| At present,navel orange processing is mainly pressed juice,discarding a large number of functional components of fruit residue by-products,accounting for about50% of the total weight of navel orange fresh fruit,such as lipids,pectin,essential oil,dietary fiber,polyphenols,etc.,with functions of regulating liver,regulating qi,relieving cough,moisturizing lung and preventing cardiovascular diseases.In order to achieve "eat dry squeeze all",realize the full utilization of resources,retain the functional active components in fruit dregs,and realize the value-added transformation of orange juice,the whole navel orange fruit was used by lactobacillus fermentation,and the fermentation process was optimized.The quality changes and metabolites changes of fermented whole juice in 23 h during processing were also discussed.The main results are as follows:(1)Whole fruit fermented beverage of navel orange was prepared by compound strains of Lactobacillus plantae and Lactobacillus casei,and the optimal technological conditions were established.The aroma substances were analyzed by HSPME-GC-MS.Response surface optimization was used to determine the number of viable bacteria and sensory score of whole fruit juice of navel orange under different conditions.The optimal fermentation conditions were as follows: temperature 34 ℃,time 23 h and inoculation amount 3%.The number of viable bacteria in whole fruit juice of navel orange was 8.91±0.11 lg cfu/mL and sensory score was 84.80.At the same time,making use of all kinds of ingredients in the matrix,Lactic acid bacteria during fermentation and esterification reaction,alcoholize reaction,etc.,make the aroma after fermentation content is richer,relative content of components with alcohols eight kinds of 5,2 kinds of lipids,ketones,2 kinds of alkene 6,aldehydes,and four other classes,the relative contents of alcohol and a lkene increase in most species,It gives the fermented fruit juice more floral aroma.Therefore,fermentation was beneficial to improve the flavor of navel orange whole juice and e ndoded it with typical flavor.(2)The effects of processing process on the structure,quality and rheological properties of navel orange whole juice were studied.The changes of particle size distribution(PSD),color,pH and soluble solids(TSS),reducing sugar and total acid contents,total phenols and flavonoids contents,sensory evaluation and rheological behavior of navel orange whole juice were evaluated under different operation units of homogenization,mixing,sterilization and fermentation.PCA was used to establish the correlation of 18 indicators,and the first 5 principal components(92.682%)were selected for comprehensive score,and the scores were fermentation,juice,homogenization,sterilization and blending in descending order.The results showed that fermentation was beneficial to improve the damage of beverage quality caused by the processing process,and the quality was the best,with a comprehensive score of1.029,which played a positive role in preparing a new Lactic acid bacteria beverage in line with consumers.(3)LC-MS untargeted omics was used to identify and analyze the differential metabolites in three different stages of navel orange whole juice fermentation broth.Combined with multivariate statistical analysis and KEGG database,significant change substances and pathways were obtained.The results showed that there were aggregations within the samples and significant differences among the sample groups,indicating that the metabolites could be used to discrim inate the fermentation process.Through screening,24 kinds of differential metabolites were obtained,and 27 metabolic pathways were enriched.The pathways with more enriched products and greater influence were mostly related to amino acid metabolism,which provided theoretical basis for further determination of functional components in lactic acid bacteria whole juice. |
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