Study On Feeds With Seaweed

Laminaria japonica belongs to brown algae. It is a large type of economic algae, which enriches in saccharides, alginic acid and mannitol and has great nutritional and economical values. It distributes very wide in the ocean and it is an important kind of feed resourses. In the present study, the effects of mixed fermentation with Acinetobacter junii and Candida utilis, autolysis and Maillard reaction on Laminaria japonica were studied and optimized. After optimization the nutrition, digestibility and flavor of feeds were improved and highly quality of seaweed feeds was obtained. The main results were as follows:1. The effects of different material to water ratio, nitrogen source, inorganic salts, temperature, fermentation period, pH on Laminaria japonica fermentation, with Acinetobacter junii as the germ for fermentation were studied. The results indicated that the optimum conditions for fermentation were as follows:material to water ratio1:40(g:ml),(NH4)2SO40.2%, MgSO40.1%, K2HPO4·3H2O0.2%, pH7.0, temperature30℃, fermentation period3days. After fermentation the alginate content degraded from162.049mg/g to77.690mg/g, and reducing sugar increased from0.035mg/ml to0.942mg/ml.2. Single factor experiment and L9(34) orthogonal experiment were conducted to study the fermentation of Laminaria japonic, with mixture of Acinetobacter junii and Candida utilis as the germs for fermentation. The effects of different carbon source, nitrogen source on fermentation were also studied. Results showed that the optimum fermentation conditions were as follows:wheat bran content4%, urea content0.4%, K2HPO4·3H2O0.3%, MgSO40.15%, pH7.0, stirring speed180r/min, inoculation amount15%, inoculation proportion1:2, fermentation period56h. After fermentation the alginate content decreased from162.049mg/g to69.190mg/g with a decreasing rate of57.30%, the content of crude protein was57.24%and the digestibility was85.64%. Compared with the fermentation with Acinetobacter junii only, the nutrition and digestability of feeds were both improved.3. The optimum conditions of autolysis and the effect of main factors including temperature, pH and amount of papain to the content of amino nitrogen on fermentation were detected. The optimum conditions of autolysis were analyzed through response surface methodology. Results showed that the optimized conditions were as follows: temperature55.39℃, pH6.10, concentration of papain0.02g/100ml. After optimization the content of amino nitrogen was improved to0.1770g/100ml. Both NSI and YASP were above60%with a good solubility. The fermentation product flavor was improved by Maillard reaction in the condition of Xylose2.5%, temperature115℃, pH8.0, in90minuts, and in this condition the total content of amino acid of fermentation liquor was improved from0.1753mg/ml to1.7277mg/ml.