Study On The Preparation Of Compound Antioxidants And Their Application

Toona sinensis originated from tall woody plants in China.It is rich in a variety of active substances.It is a kind of medicinal and edible plant with good antioxidant activity.In addition,hawthorn leaves and grape seeds are also natural products with high antioxidant activity and high safety.In this study,three plant extracts were used as raw materials and sodium alginate was used as assistant to preserve potato slices.Through the combination,natural composite antioxidants with high antioxidant activity were obtained,which effectively prolonged the shelf life of fresh cut potatoes.The main results and conclusions of this paper are as follows:（1）The antioxidant activities of leaves,bark,roots and seeds of Toona sinensis were measured,the antioxidant properties of extracts of Toona sinensis leaves,hawthorn leaves and grape seeds were compared with tea polyphenols and V_C,and the correlation between polyphenols and antioxidant activity of Toona sinensis leaves was analyzed.The results showed that compared with skin,root and seed,Toona sinensis leaves had higher antioxidant activity;Compared with the extracts of Toona sinensis leaves and hawthorn leaves,grape seed extract has stronger antioxidant capacity;For ABTS⁺·clearance,the scavenging capacity of grape seed extract was higher than that of V_C and tea polyphenols;There was a significant correlation between Toona sinensis leaf polyphenols and DPPH·and ABTS⁺·clearance and total reducing power（P<0.05）.（2）The fresh-keeping effect of fresh cut potato was studied through single factor test.The optimum concentrations of extracts from Toona sinensis leaves,hawthorn leaves,grape seeds and sodium alginate were determined to be 0.10%,0.05%,0.01%and 0.50%respectively.On this basis,the response surface test was carried out,and the optimal compound formula was obtained:the extract of Toona sinensis leaf,hawthorn leaf,grape seed and sodium alginate were 0.110%,0.060%,0.011%and 0.520%respectively.（3）The effects of single and compound antioxidants with the same concentration on the antioxidant activity and antibacterial activity of fresh cut potato were studied.The results showed that the compound antioxidant could significantly inhibit the increase of total phenol content in fresh cut potato（P<0.05）,and better maintain the DPPH·clearance,ABTS⁺·clearance and total reducing power of fresh cut potato chips at a high level.In addition,the compound antioxidant can more effectively inhibit the growth of total colony number,and inhibit Escherichia coli,Salmonella and Staphylococcus aureus to varying degrees.The minimum inhibitory concentration（MIC）of the three are 0.0125 mg/m L,0.0200 mg/m L and 0.0036 mg/m L respectively.Among them,the MIC of the compound antioxidant on Escherichia coli is the same as that of the single antioxidant,However,the MIC of the other two strains was less than that of a single antioxidant.（4）The effects of different conditions on the antioxidant capacity of compound antioxidants were studied.The results showed that the antioxidant activity of compound antioxidants was stronger with the increase of temperature.It is suitable to store at 4℃away from light.Acid and alkali will reduce its antioxidant capacity;Adding a certain mass fraction of glucose,sodium chloride,tea polyphenols,V_C,citric acid and sucrose could improve its total antioxidant capacity,and tea polyphenols and V_Chad a significant effect（P<0.05）;The addition of Al³⁺,K⁺,Ca²⁺,Zn²⁺,Mg²⁺,Fe³⁺and Cu²⁺promoted the ABTS⁺·clearance and total reducing power,but significantly inhibited the·OH clearance（P<0.05）.For DPPH·clearance rate,except Mg²⁺,others have obvious promoting effect on it;Compared with boiling sterilization and high-pressure sterilization,pasteurization process can better maintain its antioxidant activity;By simulating gastrointestinal digestion in vitro,it was found that gastric digestion group and intestinal digestion group could release more polyphenols.At the same time,compared with the gastric digestion stage,the release of polyphenols in the intestinal digestion stage increased,which could significantly increase the·OH clearance rate,but significantly reduce the DPPH·and ABTS⁺·clearance rate and total reducing power（P<0.05）.