Optimization Of Fermentation Process Of Quinoa Fermented Thick Pulp By Response Surface Methodology

Quinoa is a pseudocereal known as “nutritious gold”.It has been recommended by the United Nations Food and Agriculture Organization as “the whole nutrition food” and has attracted worldwide attention.In addition to traditional methods of cooking such as steam,the domestic and foreign researchers began to use quinoa as a raw material to develop a new quinoa food.It mainly about quinoa grinding into powder used in the production of traditional pasta,and mixed with other grains to make biscuits and other fields.But with pure quinoa as the raw material,without adding other raw materials and food additives,the research on the preparation of new quinoa products by modern fermentation technology is still very rare.In this paper,white quinoa is used as a raw material in wutai mountain,Shanxi Province.Single factor experiment and orthogonal experiment were conducted to explore the best conditions for the gelatinization,liquefaction and saccharification of quinoa.Under the best conditions,the enzymatic hydrolysate of quinoa was obtained as the fermentation substrate.To explore the growth status and acid production capacity of lactobacillus plantarum,lactobacillus casei,lactobacillus paracei,lactobacillus acidophilus and compound bacteria in the culture medium of quinoa,and combined with the preliminary sensory evaluation,we screen out the most suitable starter for quinoa fermentation thick pulp.Based on the fuzzy mathematics method and response surface method,the optimal fermentation process of quinoa fermentation thick pulp was determined by using sensory score as evaluation index.In order to develop a good sensory quality,without adding pure quinoa fermentation thick pulp,the main research results are as follows:According to the national standard,the basic components of quinoa were determined to have a protein content of 15.10g/100 g,a fat content of 6.97 g /100 g,a starch content of 50.39%,a reducing sugar content of 4.27mg/g,a polyphenol of 3.313 mg/g of flavonoids of 2.974mg/g.Using the gelatinization degree as the evaluation index,the optimal level range of the three factors of material-liquid ratio,temperature and time in the gelatinization process was screened by single factor experiment,and the optimum gelatinization conditions of quinoa thick pulp were determined by orthogonal test.The results showed that the gelatinization degree of the quinoa was 96.23% at a ratio of 1:10,a gelatinization temperature of 80 °C and a gelatinization time of 40 min,which basically reached complete gelatinization.And its protein content is >1%.Using the DE value as the index,the optimal level range of the three factors of enzyme addition,temperature and time during liquefaction and saccharification was screened by single factor experiment.The optimum liquefaction and saccharification conditions of quinoa thick pulp were determined by orthogonal test.The results showed that when the amount of ?-amylase was 14 U/g,the liquefaction temperature was 70 ° C,and the liquefaction time was 60 min,the DE value of the quinoa hydrolysate was 23.98%.The amount of ?-amylase added was 200 U/g,the saccharification temperature was 55 ° C,the saccharification time was 1.5 h,and the DE value of the quinoa hydrolysate was 49.73%.By explore the growth status and acid production capacity of various starters in quinoa medium,the four starters with high viable count and acidity were Lp,La,Lp-Lc and Lp-La.Further preliminary sensory evaluation was performed,and the sensory scores were ranked as follows: Lp-Lc>Lp-La>Lp>La.Therefore,Lp-Lc was selected as the optimum starter for quinoa fermented thick pulp.Using the sensory score as an indicator,the single factor experiment was used to screen out the optimal range of three factors: inoculum size,strain ratio and fermentation time.Combining fuzzy mathematical sensory evaluation method and response surface analysis method to obtain optimal fermentation conditions for quinoa fermented thick pulp.The results showed that when the inoculation amount was 2.8 %,the fermentation time was 10 h,and the ratio of the strain was 2:1,the sensory score of the quinoa fermented thick pulp was 92.5 points.The number of viable bacteria in quinoa fermented pulp reached 1.79×109 CFU/m L,and the acidity value was 79 °T.The color was bright,the state was stable,the flavor was outstanding,and the taste was sweet and sour.After fermentation,the protein content of quinoa thick pulp did not change significantly,the reducing sugar content decreased significantly,the fat content increased slightly,the polyphenol content increased from 0.265 mg/m L to 0.314 mg/m L,and the flavonoid content decreased from 0.207 mg/m L to 0.094 mg/m L.