EVALUATION OF POLYPHENOL EXTRACTION FROM APPLE POMACE
Food industry is searching for natural additives because consumers demand natural, safe and environmentally sound food additives. The use of different plant extracts such as grape pomace and cranberry extracts which have antimicrobial effect in food preservation has gained an increasing interest. In the latest years many researches deal with investigation of the antimicrobial effect of apple pomace extracts. Apple pomace, a residue from apple juice production, contains high amount of polyphenols which are known to have antioxidant effect. Apple pomace is a by-product of the apple juice and cider processing industry and represents about 20–35% of the original fruits. It can be used for value-added products, because it is rich in pectin, fibre, macro and micro elements and antioxidants mainly, polyphenols. Previous studies indicate that the apple pomace has high phenolic content and antioxidant activity and thus can be regarded as a valuable source of antioxidants and bioactive compounds. The contents of phenolic compounds vary greatly among different varieties of apples. Moreover, apple peels contain higher concentration of phenolic compounds compared to flesh. Conventional production of apple juice results in a juice with poor phenolic content and with only 3–10% of the antioxidant activity of the fruits that they are produced from. Thus, leaving huge amount of the phenolic compounds in the pomace. Because of this, studying extraction method for extracting high amount of polyphenol from the pomace is important. In this paper apple pomace was dried with different drying method (atmospheric and vacuum ovens, 80° C and 60°C). Extraction was performed using distilled water as solvent, and the extracts were evaluated by the colour, water soluble sugars, total polyphenol content (TPC) and antioxidant capacity.
Keywords: Food waste, Apple pomace, Drying, Extraction, Antioxidant activity.