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|標題:||Study on Solid-state Fermentation of Soybean Meal by Aspergillus oryzae for Removal of Oligosaccharides and Allergenic Proteins|
利用Aspergillus oryzae 固態發酵處理黃豆粕以去除寡醣暨過敏性蛋白質之研究
Aspergillus sp. Aspergillus sp.
|摘要:||大豆粕(soybean meal；SBM)是大豆經過抽油加工後主要的副產物，因富含蛋白質(40%)，故常被當作家畜飼料中蛋白質的主要來源。唯豆粕中含有抗營養因子，降低其利用率。本研究旨在探討利用米麴菌(Aspergillus oryzae)在固態發酵模式下去除大豆粕之抗營養因子：包括脹氣因子(寡醣類)與抗原蛋白質(β-conglycinin和glycinin)之可行性。
首先進行發酵基質前處理，發現豆粕吸水力極佳，其與水比例為1:2.5以上時吸水之程度可達飽和，而加熱蒸煮過之豆粕其水分含量值偏高因此可省略此步驟。利用三角瓶(250 ml)進行A. oryzae之豆粕固態發酵培養最適培養條件為：豆粕與水比例1:1、接種量5%以及培養溫度為25℃，α-半乳糖苷酶(4.52 U/g)和酸性蛋白酶(109.85 U/g)的活性最高，且粗蛋白質含量增加10.73%。其次利用麴盤式進行豆粕之固態發酵培養，其最適培養條件為：豆粕與水比例2:1、接種量1%、培養溫度30℃及相對溼度90%下，培養時間30~35小時，此時有較佳活性的α-半乳糖苷酶(4.83 U/g)和酸性蛋白酶(43.05 U/g)，且能完全消除豆粕中的寡醣以及抗原蛋白質β-conglycinin，並降低glycinin含量。粗蛋白質和胺基酸態氮含量也分別增加為51.43% 和0.45%。
Soybean meals have been used extensively as protein sources in animal feedstuffs because of their high protein content (around 44%). However, the thermo-stable anti-nutritional factors, i.e., allergenic proteins (mainly β-conglycinin and glycinin) and flatulence-producing factors (mainly stachyose and raffinose) that commonly exist in these soybean meals will affect the growth and health of animals and have limited their use in young animal diets. The purpose of this study was to investigate the factors affecting the solid-state fermentation condition of soybean meal by koji-mold Aspergillus oryzae in order to reduce anti-nutritional factors and improve its nutritional value. Pre-treatment of raw material before fermentation was investigated. The water absorption ability was good for soybean meal. The moisture content reached equilibrium when ratio of soybean meal to water was at 1: 2.5, and which was independent of soaking time. Cooking methods had no effect on moisture content and could be omitted. The optimum fermentation conditions performed in Erlenmeyer flasks (capacity 250 ml) were established. The optimal ratio of soybean meals to water was 1:1 (moisture content 58.82%), and the fermentation was performed at 25℃ for 6~7 days with inoculum size at 5% (v/w). Peak activities of α-galactosidase and acid protease obtained were 4.52 and 109.85 U/g, respectively. The optimum solid-state fermentation conditions by tray method were established. The optimal ratio of soybean meals to boiled water was 2:1 (moisture content 41.09%), and the fermentation was performed at 30℃ under 90% RH for 30~35 hr with inoculum size at 1% (v/w). Maximumα-galactosidase activity and acid protease activity obtained were 4.83 and 43.05 U/g, respectively. The oligosaccharides (stachyose and raffinose) of soybean meal were removed after fermented for 42 hr. Theβ-conglycinin of allergenic protein was also removed and the amount of glycinin decreased. Moreover, crude protein content and the amino nitrogen content of soybean meal increased after fermentation for 30~35 hr, and the maximum values obtained were 51.43% and 0.453%, respectively. The optimum temperature and pH for both α-glactosidase and acid protease activity from crude enzyme solution of a fermented soybean meal (24 hr) were determined. The optimum temperature of α-galactosidase and acid protease activity were 47℃and 52℃, respectively. The optimum pH of α-galactosidase and acid protease activity were 4.5 and 2.6 U/g, respectively. These two enzymes were stable in the temperature range of 37-52℃. The optimum conditions of limited enzymatic hydrolysis of 24 h fermentation were determined. The ratio of fermented soybean meal to water was 1:2, and the reaction was carried out at pH 3.0 and 42℃ for 1 hr. Under this condition, all stachyose and part of raffinose in the fermented soybean meal were removed. The β-conglycinin of allergenic protein was degraded and the amount of glycinin also decreased considerably. It is concluded that solid-state fermentation of soybean meal by Aspergillus oryzae produced high levels of α-galactosidase and acid protease, and thereafter increased crude protein and amino nitrogen content. Contents of both flatulence-producing factors and allergenic proteins were largely removed. Nutritional value of soybean meals by such solid-state fermentation will be considerably upgraded.
|Appears in Collections:||食品暨應用生物科技學系|
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