The Effect of Aleo Vera Gel Coating on Physicochemical Characteristics of Two Apricot Fruit Cultivars during Storage Time

Abstract
Introduction Apricot fruit is a carbohydrate-rich commodity and is a good source of fibers, essential minerals, vitamins and organic acids. It is also rich in bioactive compounds i.e. polyphenols and carotenoids that have certain antioxidant character in biological system. It is consumed in fresh, dried and frozen forms or used for the preparation of jam, juices, nectars and extruded products. Therefore, apricot being an attractive nutritious fruit is appreciated by consumers and farmers all over the world and has gained great economic importance over the years. Apricot is a climacteric fruit that presents a high respiratory and metabolic rate and, among stone fruits, is the one that presents the highest ethylene emission. One of the major problems of apricots is the rapid postharvest softening, which limits its storability and marketability. These features results that, at the postharvest, have an extremely short shelf-life of only 1-2 weeks in the cold storage, and pass quickly from maturity to overripe. One of the major problems of apricots is the rapid postharvest softening, which limits its storability and marketability. For this reason, to have acceptable quality fruits, they must be stored with adequate techniques to limit the post-harvest losses. As apricot production and export increase, demands for practical methods of post-harvest quality retention are necessary to improve the post-harvest quality of apricots during postharvest life. Several pre- and postharvest technologies have been used to control postharvest losses, but the use of chemicals as fungicides is restricted in most countries and consumers demand agricultural commodities without pesticide residues. Consumers around the world demand for food of high-quality, without chemical preservatives, and extended shelf life. Therefore, an increased effort has been made to develop new natural preservatives and antimicrobials. Many storage techniques have been developed to extend the marketing distances and holding periods for commodities after harvest. Among these technologies, edible coatings are traditionally used to improve food appearance and preservation. Edible coatings are thin layers of edible material applied to the product surface in addition to or as a replacement for natural protective waxy coatings and provide a barrier to moisture, oxygen and solute movement. They are applied directly on the food surface by dipping, spraying or brushing. Edible coatings are used to create a modified atmosphere and to reduce weight loss during transport and storage. In fact, the barrier characteristics of gas exchange for films and coatings are the subjects of much recent interest. Recently, researchers have developed a gel based on Aloe vera that prolongs the conservation of fresh fruits. This gel is tasteless, colorless and odorless. This natural product is a safe and environmental friendly alternative to synthetic preservatives such as sulfur dioxide. This gel operates through a combination of mechanics, forming a protective layer against the oxygen and moisture of the air and inhibiting the action of micro-organisms that cause food-borne illnesses through its various antibacterial and antifungal compounds. Aloe vera gel-based edible coatings have been shown to prevent moisture and firmness losses, control respiratory rate and delay ripening process slow oxidative browning and reduce microorganism proliferation in fruits. Present study was conducted to evaluate the increasing of apricot storage time, introducing suitable cultivars based on Aloe vera gel coating, effects of Aloe vera gel on the qualitative characteristics of fruit and obtain the optimum concentration of Aloe vera gel required to coating apricot fruits.
Material and methods: Therefore, a factorial experiment was carried out based on a completely randomized design with four replications. The evaluated factors including cultivars “Dorosht-e Malayer” and “Ghermez-e Shahrood”, concentrations of Aloe vera gel [control (non-gel coating fruits), 25% and 33%] and storage time [0 (Harvest), 7, 14 and 21 d)]. Moreover, total soluble solids (TSS), titratable acidity (TA), fruit firmness, pH, percentage of weight loss, antioxidant activity and vitamin C content were determined during storage time.
Results: The results showed that treatment of apricot fruits with Aloe vera gel, especially at 33% concentration, significantly enhanced vitamin C content, titrable acidity, antioxidant capacity and improved tissue firmness, but also reduced soluble solids, weight loss and pH content. Moreover, it was found that vitamin C content, titratable acidity and fruit tissue firmness significantly decreased during storage time, while soluble solids content, weight loss and antioxidant capacity significantly increased. Among the cultivars, “Ghermez-e Shahrood” cultivar had higher soluble solids content, weight loss, pH and antioxidant capacity during storage time, whereas “Dorosht-e Malayer” cultivar had higher titrable acidity, tissue firmness and vitamin C at the end of storage time.
double and triple interaction effects of evaluated factors significantly affected all characteristics, except in antioxidant activity, where just storage time had a significant effect. It was found that the highest vitamin C content in “Dorosht-e Malayer” and “Ghermez-e Shahrood” was obtained at the end of the second week in coated fruits with 33% of Aloe vera gel. TSS content in fruits of “Dorosht-e Malayer” cultivar that coated with 25% and 33% of Aloe vera gel was less than “Ghermez-e Shahrood” cultivar, while Aloe vera gel had no significant effect on TSS content in “Ghermez-e Shahrood” cultivar. Aloe vera gel had no defined pattern on TA concentration but generally, “Dorosht-e Malayer” fruits had higher TA concentration comparing “Ghermez-e Shahrood” fruits During the storage time, the fruit weight loss and firmness were higher in “Ghermez-e Shahrood” as compared with “Dorosht-e Malayer”, however, in the both evaluated cultivars, treatment with Aloe vera gel had a significant positive effect to controlling of fruit weight loss and firmness. Furthermore, coating with Aloe vera gel improved the antioxidant capacity in both evaluated cultivars.
Conclusion: Overall, according to the results, it can be concluded that as compared with “Ghermez-e Shahrood” cultivar, “Dorosht-e Malayer” cultivar showed better quality based on the evaluated parameters and maintained its quality for a longer time. As a conclusion, considering the positive effects of Aloe vera gel, it can be in order to increase the shelf-life and maintaining the quality of apricot fruits.