Biotechnology of flavor formation in fermented dairy products

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Chapter 4

Biotechnology of flavor formation in fermented dairy products Balasubramanian Ganesan and Bart C. Weimer

Introduction

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Production of fermented dairy products follows a general metabolic theme (Fig. 4.1). The steps that involve biotechnology are mostly the addition of a recombinant enzymatic coagulant or the addition of a modified bacterium as a starter culture. In both cases, the primary motivations are manufacture economy and flavor production. Dairy product flavors result from the comprehensive microbial metabolism that arises from the cultures’ genomes related to their metabolic capability. Processing conditions profoundly influence the microbial cells’ physiology and, thus, the exact set of metabolites produced during dairy product fermentation. Abiotic conditions that alter the culture’s metabolism include temperature, pH, oxidation–reduction potential, osmotic status, nutrient availability, and the interaction between these parameters to induce microbial stress that shapes the pool of metabolites. Genetic modification in lactic acid bacteria (LAB) has been successfully used historically in dairy product fermentations. Single gene effects for milk fermentation are important for the primary traits – sugar use for lactic acid production, bacteriophage resistance, and protein degradation – which allow a successful fermentation. Use of genomic sequences and functional genomic tools reveals additional interactions and identifies genes relevant for flavor production. Evidently, complex, multi-gene/protein interactions are needed to optimize milk fermentation for a consistently high-quality product. For example, lactose utilization and proteolysis require multiple genes organized in operons to function from lactate transport to generation of the final peptide products. Biotechnology in Flavor Production, Second Edition. Edited by Daphna Havkin-Frenkel and Nativ Dudai. © 2016 John Wiley & Sons, Ltd. Published 2016 by John Wiley & Sons, Ltd.

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