The Study On The Development Of Fermented Orange Beverage By Lactic Acid Bacteria And Its Functional Research

Fruit and vegetable juice fermentation technology is a flourishing industry in the21 st century.It can not only remain the nutritions of fruit and vegetable juices,but also it give a unique fermentation flavor.Fruit and vegetable juice fermentation products are liked by more and more consumers.Nanfeng orange,well known as “tribute oranges”throughout the world,not only tastes delicious,but also contains many nutrients with antioxidant functions.However,its short preservation period,mildew,rot,and single processing methods restricts its development.The new type of orange products is yet to be developed.In this paper,the Nanfeng orange was selected as the research object,and the lactic acid bacteria suitable for the fermentation of orange were screened.The lactic acid bacteria fermentation technology was used to develop a lactic acid bacteria orange beverage with pleasant sweetness and sourness,unique flavor and rich citrus aroma.At the same time,the optimization of fermentation processes,flavoring substances,and the main antioxidants and in vitro antioxidant activities before and after fermentation were also studied.In this paper,the main researches and conclusions were as follows:(1)Screening and identification of lactic acid bacteria with excellent fermentation performance: After four strains of lactic acid bacteria were screened,re-screened,a strain with strong performance was obtained.By its morphological,molecular identification and constructed phylogenetic tree,L1 was Lactobacillus planetarum and was named NCU1125.The fermentation performance was measured by the number of viable cells,acid production capacity and p H,L1 was an excellent strain suitable for fermentation of Nanfeng orange.(2)Study on the in vitro performance of Lactobacillus plantarum NCU1125: When Lactobacillus plantarum NCU1125 was cultured in liquid MRS medium.,lactic acid bacteria grew rapidly into logarithmic period,the concentration of viable bacteria increased rapidly after 2 hours,and reached a stable period around 8 hours.The colonyforming units was 9.73 Log(CFU/ml)and the viable count remained at 8.1Log(CFU/ml)after 48 hours;The colony-forming units did not change significantly after NCU1125 was cultured in artificial gastric and intestinal juice with p H=3 after 3hours.The survival rate was still above 95%;With the increase of bile salt concentration,the viable cell count showed a decreasing trend.When the bile salt concentration was0.3%,the number of viable cells was 5.59 Log(CFU/ml)and the survival rate was 71.6%after 12 hours;The MRS fermentation supernatant of NCU1125 has antibacterial effect against 6 common pathogenic bacteria.The antibacterial substances produced by NCU1125 in the fermentation process are mainly organic acids,such as lactic acid,and have no hydrogen peroxide.Maybe the antibacterial substances is some proteins that are not sensitive to heat,some macromolecular bacteriocins with protein or small thermodynamically stable molecular peptides.(3)Study on optimization of Fermentation process of Nanfeng orange Beverage fermented by lactic acid bacteria: The optimum fermentation process of Nanfeng orange Beverage by lactic acid bacteria was determined by single factor and orthogonal experiments with acid-producing capacity,p H and sensory scores.The result was 7%syrup,2‰ inoculum concentration,fermented at 37 ? for 58 h.The sensory scores and viscosity values were used as indexes to determine the optimal stabilizer compounding ratio by single factor and orthogonal test.The result was 0.09% of CMCNa,0.04% of xanthan gum,and 0.05% of trehalose.The last product was a lactic acid bacteria orange beverage with pleasant sweetness and sourness,unique flavor and rich citrus aroma.(4)Changes in main metabolites and flavors of orange beverages fermented by lactic acid bacteria: The content of sugar,fructose and glucose decreased with the fermentation time gradually.Citric acid,malic acid and acetic acid were easily metabolized and were decreased during the fermentation.As the major metabolic product,lactic acid was rapidly increased from 0.44 mg/g to 13.05 mg/g during the fermentation.Vitamin C remains above 80%,however flavonoid and polyphenol were dramatically increased and improved to 12.9% and 8% respectively.The constitute of flavor amino acids after fermentation changed and the total of amino acids decreased13.9%.The composition,quantity and proportion of flavor constituents were different before and after fermentation.The content of alcohols,ketones and hydrocarbon compounds increased significantly while the content of olefins,aldehydes and esters decreased.The content of main aroma substances decreased after fermentation.The increased content of floral,lemony,lilac,and fruity aromas further enriches the aroma components of the orange beverage fermented by lactic acid bacteria.(5)Determination of main antioxidative substances and in vitro antioxidant capacity of orange beverage fermented by lactic acid bacteria: During the fermentation process,the content of limonin appeared to decrease firstly and then fluctuate and the debitterizing rate reached 24.8%,and the debitterizing effect was significant;Vitamin C content remained above 80%;However flavonoid and polyphenol were dramatically increased and improved to 12.9% and 8% respectively;Orange beverage fermented by lactic acid bacteria can significantly increase the scavenging ability to DPPH radical and FRAP antioxidant capacity;In the total antioxidant study of ABTS,although the antioxidant capacity decreased after fermentation,the scavenging ability to ABTS radicals are still higher before and after the fermentation of orange beverage.