响应面法优化蛋壳豆渣发酵工艺生产高钙饲料

大量废弃的蛋壳和湿豆渣是良好的钙和氮素资源,为探索一条解决两类农业废弃物合理利用的新途径,本实验选用枯草芽孢杆菌、植物乳杆菌和粪肠球菌固体生料发酵鸡蛋壳、豆渣混合物。以乳酸钙含量为指标,利用单因素实验研究了豆渣蛋壳比例、固水比、葡萄糖添加量、接种量、混合菌种比例、发酵温度和发酵时间对发酵产乳酸钙的影响,并利用响应面试验优化发酵产乳酸钙的工艺条件。实验结果表明:在豆渣蛋壳比例90:10、枯草芽孢杆菌:植物乳杆菌:粪肠球菌为1:1:1(体积比)、固水比1:2.5、葡萄糖添加量15.6%、接菌量14.7%、发酵温度37℃、发酵6 d的条件下,蛋壳豆渣混合物中的乳酸钙含量达到13.58%。与发酵前相比,发酵后豆渣饲料中的游离氨基酸、乳酸钙含量显著提高(P<0.05),pH、粗脂肪、可溶性蛋白显著降低(P<0.05)。综上所述,利用益生菌发酵蛋壳与豆渣,可以制备一种高钙饲料。

Optimized the Fermentation Process of Eggshell and Soybean Dregs to Produce High Calcium Feed by Response Surface Methodology

Discarded eggshells and wet soybean dregs are rich sources of calcium and nitrogen. This study aimed to establish a novel optimized method for the utilization of agricultural wastes. Eggshells and soybean dregs were the primary raw materials used in this study. Bacillus subtilis, Lactobacillus plantarum, and Enterococcus faecalis were the probiotic strains selected for mixed fermentation. Harman’s single-factor test based on the assessment of calcium lactate content in the fermented forage was used to screen the following process parameters: Ratio of soybean dregs to eggshells, solid to water ratio, addition of glucose, inoculation amount, ratio of probiotic strains, fermentation temperature and duration. Optimum fermentation conditions were determined using response surface methodology. The results revealed that the conditions required for optimum fermentation were as follows: Soybean dregs to eggshells ratio of 90:10, solid to water ratio of 1:2.5, addition of 15.6% glucose, inoculation amount of 14.7%, Bacillus subtilis, Lactobacillus plantarum and Enterococcus faecalis in the ratio of 1:1:1 (v/v), and fermentation duration of 6 days at 37 °C. The amount of calcium lactate in the fermented forage was 13.58%. Free amino acid and calcium lactate concentrations in the fermented forage were significantly higher (P<0.05) in comparison to their concentrations in the raw materials. A significant decrease in pH and concentrations of crude fat and soluble protein in the fermented forage was also observed (P<0.05). In conclusion, this study established a novel optimized method for the production of high calcium feed from eggshells and soybean dregs using probiotic fermentation.