that made
from fresh fruit.
9. The quality of the dehydrated apple is not materially damaged by
rough handling in transit.
These facts from the cost standpoint are explained in detail in the ensuing
paragraphs.
Cost of Marketing Domestic or C Grade Cooking Apples
The cost of marketing apples of Eastern and Western Canada varies con-
siderably due to the different methods of packing. The situation in Eastern
Canada where apples are barreled in the orchard is quite different from the
procedure in British Columbia where the apples are hauled to central plants
for grading, packing and shipping. As a consequence, two tables of costs are
provided, dealing with the eastern and western conditions respectively.
COST OF MARKETING 100 POUNDS OF DOMESTIC GRADE ONTARIO APPLES ON THE
BRITISH MARKET
$
Picking 0 14
Cost of barrel 0 54
Packing 0 25
Cost of transportation and selling charges in England 1 43
Hauling and storage 0 07
Total 2 43
Average cost per pound 0 • 0243
'COST OF MARKETING 100 POUNDS OF C GRADE BRITISH COLUMBIA COOKERS ON
THE BRITISH MARKET
Per box
$ 41 pounds
Cost of picking
Cost of hauling out of orchard
Cost of hauling to packing house
Packing charges
(shook, making of box, packing, etc.)
Transportation charges
Marketing charges
Storage
Total Cost.
Average cost per pound .
0073
0 03
0-024
0 01
0-049
0 02
0-975
0 40
2-80
1 15
017
0 07
0-146. ..
0 06
4-237
1 74
0042
0042
1 Figures from Dominion Fruit Branch. Ottawa.
2 Average cost figures as compiled by the Penticton Co-operative Growers, Penticton, B.C.
10
Rather than packing C grade cookers and shipping them fresh, experiments
have shown that it is a more logical practice to separate them when packing
the higher grades, and to dehydrate the " Domestic " or C grade. Charges on
British Columbia C grade fruit for dehydrating, therefore, include hauling
charges to the packing house.
COSTS OF DEHYDRATING 100 POUNDS OF C GRADE BRITISH COLUMBIA APPLES
AND DELIVERING SAME ON BRITISH MARKET
cts.
Cost of picking 7-3
Cost of hauling from orchard 2-4
Cost of hauling to central packing house 4-9
Piece work 16-0
Day work 14-0
Power (for fan) 2-0
Fuel 2-64
Overhead 22-0
Cost of case 6-25
Packing, insurance and strapping 1-75
Transportation 17-50
Marketing 2-0
Total 98-74
The yield of dehydrated apples from a hundred pounds of fresh fruit will
approximate 12-?- pounds, giving an average cost of 7-9 cents per dried pound.
As a pound of dehydrated apples is equal to approximately eight pounds
of fresh apples, the cost of a pound of actual apple flesh from British Columbia
landed in England is one cent, and the cost of the same amount from Ontario
is still lower.
With dehydrated apples, costs of preparation should be taken into con-
sideration as the baker is relieved of this charge. Accordingly, an English
baker could afford to pay a little more per pound for a proportional weight
of dehydrated apples, as his own preparation costs are reduced.
In the spring months the dehydrated apple is a superior product as it is
of the same quality as when dehydrated in the autumn, while the fresh apple
is past its prime.
Transportation Costs of Dehydrated versus Canned Apples
A comparison of dehydrated and canned apples logically centers on costs
per unit of delivering the respective products on the market. In the " Meat
and Canned Foods Act " of 1929 the minimum weight of apples packed in
water required per number 10 can is 64 ounces, and a minimum net weight of
all contents of 94 ounces. The 64 ounces of apple, if dehydrated would yield
approximately 15-19 ounces and with its carton would not weigh more than
J 7 or 18 ounces. The total weight of the same amount of fruit canned plus
the can is nearly 7 pounds. In addition to the transportation charges on the
canned fruit, the cost of the can is practically one cent per pound of contents
while the cost of the cartons for the dehydrated fruit (if purchased in similar
volume to the can purchases) would be from one and a half to two and a half
cents a pound of dehydrated product. Cellophane packages will cut this down
to one cent a dehydrated pound. The cost of wooden or fibre cases for the
canned goods is almost nine times the cost of cases for the dehydrated fruit,
The weight differential on a case of canned apples as compared with a case of
dehydrated is explained as follows: —
Canned Apples —
1 case weighing approximately 50 pounds, of 6 No. 10 cans contains
6 x 64 = 384 ounces prepared apple.
11
Dehydrated Apples —
1 case weighing approximately 50 pounds, contains 211 pounds prepared
fruit or 3,376 ounces.
3376 -f- 384 = 8-7
One 50-pound case of dehydrated apples thus holds the actual fruit con-
tained in nearly nine cases of canned apples.
Dehydrated versus Evaporated Apples
Dehydrated apples are often confused with evaporated fruit. It must be
borne in mind, however, that dehydrated apples are made under absolutely
sanitary conditions, the actual process of dehydrating being a sterilizing agent,
and also that the excess water is removed in five or six hours while the evapor-
ated apple is only slowly dried. The nutritive value of a dehydrated apple is
practically the same after the process while the same cannot be said of evapor-
ated apples.
DEHYDRATION OF PRUNES
As factors such as maturity and condition of prunes for dehydration have
already been mentioned the actual dehydration and related processes may be
discussed directly.
Lye Dipping
Prunes are dipped in a weak lye solution of approximately 1^ per cent to
slightly check the skin and consequently facilitate the removal of their excess
moisture. The amount of lye necessary to check the skin varies with the dis-
tricts in which the fruit is grown. Consequently trial batches have to be made
to determine the amount of lye needed. Too much lye causes unnecessary
damage by cracking the skin and dissolving the skin pigments and consequently
dehydrated prunes that are subjected to strong lye become dull and lack the
shiny black colour of those dipped in a weak solution. The solution is held just
below the boiling point and the prunes are immersed for a period of 2 to 4
seconds. Immediately upon their removal from the lye solution they are placed
in clean cold water. From this they are trayed and placed in the dehydrator.
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Prune lye dipper, trayer, washer and trayer.
(Courtesy Miller Dehydrator Co., Eugene, Oregon.)
Operations in Dehydration of Prunes
The fruit is then placed in the dehydrator where the temperature ranges
up to 165° F. The relative humidity is maintained at between 15 and 25 per
cent, eighteen being the most desired percentage. The drying time will vary
with the type of dehydrator but will approximate 20 to 24 hours.
12
Curing and Packing
The prunes are stored in bins where the moisture content between individ-
ual fruits is equalized. The fruit is removed from these bins at the end of the
season, is graded, processed in boiling water for three minutes, and packed in
suitable containers. At present, the large quantities are packed in 25-pound
wooden cases lined with wax paper but the trend is towards containers of one
and two pound capacity.
Prune Dehydration Projects in Progress
Most of the experimental dehydration of prunes in Canada has been lim-
ited to the Okanagan Valley of British Columbia. The aim of the investiga-
tion is to determine the possibilities of the industry and to ascertain the most
adaptable varieties for dehydrating.
Variety Tests
Besides hardiness and good cropping habits, the three most important
qualities of the fruit that have been sought are: (1) a sugar content sufficiently
high to compare favourably with that of the imported products; (2) attrac-
tive flavour; and (3) good appearance in the finished product. The following
table outlines the results obtained: —
QUALITIES OF PRUNE VARIETIES TESTED FOR DEHYDRATING
Variety
Date of ripening
Size of fruit
Texture
Sweetness
Flavour
Appear-
ance
Sept. 13-23
Sept. 12-23
Sept. 12-23
Sept. 23-Oct. 15...
Oct. 1-10
Small ..
Good
Good
Good
Good
Good
Good
Poor
Very soft...
Good
Good
Good
Small to medium.
Small
Good
Good
Good
Date . .
Good
Good
Good
Medium to large..
Good with earlier
part of crop.
Fair to good
Fair
Good
Good
Fair to good..
Fair
Fair
Sept. 6-12
Extra large
Sept. 11-23
Sept. 12-22
Poor
Poor
Poor
Poor
Poor
In the above it may be noted that the French Petite, Mammouth French,
Date, and Italian prunes are promising varieties. Unfortunately, however,
there are disadvantages in each case. Generally speaking the French Petite,
Mammouth French, and Date produce frail trees which are inclined to bear
large crops of small fruit. Even when the trees are young the fruit does not
attain a reasonable size for dehydrating. The Italian, on the other hand, is a
hardy variety but matures late in the season. During autumns with a great
deal of cloudy weather many of the individual fruits do not develop as much
sugar as is desired. However, an early ripening bud sport of this variety has
been ' found and is being propagated at the Dominion Experimental Station,
Summerland, B.C. This strain ripens to full maturity by the end of August
and small samples that have been dehydrated have been more uniformly sweet
and thus of higher quality than the ordinary strain of Italian prune.
DEHYDRATION OF APRICOTS
Cutting
The fruit as soon as received from the orchard is cut and the halves laid
on trays with the pit cavity up. It is imperative to guard against careless cut-
ters slipping the pit out of the fruit and tearing it in half. Even the best fruit
if handled in his manner makes only a very low grade product.
13
Traying
The ideal situation is to have the apricots as close together as possible
without touching. Little is gained by crowding as the apricots stick together
when they start to dry and pull one another into undesirable shapes. Full trays
are loaded on cars and run into sulphur chambers.
Sulphur Chambers
The sulphur houses in use at this Station are of double thickness board
construction with building paper between the boards. Each chamber is just
large enough to comfortably accommodate one car of trays and has a ventilator
at both the top and bottom. There are many more elaborate plans for sulphur
chambers but the aforementioned is the simplest and is sufficient for local needs
at the present time. Whatever the type, it is essential that the sulphur chamber
be practically air tight to prevent leaks during sulphuring.
Sulphuring
Seven pounds of sulphur per green ton has been used with satisfactory
results. The sulphur should be of a grade free from arsenic and dry enough
to burn easily. If difficulty is encountered in causing complete combustion of
the sulphur, three to four per cent of powdered sodium or potassium nitrate
added to the sulphur will overcome this difficulty. The simplest method of
burning the sulphur is to place it in a shallow tin plate, supported at least an
inch above the floor. The sulphur may be ignited with burning shavings or
with hot coals. The ventilator on top of the chamber is kept open until the
sulphur fumes begin to pass out quite freely. Apricots for dehydrating are
exposed from one to two hours.
Operations in Dehydration of Apricots
Upon removal from the sulphur chambers the trays are placed in the
dehydrator where the air is heated to 135° F. while a relative humidity of
15 per cent is maintained. The temperature never exceeds 150° F. at any
time to avoid caramelizing the sugars. The apricots are sufficiently dried when
they will not remain in a ball when squeezed in the hand. Apricots that crack
when pressed have been dried too much. This dried fruit is next placed in
clean wooden bins where it cures until the end of the season.
Processing
In California where this industry is extensively developed the dried fruit is
sold by the grower to a processing and packing company. Here the apricots
are sorted, graded, resulphured, and steamed to a definite moisture content
(around 22 per cent). While the fruit is still hot it is pressed into paper
lined cases.
Apricot Dehydration and Sun Drying Experiments in Progress
Much of the work in dehydrating and sun drying of 'apricots has been
centered around variety tests, and although the results have shown Royals,
Blenheim, and Tilton to be the best varieties grown in Canada, the Wenatchee
Moorpark is the most hardy and the heaviest bearing. This work thus resolves
itself into investigation whereby the Wenatchee Moorpark variety can be
dehydrated or sun dried to produce a high quality product. The two projects
on this subject may be outlined as follows:
14
Minimum Sulphur for Dehydrated Apricots
Although sulphur dioxide is a preservative and is sometimes used in excessive
amounts in foods, it is essential to use a certain amount to preserve an attractive
colour in dried fruit. It has also been proven by experiments conducted in
California, that sulphur dioxide preserves the vitamin C content of the fruit.
It is thus apparent that sulphur dioxide is necessary in dehydrating or sun drying
fruit but the minimum amount that will give these desirable qualities is still
undecided and an experiment has been outlined to investigate this problem.
Sun Drying for Colour
As the colour of sun dried apricots is much richer than that of the dehydrated
fruit an experiment has been outlined in which the apricots are partly dried in
the sun to develop colour and are then placed in the dehydrator where the
removal of the remaining excess water is completed. It is expected that this
method will yield a product with the desirable colour of the sun dried fruit with
the greater cleanliness and reduced risk of danger from inclement weather.
Costs of Production
During years of small crops and high prices for fresh apricots it would
not be practical to dehydrate the fruit, but in years of bumper crops and low
prices dehydration may provide a worthwhile outlet for part of the crop and
thus bolster the price of that sold fresh.
In order to determine the practicability of growing apricots for these
products the Dehydration Committee has planted a five-acre apricot orchard
at Osoyoos, B.C., where all costs are recorded. This will provide a fund of
information when in full bearing.
DEHYDRATION OF PEACHES
Although the dehydrated product from this fruit is quite satisfactory, the
peach surplus is not a serious factor. The fresh market and the canneries can
consume more peaches than are being produced in Canada and can pay a price
considerably in excess of what could be paid for the same fruit for dehydrating.
If the peach growing industry is developed sufficiently for a surplus to exist after
filling the two markets already mentioned, dehydration could take care of con-
siderable tonnages.
The following table gives the drying ratio and percentage of pit for several
peach varieties: —
Variety
Drying
ratio
Percentage
pits
Elberta
9-8—1
9-0—1
10-4—1
6-8—1
12-9—1
5-8—1
8
Early Crawford
6-4
Late Crawford
J. H. Hale
8
Tuscan Cling
Muir
15
16
PRINCIPLES OF DEHYDRATOR CONSTRUCTION
The recirculation tunnel dehydrator is now generally considered the most
economic and satisfactory type. Although there are many modifications, the
principle involved is essentially the same. The two most popular types in the
northwest, namely the filler, and the 2O.A.C. are quite similar in actual
tunnel construction but differ mainly in the method of circulating the heated
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Cross section of diagram of Miller type. (A) heating unit, (B) tunnel, (C, D, and E)
ventilators in top of tunnel, (F) moist air outlet, (G) multivane fan, (H) fresh air inlet.
Arrows through "C", "D", and "E" indicate course of air.
air. Whereas the O.A.C. type, illustrated in the accompanying graph, has
the heating unit and fan in a duct below the main tunnel, the Miller type has
this equipment at one end of the tunnel as illustrated in the other graph. In
the O.A.C. dehydrator the air travels the full length of the tunnel before
returning to the heating unit. In the latter type provision is made for part of
the air to return to the heating unit at two or more places in the roof of the
tunnel (C, D, and E of diagram). This construction allows for an upward
movement of air through the trays and increases the uniformity of the drying.
The mechanism of a Miller dehydrator. Note the plastered
tile construction, oil burners, and electric motor for fan.
1 Patented by the L. N.. Miller Dehydrator Co., Eugene, Oregon.
2 Designed by Prof. E. H. Wiegand, Oregon Experiment Station, Corvallis, Oregon.
17
Materials
Heating Unit. — The heating unit will depend directly on the type of fuel
to be used. Oil, wood and coal are being used, depending on which is cheapest
in regard to its cost and yield of B.T.U.'s. In dehydrators operated as sidelines
of canneries where steam is available, this source of heat is very satisfactory.
It is not economical, however, to instal steam where only a dehydrator would
be supplied. The size of the furnace and radiating pipes will depend directly
on the capacity of the plant.
Puccinelli dehydrator.
Walls. — Permanent plants are largely constructed of hollow tile. This
is free from cracks and can easily be plastered giving a fine clean appearance
and suitable insulation.
Floor. — It is advisable to use reinforced concrete for cleanliness, strength
and permanence.
Doors. — The doors are usually made of wood covered with sheet metal.
This maintains a tight surface and overcomes the difficulty caused by cracks
in wooden doors.
18
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19
Temperature Control Apparatus
Equipment is available that will automatically control the dry bulb tem-
perature and humidity and thus overcome any danger of spoiling the fruit
through neglect of the operator. If this equipment cannot be purchased, a
recording hygrometer will keep a very good check on the temperature and
humidity.
Ty
ng hygrometer with cistern feed water system.
Dehydration Equipment
Besides the actual mechanism for dehydrating fruit or vegetables, there
are many other pieces of machinery and features of the plant to be considered.
In Canada at the present time the primary interest is in the dehydration of
apples, prunes, apricots, and loganberries. The equipment needed for the
preparation of these fruits varies and may be listed as follows: —
Apples. — Peelers, corers, seed cellers and slicers.
Prunes. — Lye dipper, washer and trayer.
Apricots. — Hand labour is needed to pit the fruit and spread it on trays.
Loganberries. — No preparation is needed.
Trays and Cars. — The trays on which the fruit is placed are illustrated
in figure 1. Trays have been made of tinned one-quarter inch hardware cloth,
galvanized hardware cloth, and of narrow wooden strips. The latter have
proven themselves to be the best as they do not contaminate the fruit with
metallic salts and do not sag in the centre.
20
The cars as illustrated in figure 2 are for conveying trays and fruit from
the preparation room and through the dehydrator.
FlG. 1. — A very satisfactory wooden tray. (Courtesy Miller Dehydrator Co.
Eugene, Oregon.)
Fig. 2. — A tunnel car of the Miller type. Note the grooved
wheels for following tunnel tracks. (Courtesy Miller
Dehydrator Co., Eugene, Oregon.)
Plant Arrangement
As far as possible it is wise to arrange the plant so that the fruit progresses
step by step without doubling back. The preparation room is located at the
end of the drier where the fruit is admitted, while curing bins are located at
the end of the dehydrator where the fruit is removed. With this arrangement
all operations are done systematically and do not conflict with one another.
The curing bins are sometimes located on different floors from the main plant.
This practice is most satisfactory in the case of dehydrated apples.
CAL/BCA OTTAWA K1A 0C5
39073 00215799 0
S
OTTAWA
F. A. ACLAND
PRINTER TO THE KING'S MOST EXCELLENT MAJESTY
1931
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