Microwave Effect Of ZSM-001 Yeast And Its Application In Fermented Rice Cake Processing

The fermented rice cake is a traditional fermented rice food in China which using old pulp fermentation methods that can keep rich flavor. In view of modern fortified yeast fermentation, the quality of the product is steady and production efficiency is high, but the flavor is single. Drying is the key operation process of direct vat set starter that often existed lower microbial activity. This paper were developed microwave drying technology of solid starter based on the research of the critical strain microwave effects and developed high production efficiency and high-quality products of fermented rice cake technology based on the research of the effects on old slurry fermentation technology combining with fortified yeast fermentation technology. The main results are as follows:1. The effects of microwave on ZSM-001 yeastThe effects of microwave treatment on cell membrane penetrability and growth of ZSM-001 yeast that is excellent strain for fermented rice cake. The results showed that: The higher intensity microwave had damaged yeast cell membrane, leaked contents and increased the concentration of intracellular free calcium in the cell that hurted the yeast chances of surviving could ultimately lead to death. When microwave doses of 1.6 w/g, microwave irradiation time of less than 160 s, the microwave processing can increase the electrolyte permeability, DNA and protein permeability and concentrations of intracellular hydrogen ions and decrease concentrations of intracellular free calcium ions in the cell which plays a certain role in promoting the yeast growth.2. Optimized technology for solid starterStarter cultures were prepared by the microwave drying method using ZSM-001 as a raw material. The effects of centrifuge inspissation and microwave drying conditions were studied on the survival rate of Brettanomyces strains. The results indicated that the optimum conditions were the centrifugal parameter of 4000 r/min for 5 min; using 80% rice flour as filler and 7.5% trehalose as protective agent; the microwave drying parameters of microwave dose 1.0 w/g for 1.5 min with intermittent time 0.5 min. Under these optimum conditions, the survival rate of bacterial strains was 38.69% and water content was 6%. With this technology, the drying time is short, strains has high survival rate, excellent production of rice steamed sponge cake flavor can be acquired.3.Optimized technology for fermented rice cake and studied the quality of fermented rice cakeResearched the effects of old slurry fermentation technology combining with yeast fortified fermentation technology on the quality of fermented rice cake and compared the quality of fermented rice cake made by pre-blent technology, fortified yeast technology and compound bacteria technology. The results indicated that the appropriate processing technology of fermented rice cake was that mixing the materials and fermenting with 10 percent of the old slurry,4 percent solid starter and one time weight of water at 35℃ for 12 hours, then steaming for 15 minutes utilizing the water vapor. Results showed that the reducing sugar content, digestibility of starch and protein in the fermented rice cake of the old slurry fermentation combining with fortified yeast fermentation technology were highest and the aroma included 29 kinds of volatile compounds, mainly were esters and the alcohols and the tastes mainly were glutamic acid, valine acid and alanine acid. The fermented rice slurry of the old slurry fermentation combining with yeast fortified yeast fermentation technology had a lower glatinization temperature, and the fermented rice cake had a soft taste and suitable viscoelastic texture. The prediction models of taste and smell of fermented rice cake had established based on electronic tongue and electronic nose with high precision.The fermented rice cake produced in the old slurry fermentation combining with fortified yeast fermentation technology maintain the nutrition and flavor characteristics of the traditional food.