Authors Martinez-Romero D L,Alburquerque N ,Valverde J M,Guillen F, Castillo S et al ,
A novel edible coating based on Aloe vera gel, accordingly to our developed patent (SP Patent Filed P200302937), has been used as postharvest treatment to maintain sweet cherry quality and safety. During cold storage, uncoated fruit showed increases in respiration rate, rapid weight loss and colour changes, accelerated softening and ripening, stem browning and increased microbial populations, these processes being more intense during the shelf-life periods. On the contrary, sweet cherry treated with A. vera gel significantly delayed the above parameters related to postharvest quality losses, and storability could be extended. The sensory analyses revealed beneficial effects in terms of delaying stem browning and dehydration, maintenance of fruit visual aspect without any detrimental effect on taste, aroma, or flavors. As far as we aware, this is the first time A. vera gel is used as an edible coating in fruit, which would be an innovative and interesting means for commercial application and as alternative of the use of postharvest chemical treatments. Sweet cherry is one of the most appreciated fruit by consumers since it is an early season fruit and has an excellent quality. The main quality indices are skin colour, which is related to fruit ripening and affected by anthocyanin concentration, and total soluble solids-total acidity ratio (TSS/TA) at harvest. Both parameters, together with the absence of stem browning determine consumer acceptance. TSS ranges between 11 and 25″Brix depending on cultivar and is mainly due to glucose and fructose and less to the presence of sucrose and sorbitol. TA depends also on cultivar, with levels of 0.41.5%, the main organic acid being malic acid. Fruit firmness is also an important quality attribute and is directly related to enhancement of storability potential and induction of greater resistance to decay and mechanical damage (Barret and González, 1994). Sweet cherry fruit deteriorate rapidly after harvest and in some cases do not reach consumers at optical quality after transport and marketing. The main causes of sweet cherry deterioration are weight loss, colour changes, softening, surface pitting, stem browning and loss of acidity, while low variations occur in TSS. Finally, special care is needed with the occurrence of decay, which is mainly due to species of the genera Penicillium, Botrytis and Monilia. This fungal spoilage can cause great economic losses, although the occurrence of rots and their influence on sweet cherry quality have been reported to be dependent on cultivar and ripening stage at harvest. Several pre- and postharvest technologies have been used to control decay, but the postharvest use of chemicals as fungicides is restricted in most countries and consumers demand agricultural commodities without pesticide residues. Among these technologies, the use of modified atmosphere packaging (MAP) has been reported to be effective in delaying the physico-chemical changes related to sweet cherry fruit quality loss. Recently, the combination of MAP with several essential oils has been shown to improve the beneficial effect of MAP on maintaining sweet cherry fruit quality during cold storage and extending shelf life. Edible coatings are traditionally used to improve food appearance and conservation. They act as barriers during processing, handling, and storage, and do not solely retard food deterioration enhancing its quality, but are safe due to natural biocide activity, or to the incorporation of antimicrobial compounds. Different compounds have mainly been used as edible coatings to prevent commodity weight loss, including wax, milk proteins, celluloses, lipids, starch, zein, and alginate. In the recent literature, there is little evidence of the use of edible coatings in sweet cherry. Thus, Semperfresh reduced weight loss and softening, extending shelf life, although fungicides should be added to avoid fungal spoilage. Derivatives of fatty acids and polysaccharides decreased sweet cherry fruit respiration rate and weight loss. In addition, edible coatings based on chitosan alone or in combination with hypobaric treatments reduced postharvest decay in sweet cherry, there is an increasing interest in the use of Aloe vera gel in the food industry, being used as a source of functional foods in drinks, beverages and ice creams. Nevertheless, processing techniques used to obtain A. vera gel are very important to ensure the product quality and to maintain almost all the bioactive components. The aim of this work was to study the effect of A. vera, applied as an edible coating according to our patent, on the change in physico-chemical parameters related to fruit quality during cold storage and shelf life in sweet cherry, as well as its role in controlling microbial spoilage. As far as we are aware, this is the first published paper in which A. vera gel is used as an edible coating in sweet cherry fruit. It could be an innovative and interesting commercial product and an alternative to the use of synthetic postharvest fungicides.
