Authors Hanaa S. Hassan,Mervat EL-Hefny,Ibrahim M. Ghoneim,Mina S. R. Abd El-Lahot,Mohammad Akrami,Asma A. Al-Huqail,Hayssam M. Ali andDoaa Y. Abd-Elkader
Strawberry is a non-climacteric fruit but exhibits a limited postharvest life due to rapid softening and decay. A strawberry coating that is natural and safe for human consumption can be used to improve the appearance and safeguard the fruits. In this study, 20% and 40% Aloe vera gel alone or in combination with 1% lemongrass essential oil (EO) was used as an edible coating for strawberries. After application of all the treatments, the strawberry fruits were stored at a temperature of 5 ± 1 “C at a relative humidity (RH) of 90%95% for up to 16 days and all the parameters were analyzed and compared to control (uncoated fruits). A. vera gel and lemongrass EO decreased acidity and total anthocyanins and maintained fruit firmness. Treatment with A. vera gel 40% + lemongrass EO 1% led to the lowest weight loss, retained firmness and acidity, but increased the total soluble solids and total anthocyanins compared to uncoated fruits during storage of up to 16 days. The phenolic compounds of A. vera gel were analyzed by HPLC, and the most abundant compounds were found to be caffeic (30.77 mg/mL), coumaric (22.4 mg/mL), syringic (15.12 mg/mL), sinapic (14.05 mg/mL), ferulic (8.22 mg/mL), and cinnamic acids (7.14 mg/mL). Lemongrass EO was analyzed by GCMS, and the most abundant compounds were identified as ?-citral (neral) (40.10%) ?-citral (geranial) (30.71%), ?-dodecalactone (10.24%), isoneral (6.67%), neryl acetal (5.64%), and linalool (1.77%). When the fruits were treated with 20% or 40% A. vera gel along with 1% lemongrass, their total phenolic content was maintained during the storage period (from 4 to 8 days). The antioxidant activity was relatively stable during the 8 days of cold storage of the fruits coated with A. vera gel combined with lemongrass EO because the activity of both 20% and 40% gel was greater than that for the other treatments after 12 days of storage in both experiments. Moreover, all the treatments resulted in lower numbers of total microbes at the end of the storage period compared with the control treatment. This study indicates that the use of Aloe vera gel with lemongrass EO as an edible coating considerably enhances the productivity of strawberry fruits and the treatment could be used on a commercial scale. Strawberry has tremendous prospects for commercial use, e.g., for the extraction of natural color with great potential for diverse value-added processed products. However, the physiological characteristics of strawberry fruits deteriorate easily, as their softening reduces their postharvest shelf life during cold storage. Recently, methods of ozone, electrolyzed water, modified/controlled atmospheric packaging, natural compounds, antifungal edible coatings, and biocontrol agents have emerged as safe alternatives and efficient preservation methods in the fresh produce industry. Edible coatings are made up of natural polymers, such as carbohydrates, proteins, waxes, and their composites, that separate fruits from the surrounding atmosphere. Coatings with edible films and essential oils (EOs) can also help to maintain the postharvest quality of fruits by reducing transpiration and respiration. They also protect fruits and vegetables from deterioration by reducing the microbial growth and enhancing the textural quality. Aloe vera (Aloe barbadensis Miller). A. vera gel is rich in soluble sugars and polysaccharides but has low properties of hydrophobic and lipid levels with gas barrier efficacy, making it an ideal edible coating material. Moreover, A. vera gel coatings act as a barrier to moisture and O2, reducing the respiration rate, thereby preventing anaerobic conditions and conserving fruit quality. As a coating material, A. vera gel maintains the texture, color, and shelf life of fruits and vegetables. It is edible, invisible, odorless, and does not affect the quality of the fruit and vegetables, moreover, it is safe for human health and ecofriendly. Furthermore, it reduces respiration rate, moisture loss, softening of tissues, oxidative browning, and proliferation of microorganisms in fruits, such as strawberry, cherry laurel fruit, and grapes. Using A. vera gel dip coating reduced weight loss, changes in the physicochemical parameters, and decay, extending the shelf life of figs and litchi fruits. lemongrass (Cymbopogon citratus), one of the important medicinal herbs, belonging to family Poaceae, is known to have strong antimicrobial and insecticidal properties. It shows a strong fungicidal effect against microorganisms in fruit juices. Lemongrass EOs are composed of terpenes and phenylpropenes compounds. In addition, they contain other chemical groups like ketones, alcohols, esters, aldehyde, and flavonoid compounds. The major components of Lemongrass EOs are nerol, ?-citral, citronellal, ?-citral, geraniol, terpinolene, myrcene, geranyl acetate, terpinol, and methylheptenone . Mixtures of A. vera gel and EOs are widely studied as edible coatings for fresh-cut and whole fruit. A. vera gel and lemongrass EO enhance the postharvest quality, bioactive constituents, and shelf life of strawberry fruit.
