Preharvest Glycerol Treatments Improve Orange Storage

Citrus fruits are among the most important fruit crops globally, with an annual production of approximately 161.8 million tons in 2021, according to FAO data. Due to their high susceptibility to postharvest fruit deterioration caused by water loss (resulting in skin wrinkles, weight loss, and senescence), softening, and rot, certain treatments are necessary to prolong their shelf life. Multi-omic analysis of citrus and transcriptional regulation mechanisms demonstrate that water loss is a key factor influencing fruit quality and further affecting postharvest storage capacity. The Cuticle: First Line of Defense Against Water Loss The cuticle, composed of cutin, wax, and suberin, is the first barrier covering the outer surface of plant epidermal cells, protecting tissues against desiccation, ultraviolet radiation, and other environmental stresses. Numerous studies have shown that the cuticle also plays a vital role in preserving fruit quality and postharvest shelf life by reducing water loss. Furthermore, it has been demonstrated that a citrus transcription factor (CsMYB96) alleviates water loss by simultaneously regulating intrinsic plasma membrane proteins and genes related to wax. Cutin and wax play important roles during citrus storage. Cutin is an essential structure in the fruit's epidermis, consisting of a polyester polymer rich in hydroxylated and epoxihydroxylated fatty acids with 16 and 18 carbon atoms, as well as glycerol. In recent decades, important genes involved in cuticle synthesis reactions have been identified. These enzymes catalyze an esterification reaction, linking glycerol and hydroxy fatty acids. In addition to structural genes involved in cutin biosynthesis and transport, some transcription factors can also influence cutin metabolism by regulating related gene expression. Glycerol Due to its non-toxic properties, glycerol is widely used in various industries, including food, syrups, pharmaceuticals, and cosmetics. It is also used as a plasticizer to produce edible films in combination with starch or water-soluble fish protein, as well as a softening agent in bakery and confectionery products. Recent studies have shown that glycerol can induce powdery mildew resistance in wheat by regulating plant fatty acid metabolism, phytohormone cross-talk, and pathogenesis-related genes. Spraying citrus with glycerol can also reduce skin damage and induce oxidative stress-related defense responses. Favorable Effects of Preharvest Glycerol Treatments Scientists evaluated the effect of exogenous glycerol on cuticle metabolism and the storage capacity of citrus. Orange fruits were treated with 10% exogenous glycerol up to 130 days after flowering, which is a critical stage in cutin biosynthesis in oranges. This treatment improved cutin biosynthesis and slowed down wax degradation. The effect of glycerol on the expression of genes related to the cuticle and fruit quality during storage was also analyzed. The results indicated that preharvest glycerol treatment mainly benefits the cuticle and further enhances the postharvest storage capacity of citrus fruits. Additionally, exogenous glycerol reduces postharvest water loss, decomposition, respiration rate, and the accumulation of off-flavor compounds like acetaldehyde, thus improving fruit storage capacity. Moreover, low levels of stress response metabolites (such as ?-aminobutyric acid) suggest that glycerol-treated fruit is in a less stressful state compared to control fruit. Preharvest glycerol treatment can be a safe and effective method to improve the storage capacity of citrus fruits by regulating cuticle metabolism. Source Zhu, Z.; Mei, W.; Li, R.; Liu, H.; Chen, S.; Yang,H.; Xu, R.; Huang , T.; Xiang, J.; Zhu, F.; Cheng, Y. (2023). Preharvest glycerol treatment enhances postharvest storability of orange fruit by affecting cuticle metabolism Postharvest Biology and Technology, 204: 112448. Imagehttps://corporativa.ahorramas.com/actualidad/naranja-navel-late-la-fruta-estrella-de-la-temporada-en-ahorramas/?