摘要:

SUMMARY–A study was undertaken to determine the effect of the dry‐roasting process on the quality of soybean protein as indicated by amino acid analyses and PER. Amino acid analyses revealed losses in tryptophan, available and total lysine, cystine and histidine of 35, 31, 17, 15 and 6% respectively. These losses are reflected in both the essential amino acid index (EAAI) and PER. Average EAAI values decreased with increasing degree of roast (68.4, 67.7 and 63.8) compared with a value of 71.4 for the raw samples. The PER values for the same roasted samples were 1.70. 1.46 and 1.28 respectively. A depressed PER value of 0.6 was obtained for the raw sample because of anti‐nutritional factors in the raw beans. Results indicate that the dry roasting process is a means of producing a palatable, nutritious food from soybeans. However, optimum palatability is gained at the expense of protein utiliz

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1971.tb02018.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

SUMMARY–Full‐fat soy flours prepared by the extrusion process were shown to have good nutritive value, flavor, and stability. A flour cooked to a nitrogen solubility index (NSI) of 30 stored well, but the addition of tertiary butyl hydroquinone was necessary to prevent rancidity in flours cooked to 19 and 11 NSI values. The 30 NSI flour was more yellow than a commercial flour cooked to the same degree by a different process. When soy flours were compared in bread to 3 and 6% nonfat dry milk on an equivalent protein, fat, and reducing sugar basis, baking properties were similar. At 15 and 20% levels of soy flour, loaf volume decreased less with the extruded products than with nonextrusion‐processed soy

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1971.tb02019.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

SUMMARY–About 14 million Ib of soybean whey protein of high biological value is disposed of as waste based on estimated production figures for soybean concentrates and isolates. An estimated 5–7% annual increase in consumption poses serious waste disposal problems and alternates should be sought. By simulated commercial procedures, yield and protein content of soybean whey were determined. Whey solids account for 2–28% of original nitrogen in dehulled, defatted flakes. Whole whey protein was prepared by dialysis, and whey was also fractionated by heating into heat‐coagulable and supernatant proteins. Whole whey protein has a good balance of essential amino acids when compared with a system followed by the Food and Agricultural Organization of United Nations based on hen's egg protein. Heat‐coagulable and supernatant proteins varied greatly: heat‐coagulable fractions had 42% of the sulfur amino acid content but 181% of the tryptophan content of hen's egg protein; supernatant protein had 142% of the sulfur amino acid content but only about 60% of the isolevcine, valine, leucine and tryptophan content of hen's egg protein. All three whey protein fractions would be suitable for additi

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1971.tb02020.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

SUMMARY–Existing ultrafiltration/reverse osmosis technology provides a means of fractionating and concentrating cheese whey into liquid fractions containing a variety of protein: lactose ratios. These ratios may range from about 1:8 (raw whey) through 3:5 (a “skim milk equivalent”) to 2:1 or higher. If a two‐ or three‐stage ultrafiltration system were used with water injection between stages, a product with a protein:lactose ratio of 20:1 could be obtained. The exact protein:lactose ratio in the concentrate stream is a function of the permeability and selectivity characteristics of the membrane, and the system design and operating conditions. Some of the sanitation problems associated with the introduction of these new unit operations in the dairy and food processing industries are also treated

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1971.tb02021.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

SUMMARY–Soybean cheeses were prepared from blends of skim milk powder and soybean milk in which the skim milk powder contributed 0, 25, 50 and 75% of total dry weight. The amount of skim milk had little effect on the flavor of the finished cheese, due to the dominating effect of the beany flavor of the soybeans. Similarly, the skim milk had little effect on the texture of the finished cheese, indicating that only a small amount of fibrous matter from the soybeans is necessary to impart a mealy texture to the product. Mold ripening resulted in desirable changes in texture, but these were offset by the development of bitter flavor

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1971.tb02022.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

SUMMARY–Permeation rate, retention, and solute flux during reverse osmosis of whey and whey fractions were compared using two types of cellulose acetate membranes. When the feed solutions contained no molecules larger than lactose, concentration polarization had little influence on performance except at the highest available driving force (applied pressure minus difference between osmotic pressures of the feed and permeate = 37.8 atm). With the more complex feeds (whey and deproteinized whey), both concentration polarization and fouling of the membrane occurred. Concentration polarization decreased both permeation rate and retention. Fouling decreased permeation rate, but its influence on retention was variable and depended principally on the feed, the solute, and the available driving force. Proteins and other macromolecules in whey had a greater influence on performance during reverse osmosis than smaller solute molecules. With whey as feed, maximum permeation rates were achieved at low available driving forces (10‐12 atm), and were similar for the two types of membranes (about 1 ml/cm2*sec). Increasing the available driving force increased retention and therefore reduced solute flux. Choice between the two membranes requires a compromise between extent of desalting and loss of lactose in the perme

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1971.tb02023.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

SUMMARY–The phenomenon of concentration polarization operates to reduce the efficiency of solvent‐solute separation in the processing of foods by reverse osmosis. The viscous nature of most food concentrates aggravates the problem. Disrupting the boundary layer by mechanically inducing turbulence in the fluid stream improves the permeation efficiency. Flux improvement of up to 3‐fold is possible with dynamic turbulence promotion involving plastic spheres moving randomly with the orange juice concentrate. Concentrate (and sphere) movement is pulsed alternately from one end of the membrane flow channel to the other. The spheres are confined within the flow channel to avoid the problem of moving them through the recycling pumps. A net movement of concentrate results when the pump volume is greater in one direction than the other. The permeation rate with dynamic turbulence promotion does not drop off significantly with time. The long‐term effects of sphere movement on the membrane surface are not known but are believed not to be

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1971.tb02024.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

SUMMARY–Measurements of the moisture and temperature distributions were made during freeze‐drying beef at a pressure of 1 torr. The transient moisture distributions measured with gamma ray techniques indicate that the phase change region would have a thickness less than 3/16 in., that no drying takes place until the phase change region reaches a given position, and that no additional drying occurs after the phase change passes a given position. A careful study of the data showed that the drying rate was influenced by heat transfer through the frozen region to the phase change posit

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1971.tb02025.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

SUMMARY–A problem arises if juice extracted from raw carrots is heated to about 180° before or during conventional canning practices. An unsightly, unappetizing coagulum forms and the color of the juice precipitates with the coagulum. The coagulum is not as evident if the carrots are heated 5 min in water prior to juice extraction, but the juice loses some of its bright‐orange color. The canned juice extracted from carrots heated 5 min in a .05 N acetic acid solution does not coagulate and the amount of juice which can be extracted from the carrots is 3.3% greater than that from carrots heated 5 min in water. The centrifuged juice from acid‐treated carrots had a brighter orange color than juice from the water‐treated carrots. The color notation was Rd, 23.7, a, 30.4 and b, 34.8 for juice from acid‐treated carrots compared with a notation of Rd, 19.2, a, 24.4 and b, 31.4 for the juice from water‐treated carrots. The canned juice extracted from raw carrots had less pectic substances and starch and about the same amount of protein as the canned juice from the carrots heated in water or .05 N acetic acid, but the canned juice from raw carrots coagulated. The juice from carrots heated in acid does not form a coagulum and maintains its orange color, probably because of the action of the heat and acid on the protoplasmic liquid of the cell before or immediately after the cell

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1971.tb02026.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

SUMMARY–Two varieties of sweet potatoes were canned at three storage intervals, six buffered pH levels, and two holding times to determine the influence on color, firmness, carbohydrates and other constituents. Color and firmness were improved when the pH was decreased from 8 to 3. There was an increase in brightness of color and firmness by holding peeled sweet potatoes 24 hr in buffers before canning. The sugars and phenolic substances were leached out during holding. Total polyphenols decreased with an increase in pH although tannic and chlorogenic acids were not changed appreciably. There was a decrease in starch and hemicellulose as a result of storage; whereas, water‐ and Calgon‐soluble pectin were not affected. Starch decreased with an increase in pH regardless of other variables. Water‐soluble pectin increased when pH was altered up or down from the normal pH of canned sweet potatoes of approximately 6.0. In comparison, Calgon‐soluble pectin and hemicellulose reacted inversely to pH. It appeared that pH had a far greater effect on color and firmness than length of post‐harvest storage of raw product after curing and other variables because of the direct effect on carbohydrate transformations and di

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1971.tb02027.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY