Effects of Alginate-based Chitosan-Starch Coating on the Physico-Chemical Properties of Guapple (Psidium guajava L. cv. Queso de Bola)

Abstract

Because of its nutritious qualities and growing demands, an attempt to support the Philippine Guapple industry was enacted through edible coating. Especially those of starch and chitosan formulation, edible coatings are known to develop low-cost and biocompatible resistance from the drastic changes that commodities experience from their surroundings. Thus, becoming a low-cost technology to prevent yield losses and decrease rate of senescence for selected fruits. With the control treatment as the designated Treatment 1, Treatment 2 Guapples are treated with coating concentrations of 2% Alginate + 0.5% Chitosan, and Treatment 3 Guapples are those that have been treated with 2% Alginate + 0.5% Chitosan + 2% Starch. This setup identifies if the variations of Starch and Chitosan concentrations affect the overall postharvest qualities of Guapples. The physico-chemical parameters were measured through non-destructive and destructive tests, as they relate to the overall process of senescence. Replicated four times in ambient conditions (28°C, ~80% RH ), the physico-chemical variables are recorded periodically in a span of one week. It was found that in moisture loss deterrence, the coating from Treatment 2 is the most effective, with significant moisture loss deterrence (vs. Control) found during Day 2. On the other hand, it was found that in preserving the Guapples from Browning, Treatment 3 does it slightly better. No other significant changes were found in terms of other chemical properties of Guapple such as Total Soluble Solids, Titratable Acidity, pH, Firmness, and Ripening Index. Furthermore, the consumer sensory evaluation suggests that they are unable to find any significant preferential difference, except for slight preferences in Visual Quality found in Guapples with Treatment 3. Moving forward, maintaining temperature in the laboratory is recommended as it is determined to be a confounding variable that may have affected results in a warm June climate.