Authors Sogvar, O.B., Saba, M.K. and Emamifar, A.
Rapid loss of quality and decay causes economic loss of strawberries after harvest. The effects of an edible coating based on natural Aloe vera (AV) gel in combination with ascorbic acid (Ascorbic Acid; 0, 1, 3 and 5% (w/v)) on postharvest quality of strawberries was studied. After treatment, fruit weight loss, firmness, titratable acidity, soluble solids content (SSC), pH value, concentrations of ascorbic acid, anthocyanin and total phenolics, total antioxidant activity, and microbial activity were evaluated at 0, 3, 6, 9, 12, 15 and 18 days of storage (1″C, 95% relative humidity). Compared with untreated fruit, Aloe Vera + Ascorbic Acid treatments delayed weight loss, had higher Soluble Solids Content, vitamin C concentrations and titratable acidity. The coatings reduced total aerobic mesophilic, yeasts and molds populations. Aloe Vera + 5% Ascorbic Acid was the most effective in delaying changes in the ripening and reducing microbial populations among the treatments. These results demonstrate that Aloe Vera and Ascorbic Acid coatings have potential to maintain postharvest fruit quality of strawberry fruit. Strawberries, one of the most popular summer fruits worldwide, are characterized by unique and highly desirable taste and flavor, and are rich in polyphenols and anthocyanin, vitamins and amino acids. However, the fruit are highly perishable resulting in a short postharvest life due to mechanical injury, physiological deterioration, water loss, fungal decay, and high respiration rate. Cold temperatures and modified atmospheres increase the storage life of fruit, but additional methods of maintaining quality are still under investigation. Recently, applications of edible coatings have been shown to be promising as a tool to improve the quality and extend storage and shelf life of various fruit such as papaya and strawberries. Coatings can act as moisture and gas semi-permeable barriers, resulting in control of microbial growth, preservation of color and texture. One such product is Aloe vera (AV), a novel edible coating for fruit storage. Aloe Vera has antifungal activity against several pathogenic fungi including Botrytis cinerea. Aloe Vera coatings modify the internal gas atmosphere, reduce moisture loss, softening, respiration rates, delay oxidative browning and reduce microorganism proliferation in fruit such as sweet cherries, table grapes, nectarines and papaya. Aloe Vera gel coating alone or in combination with shellac, preserves physicochemical parameters such as color and firmness in apple slices. Ascorbic acid (AA) and its derivatives have been used in numerous studies in fruit in concentrations ranging from 0.5 to 4% (w/v). Anti-browning effects of Ascorbic Acid have been demonstrated in several fruit fresh-cut products under a wide range of conditions. In addition, AA as an antioxidant that reduces vitamin C lost can be added to the edible coating material. Some studies have suggested that Ascorbic Acid in combination with lactic acid has antimicrobial effects against Listeria monocytogenes and on Escherichia coli O157:H7 in carrot juice. Antimicrobial effects of Ascorbic Acid on fresh cut fruit such as jackfruit, apple and papaya have been reported.
