大豆胰蛋白酶抑制剂失活方法探讨

胰蛋白酶抑制剂是大豆食品与饲料的主要抗营养因子 ,大豆胰蛋白酶抑制剂的失活能明显提高大豆食品与饲料的营养价值和食用安全性。大豆胰蛋白酶抑制剂的钝化方法有物理、化学、生物还原、酶解、发酵以及天然化合物络合法等。文中介绍了大豆胰蛋白酶抑制剂失活诸方法与技术 ,并对其发展前景作了初步探讨     

大豆胰蛋白酶抑制子失活方法的研究进展

胰蛋白酶抑制子是大豆食品与饲料的主要抗营养因子,这种抑制子的失活能明显提高大豆仪器与饲料的营养价值和食用安全性,大豆胰蛋白酶抑制子的钝化方法有物理、化学、生物还原、酶解、发酵以及天然化合物法等。本文介绍了大豆胰蛋白酶抑制子失活诸方法与技术,并对其发展前景作初步探讨。     

生物法失活大豆胰蛋白酶抑制剂的研究

对生物法失活大豆腋蛋白酶抑制剂进行了研究。测定了豆制品中胰蛋白酶抑制剂的活性;比较了外源蛋白酶失活胰蛋白酶抑制剂的能力,确定了碱性蛋白酶失活胰蛋白酶抑制剂的最优条件为pH值8.88～9.05、温度43.40～44.70℃、酶用量10.44～11.29μL/g、底物浓度6.51%～7.18%。以发芽12h的大豆加工的熟豆乳中胰蛋白酶抑制剂活性降低了83.2%。保加利亚乳杆菌(Lb)、米黑毛霉(M.M)和米根霉(R.O)发酵能有效失活豆乳中的胰蛋白酶抑制剂活性。     

STI的抑制作用及茶多酚作用下STI的失活探讨

大豆中的两种主要的胰蛋白酶抑制剂对胰蛋白酶的活性有很强的抑制作用,随着胰蛋白酶抑制剂的增加,胰蛋白酶活性几科能完全被抑制;茶多酚能有效地和胰蛋白酶抑制剂络合而使抑制剂对胰蛋白酶的抑制作用减弱,同时研究表明茶多酚络合失活胰蛋白酶抑制剂还受温度的影响。     

大豆胰蛋白酶抑制剂失活方法的研究

研究了豆奶中胰蛋白酶抑制剂的三种失活方法;热处理失活、木瓜蛋白酶水解失活及茶多酚络合失活。实验证明,这三种方法都可以有效地使胰蛋白酶抑制剂活性降低。同时都有其最佳失活条件,否则会影响其产品质量或影响胰蛋白酶抑制剂的失活效果;热处理过度,会使豆奶产生焦味和褐变;木瓜蛋白酶的加入量达到最佳值后胰蛋白酶的活性趋于稳定而不再呈上升的趋势,茶多酚的用量过多时,剩余量会对胰蛋白酶产生抑制作用而降低失活效果,同时还探讨了温度、受热时间对茶多酚与大豆胰蛋白酶抑制剂络合物的影响,温度偏高或加热时间过长,络合物就会部分解络,从而达不到预期的效果。     

大豆抗营养因子及其消除方法的研究进展

大豆中含有胰蛋白酶抑制因子和脂肪氧化酶等多种抗营养因子,它们直接影响大豆食品与饲料的营养价值和食用安全性．降低了大豆的利用率。本文综述了胰蛋白酶抑制剂和脂肪氧化酶的抗营养作用以及消除方法的研究进展。     

转基因食品胰蛋白酶抑制剂活性的测定

目的通过测定转基因食品的胰蛋白酶抑制剂活性,为建立转基因食品营养评价标准提供数据。方法首先通过探讨胰蛋白酶-底物-胰蛋白酶抑制剂的剂量反应关系,建立转基因食品胰蛋白酶抑制剂活性测定的最佳反应体系,并以此为基础分析了部分转基因玉米、大豆的胰蛋白酶抑制剂活性及与亲本食品的差别。结果所检转基因食品胰蛋白酶抑制剂活性大多与亲本食品差别不大,尽管个别产品出现胰蛋白酶抑制剂活性增高或降低现象,但都在可接受范围。结论在规范检测技术前提下加强对非转基因食品基础数据建设对制定转基因食品营养评价标准十分必要。     

大豆胰蛋白酶抑制剂研究概况

该文介绍国内外研究大豆胰蛋白酶抑制剂概况,并对其失活和测定方法进行初步探讨。     

固定化酶法分离纯化大豆胰蛋白酶抑制剂

大豆分离蛋白生产中的大豆乳清废水中含有多种生理活性成分,其中大豆胰蛋白酶抑制剂可作为癌症和糖尿病治疗的药物。利用固定化胰蛋白酶分离纯化大豆胰蛋白酶抑制剂可得到高纯度的大豆胰蛋白酶抑制剂。研究结果表明:大豆胰蛋白酶抑制剂通过各阶段纯化后其活性从0.95TIU/mL增高至325.5TIU/mL,纯化程度提高324.6倍,得率0.033%;电泳结果表明:利用固定化胰蛋白酶分离纯化的大豆胰蛋白酶抑制剂有单一谱带,纯化效果明显。     

大豆抗营养因子钝化失活速度的研究

对不同热处理条件下,大豆不同抗营养因子的钝化失活速度进行研究。结果表明,在脲酶完全失活条件下,胰蛋白酶抑制素仍残留一定活性。因此在大豆加工中以脲酶做为抗营养因子失活指标不能全面反映大豆及其制品中抗营养因子的失活状况。     

Preparation of trypsin‐immobilised chitosan beads and their application to the purification of soybean trypsin inhibitor

BACKGROUND: Trypsin inhibitors are among the most important antinutritional factors in legumes. Recent research has shown that soybean trypsin inhibitor (SBTI) exhibits multiple bioactivities, but very few studies on the purification of SBTI are available. Enzymes are commonly used as biospecific ligands in affinity purification of their substrates or inhibitors. The aim of the present study was to prepare trypsin (EC 3.4.21.4)‐immobilised chitosan beads and use them to purify trypsin inhibitor from soybean whey. RESULTS: Compared with free trypsin, the immobilised trypsin had higher thermal and pH stability. The adsorption ratio of SBTI from crude SBTI aqueous solution by trypsin‐immobilised chitosan beads was 33.3%. The purified SBTI obtained by affinity chromatography was characterised by sodium dodecyl sulfate polyacrylamide gel electrophoresis as a single polypeptide band with an M_r of 8.3 kDa belonging to the Bowman–Birk family. CONCLUSION: Trypsin‐immobilised chitosan beads were effectively used in the affinity separation of trypsin inhibitor from soybean seeds, thus indicating that immobilised trypsin may have practical application in the soybean‐processing industry. The results of this study provide a background for further investigation of potential applications of soybean bioactive constituents in the areas of agriculture and food. Copyright © 2008 Society of Chemical Industry     

Removal and recovery of antinutritional factors from soybean flour

An integrated process for removal purification of two antinutritional factors, namely soybean trypsin inhibitor and soybean agglutinin, from soybean flour has been developed. The process is based upon binding of soybean trypsin inhibitor and soybean agglutinin to an immobilized metal affinity chromatography medium, consisting of zinc alginate beads. Both soybean trypsin inhibitor (95%) and soybean agglutinin (94%) could be removed from an aqueous extract of soybean flour. The bound protease inhibitor and lectin could be recovered by washing the zinc alginate beads with 0.05 M imidazole solution and dissolving the beads in 0.01M EDTA, respectively. Recoveries of 89%, in the case of soybean trypsin inhibitor and 81% in case of soybean agglutinin, were possible. Both purified proteins gave single band on SDS–PAGE. Thus, soybean flour, free of these two antinutritional factors, could be obtained. Simultaneously, these two antinutritional factors were purified as value-added products.     

Biochemical Characterization of a Low Trypsin Inhibitor Soybean

A low trypsin inhibitor soybean (LTI) was characterized using electrophoresis, enzyme activity measurements, and gel exclusion chromatography. The protein profiles were similar to a control soybean. Gel exclusion chromatography resulted in two peaks of trypsin inhibitor activity in the control. The first peak, absent in LTI, proved to be Kunitz trypsin inhibitor and was electrophoretically isomorphic. The second inhibitor consisted of at least five isotypes and co-eluted with Bowman-Birk trypsin inhibitor. Shorter heating times were required to inactivate both trypsin and chymotrypsin inhibitor activity in LTI compared to control soybeans. The use of LTI may increase the economic viability of soybeans as protein supplements for humans.     

Effect of soaking,dehulling, cooking and fermentation with Rhizopus oligosporus on the oligosaccharides,trypsin inhibitor,phytic acid and tannins of soybean (Glycine max Merr.), cowpea (Vigna unguiculata L. Walp) and groundbean (Macrotyloma geocarpa Harms)

Soybean, cowpea and groundbean, three locally grown legumes in West Africa, were processed into tempe, an Indonesian-type fermented food. Changes in oligosaccharides, trypsin inhibitor, phytic acid and tannins were monitored during the pretreatments (soaking and soaking–dehulling–washing–cooking) and fermentation with Rhizopus oligosporus. About 50% of raffinose and more than 55–60% of sucrose and stachyose were lost during the pretreatments of the beans. Stachyose decreased during fermentation with a reduction of 83.9%, 91.5% and 85.5% respectively for soybean, cowpea and groundbean while raffinose remained fairly constant. Galactose, the predominant sugar, glucose, fructose, maltose and melibiose increased during the first 30 and 36 h of fermentation of cowpea and groundbean, but decreased thereafter. Soaking the beans for 12–14 h had no effect on the level of trypsin inhibitor of the beans while it increased the phytic acid content to 1.7% in soybean and to 0.8% and 0.7% in groundbean and cowpea. Cooking soaked and dehulled soybean, cowpea and groundbean for 30, 7 and 15 min respectively resulted in 82.2%, 86.6% and 76.2% in trypsin inhibitor. However, a slight increase in trypsin inhibitor was observed during soybean fermentation. Phytic acid decreased during fermentation by 30.7%, 32.6% and 29.1% respectively in soybean, cowpea and groundbean at the harvesting time. Tannins mainly located in seed coat were removed as a result of pretreatments mainly dehulling. These changes are beneficial especially in infant feeding based on cereal and legume-based foods.