Effects of probiotics fermentation on physicochemical properties of plum (Pruni domesticae semen) seed protein-based gel.

The plum seed protein isolates (PSPI) were used to prepare a gel by probiotics fermentation. The effects of fermentation time (from 0 to 12 h) on the physicochemical properties of PSPI gel were evaluated. The results showed that PSPI started to form a gel after 6 h of fermentation, as evidenced by a decrease in pH from 6.6 to 5.2, an increase in particle size from 10 μm to 40 μm, appearance of a new peak with retention time of 10 min in gel filtration high-performance liquid chromatography, and formation of aggregation and porous structure observed by fluorescence and scanning electron microscope. The PSPI gel from 9 h of fermentation exhibited the highest viscosity (318 Pa.s), storage modulus (18,000 Pa), water holding capacity (37 %), and gel strength (21.5 g) due to stronger molecular interactions such as hydrogen bond, electrostatic, hydrophobic interaction and disulfide bond. However, increasing fermentation time over 9 h led to disrupture of PSPI gel. Furthermore, the subunit around 15 kDa of PSPI disappeared after fermentation, indicating that the formation of PSPI gel was induced by both acidification and partial hydrolysis. Our results suggest that PSPI can provide an alternative for developing plant-based gel products.