Fermentation of plant-based dairy alternatives by lactic acid bacteria

Abstract

Ethical, environmental and health concerns around dairy products are driving a fast-growing industry for plant-based dairy alternatives, but undesirable flavours and textures in available products are limiting their uptake into the mainstream. The molecular processes initiated during fermentation by lactic acid bacteria in dairy products is well understood, such as proteolysis of caseins into peptides and amino acids, and the utilisation of carbohydrates to form lactic acid and exopolysaccharides. These processes are fundamental to developing the flavour and texture of fermented dairy products like cheese and yoghurt, yet how these processes work in plant-based alternatives is poorly understood. With this knowledge, bespoke fermentative processes could be engineered for specific food qualities in plant-based foods. This review will provide an overview of recent research that reveals how fermentation occurs in plant-based milk, with a focus on how differences in plant proteins and carbohydrate structure affect how they undergo the fermentation process. The practical aspects of how this knowledge has been used to develop plant-based cheeses and yoghurts is also discussed.

Fig. 1

Sales in USD of different categories of plant‐based dairy alternatives in the USA in 2020. Categories in dark grey are those which can utilise fermentation. Adapted from Good Food Institute (2021).

Fig. 2

Generalised depiction of the proteolytic system of lactic acid bacteria. Protein is first broken down by cell envelope proteinase (CEP). Opp, Dpp and DtpT systems transport different sized peptides into the cell. PepX, PepN and PepC intracellular proteases catabolise larger peptides into di‐ and tripeptides. Dipeptidases (DP) and tripeptidases (TP) break di‐ and tripeptides down into free amino acids (FAAs). A wide range of catabolic enzymes then break the FAAs down into volatile organic compounds (VOCs).