THIAMINE CONTENT OF VEGETABLES Effect of Commercial L. E. Clifcorn a n d D. G. Heberlein RESEARCH DEPARTMENT, CONTINENTAL CAN COMPANY, INC., CHICAGO, ILL.
HE importance of vitamins in human nutrition, and knowledge of their distribution and physical and chemical properties have led food industries to focus attention on any vitamin losses that may occur in refining or preservation processes. Only a limited amount of information is available on the effects of commercial canning operations on the retention of thiamine during the canning of vegetables. Reports in the literature on the effects of experimental and home canning operations can be correlated with commercial operations only when the nature and treatment of the raw products, and canning methods employed are parallel. Since the present trend of the canning industry is t o adopt those procedures which are most favorable to vitamin retention, it was felt that surveys on the effects of commercial canning operations on the thiamine content of vegetables were important. Harris and associates (6) studied the effect of experimental canning on the thiamine content of vegetables and reported thiamine retentions for the various vegetables as follows: asparagus {whole stalk) 65-9070, cut green beans 83%, lima beans 32-60%, cut wax beans SO%, sliced beets 92%, diced carrots 767,, peas (not blanched) 77-92%, spinach 18-44%, squash 32-39%, and tomatoes 76-907'. Asparagus canned experimentally and commercially from the same lot of raw product showed approximately the same thiamine retention-Le., 65 and 63%, respectively. For a number of canned vegetables analyzed, the liquid portions of the cans contained 24-517' of the total thiamine. Fellers, Esselen, and Fitzgerald (4)determined thiamine retentions by the bioassay method on four vegetables over the entire commercial canning operations with the following results: asparagus 72 yo, peas SO%, lima beans 28%, and spinach 71%. Farrell and Fellers (3) determined the losses occurring upon the experimental canning of green snap beans, and reported an 83y0 retention of
T
168
thiamine after canning and a 56% overall retention after storage for one year. Mayfield and Richardson (9) found a 67% retention of thiamine in homecanned green beans, stored for six months and heated for serving. A commercial sample, canned in the same locality and similarly treated, was found to have the same thiamine content. Homecanned peas (11) retained 80% of their thiamine upon canning and showed no loss after storage for six months and heating for serving. Langley, Richardson, and Andes ( 7 ) found that carrots canned in the autumn lost only a small percentage of their thiamine; similar carrots canned after storage until spring showed a loss as high as 50%. Lunde, Kringstad, and Olsen (8) made experimental studies and reported 75y0 retention of thiamine in canning sweet peas and goy0 in canning cauliflower. A 15% extraction loss of thiamine was noted upon blanching- sweet peas. Fincke (5) observed that thiamine extraction losses in peas increase, in general, with the increase of temperature and time of blanching. Little difference was noted between steam and hot water blanching, both at 210" F. Moyer and Tressler (10) observed slight decreases in the thiamine contents of asparagus and peas during blanching. Adam (2) indicated that losses of thiamine may be expected during blanching due to leaching of the water-soluble thiamine from the product, and during processing due to destruction by heat. EXPERIMENTAL DETAILS OF SURVEYS
I n order to have a broad picture of the effects of the various steps in commercial canning operations on the thiamine content of vegetables, it would be most desirable to have a number of plant surveys for each significant product. This was impossible because of the large amount of work involved. The number of products studied was also limited. The surveys reported here were made in plants packing relatively large volumes of the products studied. The canning methods used in some instances may not be representative of average commercial practice. The 1941 surveys included over-all retention studies of thiamine for a number of vegetables during commercial canning, while the 1942 studies were made on samples of the vegetables during preparation and canning, taken after each significant step in the operations. I n each instance large lots of the raw products were followed through the canning operations. Samples representing one fiftieth to one twenty-fifth of the weight of the vegetables were taken before and after each important operation. These samples were chopped (if necessary), divided, rechopped, divided, etc.,
February, 1944
INDUSTRIAL AND ENGINEERING CHEMISTRY
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The straight stalks were then cut on a whole stalk cutter, giving a 4.5-inch (from top of spear) whole spear, two 1.5Asparagus Enters Factory First Cutting Operation, B u t t Cutter inch center cuts, and waste I (short cuts from lower part of Edible stalks, 157 micrograms/100 grams" Bottom'cuts, 97 Ground cuts, 84 stalks). Flumed and washed 152 Inspected and sorte6 into straight and crooked stalks The w h o l e s p e a r s w e r e Straight sdalks, 154 Crooked stalks: 150 h a n d l e d i n t h r e e different Whole stalk cutter Cut for fancy-cut asparagus ways: ( a ) One portion was I Soaked cold water 8 min.) 148 7 45 seconds at l 6 O o F* Blanche6 (1,5 min., 170" F.;, 149 Whole spears, 205 Center cuts, 99 Waste, 92 Filled into No. 300 can8 and then canned. This repI 1 Washed (4 min. cold water) Brine added resented the most common 170° FJ, 111 Processed (14 min., 248O F.) commercial practice. ( b ) The Washed (4 rnin., Blanched ( 3 / 4 rnin., Blanched Filled into(1.5 No.rnin., 300 cans Canned fancy-cut 13O'F.) 197 lGOO.F.),199 BI ine added Solids, 61 s e c o n d p o r t i o n was steam Blanched ( 3 / 4 min , Filled into No. 300 Processed (14 min. 248O F.) Liquid, 70 blanched 1.5 minutes a t ap160°,F.), 185 cans Canned center cuts Combined, 6 5 proximately 180-190° F., and Retention after Brine added Solids 47 Retention (sterilization proowashing and Processed (14 rnin., Liquid, 48 4 , 64% canned in order to determine blanching, 90% 248' F.) Combined, 47 Over-all retention, 63% any possible advantages of Canned whole spears Retention (sterilization process), steam blanching. ( c ) Since the Solids 90 63% whole spears are given an addiLiquid, 97 Over-all retention, 70% Combined, 92 tional w a s h i n w h e n v e r y Retention (sterilizadirty, the thircf portion was tion process), 66% Over-all retention, washed 4 minutes at 130' F. 63% and then blanched as in step a. T h e c e n t e r - c u t asparagus a Thiamine values with exception of those on canned samples corrected to moisture content (92.2%) of original fresh sample. was flumed, washed with a shaker washer 4 minutes a t 60-70' F., blanched, washed again briefly, and canned. COXTFNT O F FIGITRE 2. EFFTCT O F P R E P A R A T I O N AND CANNING ON THIAMINE REFUGEE GREENBEAXS The crooked and broken spears of asparagus were cut and placed in a cold water Green Beans Enter Factory and Are Emptied into Snipper storage tank where the were held for 8 Snipped Beans, 80 Micrograms/100 GramsQ minutes, the average hording time in comSize-Graded and Inspected 1------I mercial practice. The fancy-cut asparagus i Size 4, 77 dze 5 Size 3, 82 size 1 d e2 was then blanched and canned in the same Small proportion Small pr.oportion Blanched (6 rnin., 170- Cut into 1-inch lengths of original 180' F.) 77 Blanched (6 rnin., 180' F.) 64 of original manner as the center-cuts. beans. Not Retention ' after blanching Retention after blanching, beans. Not I n all of this work the products were filled analyzed analyzed into tared cans and the weight of product Filled 94 %.into No. 2 cans Filled 83 %into No. 2 cans Brine added Brine added in each individual can recorded. The cans Processed (20 rnin.. 240" F.) Processed (20 rnin., 240° F.) were all water-cooled after processing. The Canned whole beans Canned cut beans thiamine contents of the asparagus a t the Solids, 36 Solids, 28 various steps in the preparation and canning Liquids, 36 Liquid, 24 Combined, 36 Combined, 26 are shown in Figure 1. The results obRetention (sterilization Retention (sterilization tained on steam-blanched whole spear asprocess) 79% process) 7 3 4 Over-all rgtention, 76% Over-all rLtent&n, 61% paragus are discussed later.
FIGURE 1. EFFECTOF PREPARATION AND CANNING-ON THIAMINE CONTENT OF MARY WASHINGTON ASPARAGUS
4 Thiamine values with exoeption of those on canned samples corrected to moisture content (9 1.89/) of original fresh sample.
until a sample of about 2 pounds was obtained. They were placed in cans and immediately put into dry ice chamber, transported to the laboratory, and analyzed as Soon as Possible. Several cases of the canned product were obtained in each instance. The samples were analyzed for thiamine content by the method
and ('It using a 'Oleman l2 photofluorometer. (Results reported here as thiamine refer to thiamine hydrochloride.) Moisture analyses were made by the vacuum oven drying method on all except the canned samples, in order to correct for moisture variations. Changes in the thiamine content of the products before and after each significant process of preparation of the products for canning were calculated on the basis of the moisture contents of the original materials. Retentions of thiamine during the sterilizing processes were calculated from the total amounts of thiamine in the cans before and after processing (Table I). The canned samples were analyzed after short storage periods 88 shown in Table I11 and thus included the effect of short storage in the value for retention of thiamine during processing.
Of
ASPA RAGU S
MARY WASHINGTON VARIETY. The asparagus entered the plant in 30-pound lug boxes. The stalks were placed in a butt cutter where two cuts (a 1-inch ground cut and a 1.5-inch bottom cut) were made from the bottom end of each stalk. The edible stalks of asparagus were then flumed and washed, inspected, and sorted into straight and crooked stalks.
BEANS
GREEN(REFUGEEVARIETY). The green beans were emptied into the snippers to remove the ends of the beans, and then graded into sizes 1, 2, 3, 4, and 5. Samples of only sizes 3 and 4 were taken since they constituted the greatest percentage of beans being canned. Size 3 beans were packed whole, and size 4 as 1inch cuts, Both styles of beans were blanched in hot water. The thiamine contents of the beans a t various steps in the operations are shown in Figure 2. LIMAs (HENDERSON VARIETY). The lima beans in this particular study were not graded for size but were packed as a standard pack, containing practically 90% or more white beans, and an extra standard pack, containing more than 50% green beans. This separation was obtained by harvesting the beans at the Proper time, since the more mature beans were white and the immature beans were practically all green.
TABLE 1. TYPICAL CALCULATION OF THIAMINE R m T I O N DURING PROCESSING (WHOLE-SPEARWATER-BLANCHED
ASPARAGUS)
Beforeprocessing
Thiamine content when filled into can, micrograms/100 g.
~
~
~
~
~
~
~
~
:
f
197" 302.5 ~596 ~
A f ~ ~ , p , r , o , c a s ~ i ~ ~ n ~ ~ i ~ ~ ~ ~ ~ ~ ~ 285.3 s Thiamine content of solids, miorograms/100 g. 90 Weight of liquid, grams Thiamine oontent of liquid micrograms/100 g. Total amount of thiamine in solids, micrograms Total amount of thiamine in liquids, micrograms Retention Total amount (392of thiamine 596) in loocan, micrograms 6s%
138.7 97
267 135
392
a Corresponds t o value 199 in Table I1 which is corrected to moisture content of 92*2%.
~
h
INDUSTRIAL AND ENGINEERING CHEMISTRY
170 TABLE rr.
EFFECT OF PREPARATIOX ASD CASSISG os T H I A M I S E COSTEST O F ~ - 1 E S u E R S O SE C S H L I J ~ A BEASS
Beans enter factory and are washed, thiamine content, micrograms/ 100 grams InsDected (loose skins and foreinn material removed) Blanched a t 208' F. Retention after blanching
Standard Pack (90% or More White Beans)
Extra Standard Pack (50% or Less White Beans)
325Q
267a
Vol. 36, No. 2
SWEET(PRINCE OF WALESTYPE). After passing through the washer and clipper cleaner, the peas were inspected and the first sample was taken. They were blanched and moved by a water lift to the quality grader where they were separated into fancy and standard peas. Both lots were canned in the regular manner. Two sterilization processes were used in order to determine the relative effect on thiamine content. The results are shown in Figure 4. T H I A M I N E RETENTION
I n the previous tables and figures, the retention of thiamine during blanching and during processing is given, and the distribution of thiamine in the solid and liquid portions of the cans of the Filled into No. 2 cans, brine added, processed 30 min. a t 240' F. various products is shown. The over-all retentions of thiamine Canned lima beans in the products for the entire canning operations, plus the short Solids 56 42 Liquid 67 49 storage periods between canning and analysis, are shown in Combined 59 44 Retention (sterilization process) Table 111. Over-all thiamine retention studies conducted in 1941 717 Over-all retention 37.3, are also included. The varieties of the 1941 products studied are Thiamine values, with exception of those on canned samples, corrected as follows: Mary Washington asparagus, Refugee green beans, t o moisture oontent (standard beans 42.3%, extra standard 56.7%) of original fresh samples. Henderson Bush lima beans, Detroit Dark Red beets, Chantenay carrots, Country Gentleman white corn, Golden Hybrid No. 2439 yellow corn, Perfection Sweet peas, Baltimore tomatoes, After washing and inspection, the beans were blanched in a Baltimore tomato juice, Some of the canned products were rotating t y e blancher and canned in the regular manner. The analyzed after various periods of room temperature storage in details of t%e canning procedure and the thiamine contents of order to determine the effect of storage on the thiamine content. the beans a t various stages of the process are shown in TabIe 11. A 4.can composite sampling was analyzed in every instance. The results in Table IV are expressed as over-all retentions of PEAS thiamine from the fresh to the canned products after the various ALABKAVARIETY. After going through the washer and the periods of storage. clipper cleaner, the peas were graded for sieve size. Sieve sizes Examination of values obtained on the various cuts of aspara1, 2, and 3 were put through the quality grader (a salt solution of varying concentration to separate the less mature from the gus shows that the thiamine content is greatest in the tips and more mature peas or fancy and extra standard or standard peas, decreases in the lower portions of the stalk. This was reflected respectively). Sizes 4 and 5 were considered standard grade and in the canned product, since the canned whole-spear asparagus therefore were not quality-graded. The peas were then blanched had about twice the thiamine content of the center-cut asparaand canned. The thiamine content after each step in the operations is shown in Figure 3. gus; this was the same relationship of thiamine content in these styles of asparagus before canning. The differences in thiamine FIGURE 3. EFFECTOF PREPARATION AND CANNING ON THIAMINE CONTENT OF ALASKA PEAS content between standPeas Enter Factory ard and extra standard Washed and Cleaned, 322 Micrograms/100 Grams Graded into Sieve Sizes lima beans, and between the various sieve Sieve 1,' 250" Sieve 2, 2680 Sieve 3: 30IQ Sieve 4: 320G Sieve 5: 323a Quality-graded Quality-graded Qualitv-graded I I . _ _ sizes and quality grades 117 1 i i (fancy and extra Extra Extra Blanched Blanched Fancy standard Fancy standard Fancy standard 7 min., 7 min., standard or standard) 233 257 240 300 279 338 170-190' F. 170-190° F. Blanched (6 min. 170Alaska peas, is mainly 190°.F.) 178 216 190 261 233 301 328 311 Retention after blanchdue t o the different 76% ing 84% 79% 84% 89% 84% 100% 96% stages of maturity of Filled into No. 2 cans, brine added, processed 35 min. a t 240' F. Canned peas the seeds. This is also Solids 71 84 76 94 91 112 109 117 Liquid 79 90 apparent in the fancy 80 110 100 141 145 137 Combined 74 86 78 100 94 122 I22 125 and standard grades of Retention (sterilization prooess) Sweet peas. I n nearly 63% 61% 64% 64 % 69 % Over-all retention 54% 50% 55% 65% 66% all instances the same Thiamine values, with exception of those on canned samples, corrected t o moisture content (sieve 1, 82.6%; sieve 2, 80.0%; sieve 3, 73.5%; Sieve 4, 70.7%; sieve 5 , 69.4%) of corresponding sieved fresh peas. pr o p o r t i o n a1 differences are observed in the canned products FIGURE 4. EFFECT O F PREPARATION AND CANNING ON THIAMINE CONTENT O F P R I N C E O F l f T ~ ~ ~ ~ as in the raw materials SWEET PEAS before canning. Peas Enter Factory Are Washed and Cleaned The i n s i g n i f i c a n t Ungraded Peas, 418 Microgrsrns/100 Grams" Blanched (8 Min 205' E' ) 316 c h a n g e s in t h e Retention after d a n c h i n g , ?6% Quality-Graded thiamine content of I 1 Fancy peas, 288 asparagus during Standard peas 362 Filled into No. 2 cans Filled into No: 2 cans blanching are explained Brine added Brine added by the relatively short Processed (35 mrin 240° F.) Processed (45'min 245' F.) Processed (35 k i n 240° F.) Prooessed (42 min 245O F.) time and low temperaCanned peas (fano;) Canned peas (fano';) Canned peas ( s t a d a r d ) Canned peas (sta&ard) Solids, 123 Solids, 110 Solids 134 Solids, 113 ture of blanching, and Liquid 131 Liquid, 116 Liquid 154 Liquid, 134 Combihed. 126 Combined, 112 Combihed 142 Combined 121 the small ratio of surRetention (sterilization proc- Retention (sterihsation procRetention (sierilization proc- Retention (sterilization process) 67% ess). 60% ess), 67% ess) 59% fabe area to mass for Over-All retention, 49% Over-all retention, 44y0 Over-all retention, 58% Over-All retention, 51% this product. No dif0 Thiamine values, with exception of those on canned samples, corrected t o moisture content (79.0%) of original fresh aample. ferences were noted between the thiamine reI
326 222 (15 min.) 68 %
286 183 (12 min.) 64 %
Eg
Q
ggR
%@
INDUSTRIAL AND ENGINEERING CHEMISTRY
February, 1944
171
AND CANNING TABLE 111. OVER-ALL RETENTION OF THIAMINE IN VEGETABLES DURING PREPARATION
Product As aragus gancy cut Whole spear Whole spear Center cuts Fancy cut Green beans Whole, size 3 Cut, size 4 Lima beans Standard Extra standard Beets Carrots Whole kernel corn White Yellow Peas Sweet peas Unsieved, fancy Unsieved fancy Unsieved: standard Unsieved, standard Alaska peas Sieve 1, fancy Sieve 1, extra standard Sieve 2,fancy Sieve 2, extra standard Sieve 3, fancy Sieve 3,standard Sieve 4. Sieve 5 Tomatoes Tomato juice Steam blanch.
TABLE IV.
As aragus &ncy cut Lot 2 Lima beans Corn, yellow whole kernel Peas, Sweet No. 5 Peas, sweet ungraded
Year
Water Blanch Min, F.'
Process Min. O F.
58 48 48 70
s',1
248 248 248 248 248
300 300 300 300 300
145 204 204 101 151
45 90 86 47 61
58 97 90 48 70
50 92 88 47 65
89 21 20 42 22
53 63 65 70 63
6 6 5 15 12 12' 4
170-180 180 175 208 208 220 212
20 20 45 30 30 30 30
240 240 240 240 240 240 240
2 2 2 2 2 2 2
82 77 266 325 267 39 68
36 28 65 56 42 16 28
36 24 76 67 49 19 32
36 26 69 59 44 17 29
32 32 54 33 33 28 38
76 61 49 37 34 69 60
250 250 245
2 2 2
104 134 349
19 40 157
21 39 144
20 40 152
76 50 84
31 47 72
2 2 2 2
416 416 416 416
123 110 134 113
131 116 154 134
126 112 142 121
21 29 33 42
49 44 58 51
233 253 245 295 296 334 320 323 76 79
71 84 76 ._ 94 91 112 109 117 66
79 90 80 110 100 141 145 137 74 55
74 86 78 100 94 122 122 125 69 55
32 33 33 38 46 46 47 52 14 57
54 50 55 50 61 65 66 89 74
1942 1942 1941 1942 1942 1941 1941
Il/n
.... ....
...
1941 1941 1941
8
266
30 30 35
1942 1942 1942 1942
8 8 8 8
205 205 205 205
36 46 35 45
240 245 240 245
6 6 6 6 6 6 7 7
170-190 170-190 170-190 170-190 170-190 170-190 170-190 170-190
35 35 35 35 35 35 35 35 35 20
240 240 240 240 240 240 240 240 212 212
60
76 61 76 39 34 37 144 123 140 148 138 132
50 48 47 65 59 69 57 63 40 29 33 152 123 135 136 129 123
"tFMpCanning & RetenAnalysis tion, %
13 14 14 14 14
2
.... ....
45 48 46 61 59 65 55 56 40 27 31 157 122 133 129 123 117
Thiamine, Micrograms/lOO G . Canned Fresh Solids Liquid Total
180 160 180-190' 170 170
1941 1942 1942 1942 1942
... ...
EFFECTOF STORAGE ON THIAMINE CONTENTOF CANNED VEGETABLES
145 145 145 149 149 266 266 266 134 134 134 349 349 349 324 324 324
Can Size No.
89 122 194 22 86 _.
54 91 132 50 85 119 84 130 174 28 69 119
53 51 49 64 61 .49 41 45 47 35 39 72 58 64 68 66 64
..4 6
..9 .. 17 9
.. 27 17
..
19 11
..
5 10
tentions as affected by steam blanching I'/z minutes a t 180190" F. and the regular commercid, hot water blanching method. During the blanching of whole, size 3 green beans, there was a 94% retention of thiamine; during the blanching of 1-inch cut beans, the thiamine retention was lowered to 83%. This is due mainly to the greater exposure of "bleeding" surfaces of the 1-inch cut beans to the blanch water. The low retention of thiamine found during the blanching of lima beans is explained by the long period of blanching, which exceeds that most commonly used for this product. The greater surface area of the smaller peas and the tender texture of the fancy peas results in a comparatively greater extraction loss of thiamine upon blanching. The extra standard pack of lima beans retained 58% thiamine upon processing; the standard pack retained 71%. Since both lots of canned lima beans were sterilized together in the same retort, there may be some differences in the heat stability of thiamine in lima beans a t different stages of maturity. The same trend is indicated upon examination of the results for fancy and stand-
2 2 2 2 2 2 2 2 21/2 3 (eylinder)
...
..
ard, size 3 Alaska peas. However, no such differences were noted for fancy and standard Sweet peas. A processing of 35 minutes at 240' F. was approximately 7% more favorable t o thiamine retention in both grades of Sweet peas than 45 minutes at 240' F. The high degree of retention of thiamine in tomatoes and tomato juice is due to the low pH of the tomatoes, which is favorable to thiamine stability toward heat, and also to the comparatively lower temperature of the sterilizing processes. The trend of the results in the studies on the stability of thiamine in canned foods upon storage indicates a decrease in thiamine content. The length of the storage periods were not so long as is desired in comparison with the average commercial storage periods for canned vegetables. Also, the work does not include storage losses starting with the canned products immediately after canning. Work is now in progress a t another laboratory to obtain more extensive information on this subject. On an equal weight basis, the thiamine content of the liquid portion of canned vegetables was found to be equal to or slightly greater than that of the solid portion. This emphasizes the dietary benefit of utilizing the liquid portion which, on the average, represents approximately one third the weight of the canned product. LITERATURE CITED
(1) Adam, W. B.,Chemistry and Industry, 1941,427-9. (2) Conner, R. T., and Straub, G. J., IND.ENO.CHEM.,ANAL.ED., 13, 380 (1941). (3) Farrell, K. T., and Fellers, C. R., Food Research, 7 , 171 (1942). (4) Fellers, C. R., Esselen, W. B., and Fitzgerald, G. A,, Ibid., 5, 495 (1940). (5) Fincke, M. L., Ibid., 4,605 (1939). (6) Harris, R. So, Procter, B. E., Goldblith, S., and Brody, J., Proc. 1st Food Conf. Inst. Food Tech., 1, 109 (1940). (7) Langley, D. D., Richardson, J. E . , and Andes, E. J., Mont. Agr. Expt. Sta., Bull. 276 (1933). (8) Lunde, G., Kringstad, H., and Olsen, A,, Angew. Chem., 53, 123 (1940). (9) Mayfield, H . L., and Richardson, J. E., Mont. Agr. Expt. Sta., Bull. 373 (1939). (10) Moyer, J. C., and Tressler, D. K,, Food Rmearch, 8, 68 (1943). (11) Richardson, J. E.,and Mayfield, H. L., Mont. Agr. Expt. Sts., Bull. 381 (1940). P R B S ~ N Tbefore ~ D the Divirtion of Agricultural and Food Chemistry a t the 105th Meeting of the AMBBICAN CHBMICAL SOCIBITY, Detroit, Mich.
