Study On Preparation And Application Of Green-skin Red Fermented Rice

Monascus spp. and Aspergillus oryzae are two microbial species commonly used in fermented food in China. Due to the different enzymes produced by both of them, they might improve fermentation rate and quality of fermented foods, when they are co-incubated in foods. In this paper, Monascus spp. that could grow well with Aspergillus oryzae were selected firstly. Then growth condition and changes of protease and amylase were researched, and their mixture fermentation products were prepared (green-skin red fermented rice). Finally, green-skin red fermented rice was used to brewing soy sauce and rice wine. The specific research results are as follows.1 Screening Monascus spp. strainsAntagonism between Monascus spp. and Aspergillus oryzae was studied, using 10 Monascus spp. preserved in the lab and A. oryzae 3.042, since antagonism often found during the mixed culture fermentation. The results showed that on PDA medium, Monascus spp. CICC5015, CICC5020, AS3.266, strain 2#,4# had no obvious restraining effect to Aspergillus oryzae, and could grow penetratively. Recult of rice culture tests showed that Monascus spp. strain CICC5015, CICC5020, AS3.266, strain 2#,4# and Aspergillus strains can grow together in the rice medium. Mycelium of Aspergillus oryzae was relatively sparse in rice medium of Monascus spp. strains CICC5015, CICC5020 and strains 4# while it is denser in rice medium of Monascus spp. strains 2#, AS3.266 and the surface of the indica rice was wrapped by a green suit cashmere. Protease activity assay results showed that The maximum acid protease activity of Monascus spp. strain AS3.266 reached 1225.93 U/g. Therefore, we choose Monascus spp. strain AS3.266 to make green-skin red fermented rice in the following step.2 Optimization of production process of green-skin red fermented riceSingle factor experiment and orthogonal experiments were carried out to optimize the production process of acid protease, neutral protease and amylase. The results showed that: the optimum conditions for green-skin red fermented rice producing acid protease were 5 d for culture time,30℃for culture temperature and inoculation ratio was 100:1(Monascus spp.:Aspergillus oryzae); the optimum conditions for green-skin red fermented rice producing neutral protease were 6 d for culture time,37℃for culture temperature and inoculation ratio was 100:1(Monascus spp.:Aspergillus oryzae); the optimum conditions for green-skin red fermented rice producing amylase were 4 d for culture time,28℃for culture temperature and inoculation ratio was 1000:1 (Monascus spp.:Aspergillus oryzae). According to above results, we chose 5 d for culture time,30℃for culture temperature and inoculation ratio 100:1 (Monascus spp.:Aspergillus oryzae) as the preparing condition of green-skin red fermented rice.3 Fermentation applications of green-skin red fermented riceSoy sauce was fermented by green-skin red fermented rice and Aspergillus oryzae respectively. Physical and chemical analysis, amino acid composition analysis and sensory evaluation were carried out. The result showed that the content of amino nitrogen in soy sauce fermented by pure Aspergillus oryzae was 0.39 g/100mL while the content of amino nitrogen in soy sauce fermented by green-skin red fermented rice was 0.48 g/100mL.The soy sauce fermented by green-skin red fermented rice was more glossy and red than the soy sauce fermented by pure Aspergillus oryzae.Rice wine was fermented by green-skin red fermented rice and black-skin-red-koji resectively. The result showed that the amino acid content, including essential amino acids, in rice wine fermented by green-skin red fermented rice were 120.22 g/100L and 35.87 g/100L respectively, they were higher than those in rice wine fermented by black-skin-red-koji which were 50.35 g/100L and 13.84 g/100L respectively. Moreover, rice wine fermented by green-skin red fermented rice seemed more glossy than rice wine fermented by black-skin-red-koji.