A novel edible coating for apple fruits

Abstract

Edible coatings are an environmentally friendly technology that is applied to many products to control moisture transfer, soluble and aromatic materials, gas exchange or oxidation processes. The objective of this research was to study the effect of tragacanth gum at the concentrations of 0, 5, 10, and 15 kg m-3 on storage life and edible quality of apple cvs. Red Delicious and Golden Delicious. After applying treatments, the fruits were kept in a cold storage at a temperature of 0±1 ˚C and relative humidity of 85-95 percent. The weight reduction, external quality, microbial load, and general acceptability of the samples were evaluated after 0, 30, 60, 90 and 120 days of storage, then compared with uncoated apples. It was found that the tragacanth gum significantly reduced fruit weight loss compared to the control, so that weight reduction in uncoated apples was eight times greater than fruits treated with tragacanth gum at 10 kg m-3. This coating preserved firmness of fruit tissue in storage and prevented the softening and senescent breakdown of apples. The tragacanth gum coating desirably preserved the external quality and improved the microbial load, sensory and external properties of the fruits, preserved quality factors of the apples, and prevented fruit ripening during storage. Among the various treatments, the coating at 10 kg m-3 was more effective than the other treatments, maintained fruit juice acidity and pH at desirable levels, and prevented increases in the contents of soluble solids during the storage.