CHARACTERIZATION OF PECTINS EXTRACTED FROM MACAÚBA CAKE USING DIFFERENT TYPES OF ACIDS

One of the products of the Macaúba (Acrocomia aculeata) production chain is the cake from the pressing of coconut pulp. Previous studies carried out by our group have shown that this cake is rich in pectin, a compound with applications in the food and pharmaceutical industries. In this sense, the present work aimed to characterize the pectins obtained in the extraction of macaúba cake using different types of acids. Pectin was extracted using hydrochloric, acetic and citric acids under optimized conditions (pH 3.0, extraction for 40 min at 65 ^oC) and characterized for molar mass, elemental analysis, monosaccharide concentration and zeta potential. The results showed a higher molar mass of pectin extracted with acetic acid (359,000 g ^mol-1) and similar values for pectins extracted with hydrochloric and citric acid (96,000 g ^mol-1). The percentage of carbon ranged from 42.7 % (w/w) for pectin extracted with acetic acid to 47.5 % (w/w) for pectin extracted with citric acid. The percentage of hydrogen was 8% (w/w). The determination of monosaccharides showed that the major compounds are: galacturonic acid (80.3-89.2 % w/w), mannose (5-10 % w/w) and glucose (9.2-17.9 % w/w). The high concentrations of glucose and mannose suggest that hemicellulose is also being extracted in the process, but further studies will be carried out to prove this fact. The pectins extracted with acetic and citric acids showed a zeta potential of -7.2 mV and the one extracted with hydrochloric acid a potential of -9.5 mV