Chemical profile of sweet corn kernels stored at low temperature

Sweet corn is an important vegetable grown worldwide; it was derived from mutations of starch biosynthesis genes in maize (Tracy, Shuler, & Dodsonswenson, 2019). Nowadays, the planting area of sweet corn in China is approximately 530,000?ha which passed the United States as the number one country (Tracy et al., 2019, Xiao et al., 2023). Sweet corn, which is rich in carbohydrates and various nutrients (vitamins, fiber and minerals), is popular with the consumer for its unique taste and pleasant flavor (Swapna, Jadesha, & Mahadevu, 2020). Sweet corn is harvested at the milk stage and produced for three distinct markets (fresh, processing and frozen) (Lertrat & Pulam, 2007). Due to the high moisture and sugar content, sweet corn has a high respiration rate as with other fresh ?cut vegetables (Kader, 2002), which make it a highly perishable product with a short shelf life, especially in the hot summer (Tefera, 2012). These factors result in great losses in the post-harvest period of fresh production. Thus, it is essential to improve the commodity value of sweet corn by extending viable storage time. Low temperature as techniques to prolong shelf lifeVarious techniques have been employed in attempt to prolong the shelf life of sweet corn, such as dehydration, packaging and use of low temperature (Geetha et al., 2017, Kumar et al., 2015). Low temperature is one of the commonest approaches for prolonging the shelf life of vegetables and fruits due to its convenience and effectiveness (Moretti, Mattos, Calbo, & Sargent, 2010). It was reported that use of a low temperature could decrease the respiration rate (Lv et al., 2022), reduce lipoxygenase and polyphenol oxidase (PPO) activities in pears (Li, Cheng, Dong, Shang, & Guan, 2017), slow metabolic activity, and delay the degradation of sucrose (Goyer et al., 2019, Wang et al., 2022). In addition, low temperature has further been revealed to inhibit microbiological development and subsequently delay quality loss (Qadri, Yousuf, Srivastava, & Yildiz, 2015). Sweet corn is primarily washed with ice water before being stored at a low temperature for production, a method that can effectively reduce the respiration and the loss of sugar (Becerra-Sanchez & Taylor, 2021). However, previous studies focused on alterations to physiological, biochemical and aroma compounds in sweet corn kernels during storage after different treatments (Xiang et al., 2020, Yactayo-Chang et al., 2022). Therefore, the metabolic changes that occur in sweet corn kernels during the storage period at low temperature remain unclear, particularly with regards to secondary metabolites. Plant metabolites play essential roles in growth and development, providing indispensable resources for human nutrition and energy (Vincenzo, Vonny, Sayaka, & Fang, 2012). Compared with traditional techniques, widely targeted metabolomics capable of identification of more than one thousand metabolites, exhibits great advantages in analyzing global changes in nutritional value (Qin et al., 2020). Recently, metabolomics has been utilized for evaluating the nutrient components of crops and vegetables in post-harvest processing (Utpott, Rodrigues, Rios, Mercali, & Flores, 2022), such as in peanut seed (Xiao et al., 2022) and Chinese flowering cabbage (Mou et al., 2023). In this study, a comprehensive metabolic landscape was constructed for sweet corn kernels stored at different temperatures. Our objectives were to investigate the effect of low temperature treatment on metabolite changes during post-harvest storage, and to identify the associated chemicals present in sweet corn kernels. AbstractFresh sweet corn has a limited shelf-life due to its high moisture and high sugar content. Low temperature storage is an effective technique employed to extend the shelf-life. However, changes in the chemical composition of sweet corn kernels at low temperatures are not fully understood. In this study, kernels stored at low temperature exhibited higher levels of soluble sugars and lower starch content. In total, 1365 metabolites were characterized in sweet corn kernels. 593 and 308 differentially accumulated metabolites (DAMs) were identified in sweet corn kernels stored at normal and low temperature, respectively. 607 DAMs were identified at low temperature compare to normal temperature. DAMs were consistently enriched in flavonoid biosynthesis, linoleic acid metabolism and sphingolipid metabolism. Moreover, dozens of metabolites were identified as potential biomarkers for post-harvest storage effects in sweet corn. These results extend our knowledge of the dynamic changes in sweet corn kernels stored at low temperatures.? SourcesImpact of low temperature on the chemical profile of sweet corn kernels during post-harvest storageYingni Xiao, Lihua Xie, Yuliang Li, Chunyan Li, Yongtao Yu, Jianguang Hu & Gaoke LiFood ChemistryAvailable online 3 August 2023, 137079In Press, Journal Pre-proofhttps://www.sciencedirect.com/science/article/abs/pii/S0308814623016977 Picture,?Huercasa sweet corn in Amazon