EVALUATING THE EFFECTS OF PRETREATMENTS AND DRYING METHODS ON PHYSICOCHEMICAL CHARACTERISTICS OF PLUM FRUIT (PRUNUSDOMESTICA L. ) FOR PRUNE PRODUCT DEVELOPMENT

Abstract

The plum fruit has essential medicinal and nutritional values. However, the seasonal behavior of its production hinders uniform distribution and availability to every corner of the country. Moreover, the as-produced fresh plum fruit cannot reach to the society in need on the right time because it can easily be spoiled without being used. Hence, a solution must be designed to solve these challenges. Therefore, we aimed to preserve the plum fruit in the form of dry product without losing its qualities for a longer storage period and make available to the end users. Accordingly, this work studied various physicochemical parameters (such as proximate compositions, dehydration and rehydration ratio, coefficient of reconstitution, non-enzymatic browning reaction, total soluble solid, acidity, pH, sugar, phenolics, flavonoids and antioxidant activity) of the dried plum fruit. Particularly, the study based its focus on the effects of pretreatments (using citric acid and 1 % lemon juice) and drying methods (sun and 45 oven ) on the qualities of the targeted parameters. The study was conducted in a category of samples untreated (T0), 1% citric acid treated (T1), and 1 % lemon juice treated (T2) solutions, respectively. After such pretreatments, a sample was exposed for drying (Sun and Oven). Then the results obtained for every parameter in each sample groups (T0, T1, and T2) were compared and the best one was selected for storage stability studies. Throughout the measurements performed, results revealed that, values recorded for every parameter show a trend of T1> T2> T0 indicating treatments of the plum fruit with citric acid (T1) and lemon juice (T2) have better effect in maintaining the nutrients and other qualities of the plum over the untreated sample (T0). Accordingly, the trend T1O > T2O >T0O was observed revealing that pretreatment of the plum fruit with citric acid followed by drying in oven could give better result. However, for storage stability studies and packaging materials (Aluminum foil and Low-Density Poly Ethylene) were studied. With our careful investigations, AF packaging bag and citric acid pretreated sample could stay longer period with best retention of sensory qualities and low microbial plate count numbers compared with untreated (T0O) and LDPE packaging material. Therefore, the dried plum packed in aluminum laminated bags was safe enough for consumption and maintained good microbial quality during the storage period of 180 days (6 months).