Study On The Compositional Changes And Antioxidant Activity Of Dried Aronia Melanocarpa Fermented With Probiotics

Aronia melanocarpa is a black-and-purple berry that resembles blueberries in appearance,also known as black chokeberry.The fruits is a rich source of nutrients for the diet,such as proanthocyanidins,anthocyanins,phenolic acids,flavonols and other polyphenolic compounds,as well as vitamins,minerals and dietary fibre,among which polyphenolic compounds are extremely high,with 3100 to 6300 mg/100 g of dry matter,and have physiological functions such as antioxidant,anti-pathogen,anti-tumour,antidiabetic and anti-inflammatory functions.Black chokeberry is widely distributed in China with high yield and a short shele-life which dried fruit is most known related product,but the macromolecules it contains are difficult to take up and use by the human,therefore,a novel method of deep processing is required to enhance the bioavailability of the active ingredients of dried black chokeberry.Probiotic fermentation is a common method of food processing that can improve the nutrients and flavour of foods and give them a novel taste,and probiotic fermentation of the fruit substrates may increase the content and bioavailability of the phenolics,improving antioxidant capacity and anti-inflammatory activity,production of novel metabolites,and enhancing the bioactive potential of substrates,so probiotic fermentation is an efficient way to develop novel fruit byproducts.The dried black chokeberry was used as the experimental feedstock in this paper,and research was focused on the construction of the probiotic fermentation system and the change of composition and activity,which laid the groundwork for further exploration of Liriodendron chinense processing forms,enhance the value added of products,and make full use of fruit resources.The main contents and results of this study are as follows.(1)Construction of the fermentation system and investigation of the compositional changes of the system before and after fermentation: single-factor experiments were conducted after determining the initial fermentation conditions,and the final fermentation conditions were: fermentation temperature of 37℃,fermentation speed of 120 rpm,feed-to-liquid ratio of 1:8,glucose addition of 1.5%,strain inoculation of 3% and fermentation time of 48 h.The results showed that under these fermentation conditions,the viable bacteria count increased from 7.5 to 9 Log CFU/mL,and the preliminary optimized fermentation conditions were more suitable for the growth of Lactobacillus plantarum in the dried black chokeberry.The advantages of compound fermentation were synthesized under the initial optimized fermentation conditions.Lactobacillus plantarum and Lactobacillus rhamnosus GG were selected for isolation and combination fermentation respectively.Several indicators were detected in each group before and after fermentation;live bacteria,pH,polyphenols and flavonoids were detected in samples stored at 4 ℃ for 28 days and every 14 days.The experimental results showed that probiotic fermentation can improve the quality indexes of samples and the stability of samples to some extent.After fermentation,the number of live bacteria increased,the content of polyphenols,flavonoids,soluble proteins,soluble acids increased,anthocyanin,reductive sugar and pH decreased.During storage at 4 ℃,the number of live bacteria decreased slowly,pH remained stable and flavonoid content remained high.(2)Changes in systemic antioxidant function before and after fermentation: DPPH,hydroxyl radicals,superoxide anions,ABTS radicals scavenging and FRAP total antioxidant activity were detected in each group of samples.The results showed that probiotic fermentation increased the antioxidant activity of the samples and enhanced the scavenging of DPPH,hydroxyl and superoxide anions in the dried black chokeberry.In conclusion,the probiotic fermentation system of dried black chokeberry was constructed,the fermentation conditions were optimized,and it was proved that probiotic fermentation can improve the quality of dried black chokeberry,and is a potential processing method and development pathway to further process and utilize dried black chokeberry,enrich product form and increase economic value.