Extraction of essential oil from Assam lemon peels and its incorporation in chitosan based coating for maintaining grape quality

Assam Lemon is one of the most important varieties of lemon, which is valued for fragrance, acidic content and natural compounds such as minerals, citric acid, ascorbic acid, essential oil, etc. The peels are also rich in various nutrients and phyto-chemicals which have antibacterial po-tential. In this study, essential oil (EO) was extracted and optimized from fresh Assam Lemon peels using microwave-assisted extraction (MAE). The experimental design was carried out using a Box-Behnken design arrangement using response surface methodology. The independent vari-ables for the extraction process were liquid to solid ratio (0.3:1-1:1 mL/g), time (10-20 min) and microwave power (500-900 W). The yield of essential oil (response) obtained was found in the range between 0.13 and 0.75%. Microwave power had a significant effect on essential oil yield. Electric power consumption by extractor was 0.85 kWh and CO2 emissions were calculated as 0.68 g for 17 min of extraction time. Further, chitosan-based coating solution was prepared by adding different concentration of the essential oil (0.25, 0.5, 0.75 and 1% v/v). The coating was then applied on fresh grapes and its effect on physico-chemical properties and storage quality of grapes were evaluated. The coating of lemon essential oil-chitosan showed that grapes coated with 1% EO coating retained the maximum quality up to 15 days of storage at room temperature (25 +/- 2 degrees C). This work could provide a base for using lemon essential oil mixture as a green preservative to improve the storage quality of grapes.