Effect Of Calcium Carbonate On The Quality Of Fermented Noni Juice

Noni（Morinda citrifolia Linn.）,a plant of the Rubiaceae family,which Polynesians have used as a medicine and health food for more than 2,000 years.Many studies have reported the biologically active ingredients and functions of noni and noni fruit.Fermented noni fruit juice is the main noni product,however it is not welcomed by most people due to the unpleasant odor,high acidity and astringency,in addition to the long fermentation time by the current traditional fermentation method.Therefore we try to develop a new fermented noni juice with good flavor and a fast fermentation method by combining calcium carbonate and inoculation fermentation.Firstly we investigated the effect of calcium carbonate on the monomeric phenol,antioxidant capacity and antibacterial capacity of noni juice,and comprehensively selected a suitable calcium carbonate concentration for further research.By monitoring the fermentation process and sensory evaluation using QDA sensory scoring standards,the fermentation process was optimized,and then the effect of in vitro simulated digestion on the active ingredients and antioxidant capacity of fermented noni juice was examined.The main findings are as follows.（1）The effect of calcium carbonate concentration on noni monomer phenol,antioxidant capacity and antibacterial capacityThe change trend is different for different monomeric phenol.Among them,the content of gallic acid increased with calcium carbonate,and the content of chlorogenic acid tended to be stable in noni juice when 0.05%-0.1%calcium carbonate,while the content of chlorogenic acid decreased by 72.6%when 0.5%calcium carbonate was added.However,no significant difference was found in the total amount of the 14 monomer phenols overall.Compared with the noni juice when 0.05%of calcium carbonate was added,no significant difference was found in the antioxidant capacity for the four kinds of noni juice,however the Cu²⁺reduction ability decreased when 0.1%calcium carbonate was added.And the four kinds of antioxidant capacity decreased significantly when 0.5%calcium carbonate was added.The antibacterial ability of noni puree was related to the content of calcium carbonate.When calcium carbonate is added to 0.5%,the noni juice showed no inhibition to 5 kinds of pathogenic bacteria such as Enterococcus faecalis,Staphylococcus aureus,Citrobacter freundii,Salmonella typhi type B and Pseudomonas aeruginosa.（2）Quality analysis of noni puree with different calcium carbonate additions during fermentationThroughout the fermentation process,most of the organic acids were in a rising state,while malic acid was in a falling state.Asperulosidic acid and deacetyl asperulosidic acid both decreased.The antioxidant capacity of DPPH and ABTS peaked on the seventh day,and then decreased.The DPPH free radical scavenging rate of the puree with 0.05%calcium carbonate was higher,and the FRAP free radical scavenging ability decreased in the first seven days,and then remained almost unchanged.In the sensory evaluation,it was generally believed that the fermented noni juice containing 0.05%calcium carbonate had lower astringency,higher sweetness and higher overall pleasure.It was finally determined that the optimal calcium carbonate addition amount was 0.05%,and the fermentation time was 7days.（3）The effect of simulated gastrointestinal digestion on the active ingredients and antioxidant capacity of fermented noni juiceThe contents of gallic acid,catechins,salicylic acid,and deacetyl asperulosidic acid in the fermented noni juice after gastric digestion increased significantly,while the content of quercetin reduced significantly,and there was no significant change for other substances.ABTS free radical removal rate and copper ion reduction ability increased,while the iron ion reduction ability decreased significantly.After intestinal digestion,the content of gallic acid and deacetyl asperulosidic acid reduced significantly compared with the content before digestion,however the content increased during intestinal digestion.The content of scopolamine and asperulosidic acid decreased.ABTS free radical clearance rate was greater after entering the small intestine than in the stomach,and the rest of the antioxidant capacity of DPPH,FRAP,and CUPRAC increased after digestion in the small intestine.The scavenging rate of ABTS free radicals in gastric digestion was mainly related to the content of total phenols and scopolamine,while the reducing ability of copper ions was related to deacetyl asperulosidic acid and asperulosidic acid.The reducing ability of iron ions in intestinal digestion was positively related to gallate acid and deacetyl asperulosidic acid,and copper ion reduction ability was positively correlated with gallic acid and deacetyl asperulosidic acid.