Study On Preparation And Quality Evaluation Of Fermented Jujube Powder

The annual output of jujube in China accounts for 95% in the world,and it is increasing year by year.Jujube is rich in sugar,flavonoids,amino acids,vitamins and minerals,and is very popular among consumers.However,the fresh jujube has high water content,is prone to deterioration after harvesting,and the deep processing technology lags behind,resulting in the loss of fresh jujube by nearly 30% per year.Dry jujube milling is an important way to solve this problem.Jujube powder processing often uses spray drying technology.Since red dates are high confectionery products,it is usually necessary to add 70% to 85% maltodextrin,which seriously affects the quality of jujube powder.Jujube pulp can reduce sugar by yeast fermentation,and can increase the nutrient active ingredients produced by fermentation.Therefore,this study used fermentation to reduce the sugar content in the jujube pulp,reduce the viscosity of the jujube pulp,reduce the amount of maltodextrin added,and maintain the jujube under the premise of ensuring that the sticking wall phenomenon is light and has a good dusting effect.Good quality and flavor of the powder.The research results are as follows:1.Screen the strains suitable for the fermentation of jujube pulp.The optimal acquisition time of the strain was determined by measuring the growth curve of brewer's yeast,wine yeast and baker's yeast.The brewer's yeast was 10 h,the baker's yeast was 8 h,and the wine yeast was 12 h.Taking the sugar-consuming ability of the yeast,the spray-dried powder yield rate after fermentation is used to select the strain suitable for the fermentation of the jujube pulp.The results showed that the total sugar and reducing sugar content of jujube pulp fermented by brewer's yeast decreased the fastest,and the flour yield was the highest.2.Determination of the degree of fermentation of jujube.Based on the flour extraction rate,powder yield and sensory quality of jujube powder,the degree of fermentation of jujube pulp suitable for spray drying was determined.The results showed that the jujube powder fermented to the total sugar content of 6 g/100 g prepared jujube powder had the highest powder yield,the highest powder yield,and the highest sensory evaluation score.3.Optimization study on fermentation process of jujube pulp.According to the single factor experiment,the suitable conditions for the fermentation of jujube pulp by S.cerevisiae are: 3% inoculation amount of brewer's yeast,fermentation temperature 33°C,fermentation time 10 h.The response surface method was used to optimize the fermentation of jujube pulp.The optimum conditions were: fermentation temperature 33.5°C,yeast inoculum 3.2%,fermentation time 10.5 h,and the total sugar content of jujube pulp was 6.12 g/100 g after fermentation.4.The effect of the amount of dextrin added on the flour yield of jujube pulp was studied.The results showed that the fermentation effect of fermented jujube pulp was better than that of unfermented jujube pulp.The yield of unfermented jujube pulp with 70% dextrin added amount reached 58%,and the fermented jujube pulp with the same dextrin added amount was as high as 75%.The 50% dextrin added amount of fermented jujube can achieve the spray effect of 70% dextrin added amount of unfermented jujube pulp,and reduce the amount of maltodextrin added by 20%.5.Comparative analysis of jujube powder quality.The effects of fermentation on the quality of jujube powder were analyzed by comparing the physical and chemical indicators and aroma components of jujube powder before and after fermentation.The results showed that the total sugar and fat content of jujube powder decreased,the content of polysaccharide,protein,flavonoids and cAMP increased,the particle size was smaller,the strength was more uniform,the hygroscopicity was smaller,and the storage was easier.The content of esters in the aroma components of the fermented jujube powder is reduced,and the fruit flavor in the jujube powder is reduced.However,the alcohol,ketones,alkanes and aldehydes in the jujube powder are elevated,making the jujube powder more mellow and with the unique aroma of yeast.