Volatile and non-volatile profiles in jujube pulp co-fermented with lactic acid bacteria

Jujube has become a popular food because of its abundant nutritional elements, but its main consumption in dried form exhibits challenging industrial processing. In current study, the effect of lactic acid bacteria co fermentation with a mixture of Lactobacillus plantarum, Lactobacillus rhamnosus GG, and Streptococcus thermophilus on volatile and non-volatile profiles of jujube pulp was investigated, with the aim to discover potentially novel products. Using headspace solid phase microextraction coupled with gas chromatography-mass spectrometry, most acids and alcohols in jujube were significantly increased before 12-h fermentation. Seven active aromas, identified by gas chromatography-olfactometry and odor activity values were altered significantly after fermentation. A total of 36 significantly differential non-volatiles were identified using ultrahigh-performance liquid chromatography coupled with quadrupole-orbitrap mass spectrometry and multivariate statistical analysis during fermentation. These non-volatiles were mainly involved in the amino acid and lipid metabolism pathways. Using Spearman correlation analysis, we found that the relative expression of 13 non-volatiles exhibited significant correlations with 7 active aroma compounds after fermentation. This study identified the metabolic differences in fermented jujube and provides clues that could improve the sensory quality of lactic acid bacteria co-fermentation products.

Automated summary

The study investigated the impact of co-fermentation of lactic acid bacteria with a mixture of different strains on the volatile and non-volatile profiles of jujube pulp. Significant increases in acids and alcohols were observed before 12-hour fermentation, along with changes in active aromas after fermentation. Additionally, alterations in 36 non-volatiles related to amino acid and lipid metabolism pathways were identified during fermentation, suggesting potential improvements in sensory quality of co-fermentation products.