Good results for in persimmon for an hydrocolloid-based edible eoating

Persimmon fruits are often affected by large postharvest losses due to rapid ripening and the early onset of senescence. To reduce such losses in fresh fruits, the application of hydrocolloid-based edible coatings was conducted. Therefore, a plant hydrocolloid-based gum, tragacanth gum (TCG) (*), was applied to persimmon fruits at 0.5%, 1%, and 1.5% TCG concentrations, and stored at 20 ? 2 ?C and 80?85% relative humidity for 20 days (analysis at 0, 4th, 8th, 12th, 16th, and 20th day). As a result of TCG application on persimmon fruits, there were greatly suppressed respiration rates, ethylene production, weight loss, decay incidence, and H2O2 and malondialdehyde content. In addition, TCG-coated persimmon fruits had higher concentrations of bioactive compounds including phenols, flavonoids, carotenoids, ascorbic acid, and soluble tannin. Higher enzymatic antioxidant activities and lower softening enzyme activities were also recorded for TCG-coated persimmon fruits. Uncoated persimmon fruits quickly lost fruit quality attributes like color, firmness, taste, and aroma during storage compared to coated ones. Based on our findings, the use of TCG, especially at the concentration of 1% TCG, can be recommended to be applied as the edible coating to maintain the nutritional, biochemical, and commercial quality of persimmon fruits during ambient storage. IntroductionPersimmon (Diospyros kaki Thunb.) is a climacteric fruit with distinct sensory quality and nutritional profile [1,2]. Fuyu persimmons, the leading non-astringent persimmon fruits, are the globally cultivated persimmons. Fuyu persimmon can be eaten from the crispy firm to ripe stages in many parts of Europe and Asia. Persimmon fruits contain a high concentration of biologically active compounds, such as ascorbic acid, carotenoids, and tannins, which are associated with a range of human health-promoting activities, such as antioxidative, anti-carcinogenic, and anti-mutagenic properties [1,3]. Like other climacteric fruits, persimmon fruit undergoes prompt ripening due to ethylene production and accelerated respiration [2]. Loss of firmness makes persimmon fruits vulnerable to mechanical damage and rot, ultimately restricting long-distance shipping [4,5]. Inhibiting ethylene biosynthesis or activity may be important in delaying ripening and extending the postharvest life of persimmon fruit [4]. Low temperatures, although effective in increasing the postharvest life of persimmon fruits, may cause chilling injury to persimmon fruit that reduces its economic and nutritional potential. The major chilling injury symptoms during low-temperature storage have been peel browning and pulp softening [6]. Storage conditions are always hospitable for fresh fruits and vegetables. Low or high temperature leads to the accumulation of reactive oxygen species (ROS) within fruit tissues that cause oxidative stress and ultimately senescence [7]. Edible coatings have been applied to extend the postharvest life of fruits and vegetables either as a whole or in fresh-cut form [8]. In addition to being cost-effective, edible coatings could be a good substitute for chemically manufactured preservatives due to their eco-friendly and biodegradable nature and natural sources [9,10]. Edible coating application on one hand reduces metabolic activities, such as respiration and ethylene production, and, on other hand, mitigates oxidative stress by decreasing the accumulation of malondialdehyde content and hydrogen peroxide and membrane leakage in coated fruits such as mango [11], persimmon [12], and guava [13]. Edible coatings suppress the accumulation of ROS by activating the enzymatic and non-enzymatic antioxidant defense mechanism, thus delaying senescence in coated produces [10,12,14]. Extension in the postharvest life of coated fruits may also be attributed to the deactivation of cell wall-degrading enzymes that have been reported in persimmon [12], strawberry [15], and apricot fruits [10]. Edible coatings based on natural gums have been widely applied for an extension in the postharvest of horticultural fresh produce [16]. Natural gums, a type of hydrocolloid, are polysaccharides comprised of sugars other than glucose and are chemically inert, inexpensive, biodegradable, odorless, non-toxic, and easily available. Gums are also known as hydrocolloids since they are water-soluble [9]. Tragacanth gum (TCG), also known as katira, is an anionic polysaccharide secreted by different species of Astragalus plants [17,18]. TCG exhibits exclusive biological and chemical features, including non-toxicity, biocompatibility, environment friendliness, and stability across a wide pH range [19]. Our studies have shown that the application of TCG to apricot and mango maintained a higher number of biochemical attributes and antioxidants and lowered oxidative stress by reducing ROS production and suppressing the activities of softening enzymes [10,20]. It has been reported that a combination of TCG with essential oil (EO) of Zataria multiflora slowed browning and inhibited microbiological infestation in button mushrooms [19]. Similarly, an edible coating based on TCG prevented browning, controlled microbial infestation, and preserved the quality of button mushrooms [21]. Therefore, the current research was performed with the hypothesis that TCG will preserve the fruit quality, delay senescence, and reduce fruit softening of stored persimmons by reducing transpirational losses, respiration rate, and ethylene production. Therefore, oxidative stress markers, enzymatic and non-enzymatic antioxidants, cell wall-degrading enzymes, and biochemical and sensory quality attributes of stored persimmon fruits were analyzed during storage conditions.(*) Tragacanthus gum is obtained from several species of Astragalus. More informationhttps://www.mdpi.com/2311-7524/8/11/1045 SourcesImprovement of Postharvest Quality and Bioactive Compounds Content of Persimmon Fruits after Hydrocolloid-Based Edible Coating ApplicationMuhammad Shahzad Saleem, Shaghef Ejaz, Muhammad Akbar Anjum, Sajid Ali, Sajjad Hussain, Sezai Ercisli, Gulce Ilhan, Romina Alina Marc, Sona Skrovankova and Jiri MlcekHorticulturae 2022, 8(11), 1045https://doi.org/10.3390/horticulturae8111045 https://www.mdpi.com/2311-7524/8/11/1045 Picture is Figure 5 of the original paper, Effect of tragacanth gum application on visual appearance of persimmon fruits stored for 20 days at 20 ? 2 ?C and 80?85% RH.