Optimization of Walnut Milk Fermentation Process by Response Surface Methodology

The defatted-walnut milk as the raw material was fermented in this experiment. Based on the single-factor experiments,the fermentation processing of walnut milk was optimized by the response surface method. The impacts of inoculation amount,ratio of strain,fermentation time and fermentation temperature on the sensory quality of fermented walnut milk were investigated. The result showed that the optimal fermentation processing conditions were as follows:Volume ratio of Lactobacillus plantarum to Lactobacillus acidophilus 1:1,8% of inoculation amount,41℃ fermentation temperature and 12.7 h fermentation time. In addition,the fermented product had the uniform color,strong walnut flavor,sweet,sour and smooth taste. After 12 h,the pH value and total acid were 3.88 and 25.63 g/kg,the number of viable bacteria was 7.78×10⁸ cfu/mL,the protein contents was 1.05 g/100 g,the amino nitrogen contents was 68.6 mg/100 g,the total content of amino acids increased by 0.1738%.