Effectiveness of Chitosan Coatings on the Quality of Strawberry (cv. Monterey) during Simulated Air-ride Truck Distribution

Strawberry is highly preferred by consumers due to its delicious taste and attractive appearance. However, strawberries are very sensitive to handling and transportation conditions because of their high softening and respiration rate. Therefore, edible films and coatings can be used as an alternative method to prevent undesirable changes during transportation. Chitosan, an edible film, improves firmness and maintains postharvest quality of fruit by modifying the internal atmosphere and reducing respiration rate of fruit. It also inhibits the microorganism growth due to antimicrobial activity.   The aim of this study was to evaluate the effect of chitosan coatings at different concentrations (1%, 2%, and 3%) on the quality of strawberry during International Safe Transit Association (ISTA) 3H procedure, which simulates an air-ride truck vibrations on a vibration table. Strawberries (cv. Monterey) were obtained from Apio Inc. (Guadalupe, CA) and transported to the Cal Poly Industrial Technology Department. Chitosan with the amounts of 10, 20, and 30 g were dissolved in 1000 mL water by using acetic acid. Then strawberries were immersed in the coating solutions for 1 minute and taken out. Strawberries dried at ambient temperature. Uncoated strawberries were chosen as control. Then, 6 kg of strawberries were placed in IFCO 6408N reusable plastic containers (RPC) (Sydney, Australia) and subjected to International Safe Transit Association (ISTA) 3H procedure which simulates air-ride truck vibrations on a vibration table (Lansmont Electrol-Hydraulic Vibration System Inc., Monterey, CA). Firmness, weight loss, and respiration rate measurements were performed. After simulated distribution, all coated samples had higher firmness values compared to the uncoated samples. It can be concluded that chitosan coatings generated a protective layer on the fruit surface and prevented the damage during distribution. Uncoated strawberries exhibited higher weight loss than coated fruits. Its possible that the semipermeable structure of chitosan reduced the migration of water from strawberry.  Chitosan inhibited the enzymes responsible for destruction of middle lamella. Its known that distribution conditions can increase the respiration rate of fruits due to physical damage. In our work respiration rate of coated samples were lower than the uncoated samples. A possible explanation for this might be that chitosan reduced the physical damage of fruit during transportation and also controlled the exchange rate of gases due to excellent gas barrier properties. [M.S. Aday thanks the Scientific and Technological Research Council of Turkey (TUBITAK) BIDEP-2219 for postdoctorate support.]