Biosynthesis and conversion of phenolics and taste active compounds in food fermentations

食品发酵中酚类和呈味活性化合物的生物合成和转化

• 批准号: RGPIN-2019-04778
• 负责人: Gänzle, Michael
• 金额: $ 5.68万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=743337
• 关键词: Biosynthesis; conversion; phenolics; taste; active

Microbial metabolism determines and maintains the quality and safety of fermented foods. Lactobacilli are dominant representatives of fermentation microbiota in most fermented foods, including fermented cereal food. The applicant's research program generally aims to link the ecology and physiology of food-fermenting lactobacilli to their competitiveness in cereal fermentations and their impact on food quality. The long term aim of the proposed research programme is to characterize the metabolism of minor metabolites, particularly the formation of taste-active peptides and the conversion of phenolic compounds by lactobacilli, and to determine the impact of these metabolites on the sensory, nutritional, and textural quality of bread. Specifically, the proposed project aims to elucidate the genetic determinants of formation of ?-glutamyl peptides and conversion of phenolic acids, to understand the role of these metabolic pathways in the ecology of lactobacilli, and their contribution to improved bread quality. Taste active ?-glutamyl peptides impact the taste of foods by altering the perception of sweet, salty, and umami tasting compounds. This taste activity has been referred to as "kokumi" activity. ?-Glutamyl peptides accumulate to active concentrations in fermentation of soy sauce, long-ripened cheese, and in sourdough; however, their formation has typically been attributed to enzymes from the raw material rather than bacterial metabolism. Recent work of the applicant demonstrated that L. reuteri produces ?-glutamyl peptides in sourdough. Bioinformatic analyses identified ?-glutamate-cysteine ligases and glutaminases as enzymes that synthesise ?-glutamyl peptides.  The contribution of ?-glutamyl peptides to the taste of bread will be determined by quantification of these peptides in sourdough and sourdough bread, and by sensory analysis of bread produced with wild type strains and mutant strains with deletions in glutaminases or ?-glutamate-cysteine synthase. Sensory analyses will particularly aim to employ strains of L. reuteri that accumulate ?-glutamyl peptides to produce salt-reduced bread without reduction of consumer preference. Phenolic acids that in cereals, vegetables, or fruits modulate the composition of fermentation microbiota through their antimicrobial activity; moreover, phenolic acids also are precursor compounds for flavour volatiles. The contribution of phenolic acid metabolism of lactobacilli to ecological fitness in cereal fermentations and the texture and sensory quality of fermented cereal foods is unknown. Work in the proposed project aims to identify putative enzymes with activity on phenolic acids by comparative genomics. Phenolic acid decarboxylases and reductases will be characterized after heterologous expression, and by characterization of isogenic deletion mutants, and their role for sourdough biochemistry and bread quality will be determined.

微生物代谢决定并维持发酵食品的质量和安全性。乳杆菌是大多数发酵食品（包括发酵谷物食品）发酵微生物群的主要表示。申请人的研究计划通常旨在将食物发酵乳杆菌的生态和生理学与他们在谷物发酵中的竞争力及其对粮食质量的影响联系起来。拟议的研究计划的长期目的是表征次要代谢产物的代谢，尤其是味觉辣椒的形成以及乳酸杆菌对酚类化合物的转化，并确定这些代谢物对面包的感觉，营养和营养和质地的影响。具体而言，拟议的项目旨在阐明形成的遗传决定因素 - 谷氨酰辣椒和酚酸的转化，以了解这些代谢途径在乳杆菌生态学中的作用，以及它们对改善面包质量的贡献。味道活跃吗？ - 谷氨酸辣椒通过改变甜，咸和鲜味的品尝化合物的感知来影响食物的味道。这种味道活性被称为“ Kokumi”活动。 ？ - 谷氨酸胡椒体在发酵酱油，长期奶酪和酸面团的发酵中积聚至活跃的浓度。但是，它们的形成通常归因于原材料而不是细菌代谢的酶。该适用的最新工作表明，L. Reuteri在Sourcedough中产生？ - 谷氨酸辣椒。生物信息学分析鉴定出？ - 谷氨酸辣椒和谷氨酸辣椒是合成的酶？ - 谷氨酰辣椒。 ？ - 谷氨酰辣椒对面包味的贡献将由量化这些辣椒和来源面包中的这些辣椒，以及通过野生型菌株和突变菌株在谷氨酰胺或？glutamate-cysteine合成酶中产生的面包的感觉分析。感官分析将特别旨在采用丙烯酸甲基丙烯酸酯的菌株？ - 谷氨酰辣椒来生产减少盐的面包而不会降低消费者偏爱。谷物，蔬菜或水果中的酚类酸通过其抗菌活性调节发酵微生物群的组成；此外，酚酸也是风味挥发物的前体化合物。乳酸杆菌对谷物发酵中生态适应性的酚类代谢以及发酵谷物食品的质地和感觉质量的贡献尚不清楚。拟议项目中的工作旨在通过比较基因组学鉴定具有对酚酸活性的假定酶。金酸脱羧酶和还原假设将在异源表达后表征，并通过表征等源性缺失突变体，并确定它们在酸味生物化学和面包质量中的作用。