Effects of adding lactic acid on the photostability of capsanthin during the shelf life of Zao chili

Zao chili is a traditional Chinese local specialty fermented chili pepper condiment. As the main pigment in red chili peppers, the light-associated conditions are the main reason for the discoloration of capsanthin during the shelf life. This study aimed to investigate the effects of different light sources and the addition of adding lactic acid on the stability of capsanthin in Zao chili. Results showed that the addition of 12.5 mmol/L and 37.5 mmol/L lactic acid to Zao chili effectively improved the shelf-life light stability of Zao chili. The analysis of ultraviolet (UV)-visible, Raman and Fourier transform infrared spectra revealed that the longer the wavelength of the light source, the smaller the damage to Zao chili and the least destructive effect was observed for red light on the C=C and C=O bonds of capsanthin. The adding lactic acid exerted a notable protective effect on the capsanthin. The hydrogen bonding formed between lactic acid and capsanthin may be the main reason for the increased stability of capsanthin chromophores. Our study can provide an experimental basis for studies regarding pigment stabilization and quality control of chilis and related products. •Discoloration is a common problem with current Zao chili.•Adding lactic acid protects the color of Zao chili during shelf life.•Red light had the least damaging effect on capsanthin compared to yellow, blue, natural, and ultraviolet light.•Addition of lactic acid reduces the degradation of capsanthin.