The quality changes and microflora analysis of commercial instant soya milk

Abstract

Soya milk can be easily contaminated because of its rich nutritional profile and simple package form, which thus may lead to short shelf life and has been considered as a public health concern. The objective of this study is to investigate the changes of sensory quality, viscosity, pH values, bacteria, and protein denaturation in soya milk samples which were stored for 0, 4, 8, 12, and 24 h at 25 ± 2°C. The results showed that the sensory properties were on the decline along with the storage time. The viscosity value increased from 1.61 Pa.s to 2.50 Pa.s, while the pH value decreased from 6.87 to 6.61. In addition, the number of total bacteria and Lactobacillus increased and the protein in soya milk denatured continually. The 16S rDNA sequence analysis indicated that the main microbial strains were Rummeliibacillus, Acinetobacter, Enterobacter, Phyllanthus, Bergia, Zhihengliuella, and Nesterenkonia. In this study, statistics in producing, packaging, and stocking process of soya milk were given, which provided experience to controlling soya milk.