The Role of Chitosan and Selenium in Improving Physico-Chemical Quality and Reducing External Chilling Injury During Low Temperature Storage of 'Fuerte' Avocado

摘要

Fuerte avocado (Persea americana Mill.) fruit is sensitive to chilling injury (CI) when exposed to lowtemperatures. High lipid content in avocado pulp makes it prone to oxidation, resulting in rancidity andsubsequent producing undesirable flavours and lossing quality during storage. Mature pre-climactericavocados were subjected in 2017 and 2018 seasons to pre storage treatments with sodium selenate solution (Se)at 0.05, 0.1, 0.15 and 0.2mg/L and chitosan solution at 0.5, 1.0, 1.5 and 2.0% as dipping for 5- minutes and theuntreated fruits were investigated, comparing to the control and commercial treatments. All treatments exceptcommercial treatment were cold stored at 5°C for one or two weeks followed by 5 days at 18°C as simulationfor marketing condition, whilst commercial treatment was stored at 10 °C for two weeks and 5 days at 18°C.The fruits were analyzed for physcio-chemical quality parameters viz. physiological loss in weight, firmness,total soluble solids, titratable acidity, salute leakage, total chlorophyll and total phenolic compound. Changesin respiration rate and ethylene production were also evaluated. The application of Se at 0.15 and 0.2 mg as wellas chitosan at 0.5 and 1.0% were effective in minimizing or preventing chilling injury symptoms and delayed theonset of climacteric peaks of respiration and ethylene production. The delay was associated with reductionsin fruit softening and cell membrane permeability as expressed by salute leakage. Also, alleviated a reductionin the chlorophyll content was obtained. Conclusion, overall, the results support that the Se at 0.15 and 0.2 mgwas the most effective for alleviation of CI and extending the marketing life of avocado fruit under lowtemperature storage compared with the control or commercial treatments.