Garlic oil -sodium carboxymethyl cellulose composite coating material improving strawberry preservation effect

Abstract: The strawberry (Fragaria x ananassa) is the most popular and year-round available berry in China and mainly consumed as fresh fruit. It is a kind of easily perishable fruit, which makes it impossible to store for a long term; thus, it should be used very quickly after harvest. Many products such as juice, jelly, nectar, puree, concentrate or jams have been developed. Despite the demand for these products, there remains an excess of strawberry crops. A possible alternative is to generate new preservation method that maintains the fruit's original quality to the maximum extent, which can either retard or inhibit the physico-chemical changes occurring and improve fruit storability. The application of edible coatings is one of the most innovative methods to extend the commercial shelf-life of fruits and vegetables by acting as a gas barrier and having a similar effect with the storage under modified atmosphere, which reduces quality changes and slows down quantity losses through modification and control of the internal atmosphere of the individual fruit. Edible coating has a thin protective layer that is applied to the skin surface of the fruit and later consumed together with the fruit flesh. Sodium carboxymethyl cellulose (Na-CMC) is a naturally-occurring compound that enjoys the potential in agriculture due to its controlling plant diseases. Garlic oil is a kind of natural essential oil, which can be evenly dispersed in Na-CMC/chitosan solution to form an edible semipermeable film on the outside surface of the fruits to extend storage life and reduce some forms of decay caused by fungi during the storage. The objective of this work was to evaluate the effect of Na-CMC/garlic oil coating on respiration rate and quality characteristics of strawberry during its storage. Fresh strawberry was treated with garlic oil/Na-CMC composite film material and then stored at 6 ℃ or 20±2 ℃ for 6 d. Changes in weight loss, respiration rate, rot index, titrable acidity, soluble solid content, ascorbic acid, and malonaldehyde content were periodically recorded. The results indicated that garlic oil/Na-CMC composite film material was effective in reducing weight loss, respiration rate as well as decay rate, significantly reduced the strawberry quality changes during the storage process, and achieved the purpose of keeping the freshness of strawberry. A trend in delaying the decomposition of the anthocyan and color-protecting was observed for coated strawberry. As the garlic essential oil content of composite film material was 4 μL/100 mL, the coated strawberry had the best quality during the storage.