Gallate Synthesis Of Gallic Acid Ester And Persimmon Extract Edible Oils And Fats Oxidation Resistance

Gallic acid (GA) is a kind of important fine chemicals, abounds in resources in our country and now is produced in a few countries, such as Japan and China. GA esters, which can be synthesized with GA and alcohols, have widely been applied to food, chemical, medicine, light industry and so on. Therefore, many scholars have still try to improve methods of synthesis of GA esters and raise degree of purity and rate of production. GA esters are good seminatural antioxidants to edible fats, but only propyl gallate(PG) has been used in food in China. For many years, artificial synthetic antioxidants, such as BHT and BHA, have largely been used in food and they have been questioned for their toxicity and byeffects. It has practical significance to develop GA esters in food instead of artificial synthetic antioxidants.We synthesized ethyl gallate (EG), PG, butyl gallate(BG), iso-butyl gallate(IBG), amyl gallate(AG), iso-amyl gallate(IAG), hexyl gallate, heptyl gallate, octyl gallate(OG) by the reaction of GA with aliphatic alcohol. In the course of synthesis, we studied catalytic activities of toluene-p-sulfonic acid, dodecylbenzenesulphonic acid, phospho-wolframic acid and cation resin. The results of experiments showed that toluene-p-sulfonic acid and dodecylbenzenesulphonic acid had good catalytic activities to synthesis of GA esters; catalytic activity of phospho-wolframic acid was poor in synthesis of BG; cation resin was a good catalyst in synthesis of BG and by means of it, BG had a high yield and degree of purity and a good crystal form. Cation resin could be used repeatedly and aftertreatment was simple. We think cation resin is an ideal catalyst in synthesis of medium and lower GA esters.Lard and Chinese prickly ash seed oil being used as substrates, we studied antioxidative activities of 9 synthesized GA esters by Schhal oven-storage test and measured their acid value. On two edible fats, 9 GA esters had good antioxidative effects, which were equal or better than that of ascorbic acid and they effectively reduced two edible fats' acid value. In the lard, antioxidative effects of PG, EG and OG were prominent and activity of PG was better than that of BHT. In Chinese prickly ash seed oil, antioxidative effects of PG, IBG and AG were prominent, lowerthan that of BHT but much better than that of ascorbic acid.Our study has important reference value to synthesis of GA esters and provides important bases for the use of GA esters-a kind of good seminatural antioxidants offood.Meanwhile, we got extracts from persimmon , the calyx and receptacle of persimmon and the persimmon leaves with 95% ethanol. For the first time, the activities of oxidation resistance of the extracts were systematicly stdudied by Schhal oven-storage test. The results of experiments showed two extracts of persimmon and persimmon leaves had good antioxidative effects on lard and Chinese prickly ash seed oil and they were better than ascorbic acid in antioxidancy and reduced two edible fats' acid value. Moreover, the two extracts have not toxicity and byeffects and they are potential and new natrual food antioxidants.Our study provides scientific bases for the use of serial extracts of persimmon as natural food antioxidants and tapping persimmon resources.