Abstract:
The study examined the effects of oxygen, light, temperature, non-covalent bonds, and metal ions on the precipitation amount, as well as the protein, starch, pectin, and tannin content in the supernatant of Sichuan bran vinegar, to determine the key factors influencing haze reformation. Using transmittance as the response value, the clarification conditions were optimized via single-factor experiments combined with response surface methodology (RSM). The results indicated that oxygen and temperature were critical factors promoting haze reformation, with significantly shorter haze reformation times under aerobic conditions compared to anaerobic conditions, and higher temperatures further accelerating the process. Investigations into non-covalent interactions revealed that the addition of NaCl and guanidine hydrochloride disrupted electrostatic forces and hydrogen bonds, significantly reducing precipitation while increasing the protein, starch, pectin, and tannin content in the supernatant. This suggested that electrostatic interactions and hydrogen bonds facilitated macromolecular complexation and subsequent precipitation. Metal ions (Fe
3+, Ca
2+) had no significant effect on haze reformation. The optimal clarification conditions determined by single-factor and RSM optimization were: acidic protease dosage of 2.10 g/L, treatment time of 2.20 h, treatment temperature of 30 °C, and standing time of 2 h, achieving a transmittance of 85.75%. This study provides a data foundation for understanding the mechanism of haze reformation and offers practical solutions for industrial production of Sichuan bran vinegar.