Enhancing the ascorbate–glutathione cycle reduced fermentation by increasing NAD+ levels during broccoli head storage under controlled atmosphere

Abstract

Abstract Broccoli is prone to adopting fermentation under inappropriate conditions, especially high−CO2 atmospheres. In this study, broccoli stalks were soaked in 0.4 % reduced glutathione (GSH) for 3 h, before being maintained in 50 % O2 + 50 % CO2 or 30 % O2 + 70 % CO2 controlled atmosphere. We compared the samples with control broccoli heads soaked in distilled water and maintained in normal atmospheric conditions. Broccoli heads from all treatments were stored at 10 ± 1 °C with 90–95 % relative humidity. Under O2/CO2 conditions, GSH pre-soaking of broccoli stimulated the ascorbate–glutathione (AsA–GSH) cycle, elevated nicotinamide adenine dinucleotide (NAD+) levels, improved the antioxidant capacity, enhanced the activities of respiratory metabolism enzymes, led to a higher adenosine triphosphate (ATP) status, and efficiently inhibited the accumulation of ethanol and acetaldehyde produced by fermentation, compared with control broccoli. Thus, GSH pre-soaking competitively inhibited fermentation by increasing NAD+ levels by promoting the AsA–GSH cycle and electron transfer chain (ETC) pathway. In conclusion, this study provides a potential technology to prevent the occurrence of fermentation in postharvest product.