Historic, archived document Do not assume content reflects current scientific knowledge, policies, or practices. Washington, D. C. v January 26, 1923 SIGNIFICANCE OF WHEAT HAIRS IN MICROSCOPI- CAL EXAMINATION OF FLOUR. By Georce L. Keenan, Microanalyst, Microchemical Laboratory, Bureau of Chemistry. CONTENTS. Page. | Page. Purpoeseiormethodins seks Se ec eaceeee _1 | Examination of commercial flours.......... Meth Ode Ree esac onnemene Peet ont eaasoece 1 | Examination of experimental series of flour-. 6 Examination of mill stocks.................- 745) TS} UWA dha NASH So AROSE OS ORSOCOU SEE BES Hoeeee Uf PURPOSE OF METHOD. Since the publication of United States Department of Agriculture Bulletin 839, “The Microscopical Examination of Flour,” further study has suggested that the number of wheat hairs present in a weighed portion of the sample might be of value in classifying it. Heretofore the grading of a fear by the original method has depended upon a count of the bran particles and hairs in a weighed portion of the sample. In practice, however, the identification of bran particles appears to be a more difficult task for the untrained eye than the recognition of wheat hairs or fragments of hairs. The bran particles occur in the flour in such a variety of forms that an analyst unaccustomed to the differentiation of histological sections under the microscope may encounter difficulties in obtaining con- sistent bran-particle counts. The wheat hairs and hair fragments, on the other hand, are readily identified and the quantity present in a sample has been found to be indicative of the flour grade.! METHOD. The method employed, which is similar to the one described in Department Bulletin 839, with some modifications, is as follows: Carefully weigh out upon an accurate balance a 5-milligram portion of flour and transfer the weighed portion to the center of a microscope slide the surface of which has been ruled with lines running lengthwise and 1 millimeter apart. The flour having been transferred to the slide, mix about 4 drops of chloral hydrate solution (1:1) with the flour by means of a preparation needle. After making a uniform mixture of the flour and the chloral hydrate solution, apply a cover- glass 22 millimeters square and gently warm the slide on the hot 1 The term ‘“‘ grade’? is here used in a general way, to classify the assembled types of flour. 16243—23 2 BULLETIN 1130, U. S. DEPARTMENT OF AGRICULTURE.” plate until the preparation is properly cleared. The clearing is com- lete when the preparation becomes transparent. Then transfer the slide to the stage of the microscope and allow it to remain until no movement is evident in the mount when viewed under the micro- scope. Count the hairs and hair fragments. The magnification giving approximately 180 diameters here employed was obtained by the use of compensating ocular 12 « and 16-millimeter apochromatic objective. If apochromatic objectives are not available, an achro- matic objective with an ordinary eyepiece giving the same magnifica- tion is satisfactory. COUNTING THE HAIRS. The counting of a slide consists in the methodical enumeration of all the hairs and hair fragments in the mount (Fig. 1). By means AZZ Zu AE eam Be Fic. 1.—Wheat hairs (180). of the mechanical stage on the microscope, no difficulty is encoun- tered in thoroughly and accurately covering the entire mount. Each hair and hair fragment is given a value of 1, the final number being taken as the value for the flour in question. SOURCES OF VARIATION IN METHOD. Department Bulletin 839 contains a full discussion of tests con- ducted to determine the sources of variation in such a method. It is evident that the variation in the counts made by two analysts is greater in the case of bran particles than in the case of hairs. EXAMINATION OF MILL STOCKS. Modern milling processes consist essentially in releasing the floury endosperm from the wheat grain, purifying it of bran substance, and eventually reducing it to what is known as flour. Any manipula- | i t i | MICROSCOPICAL EXAMINATION OF FLOUR. 3 tion in the various steps of milling leading to the removal of an insuf- ficient quantity of the bran material will eventually reveal itself in the finished flour. The method already described has been devised to detect such irregularities. The break rolls in a mill are designed to crush the wheat kernel so that the inclosed endosperm may be released and later reduced to the fineness of flour on the smoother rolls. The general practice in milling is to make as little break flour as possible. When made to any extent, break flour invariably contains a large quantity of offal, consisting of hairs, hair fragments, and bran particles. The middlings 4. COUNT PER 5S 4C. OF FLOUR Qiao ott Sean CB) (710) (10) (7) COIOIOV C12) C10) C17) 092) (A) C3) C7) Fic. 2.— Average hair counts on 35 break flours and 74 middlings flours. za BULLETIN 1130, U. S. DEPARTMENT OF AGRICULTURE. (granular particles of endosperm), on the contrary, are relatively free from hairs and bran particles after proper purification. To illustrate these differences in break stocks and middlings stocks, a composite chart (Fig. 2) has been constructed. It is based on data obtained from 35 break flours and 74 middlings flours, the hair count being the average on all samples examined for each grade. The break flours in each instance show a much higher hair count than any of the middlings stocks. The hair count of the middlings stock. begins to increase with the fifth middlings, indicating that the first four middlings are much cleaner than the succeeding ones in the series. EXAMINATION OF COMMERCIAL FLOURS. Commercial grades of flour generally fall into four more or less sharply defined classes known as “patents,” “straights,” “clears,” and “low grades.’ As a rule the so-called patent flours are limited to those which are composed of the first-class flour streams, most often those ground from purified middlings stocks. However, stocks other than first-class ~ middlings are often passed into patent flours. When this is the case the proportion of offal in the flour increases. In Figure 3 the hair count of patent flours made from middlings stocks only is compared with that of patent flours containing lower-grade stocks in addi- tion to middlings stocks. : The average hair count on 13 samples of patent flours made from middlings only is 13; the average hair count on 13 samples of patent flours made from lower-grade stocks in addi- tion to middlings is 28. When only one grade of flour is manufactured in the mill, it is commercially designated as a straight flour. It usually consists of all the flour that can be obtained from the wheat grain with the exception of some low-grade flour. Such a flour naturally contains more offal than a patent flour. : The so-called clear flours usually contain the lower grades of middlings and break flours, although they may contain the purer mid- dlings from the tail of the mul. Naturally, the offal content of such flour is higher than that of Fic. 3. Average hair countson patent and straight flours. patent flours made from mid- = dlings only and onthosemade ‘The low-grade flour is made from low-grade Bede oOo ay Midas stocks, the better stocks in the mill having been only; (6) middlingsandlower already diverted into the higher grades. 7 Table 1 shows the hair counts obtained on the samples of commercial flours examined. As might be expected, there is a variation in the counts for the different classes, doubtless due to the lack of uniformity in milling procedure. Figure 4 illustrates the differences between the four so-called com- mercial grades of flour, based on the average hair count obtained for MOIR COUWT FER § 19G,.OF FLOOR eT See — ee MICROSCOPICAL EXAMINATION OF FLOUR. 5 all samples examined under each grade. According to the manu- facturers, these flours had been milled from hard, blended, and soft wheats, respectively, and the results obtained have been classified under these three general classes of wheat. TaBLeE 1.—Hair counts obtained on commercial samples of flour. 1 | Clear flours. | Low-grade flours. | Patent flours.. Straight flours. | | Sample No. |. | - Hard Papen] Soft Hard eee Soft | Hard Bet Soft | Hard Biead: Soft | wheat. wheat,| Wheat. wheat.) wheat, wheat. wheat.| heat. wheat.) wheat. saan. wheat. | 1 eS Saas 34 17 10 | 34 | 26 | 40 45 61 | 72 | 91 132 27 his eke, co Fey Le 55| 22 51 Paz | S965 68| 129| 131| 257 8 een ane sees 15 40 11 45 28 38 114 | 73 ay4|| ail 94 | 145 CE er ees ZS 27° | 32 33 18 58 133 40 39°} — 112 183 261 G5 Gee 12 19 | 1 25 36 26 43 96 40 155 141 219 Gxt ee ee Gees 30 | 13 | 34 39 40 60 178 45 44 88 76 139 hs ares i 10 | 37 | 17 31 | 31 | 70 49 49 143.| 301 61 124 iene Jap eee 16 25 12 51 | 38 54 57 47 167 335 59 80 Rane ya aie ae 19 | 15 22 61 47 | 27 71 142 30 264 |S e cacao eee 102.4 beeen 18 29 87 30 | vat 93 | 98 66 TUG To eee be 10 Ree, Saas See 28 13 19 65 28 81 CUA ay 99 OB tOS Bacar boob PA et es eS Sil toplist 2 26 19 | 29 | 40 102 67 GAS ee ee ee ose eho [Be en ee 28d tere 30 26. | 26 22 AA us| eercyoret cts tL Sraliessreraers)| ate ec ohere lls ato craters NAS ed eS Dae Sea oe oss 3 47 | 37 | 34 TAQ TS eo eter eel as atl aes cee [eee rae 1 Se on See 1S eee - | Ssanooe 61) 45 39 1S iol ee oe eee bee ooe ear ees ae Se ea LO SRE | Sane LZ ese al ree Sa Le AOAC te Bll ces ose dlaccrchordparel aes W/o os = a Sen SGelter sea eee. 22 | 58 | 38 OF fae es Ae Pree aes) Dene teen (epee. leseSsce rial ot aes in| ete | ae ieee beet ae acy aomeeae 68a Boer eer anal eee caere eee ee Lom eee Pow Teme | she iewal| 2) Sala peestas ete. iti Ear eine eres foe Sat oe ee Dae te So eae To) egal SU EEER Oe a ee a ees TQS ee ord Se epee eee a | pee [eer eale «| aie be ae ieee lhe ae FOTO Len ues ees (Ese (eae | a eee et er ores ES TEN REIT lee Ge tod. . Beets Dea Set | (|, Sas eae Pe gee |e Mah Bes. 1024/9: Ste leis Ee Saeee | cee PES Be ee TESTS) | RS ere ve ae set ees PTS er CH a Eee (ne eed Se Save Sie mp eae ize SaaS, 58 RO Vea a aan en ae, ae GRR SA an. S| Ue [ee Seana ie) ceed | Agere pase Pears oe (ie ees gee tates Seka ZAR ae 28 Sa Serer oe \Scgesenhe: 2 Uy Sea ene | |e creel [es eaNeS ies] eee Ufo) [A RS eae ere Se aoenee ae mn It a ee ESE oes alates | IL cee ran SE Rear ciara Seca sires |widcate Ss nfmercics oS DOM Baeiescn eee tice cease Sect ise ce = 2 Siac Soe A ee eee a | oan) ee Ee 1,0. Aeeee Sees aso ase Sissies isc sone a le 5 oe eae Ral |< canta 3) ee eee ee A a 1G 26] BS eee oan |e eet | Sees esate aye ae SEE BE Oi! SETS |e Se cy 1 Seca (Se aes SER Se [SR eee Ae eee epee Shee aS Ste Sea SE OEE 45 2obeses|sos06ga} sates) Se=Sebq|Scocsee|soosssc + obauadscodaca||lsposcee |soteouc lSSeesee pt ie a 2 Pb les = 22 ef ces 2 (S222 5 e FS eee aa fer gc RA ee a ai ai eke ak ee |. re SEE oR Opes ral ge eles ele see: es set (sear, ean | see Laer es baa ei Rae" ne Al sh SCRE ee 8 ee ee ere Smears Se rec Aare ayn lens cot a eee ee bee [erect OM ee Sees ema Sere Average... 18 | 21 20 42 | 34 | 44 110 68 86 182 109 | 156 1 As the flours examined were milled under different conditions the counts vary with the milling practices at the various mills. The average hair count on all patent flours examined was 19; on all straight flours, 40; on all clear flours, 88; and on all low-grade flours, 149. The average hair count obtained for each grade shows how distinctive the classification of these flours can be made by the method here described. With the exception of the hard-wheat clear flour and the soft-wheat low-grade flour, there is no indication that one grade overlaps another. The exception noted emphasizes the fact that grading practices in various mills lack uniformity. In other words, the same grade of flour from two mills might show. a variation in the hair count as a result of the variations in the com- position of the finished flour. 6 BULLETIN 1180, U. S. DEPARTMENT OF AGRICULTURE, EXAMINATION OF EXPERIMENTAL SERIES OF FLOUR. A study was also made of samples of flour whose composition, in so far as the mill streams entering into them is concerned, was definitely known. Table 2 shows the hair counts obtained on these samples. These — counts are more uniform and consistent than those for the commercial flours examined (Table 1). The results have been plotted in Figure 5. An examination of the results obtained on the experimental series of flours, as compared with those obtained on the commercial flours, justifies the statement previously made that but little uniformity exists in grading finished flours in different mills. In other words, there is less overlapping between grades in the experimental flours than there is in commercial flours. AY ENR «555 ae Ot F hasane ; MARS Wi tas B >.b ote rae mm sg ¥ bee : 4 > iy : aly ere “ = a | G Le EB Nw j fit et Sm oheng ‘ Me ae ak Vel reur s 14 59 i aL Mga Ree Le TE Te rte eg ar a . : 3 AT a ayy fiy Naa eas ai ae ea aed Pah IRS! cite dly eNO of ek! ; a et Bye ATR fee oR OE a ce Ee tiey een y we Mees Day NEO aD L a mame PMR, $212 PARRY K ie HAIR COUNT PER 5 MG.O0F FLOUR py TL Ave et Os os Hebe APES ut % ote u Sour yee vata < a aL : SNe Ld ca rc ak pe Tad red ae ketene ean hn, NS WO TE Ca ABE TE ty ort Ve 1 SRL MEMA GR Lae a a Ue es SAMOS pire g dA LAPT pty A TENS ‘ Y PRL eae Te Re TR Tae RTs Rs | SVMS oy a E Re Meet ponte x ¢ fad 19 t& Ei iy AN, mw rae Oy i Feri 5 Rn AAO My CPE PS LG Fe UR aa A ee 4 SP ain Ones OMe tais A a PE RET PEL Era Pa HS 8 HSB His eas PATENTS" "STRAIGHTS" “CLEARS” Z0W GRADE’ Fic. 4.—Average hair count on 61 patent, 56 clear, 52 straight, and 16 low-grade flours. MICROSCOPICAL EXAMINATION OF FLOUR. 7 - TasLe 2.—RHair counts obtained on experimental samples of flour. ! Types of flour. Sample No. | | 70 per 97.5 per 90 per | 27.5 per } 2.5 per cent. cent. cent. | cent. | cent. | | Hol Bate oe aes Sipe Sees cae: biel aera aan 13 28 26 45 | 129 Whigs Ae Ae Sale AOS gna ye a a | 13 29 22 49 131 ie eat a Tee eee SRL ae | 18 26 | 28 47 112 Dies i ae Salon ae GR asthe oO An mie eae oy | 12 39 31 G5 ie ee eae Geeta te ee ites ot es ee to eS 9 29 28 | Bilis |e ea 2 Ce en sree. SMM EE | eee PS. | eee 30 | 34 AQ | ike eee 3 IASU BIAS Capa see ari eioee es aele oo oes cle bls ete etes Soeee | 13 30 28 49 | 124 | | 1 As these flours were made under the supervision of the Bureau of Chemistry, their constituent streams were known. A description of thestreams composing them is given in Department of Agriculture Bulletin 839. SUMMARY. Experimental data secured by the Bureau of Chemistry have shown in a general way the existence of a significant relationship between the wheat-hair count and the flour classified according to milling practices. Reliable informa-. tion on the quality of the mill streams composing any finished flour was avail- able onlyin the case of the experimental samples of flour. Consequently, any suggestion as to the tolerance to be applied in a method of this kind would be justified only when definite infor- mation concerning the milling process, such as the streams employed in com- posing a flour and the cleaning of the wheat, is at hand. The data obtained on the exper- imental samples of flour, however, in- dicate the possibility of making an in- teresting classification based on the hair count alone. It is possible, of course, that the number of hairs or hair fragments from the brush of the wheat grain might differ materially, ac- cording to the variety of wheat used and the milling operations employed. Nevertheless, an examination of a large number of samples representing a great variety of milling practices indicates PAT. STE STAGES LG” that flours made from purified mid- Fie. 5—Average hair count ona 70 per cent dlings material show a low hair count, 3772, Mont cleat ona Dee aight, while flours containing lower-grade mill —_stade flour. stocks show a higher hair count. HAIR COUNT PER § 106. OF FLOUR ORGANIZATION OF THE UNITED STATES DEPARTMENT OF AGRICULTURE. ISECLELGTUNOF A QTICULLUT CR oe cae 3 eee =e ae HENRY C. WALLACE. A SSUSLOTUL SCCTELOT Ye ate ore ee 2 ee ee eee C. W. Puestey. Director of Scientific Work. .. .. 22sec se oe ee E. D. Batt. Director of Regulatory Work....................-- Weather Butea. 20sec eee ee ew eee eee ee CHARLES F. Marvin, Chief. 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