| Monascus and Aspergillus oryzae ferment the porcine bone extract by liquid and solid-state method. Using single factor and orthogonal tests determine the optimal fermentation process of microorganisms, when acid protease activity of Monascus, neutral protease activity of Aspergillus oryzae, production of nitrogen recovery and sensory analysis as indicators. The results showed that the Monascus liquid fermentation conditions were that the addition of porcine bone extract was 3%, temperature was 30℃～32℃, shaking speed was 150r/min, pH was 5, the protease activity and nitrogen recoveries respectively were 34.86U/mL and 90.13%; Aspergillus oryza liquid fermentation conditions were that the addition of porcine bone extraction was 4%, temperature was 32℃～34℃, shaking speed was 150r/min, pH was natural, the protease activity and nitrogen recoveries were respectively 38.96U/mL and 91.25%; The optimum conditions of Monascus solid-state fermentation were that the addition of porcine bone extract was 35%, temperature was 31℃, pH was 5, its protease activity and degree of hydrolysis were respectively 289.57 U/g and 80.14%; The optimum conditions Aspergillus oryza solid-state fermentation were that the addition of porcine bone extract was 65%, temperature was 32℃～34℃, the pH was natural, the protease activity and degree of hydrolysis were respectively 402.33U/g, and 82.76%.In liquid fermentation process, the protease activity and degree of hydrolysis increased with fermentation time increasing. The protease activity of Monascus fermentation and hydrolysis were maximum at the 5th day, were respectively 38.66% and 35.92U/mL, then they were decreased slightly. Aspergillus oryzae protease activity reached the maximum at the 4th day, reached to 38.01U/mL, degree of hydrolysis was maximum at 5th day, reached to 39.27%, and then there were no change. In Solid-state fermentation process, the protease activity and degree of hydrolysis increased with the fermentation time increaseing at fermentation early. The enzyme activity of Monascus fermentation and hydrolysis degree reached to maximum at 5th day, were respectively 307.16U/g and 46.58%. Aspergillus oryzae fermentation enzyme activity and degree of hydrolysis reached to the maximum at 4th day, were respectively 386.05U/g and 48.70%, and then the degree of hydrolysis did not change significantly, but the protease activity decreased gradually after the 10d. The protease activity of Monascus fermentation and Aspergillus oryzae fermentation were almost undetectable, when the fermentation time was 30 day and 40 day.In liquid fermentation process, the peptide-based nitrogen and free ammonia nitrogen increased with fermentation time increasing. Peptide-based nitrogen and free ammonia nitrogen of Monascus fermentation reached the maximum at the 5th day, they were respectively 74.21% and 8.42%, and then they were stable, soluble nitrogen content decreased from 89.96% to 80.40% at the previous two days, and then increasing to the maximum at the 5th day, was 88.45%, and then it was stable. The peptide-based nitrogen and free ammonia nitrogen of Aspergillus oryzae fermentation has been showing an increasing trend, they were respectively 78.85% and 8.02% when it was at the 10th day. The soluble nitrogen content is not obvious, reached 88.91% at the 10th day. In solid-state fermentation process, the soluble nitrogen, peptide nitrogen and free ammonia-based nitrogen content were increasing. Peptide-based nitrogen of Monascus fermentation was maximum at the 20th day, reached 71.33%. Free ammonia nitrogen reached the maximum at the 40th day, was 5.21%. Soluble nitrogen reached the maximum at the 15th day, was 76.16%. Peptide-based nitrogen and free ammonia nitrogen of Aspergillus fermentation has been increasing, were respectively 70.26% and 5.71% at the 40th day, soluble nitrogen content reaches a maximum at the 20th day, was 79.45%. Electrophoresis analysis of fermentation products showed that the molecular weight decreased with fermentation time increasing.Total free amino acids of the product increased with fermentation time increasing whether they were liquid or solid fermentation. The delicious amino acids of Monascus liquid fermentation was the highest at the 5th day, and the bitter amino acids was the lowest. The delicious amino acids of Aspergillus oryzae liquid fermentation was the highest at the 3th day, while the bitter amino acids was the lowest. The delicious amino acids increased with the fermentation time increasing in solid-state fermentation process, and the bitter amino acids were decreasing. By comparison, the proportion delicious amino acids of Aspergillus oryzae were the highest.In liquid fermentation process, taste nucleotide disodium (I+G) content was little and almost no change in the whole process, it maintained at 0.5mg/100mL. It showed that the main effect were the amount of flavor amino acids in the liquid flavor. In solid-state fermentation process, taste nucleotide disodium (I+G) content increased with the fermentation time was increasing. The sensory evaluation and the changes of taste amino acid showed that the effects were the flavor amino acids and the nucleotide flavor in solid-state fermentation process.GC-MS analysis showed that, There can be detected 122 volatile compounds in Monascus liquid fermentation, including 32 alcohols,12 aldehydes,8 ketones,2 phenols,4 acid,34 esters and 30 hydrocarbons, in which the amount of alcohols was at advantage. There can be detected 28 volatile compounds in Aspergillus oryzae liquid fermentation, including 8 alcohols,3 aldehydes,1 ketones,2 phenols,2 acids, 9 esters and 3 other compounds. There can be detected 174 volatile compounds in solid-state fermentation process of Monascus, including 38 alcohols,16 aldehydes, 23 ketones,8 phenols,3 acids,22 esters,10 heterocyclic compounds,1 sulfur compounds and 53 hydrocarbons, in which the alcohol and phenol were at advantage. There can be detected 216 volatile compounds in Aspergillus oryzae solid-state fermentation, including 29 alcohols,13 aldehydes,29 ketones,7 phenols,11 acid,28 esters,50 heterocyclic compounds,2 sulfur compounds and 48 hydrocarbon compounds, in which the heterocyclic compounds was at advantage. |
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