| 其他摘要 | 菜籽粕高含粗蛋白，而且氨基酸比例均衡，是一种优质的植物蛋白质资源，可以应用于动物饲料及人类食品。但是，由于多种抗营养因子的存在，如硫苷、纤维、植酸和单宁等等，使得大部分菜籽粕得不到有效的利用。为了充分地利用这一蛋白资源，本研究以去除上述抗营养因子为目标，考察了汽爆和微生物发酵两种方法对它们的去除效果，得到了以下的结果。通过单因素试验考察了汽爆过程中菜籽粕细度、装填量、含水量、蒸汽压力和保留时间对硫苷热解率的影响。结果表明菜籽粕的细度和装填量对硫苷的热解率没有显著的影响；低含水量对硫苷的热解也没有影响，但高含水量会降低热解的效果；当蒸汽压力为 1.6 MPa 以上时，硫苷的热解率可以在 180 s 以内达到 99%；汽爆之后（1.6 MPa，180 s）赖氨酸、精氨酸、天冬氨酸、胱氨酸和甲硫氨酸的含量显著下降，分别下降了 41%、44%、14%、5%和 12%；中性洗涤纤维的含量没有显著的变化，植酸和单宁的含量略有下降。上述结果表明，汽爆处理只对硫苷有效；这种方法快速且简单，但会造成氨基酸的损失。通过液态发酵单因素试验比较了米曲霉和白地霉两者的硫苷降解能力，确定将米曲霉用作固态发酵菌株。通过单因素实验确定米曲霉的最佳固态发酵条件为：10 g 菜籽粕、4 g 麸皮、2 mL 接种量、12 g 水，30℃发酵 48 h，在此条件下硫苷的降解率达到 90%左右，表明微生物固态发酵法也可以有效地去除硫苷。通过单因素实验确定绿色木霉的最佳固态发酵条件为： g 菜籽粕、 g 水、10820%接种量、培养温度 30℃、发酵时间 96 h、1.5% NH4NO3、0.15% CaCl2 和 0.15%吐温-80。在此条件下中性洗涤纤维（NDF）的降解率仅有 25.3%，表明微生物固态发酵法不是去除纤维的有效方法，另外，汽爆菜籽粕的发酵结果与未汽爆的样品一致，表明汽爆处理没有影响中性洗涤纤维的降解率。通过固态发酵比较了枯草芽孢杆菌、蜡样芽孢杆菌和混菌降解植酸和单宁的能力，发现枯草芽孢杆菌降解植酸的能力比较强，蜡样芽孢杆菌降解单宁的能力比较强，两者混菌发酵的效果优于单一菌种的发酵效果。通过单因素实验确定了最佳的混菌固态发酵条件：接种比例（枯草芽孢杆菌∶蜡样芽孢杆菌） 2∶1，为麸皮添加量为 4 g，添加水量为 16 g，接种量为 6%，发酵温度为 30℃，发酵时间为 48 h。在此条件下植酸的降解率为 65.6%，单宁的降解率为 63.8%，表明微生物发酵法可以有效地去除植酸和单宁。通过单因素试验初步优化了米曲霉和绿色木霉混菌固态发酵的条件，确定接种比例为 1∶1，含水量为 40%，接种量为 25%，最佳的发酵时间为 96 h。通过正交试验确定最佳组合为：含水量 40%、接种比例 1∶1、发酵时间 96 h，其它因素任选。在这一条件下，硫苷的降解率为 86.82%，中性洗涤纤维的降解率为19.14%，表明纤维是目前菜籽粕中最难去除的抗营养因子。; Rapeseed meal is a kind of high quality plant protein resource because of high content of crude proteins and well-balanced amino acids. Rapeseed meals have been used in animal feed and human food, but most of them can’t be utilized effectively due to the presence of anti-nutritional components including glucosinolates, fiber, phytate and tannins etc. In order to make good use of them, steam explosion and solid-state fermentation were tested in this work to reduce anti-nutritional factors. Results are listed as follows.The effects of fineness, feeding volume, water content, and steam pressure, retention time on the thermolysis ratio of glucosinolates during the steam explosion process were investigated with single-factor experiments. Results showed that the fineness of rapeseed meals and feeding volume had no significant effects on the thermolysis of glucosinolates. Low water contents didn’t influence the reduction of glucosinolates, but high ones hindered the thermolysis of them. When the steam expressure was 1.6 MPa or higher, the reduction ratio of glucosinolates reached 99% within 180 s. After the explosion (1.6 MPa, 180 s), the contents of some amino acids including Lys, Arg, Asp, Cys and Met decreased significantly by 41%, 44%, 14%, 5% and 12% respectively. The content of neutral detergent fiber (NDF) had no significant changes. Phytate and tannins decreased slightly. These results indicated that only glucosinolates are influenced by steam explosion. Though it is a fast and simple method, it will make losses of amino acids.The degrading capabilities of glucosinolates were compared between Aspergillus oryzae and Geotrichum candidum in single-factor liquid-state fermentation tests. Results showed that Aspergillus oryzae was more suitable for solid-state fermentation. The optimal fermentation conditions determined by single-factor experiments were 10 g meals, 4 g bran, a inoculation amount of 2 mL, 12 g water, 30 °C and 48 h. Under these conditions, the reduction ratio of glucosinolates was about 90% which indicated that solid-state fermentation is also an effective detoxification method.Trichoderma viride was used to degrade fiber of rapeseed meals. The optimal fermentation conditions determined by single-factor experiments were 10 g meals, 8 g water, a inoculation amount of 20%, 30 °C and 96 h. Furthermore, 1.5% NH4NO3, 0.15% CaCl2 and 0.15% Tween-80 were also added. Under these conditions, the reduction ratio of NDF was only 25.3%, which indicated that solid-state fermentation is not an efficient method to remove fiber. In addition, rapeseed meals treated by steam explosion were also fermented and the reduction ratio of NDF was equal to that of untreated meals which showed steam explosion has no effect on the degrading ratio of NDF.The degradation of phytate and tannins were compared among Bacillus subtilis, Bacillus cereus and mixed strains in solid-state fermentation experiments. Results showed that B. subtilis was stronger to degrade phytate and B. cereus was more advantageous to reduce tannins, but mixed strains were the best to both phytate and tannins. The optimal solid-state fermentation conditions determined by single-factor experiments included an inoculation ratio of 2 : 1 (B. subtilis : B. cereus), 4 g bran, 16 g water, an inoculation amount of 6%, 30 °C and 48 h. Under these conditions, phytate was reduced by 65.6% and tannins were 63.8% which indicated that solid-state fermentation is effective to remove phytate and tannins.The solid-state fermentation conditions of Aspergillus oryzae and Trichoderma viride were preliminary optimized by single-factor experiments. Results were an inoculation ratio of 1 : 1, a water content of 40%, an inoculation amount of 25% and a fermentation time of 96 h. The optimal combination determined by orthogonal tests were a water content of 40%, an inoculation ratio of 1 : 1 and a fermentation time of 96 h. Other factors have no significant effects. Under these conditions, glucosinolates were reduced by 86.82% and NDF by 19.14% which showed that fiber is the most difficult to be removed among anti-nutritional factors of rapeseed meals. |
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