The Effect of Edible Coatings (Spirulina and Chitosan) on the Quality and Shelf Life of Starfruit (Averrhoa carambola L. cv. B10) Throughout Storage

The edible coating is one of the preservation methods widely applied by food industries as it is beneficial in suppressing respiration, minimising moisture loss, and reducing food wastage. This study investigates the effects of edible coating (Spirulina platensis and chitosan) on the quality and shelf life of B10 throughout storage at room temperature 27°C. The quality analysis of colour (L*, a*, b*, and hue), browning index, fresh weight and physical appearance were evaluated on days 0, 4, 8, 12, and 14. There was a significant difference for all quality analyses between storage days (p < 0.05). The physical appearance showed that at day 8, B10 coated with spirulina maintained the greenish colour while chitosan-coated and controlled turned the fruit bright yellowish, indicating ripening. Control samples were observed to have major browning at day 12, whereas samples coated with spirulina and chitosan only showed early signs of browning. Samples with spirulina coating have the least a* (greenness-redness) and b* (blueness-yellowness) values, which showed that spirulina was able to slow down the ripening process in comparison to chitosan and control (p < 0.05). For the hue value, samples with chitosan coating showed the least colour changes (p < 0.05), followed by spirulina and control with 9.04, 9.43, and 30.82°, respectively. It proved that coated samples provide the best results in slowing down the colour changes and browning of the carambola compared to the control. Besides, the regression analysis resulted in a good fitness (R2 near 1) for browning and weight loss analysis for all coatings, which were agreed to be reliable and had a good predictive indicator power when the storage days were extended. Hence, these results would be potentially useful for the fresh produce industry to prolong the shelf-life of B10 during distribution, transportation, and commercialisation.