Seo W H, Lee H G, Baek H H
Department of Food Engineering, Dankook University, San 29, Anseo-dong, Cheonan 330-714, Korea.
J Food Sci. 2008 Jan;73(1):S41-6. doi: 10.1111/j.1750-3841.2007.00610.x.
Although enzymatic hydrolysates of soy protein isolate (SPI) have physiological functionality, partially hydrolyzed SPI exhibits bitter taste depending on proteases and degree of hydrolysis (DH). To determine proteolysis conditions for SPI, it is important to evaluate bitterness during enzymatic hydrolysis. Taste dilution analysis (TDA) has been developed for the screening technique of taste-active compounds in foods. The objectives of the present study were to evaluate bitterness of enzyme-hydrolyzed SPI by TDA and to compare bitterness of SPI hydrolysates with respect to kinds of proteases and DH. SPI was hydrolyzed at 50 degrees C and pH 6.8 to 7.1 to obtain various DH with commercial proteases (flavourzyme, alcalase, neutrase, protamex, papain, and bromelain) at E/S ratios of 0.5%, 1%, and 2%. The DH of enzymatic hydrolysates was measured by trinitrobenzenesulfonic acid method. The bitterness of enzymatic hydrolysates was evaluated by TDA, which is based on threshold detection in serially diluted samples. Taste dilution (TD) factor was defined as the dilution at which a taste difference between the diluted sample and 2 blanks could be detected. As DH increased, the bitterness increased for all proteases evaluated. Alcalase showed the highest TD factor at the same DH, followed by neutrase. Flavourzyme showed the lowest TD factor at the entire DH ranges. At the DH of 10%, TD factor of hydrolysate by flavourzyme was 0 whereas those by protamex and alcalase were 4 and 16, respectively. These results suggest that TDA could be applied for the alternative of bitterness evaluation to the hedonic scale sensory evaluation.
尽管大豆分离蛋白（SPI）的酶解产物具有生理功能，但部分水解的SPI会因蛋白酶和水解度（DH）而呈现苦味。为了确定SPI的蛋白水解条件，评估酶解过程中的苦味很重要。味觉稀释分析（TDA）已被开发用于食品中呈味活性化合物的筛选技术。本研究的目的是通过TDA评估酶解SPI的苦味，并比较SPI水解产物在蛋白酶种类和DH方面的苦味。在50℃和pH 6.8至7.1条件下，使用商业蛋白酶（风味酶、碱性蛋白酶、中性蛋白酶、木瓜蛋白酶、木瓜蛋白酶和菠萝蛋白酶）以0.5%、1%和2%的酶/底物（E/S）比例水解SPI，以获得不同的DH。通过三硝基苯磺酸法测定酶解产物的DH。通过基于系列稀释样品中阈值检测的TDA评估酶解产物的苦味。味觉稀释（TD）因子定义为能够检测到稀释样品与两个空白之间味觉差异的稀释倍数。随着DH的增加，所有评估的蛋白酶的苦味均增加。在相同的DH下，碱性蛋白酶的TD因子最高，其次是中性蛋白酶。在整个DH范围内，风味酶的TD因子最低。在10%的DH时，风味酶水解产物的TD因子为0，而木瓜蛋白酶和碱性蛋白酶水解产物的TD因子分别为4和16。这些结果表明，TDA可用于替代享乐尺度感官评价进行苦味评估。
