August 1947
INDUSTRIAL AND ENGINEERING CHEMISTRY
content was retained when lima beans were water-blanched for 8 minutes at 200” F. 6. The practice of blanching successive batches of peas in the same blanching water was not found to he warrant,ed on the basis of greater ascorbic acid retention. 7 . Loss of ascorbic acid from peas during the course of blanching does not always parallel loss of weight (moisture and soluble solids), but the proportion of vitamin losses usually exceeds that of loss of weight. Siiice thcse conclusions concern, for the most part, the more adversc effects of duration and temperature of blanch on vitamin rc>ic‘ntion.it, is not to be construed that eatisfact,ory vitamin retention was not. observed under the more favorable conditions of blanching employed in these studies, nor that commercial cannerit,s operating under optimal conditions do not produce canned foods having a high vitamin content,. ACKVOWLEDGWENT
This n o ] k vab supported in part by a grant from the Siitional Canners Aworiation Can Manufacturers Inqtitute Sutrition Proumm
1007
LITERATURE CITED
B..Univ. of Bristol, Ann. Rept. Fruit and Vegetabk Preseruina Research Sta., p. 20 (1944). (21 -issociation of Official Agricultural Chemists, Official and Tent,& (1) Ada!n, W.
tive Methods of Analysis, p. 357 (1940). (3) Clifcorn. L. E., and Heberlein, D. G.. IXD.E r c . CHSM.,36. 16s
(1944). (4) Feaster, J. F., and Alexander, 0. It., Ihid., 36, 172 (1944) (5) Guerrant, N. B., Vavich, M.G., Fardig, 0. B., Dutcher, R . A.. and Stern, R.M., J . Nutrition, 32, 435-59 (1946).
(6) Krehl, TV. A,, Strong, F. M., and Elvehjem. C. h., 1 s ~Exc, . CHEM.,d s a ~ED., . 15, 4 7 1 (1943). (7) Moore, L. A,, and Ely, R., I t i d . , 13,600 (1941). ( 8 ) >foyer, J. C., and Stota, E., Science, 102, 65 (1945). (9) Retrer, J. S., Van D u p e , F. O., Chase, J. T., and Simpsori. J. I., Food Research, 10, 518 (1945). (10) Snell, E. E., and Wright, L. D., J. B i d . Cham., 139, 675 (1941,. (11) Stokes, J. L., and Martin, B. B.,I b i d . , 147, 483 (1043). (12) \‘avich. >I. G., Stern, R. M.,and Guerrant. N . B.. ISD.ENG. CIICM.,ASAL. ED.,1 7 , 531 (1945). (13) Wadsworth, H. I.. and Wilcox. E. B., J . Am. Dietet. Assoc.. 21. 2S9 (1945). Paper S o . 1357 in the Journal Series of the Pennsylvania Agricultural Ex. perirnent Station.
(Nutritive Value of Canned Foods)
EFFECT OF DURATION AND TEMPERATURE OF BLANCH ON PROXIMATE AND MINERAL COMPOSITION OF CERTAIN VEGETABLES’ 4MIHUD KRAMER AND MARY H. SiMITH University of Maryland, College Park. M d . Studies were made on the effect of the duration, teniperature, and type of blanching on the proximate and mineral composition of peas, green beans, lima beans, and spinach. Steam blanching caused no significant change in the composition of all but spinach, where moderate losses were noted in carbohydrates, ash, and phosphorus contents, and slight pains noted in calcium contents. For the water blanch in general the effect of time was more important than temperature. Carbohydrate losses were most serious in spinach: they reached about 30% of the total found in the unblanched sample, as compared to little over 10% for peas and lima beans, and only about 5% for green
beans. Protein losseb rarely exceeded lo70 for the peas. lima beans, fancj green beans, and spinach, and reached only 57, for the more mature green beans. The mineral constituents were affected in about the same way, but to a greater extent than the carbohydrates; thus, for example. the se\erest water blanch caused a reduction of 51% in the ash content of spinach. The calcium content of green beans was not affected by the water blanch, that of lima beans slightly increased, and that of peas and spinach increased by as much as 79 and 5t%, respectitely. The phosphorus content of spinach was reduced by as much a* .to% but rarely more than 10% for the other vegetables.
P
Adam, Horner, and Stanworth ( I ) reported sugar losses of about 2070 when commodities consisting of small units, such m peas and diced or sliced vegetables, were t.ilanched for 1 minute in water or 3 minutes in steam. The losses increased to about 357, n-hen the duration of the water blanch was increased to E minutes. Large unit commodities, such as potatoes and whole heans, lost only 5 to 20% of their sugars. Prot,ein losses rarely exceeded 20% for the small unit vegetables and 10% for thP large unit vegetabies. Afore information is available for the mineral constituents. particularly calcium. Horner (4) and Lee and Whiteombe (6‘) agree that the calcium content of peas increases as a result of blanching in hard water. Horner ( 4 ) shows similar increases in calcium content for green beans, carrots, potatoes, and spinach, and considerable losses of magnesium, potassium, and phosphorus as a result of blanching of peas, potatoes, and especially spinach, whereas green bcans and carrots retained almost all of
RE\-IOUS investigations on the proximate and mineral
composition of canned foods revealed surprisingly large variations aniong samples of the same commodity (a. I n connection with similar work on vitamin content (3)this xork was undertaken to sho\v the effect of variations in blanching treatment on the composition of vegetables for canning. There is littlc information available concerning the loss of solu1)le carbohydrates and proteins as a result of blanching. Magoon and Culpepper ( 7 ) reported a loss of about 307, of the total sugar and up to 10% of the protein in peas, and losses of over half the total sugars and 10% of the proteins from spinach. Horner (4) reported losses of 237, sugar and 227, proteins from peas, 8% sugar and no protein loss from beans, and 13% sugar and l8yc protein loss from carrots, m-hen each vegetable was blanched for 3 minutes a t 100” C. 1 This is the twenty-fourth of a series of papers dealing with the general subject “Nutritive Value of Canned Fooda.”
INDUSTRIAL AND ENGINEERING CHEMISTRY
1008
TABLE I. CHANGES IN PRO~IMATE AND MINERAL COMPOSITION O F CANNED PEASAS A RESULT OF BLANCHING, FILL-IN WEIGHTBASIS Type of Blanch,
Sone Water Water Water Water Water Water Water Water Water Steam Steam Steam
hloisture
Proximate Compn., % Protein Fat Fiber Ash
Fancy Grade 82.19 81.99 82.65 83.24 82.22 82.65 84.28 81.93 83.04 83.76 81.14 80.54 80.74
Sweet Peas, Xo, 4 Sieve Size 5.04 0.36 1.86 0.56 5.03 0.40 2.04 0.60 4.82 0.37 2.09 0.54 4.75 0.34 2.11 0.51 4.94 0.40 2.11 0.56 4.63 0.38 2.14 0.55 4.57 0.36 1 . 9 7 0.58 4.99 0.41 1.99 0.55 4.76 0.38 1.92 0.56 4.46 0.35 1.93 0.55 5.42 0.38 2.06 0.61 5.75 0.42 2.24 0.56 5,57 0.40 2.42 0.57
Blanching Temp., Time, O F. min.
, I
.
.
180 180 180 190 190 190 200 200 200 210 210 210
. 3 6 9 3 6 9 3 6 9 1 2 3
Mineral Compn , Mg./100 G . CarboGalPhoshydrates cium phorus
9.99 9.89 9.53 9.05 9.77 9.66 8.24 10.13 9.34 8.95 10.39 10.49 10.30
It,
25 30 33 29 31 32 30 32 34 22 22 23
63 74 61 61 65 63 65 67 65 62 70 78 79
Vol. 39, No. 8
uct before blanching may be compared to its composition as affected by the blanching treatments. For certain purposes, such as comparisons of changes in the proportions of the proximate components, the data may be more informative when recalculated on a solids basis or on the basis of the moisture content of the raw material before blanching. Such recalculations may he readily made from the data included in the tables. PEAS
D a t a on the effect of blanching on the proximate and mineral composition Standard Grade Sweet Peas, No. 4 Sieve S i z ~ of peas are presented in Table I. Steam 77.10 5.96 0.46 2.34 0.71 13.45 63 1u7 blanching reduced the moisture content None ... 180 'i 76.16 6.36 0.48 2.48 0.65 13.88 40 108 Water by 1 to 2%. The corresponding small 6 77.07 6.34 0.42 2.31 180 0.60 13.26 42 106 Water 180 Water 9 77.20 6.18 0.46 2.42 0.56 13.18 44 104 increases in all the components there12 78.82 180 5 . 8 8 0 50 2.42 0.51 11.87 45 117 Water 3 76.75 6.12 0.48 2.52 0.63 13.50 40 110 fore indicate that there was little or no 190 Water 6 77.57 6.01 2.38 0.56 0.51 12.97 43 105 190 Water change in the proximate or mineral com9 78.77 5.84 0.48 2.45 0.53 11.93 42 96 190 Water 190 Water 12 78.80 5.64 0.50 2.53 0.56 11.97 48 98 position of the peas as a result of steam 3 76.80 6.19 0.49 2.57 0.63 13.32 42 106 200 Water blanching. 6 77.56 5.78 0.53 2.40 0.62 13.09 46 107 Water 200 9 78 30 5.73 200 0.51' 2 . 4 3 0.60 12.41 48 105 Water Regardless of temperature, the short12 79.25 5.33 0.50 200 2.50 0.54 11.88 45 99 Water 210 1 75.62 6.24 0.56 2.57 0.83 14.15 18 119 water blanching period of 3 minutes Steam 3 76.20 6.19 0.51 2.54 0.82 13.74 38 119 210 Steam 6 78.38 6.29 0.50 2.36 0.82 11.75 34 112 caused a slight 1055 in moist,ure con2 10 Steam tent. As the blanching time was increased, however, the moisture content increased with time and temperature until the 9-minute blanch a t 200' F. resulted in a 1.57% increase in the last three minerals. Lee and FVhitcombe (6) report no moisture for the fancy peas, and the 12-minute blanch a t 200" F. significant change in iron content as a result of blanching in hard, resulted in a 2.15% increasr in moisture for the standard peas carbonated, or iron-containing waters. According to Adam, The increases in moisture content were compensated for by Horner, and Stanworth ( I ) , mineral substances in general were corresponding decreases in protein, ash, and carbohydrate conlost approximately a t the same degree as the sugars. tents. Almost one third of the loss in solids q-as accounted for by the proteins, and about two thirds by the carbohydrates. SAMPLE TESTING Although considerable losses were recorded for the ash content, The preparation of the samples is described in dctail by Guerespecially of the standard peas, the total ash content of about 0.5% rant et al. (3). The proximate and mineral constituents n-ere did not influence materially the general proximate compo4tion. determined from aliquots of the samples prepared by Guerrant et al. for moisture determination as follows: T a B L E 11. CHANGES I N PROXIMATE A S D LIINERAL COMPOSITION O F GREENBEAKS Equal weights of the properly blanched AS h RESULT O F BLAKCHING, FILL-IStJ'EIGHT BASIS product and distilled water were placed in No. 2 cans, closed, and 21iner a1 Compn., sterilized by heating in a retort under Blanching Proximate Compn., (5 hIg./100 0. Type the usual processing conditions. Beof Temp., Time, .LloisFroCarboGalPhosBlanch ' F, inin. cure tein Fat Fiber .Ish hydrates cium phorus fore proceeding with the analyses, the contents of two cans were pureed Whole Green Beans, S o . 2 Sieve Sine 111 a Karing Blendor to form a homoXone 1.64 ... 92.10 0.13 0. ti2 1.00 4.51 54 :10 Water i66 1 1 . 5 5 0.16 92.29 0.57 0.94 4.49 geneous puree. Analyses were made 52 31 Water 160 1.54 0 . 1 0 3 92.33 0.97 0.56 4.50 51 28 on appropriate aliquok of the pureed Water 160 5 1.48 0.10 0.93 92.46 0.55 4.48 51 29 Water 180 1 1 . 6 1 0.11. 0.94 92.27 0.57 4.50 53 :3 1 material. \Vater 180 3 1.53 0.12 92.33 0.95 0.56 4.51 31 Water 5 180 1 . 4 9 0.16 92.33 0.91 0.56 4.55 Moisture, protein, fat, fiber, ash, :;, 38 Water 200 1 1.61 0.16 92.26 0.88 0.57 4.52 50 30 calcium, and phosphorus Tere deterKater 3 200 1.54 0.18 92.55 0.89 0.53 4.31 29 50 Water 200 5 1.45 0.18 92.68 0.85 0.55 4.28 28 51 mined by methods approved by the Steam 210 1 92.11 0.17 1 75 0.92 0.65 4.40 52 26 Steam 210 3 92.02 1 . 6 9 0.17 0.90 0.62 Association of Official Agricultural 4.60 28 53 Steam '10 5 1 74 0.18 9 1 84 0.89 4.70 0 65 54 98 Chemists ( 2 ) . Carbohydrates other than crude fiber were determined by Cut Green Beans, No. 5 Sieve Size difference, and iron by a modification 160 1 Water 39.74 2.03 0.32 1.17 0.68 6.06 40 35 R'ater 1.99 3 160 90 00 0.32 1.21 0.64 5.84 of Stugart's method (6). 35 40 160 5 Water 1.99 0.28 89.84 1.21 0.63 6.05 39 36 The data are presented in Tables Water 180 1 2.04 89.58 0.26 1.24 0.69 6.19 39 35 180 3 89.95 2.03 0.32 Water 1.18 0.67 5.85 40 35 I to IV. Since the sample cans con180 5 1 . 9 1 0.24 Water 90.10 1 . 2 5 0.59 5.91 44 35 tained equal parts of the blanched 200 1 89.90 2.00 0.23 1.21 0.61 Water 6.05 43 83 200 1.78 0.22 Water 3 90.56 1.21 0.55 42 5.68 32 product and distilled water, the reWater 200 5 1.94 90.14 1 . 2 5 0.57 0.22 5.88 44 33 2 . 1 2 210 1 89.22 1.34 0.65 0 . 2 1 Steam 6.46 40 36 sults were multiplied by 2 and re210 3 89.54 1 . 9 8 0.22 Steam 1.32 0.64 6.30 44 34 a10 5 39.44 2.06 0.24 Steam ported on the fill-in wet-weight basis, 1 . 3 0 0.62 6.34 43 36 so that the composition of each prod-
INDUSTRIAL AND ENGINEERING CHEMISTRY
August 1947
T ~ B L111. E
CHANGES IN PROXIMATE AND MINER.4L COMPOSITIOX O F
RESCLTOF BLANCHING, FILL-INWEIGHTBASIS
AS .4 Type
of
13lanch \-one Water Water Water Water Water Water Water Water Water Water Water Water Jteam dteam
