Effect of Chitosan Coating Treatments and Calcium Dips on Quality and Shelf-life of Strawberries

Strawberries are a highly perishable fruit and storage life may be less than a week. In these investigations strawberries were treated with one of the following treatments: I) 1 % calcium chloride dips (1 % CaCl2), II) 2 % irradiated (150 kGy in the solid state) chitosan (CS) (2 % Irr. CS) and III) with a coating formulation containing 2 % Irr. CS + 1 % CaCl2. They were then stored at 6 degree C for up to 24 days. The effectiveness of the different treatments was assessed by evaluating the microbiological, physicochemical and sensory properties of strawberries during the storage period. Results indicated that no sign of strawberries decay were observed in the fruits treated with CS formulation containing 2 % Irr. CS + 1 % CaCl2 up to 20 days, where 6.1 % wt loss was detected. This treatment slowed the ripening of strawberries as shown by their retention of firmness and delayed changes in their external colour anthocyanin. To a lesser extent titratable acidity and ph were also affected by coatings. This treatment decreased the initial log counts of total aerobic bacteria, mould and yeast, coliform and E. coli. After 20 days of cold storage, the log counts of these micro organisms were lower than the log count of uncoated strawberries. Thus, CS can be used as a natural antimicrobial coating on fresh strawberries to improve microbiological quality and extend shelf-life. CS formulation contains 2 % Irr. CS + 1 % CaCl2 extended the shelf-life of strawberries to 20 days in cold storage at 6 degree C with acceptable appearance, firmness, flavour and colour, while uncoated strawberries only lasted for 4 days as a result of mould growth and loss of surface appearance