Study On The Fermentation Of Silkworm Pupa With Multi-strains

Silkworm pupa, as the byproduct of the silk reeling, was rich in protein and other nutrients. However, the utilization of silkworm pupa was just the beginning, and this valuable resource was not developed or utilized to the best advantage. This study aimmed at making good use of protein resources, enriching the flavourings and looking for a new way for the deep processing of silkworm pupa, which was a good way to realize the effective use of silkworm pupa resource.Taking the silkworm pupa as the main material, the optimum stain for koji-making was confirmed by screening different aspergillus oryzaes. The influences of time and temperature of koji-making, moisture content of substrate, carbon source, additive amount, and inoculum amount were discussed. Basted on the research above, the influence of brine concentration, proportion of saline to brewing materials, temperature and time on fermentation, and adding yeasts on fermentation, were studied. Besides, the fermentation without salt by adding totarols was also discussed.The optimum stain was confirmed to be As3.042by screening different stains. By single factor experiment, the optimal conditions for koji-making were determined as follows:the weight of fresh silkworm was about170g, the time and temperature for koji-making were72hours and30℃, the moisture content of substrate was40%, the inoculum amount was0.5%, taking glucose as the main carbon source and its additive amount was1%. Under the best process of koji-making, the max neutral protease activity was2215U/g, the mounts of spores were1.97×109cfu/g, and the amino-acid nitrogen content was1.112g/100mL. Moreover, the smell of silkworm pupa had bettered a great deal after that. The optimal conditions for fermentation were determined as follows:the weight of koji was60g, the brine concentration was12%, the proportion of saline to brewing materials was2:1, set the former12days at40℃, the later8days at45℃as its fermentation time and temperature. The double yeasts and proportion were As2.297:As2.378=1:1,and the inoculum amount was2.4×10’per gram of fermented liquors, and went on with the fermentation for16days at32℃after adding mixed yeasts. By the best fermentation process of koji-making and fermentation, physical and chemical indices for the the first oil were as follows:60grams of dried silkworm pupa with the moisture content about30%could be gotten from170grams of fresh silkworm pupa. The volume of the first oil was105mL, the amino nitrogen content was1.272g/100mL, the content of total nitrogen was1.972g/100mL, the content of total ester was65.264mg/L, the content of soly salt-free solid was15.213g/100mL, and the availability of the nitrogen of the amino acid was64.41%. The product gotten with this process was delicious in taste, and without the foul smell of silkworm pupa.