大豆蛋白热变性程度对豆腐品质的影响

本文主要研究了豆腐加工过程中 ,生豆浆在不同加热处理条件下对豆腐强度和失水率的影响 ,得出豆浆在 95℃ ,保温 10min的加热条件下 ,豆腐的强度最大 ,失水率最低。分析了不同加热条件下 ,豆浆中蛋白的表面疏水性和巯基含量 ,得出豆浆蛋白表面疏水性的增加和巯基含量的增多 ,可以使豆腐强度增大 ,失水率降低。本文为豆腐的工业化生产提供了理论依据和有益的参数。     

Heart current in an anatomically realistic human model due to contact with a low-frequency energized source

Distributions of 60 Hz contact current around and inside the heart of the anatomically realistic human body are demonstrated under four scenarios: left hand to both feet, right hand to both feet, hand to hand, and foot to foot. The heart-current ratios and the heart-current factors are calculated. The new numerical method which is partly modified from the conventional scalar potential finite difference (SPFD) method is proposed. It is found that a part of ∼33–40% of the total contact current passes through the heart in three scenarios of one hand to either the other hand or feet, and these heart-current ratios are much larger than the ones reported by Freiberger. Furthermore, the heart-current factor is almost the same as the one in IEC 60479-1 for the right-hand-to-feet path, but is twice as much as the one in IEC 60479-1 for the hand-to-hand path. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Degradation Profiles of Potato Starch Melts Through a Capillary Tube Viscometer

The effects of time‐temperature and strain history on potato starch melts at 150 °C were investigated by use of a capillary tube viscometer. Reciprocating and single extrusions were performed in this study. Shear stress at single extrusion decreased gently as initial heating time increased, while shear stress at reciprocating extrusion decreased rapidly as the number of extrusion strokes increased. A high degree of cold water solubility was obtained by reciprocal extrusion at lower moisture content. From the results of gel filtration it could be concluded that starch molecules were depolymerized by high and reciprocal shear stress. According to these results time‐temperature history was more effective on the depolymerization of starch molecules and degradation of starch granules at higher moisture content, while strain history was more effective at lower moisture content.     

Screening of α-Amylase Suitable for Evaluating the Degree of Starch Retrogradation

To estimate the degrees of starch retrogradation in the complex foods, an enzymatic method using α-amylase from Bacillus subtilis was proposed in the previous report (Tsuge, H. et al.: Starch/Stärke 42 (1990), 213–216). However, actual digestibility of the enzyme for the native starch granules was not checked at that time. A comparative study to see the digestibility of native starch granules was carried out using four different α-amylase preparations and digestion of retrograded wheat starch was tested by two α-amylase preparations. Pancreas α-amylase preparation digested some native starch granules to a great extent, while Aspergillus oryzae enzyme did not digest native starch granules virtually. In conclusion, α-amylase preparation from A. oryzae was an ideal enzyme as the tool to distinguish between raw and gelatinized starches. It was justified for the use of A. oryzae enzyme as well as B. subtilis α-amylase to evaluate the retrograded starch contents in the complex foods.