Structural And Antioxidant Activities Changes Of Anthocyanin After Different Thermal Treatments

Eggplants and purple potatoes were deep-colored vegetables,which were rich in anthocyanins.Anthocyanins had various beneficial functions,such as prevention of cardiovascular disease,antioxidant,anti-inflammatory activities.Natural anthocyanin was not stable,and was susceptible to temperature,light and pH values.The purification and identification of eggplants and purple potatoes were conducted.At the same time,the effects of different treatments including steaming,microwaving and frying was investigated on the changes of structural and antioxidant activities of anthocyanins.Due to the complexity of anthocyanin extracts,it's difficult to figure out the degradation rule of one of the composition.Thus,delphinidin and petunidin were chosen to investigate the specific degradation rules of anthocyanin after heating,microwaving and ultrasonic treatments.Besides,the antioxidant activities before and after treatments were also compared on these two anthocyanin standards.This study aimed at providing a reasonable cooking and storage methods of deep-colored vegetables.The main research results were as follows:1.Combination of HPLC-QQQ-MS and HPLC-QTOF-MS was used to identify anthocyanins profiles in eggplants and purple potatoes.And the MS/MS results showed that the main compounds in eggplant extract was as follows: delphinidin-3-glucoside,delphinidin 3–(p–coumaroyl)–rutinoside–5–glucoside,delphinidin 3–(p–coumaroyl)–rutinoside,pelargonidin 3–p–coumarylglucoside,pelargonidin 3–(4–p–coumarylrutinoside)–5–gulcoside and petunidin 3–O–beta–D– sambubioside.While,the main anthocyanins in purple potatoes were cyanidin 3– sophoroside–5–glucoside,peonidin 3–sophoroside–5–glucoside,peonidin 3–p– hydroxybenzoylsophoroside–5–glucoside,peonidin 3–caffeoylsophoroside–5– glucoside,peonidin 3–(6?–feruloylsophoroside)–5–glucoside,cyanidin 3–(6 – caffeoyl–6–feruloylsophoroside)–5–glucoside,peonidin 3–caffeoyol–p– hydroxybenzoylsophoroside–5–glucoside,peonidin 3–(6–caffeoyl–6? –feruloylsophoroside)–5–glucoside,peonidin 3–feruloyl–p–hydroxybenzoyl sophoroside–5–glucoside,peonidin 3 –(6?–diferuloylsophoroside)–5–glucoside.Besides,the total anthocyanin contents in eggplants and purple potatoes were 1.96 and 0.33 mg C3G/g DW by pH-differential method.2.The changes of anthocyanin structures were investigated in fresh eggplant and purple potato after steaming,microwaving and fring treatments.The results showed that,these processes had no significant influences on the structure of anthocyanins but had a great acceleration effects on the extraction of anthocyanins.At the same time,the antioxidant activities were also studied by DPPH,FRAP and ABTS methods.It was founded that,the antioxidant activities were significantly increased by these treatments.3.HPLC-QQQ-MS method was adopted to investigate the degradation products of delphinidin and petunidin.Results showed that the contents of delphinidin and petunidin decreased and some new components were produced.The main pyrolysis products in delphinidin were 2,4-dihydroxy benzoic acid,3,4,5-trihydroxy styrene,3,4,5-trihydroxybenzoic acid and trihydroxy phenol.Furthermore,petunidin was broken into 2,4-dihydroxy benzoic acid,3-methoxy-4,5-dihydroxy styrene,3-methoxy-4,5-dihydroxybenzoic acid,1-methoxy-2,3-dihydroxy phenol.Besides,the antioxidant activities of delphinidin and petunidin were measured by DPPH and ABTS methods after steaming,microwaving and ultrasound treatments.Results showed that,the total antioxidant activities of anthocyanin solutions were significantly decreased after these thermal processing.It might get the conclusion that the loss of anthocyanin bioactivity could not be compensated by the antioxidant capacity of newly formed colorless phenolics upon different treatments.