Study On Extraction And Physical-chemical Properties Of Pectin From Sweet Potato

Pectin is a natural polymer, existing in primary cell and cytoplasm of advanced plant, composed largely of a backbone of α-1, 4 linked D-galacturonic acid units, many of which are esterified with methyl alcohol at the carboxylic acid, interspersed with a few L-rhamnose residues and asafetida acid linked to neutral arabinogalactan side chains. Due to its good gellifying properties and emulsification stability, extensive applications have been achieved in food industry.Sweetpotato is a important crops with high yield in China. There are sweetpotato planted in a lot of area of the country. It had been mainly used in production of sweetpotato starch or vermicelli, except for consumption directly or processed as small food. The industry of sweetpotato starch produced a mass of sweetpotato pomace. At present, sweetpotato pomace is sold to local farmer used as feed or firewood. There contained 10%-30% of pectin in sweetpotato pomace. So it is an important pectin resource. The present research is intend to optimize the parameter for extraction of pectin from sweetpotato pomace, and the physical-chemical Properties of the sweetpotato pectin was also investigated.The results showed that it is necessary to hydrolyzing pomace starch with 0.02% of α-amylase ahead of petin extraction, for sweetpotato pomace contained about 40% of starch, which severely impact the process of pectin extraction by hydrochloric acid, phosphoric and sulfurous acid or their blend. But the best choice is Hydrochloric acid.The optimization of parameters in extraction process including pH, temperature and time were studied and optimized through Response Surface Analysis (Central Composite Design). The results showed that the optimal temperature was 88℃, pH 1.8, duration of 130min, the extraction ratio for pomace pectin reached 65.86%.Crude petin extract was further treated with ultrofiltrate, precipitated by alcohol. Alcohol concentration, Concentration ratio, washing times were studied in orthogonal experiment design. Pectin purity and gain ratio were used as index of the precipitated process. The results showed that concentrate multiple 1/4, alcohol concentration 75%,...