EFFECT OF ORANGE PEEL PECTIN EXTRACT ON THE SYNERESIS AND PHYSICOCHEMICAL CHARACTERISTICS OF YOGHURT

Abstract

Orange peels are rich in a natural substance known as pectin. Adding this pectin to yogurt prevents it from getting watery, keeping the creamy texture intact. It's a smart way to use fruit leftovers and make yogurt better. The aim of the present study was to extract and optimize pectin from orange peel using alcohol (ethanol) as precipitant. Ripe orange peel was peeled off and it was dried until its moisture reached ~10%, dried orange peels were grinded in grinder until very small uniform powder (80mm) were formed. The powdered orange peel sieved (80mm) mesh size was subjected to acidic pH (pH 1,2 and 3 maintained with HCL acid) and heated in water for until 60,90- and 120 min. Response surface methodology with central composite design at three-level three-factor general factorial design was applied for the maximum yield. The obtained pectin was grinded and utilized in preparation of set yoghurt and analyzed by sensory evaluation. The pectin yield of orange peel at pH 1 was significantly greater. The yield was 29.87% at pH 1. In order to obtain maximize yield, the optimum condition of pH, temperature and time for pectin extraction from orange peels was 1, 95℃, 120 min respectively. The Ash content, Moisture content, Methoxyl content, Pectin grade, Anhydrounic acid content, Degree of esterification, and Equivalent weight of extracted pectin from orange were found to be 8.3±0.15, 10.12±0.1, 5.61±0.07, Low methoxyl, 40.48±0.30, 43.4±0.06 and 820.55±1.22 respectively. These data confirmed that thus extracted pectins can be used in commercial usage. The yoghurt prepared with 0.25% pectin had lower syneresis and optimum sensory score. Syneresis was lowered by 29.5% on 12th day compared to control. The sensory parameters appearance, texture, taste was significantly different (p<0.05) to control samples. The findings of this study showed that sweet oranges are a strong source of pectin and have the potential to be crucial raw materials for the food processing industry.