Effect of whey protein concentrate edible coating and Trachyspermum copticum essential oil on the microbial, physicochemical and organoleptic characteristics of fresh strawberries during storage

Background and Aim: Strawberry is a valuable product that has a relatively short storage life. Use of chemical fungicides to extend storage life has been a matter of concern. In recent years, use of edible coatings has been regarded as a safe method in order to replace synthetic coatings. The aim of this study was to increase the storage-life and maintain the quality of strawberry by using edible coatings of whey protein concentrate and Trachyspermum copticum essential oil during a storage time of 10 days at 4 ± 1 ° C and relative humidity of 75 ± 5%. Materials and Methods: We extracted the essence of the seeds by Clevenger apparatus. Then, the active components of the essence were identified by gas chromatography - mass spectrometry (GC-MS) method. In this study we used edible coating of whey protein concentrate and Trachyspermum copticum essential oil at different concentrations (0.2, 0.4 and 0.6%).Microbial quality )number of molds and yeasts, total microbial count(, physicochemical characteristics (weight loss, acidity, pH, soluble solids, texture firmness, and decay) and organoleptic characteristics were assessed in the experimental group after packing, before storage (at the beginning of storage ) and then 3, 5, 8 and 10 days after storage and compared with those in the control group. Results: This coating significantly delayed the growth of microorganisms. By increasing concentrations of 0.4 and 0.6%, the mold and yeast counts after 10 days of storage reached zero and we found a logarithmical cycle reduction in the microbial load. As well texture firmness, weight loss, and decay percentage significantly decreased in the experimental group compared to those in the control group. On the 10th day, the decay rate was 86% for the control group and 10% for the case group containing 0.6% essential oil. Changes in PH, acidity and soluble solids were not significant. The best organoleptic properties were related to the priming with 0.2% essential oil, which also had a positive effect on the parameters in our study. Conclusion: Strawberry fruit coating with whey protein concentrate and Trachyspermum copticum essential oil can be regarded as a safe and effective way to increase the storage life and quality of strawberry fruit in cold environments.