The Research Of Walnut Protein Fermentated Yogurt’ Production Crafts

Walnut is the fruit of Juglandaceae plants, its nutrition and healthcare value has been recognized by the public. The unsaturated fatty acids accounted for more than 90% of the walnut oil, its healthcare function is getting more favor, and most walnut processing enterprises generally produce walnut oil. However, it is a pity that the walnut dregs are processed as feed, fertilizer or simply waste. To take advantage of the walnut dregs, their composition was analyzed in this study. We found that the content of high-quality plant protein in the walnut dregs can be up to 40%.In addition, the walnut dregs also contain essential dietary fiber, trace elements, vitamins and other active ingredients. Therefore, this paper carried out the research on the walnut protein fermentation yogurt using walnut dregs as the main materials.(1)The preparation conditions of the walnut dregs slurry were investigated by single factor experiment, taking the ratio of water to material, soaking time, soaking temperature, soaking pH and the pulping number as the single factor. The pulping conditions were determined as follows:the ratio of water to material was 19, soak time was 5 h, soaking temperature was 67 ℃, soaking pH was 4and the pulping number was 5.(2)The selection and domestication of the fermentation strains were perfomedin this study Lactobacillus plantarum(Lp), Streptococcus thermophilic(St), Lactobacillus bulgaricus(Lb), Bifidobacterium(B) and Lactobacillus acidophilus(A) were vaccinated to the walnut slurry. The strain that is suitable to grow in the walnut dregs slurry was selected according to sensory state of the fermentation product. Then this strain was vaccinated into1-7 culture medium with a volume ratio of skim milk to walnut dregs 1:0,2:1,3:2,1:0,1:1,2:3 and 1:2.Eventually, Lactobacillusplantarum(Lp) and Streptococcus thermophilic(St) were selected as the optimal fermentation strains.(3)Based on the single factor experiment, the fermentation conditions were optimized by the orthogonal test.The optimal conditions was shown as follows:the loading quantity was 90%, the inoculum concentration was 1%, the proportion of inoculation was 1:1, sucrose was 8%, fermentation initial pH was 6.8, the fermentation temperature was 38℃ and the fermentation time was 16h.(4)The species and addition amount of the emulsion stabilizer were optimized by the single factor experiment and orthogonal test. The composition of stabilizer was shown as follow:sucrose ester was 0.8g/kg, monoglyceride was 2.2g/kg, cmc was 1.5g/kg and arabia rubber was 2g/kg.(5)A new technology for the production of the walnut protein fermentated yogurt was established in this study. And two new products of walnut protein fermented yogurt by adding the red dates and yam were developed.This research provides technical parameters for the industrial production of walnut protein fermented yogurt.