Effect of Cooking and Processing on Quantitation of Soybean Proteins

Lupine and soybean are important technological aids for the food industry. However, they are also capable of inducing severe allergic reactions in food-sensitized/allergic individuals. In this context, this work intended to study the combined effects of thermal processing and food matrix on the immunoreactivity of lupine and soybean proteins used as ingredients in bakery and meat products, respectively. For this purpose, the effects of baking, mild oven cooking, and autoclaving on the protein profiles were evaluated, using model mixtures simulating the production of lupine-containing breads and soybean-containing cooked hams/sausages, by native- and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and immunoblotting using specific antibodies. The results showed that lupine gamma-conglutin immunoreactivity was slightly decreased in wheat flour mixtures compared to rice, but it was more pronounced in baked products. In meat mixtures, substantial protein fragmentation was noted after autoclaving, with decreased immunoreactivity of soybean trypsin inhibitor. The analysis of 22 commercial products enabled the identification of lupine gamma-conglutin in four bakery samples and soybean trypsin-inhibitor in five sausages, and further differentiated autoclaved from other milder thermally treated products. Generally, the immunoreactivity of target proteins was reduced by all the tested thermal treatments, though at a higher extent after autoclaving, being slightly altered by the food matrix.

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Rumen protection of heat-treated soybean proteins

Canadian Journal of Animal Science ◽

10.4141/cjas92-008 ◽

1992 ◽

Vol 72 (1) ◽

pp. 71-81 ◽

Cited By ~ 6

Author(s):

B. M. Mosimanyana ◽

D. N. Mowat

Keyword(s):

Soybean Meal ◽

Block Design ◽

Soybean Proteins ◽

Passage Rate ◽

Heat Treated ◽

Ruminal Degradation ◽

In Situ Degradation ◽

Exit Temperature ◽

Forced Air

The effects of processing variables on soybean crude protein (CP) ruminal degradation were investigated. Soybean meal (SBM) was heated in a forced-air oven (90 °C, 1 h) with blood (0, 5, 10 and 20% dry matter) and/or xylose (3 mol mol−1 SBM-blood lysine) in a randomized complete block design. In another experiment, whole soybeans were utilized using the following treatments: raw; roasted (in Gem Co. unit exit temperature 150 °C) and steeped for 0 or 2 h; roasted, flaked (exit temperature 111 °C) and steeped for 0, 1, 2, 3 h or 1 h with 4% xylose and/or 10% blood. Solubility of SBM CP was reduced (P < 0.01) by the addition of xylose, without adverse effects on pepsin-digestible CP and acid detergent insoluble nitrogen. In situ degradation of CP (EDCP), assuming a passage rate of 5% h−1, of SBM was reduced by the addition of blood (P < 0.05) and particularly xylose (P < 0.01). Soybean CP solubility was reduced (P < 0.01) by roasting and flaking (65.6 vs. 17.6% total CP). Not flaking the roasted beans further reduced (P < 0.01) CP solubility (to 10.4%) probably due to less rapid cooling. The EDCP of raw soybeans (87.6%) was reduced by roasting (64.2%), steeping whole (57.6%) or flaked (61.1%) beans. These data support xylose to effectively reduce ruminal degradation of SBM and simple steeping (1 h) with or without flaking to further reduce EDCP of roasted soybeans. Key words: Soybean meal, soybeans, xylose, blood, steeping, protein degradation

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