| Paeonia ostii is mainly produced in Tongling,Anhui Province.It is mainly used for medicinal and oil use.It was approved by the National Health and Family Planning Commission as a new food raw material in 2013.As the planting area of oil peony is expanding year by year,the yield of Fengdan flowers,a by-product,has increased dramatically,and it is especially important to process and use Fengdan flowers.In this paper,a kind of lactic acid bacteria drink with antioxidant activity was prepared by mixed fermentation with two kinds of lactic acid bacteria using Fengdan flowers as material,which has the functions of phoenixis and lactic acid bacteria.Increased the added value of Fengdan flowers and provided ideas for the development of new Fengdan products.The optimum technological conditions for enzymatic hydrolysis of Fengdan flowers were determined by single factor experiment and orthogonal experiment.The suitable fermentation strains were determined by comparing the effects of different strains on the fermentation effect and phenolic substances of Fengdan flowers.Determination of optimum process conditions for fermentation by single factor test and response surface optimization.The changes of phenolic substances and free amino acids before and after fermentation were examined,and the preservation period of the products was studied.The specific research contents are as follows:1.Effects of 8 kinds of extraction methods on the total flavonoids and total phenolic content in Fengdan flowers slurry.The optimal conditions for enzymatic hydrolysis of Fengdan were studied by single factor test and orthogonal test with total flavonoids and total phenol as indicators.The optimum process was: enzymatic hydrolysis temperature 70?,time 90 min,enzyme addition amount 0.65 mg/mL,enzymatic hydrolysis p H 5,under these conditions,the total flavonoids,total phenol content were 69.27 ?g/mL,1617.35 ?g/mL.2.The lactic acid bacteria were screened out by comparing the effects of different strains on the fermentation of Fengdan flowers and the effects on the phenolic substances and antioxidant activities.The content of total phenol and total flavonoids after HZLp-005 fermentation was the highest,increasing by 4.95% and 12.51%(P<0.05).After fermentation with HZLb-006,rutin and quercetin increased by 3.16%and 0.81%,respectively(P<0.05).After HZLp-005 fermentation,the DPPH free radical scavenging rate increased by 11.14%(P<0.01),ABTS free radical scavenging rate increased by 6.58%(P<0.05),and the reducing power increased by 16.19%(P<0.05).The oxidizing power is the strongest.After HZLp-005 fermentation,the total color difference ?E>2,the color of the fermentation broth is deep,and HZLb-006 is relatively good.Therefore,HZLp-005 and HZLb-006 were selected as fermentation strains.3.By comparing the changes of total phenolics,total flavonoids and monomeric phenols after fermentation of Fengdan flowers under different strains,Lactobacillus plantarum: Lactobacillus bulgaricus(HZLp-005:HZLb-006)=4:1 was selected as the suitable strain ratio;The optimum fermentation conditions were determined by single factor test and response surface test: fermentation time 25 h,fermentation temperature37?,inoculum volume 3%;optimal stabilizer and 0.22% xanthan gum.4.By detecting changes in the content of phenolic substances and free amino acids before and after fermentation of lactic acid bacteria,The results showed that the content of total flavonoids and total phenols increased by 131% and 23.67%(P<0.05)after fermentation of Lactobacillus plantarum(HZLp-005)and Lactobacillus bulgaricus(HZLb-006),respectively.The DPPH free radicals and ABTS free radical scavenging rates of Paeonia ostii fermentation broth were significantly increased after fermentation(P<0.05),which increased by 10.42% and 7.77%,respectively.After fermentation,the content of essential amino acids was significantly increased,which made Fengdan more nutritious. |
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