Tri-cultured lactic-acetic acid co-fermentation improves stored jujube puree functionality, physicochemical, volatile compounds, and sensory characteristics

Abstract

Jujubes, known for their bioactive compounds, are underutilized due to their unappealing dry qualities with lingering bitterness, and short shelf-life when fresh. Co-fermented jujube puree storage could enhance its functional food potential. For the first time, the impact of storage on 8-day tri-cultured Junzao jujube puree experimented with commercial and indigenous Chinese lactic and acetic acid bacteria on the functionality, physicochemical, volatile compounds, and sensory characteristics was investigated. Despite a decline in microbial loads, the stored purees exhibited excellent viability, with specific tricultures showing promising probiotic activity of more than 6-log CFU/mL of viable counts. Stored purees demonstrated improved acidification, increased total acid content, and reduced pH. Fourier-transform infrared spectroscopic analysis indicated structural changes in polysaccharides, and total flavonoid content quintupled (31.05%), with the highest observed in tri-culture: Lactobacillus casei, Lactobacillus plantarum and Acetobacter pasteurianus (98.74 mg rutin equivalent/100 g) with peculiar formation of l-methionine (1.93 mg/100 g). Antioxidant capacity varied among stored tri-cultured purees, and sensory analysis showed sourness, fruity, floral, thickness, intense yellowish color was associated with the stored tricultures compared to the unfermented sample. Headspace solid-phase microextraction gas chromatography-mass spectrometry analysis identified 80 volatile compounds, with esters (38%) being predominant. Overall, the results demonstrated that lactic-acetic acid tri-culture storage could bio-valorize Junzao jujube puree, improving its organoleptic appeal and shelf-life.