Fermentation process and bioactivity of peptides prepared from fermented goat placenta residues

Abstract: Goat placenta has been used in Chinese traditional medicine, and the latest studies have demonstrated that it is an animal recourse rich in biological and therapeutic components. At present, the water-soluble immune active peptides were extracted as health care ingredient and so on, and the rest was used to prepare bioactive peptides. Bioactive peptides have been defined as specific protein fragments that have a positive impact on body functions or conditions and may ultimately influence health. The preparation of goat placenta peptides by using enzymatic hydrolysis has been carried out. Nevertheless, little information is available for its immune activity of the hydrolysates, and little information is known about goat placenta peptides prepared by fermentation. In this article, the goat placenta residues were fermented by using Bacillus subtilis to prepare bioactivity peptides. During the fermentation process, the activity of protease, the average chain length of polypeptides, immunoactivity and the antioxidant activity of fermentation broth were investigated. The results revealed that as fermentation time was prolonged, the degree of hydrolysis of goat placenta residues and the activity of protease gradually increased and the average chain length of polypeptides decreased. The immunoactivity and antioxidant activity of fermentation broth increased at first and then reduced. At fermentation of 30 h, the DPPH radical scavenging capacity of fermentation broth reached 87.16%; however, the fermentation broth showed the best effect on proliferation of mouse spleen lymphocytes with fermentation time at 35 h. It can be seen that the surface of the goat placenta residues after fermentation displayed rough and appeared more holes and small particles. The result showed that the goat placenta residues were eroded by the bacteria and its metabolites. The immune and antioxidant activity of fermentation broth were closely depending on the concentration of protein, the EC50 values on hydroxyl radical scavenging activities at 0.667mg/mL. At fermentation with 35 h, the fermentation broth was ultra-filtrated through membranes with different molecular weight cut-off (MWCO). The immunoactivity and antioxidant activity of different fractions were measured. It was found that peptides in the range of >3-10 kDa mainly accounted for the immune activity and peptides in the range of ≤3 kDa mainly accounted for the antioxidant activity. There are certain correlation between the bioactivity of goat goat placenta peptides and its molecular weight. It is recognized that, due to their lower molecular mass, peptides can be more reactive than those with higher Mw, and the bioactivity ability of peptides is also related to the material characteristics, restricted enzyme sites and its space structure. This finding is in agreement with previous studies, which support the fact that the bioactivity ability of peptides is related to molecular mass. Goat placenta has a great potential of supplying peptides. Bioactive peptides can be incorporated in the form of ingredients in functional and novel foods, dietary supplements and even pharmaceuticals with the purpose of delivering specific health benefits. Bioactive peptides derived from goat placenta offer a promising approach for the promotion of health by means of a tailored diet and provide interesting opportunities to the food industry.