College of Food Science and Engineering, Hainan University, Haikou 570228, China; School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China.
School of Sciences, Hainan University, Haikou 570228, China; Key Laboratory of Food Nutrition and Functional Food of Hainan Province, Haikou 570228, China.
Food Res Int. 2021 Mar;141:109999. doi: 10.1016/j.foodres.2020.109999. Epub 2020 Dec 18.
Noni (Morinda citrifolia L.) has been recognized as an important herb for treating various physiological disorders worldwide. Fermented noni fruit juice, established as a novel food in European Union, is the most important noni product. However, the structure, functions and enzyme profiles of microbiome during fermentation remain unclear. The metatranscriptomic was used to comprehensively explore the active microbial community and key metabolic function. Acetobacter sp., Acetobacter aceti and Gluconobacter sp. were the major microorganisms and appeared in succession during fermentation. According to principal components analysis (PCA) of metabolism-related unigenes by KEGG database, the fermentation process was divided into three stages and almost completed at the end of the second stage. Furthermore, carbohydrate-active enzymes (CAZymes) and the expression of key enzymes in major metabolic pathways were analyzed systematically. Analysis by HS-SPME-GC-MS and odor active value (OAV) revealed that butanoic acid and hexanoic acid were the main volatile compounds for the unpleasant odor of fermented noni fruit juice. The microbiome in the fermentation process lacked key enzymes that degrade butanoic acid and hexanoic acid, which imparted rancid and sweat odor. This study provides theoretical basis for product improvement and new product development, thus promoting the development of noni food industry.
诺丽（Morinda citrifolia L.）已被公认为一种可用于治疗世界各地各种生理失调的重要草药。发酵诺丽果果汁已在欧盟被确立为一种新型食品，是最重要的诺丽果产品。然而，发酵过程中微生物组的结构、功能和酶谱仍不清楚。本研究采用宏转录组学方法全面探索了活跃的微生物群落和关键代谢功能。醋杆菌属、醋化醋杆菌和葡萄糖酸杆菌是主要微生物，并在发酵过程中依次出现。根据代谢相关基因的 KEGG 数据库主成分分析（PCA），发酵过程可分为三个阶段，在第二阶段结束时几乎完成。此外，还系统分析了碳水化合物活性酶（CAZymes）和主要代谢途径中的关键酶的表达。通过 HS-SPME-GC-MS 和气味活值（OAV）分析发现，丁酸和己酸是发酵诺丽果果汁产生不良气味的主要挥发性化合物。发酵过程中的微生物组缺乏降解丁酸和己酸的关键酶，这赋予了发酵果汁腐臭和汗味。本研究为产品改进和新产品开发提供了理论基础，从而促进了诺丽果食品工业的发展。
