Production of High-Quality Wheat Sprouts of Strong Antioxidant Capacity: Process Optimization and Regulation Mechanism of Red Light Treatment

Abstract

Light treatment is an innovative method to enhance the synthesis of secondary metabolites in plants and improve the quality of plant-based food ingredients. This study investigated the effects of red light treatment on the physiological and biochemical changes during wheat germination, aiming to produce high-quality wheat sprouts with strong antioxidant capacity. Using response surface methodology, the study optimized the conditions for phenolic accumulation in wheat sprouts under red light treatment and explored the molecular mechanisms behind the enhancement of total phenolic content (TPC) and quality. The results indicated that red light treatment significantly increased the TPC in wheat sprouts. The highest TPC, reaching 186.61 μg GAE/sprout, was observed when wheat sprouts were exposed to red light at an intensity of 412 μmol/m²/s for 18.2 h/d over four days. Compared to no light, red light treatment significantly increased the content of photosynthetic pigments (chlorophyll and carotenoids). Red light treatment notably heightened the levels of both free and bound phenolic in the germinating wheat. Red light treatment markedly boosted the activities and relative gene expression levels of enzymes related to phenolic biosynthesis, including phenylalanine ammonia-lyase, cinnamate-4-hydroxylase, and 4-coumarate-CoA ligase. Additionally, red light treatment enhanced the antioxidant capacity of wheat sprouts by improving the activity and gene expression of four key antioxidant enzymes, thereby promoting growth and germination. This research suggested that red light treatment is an effective strategy for stimulating total phenolic biosynthesis, enhancing antioxidant capacity, and producing highly nutritious wheat sprouts, thus laying the groundwork for developing total phenolic-enriched wheat sprouts as valuable food ingredients in the future.