Microbial safety challenges in plant-based foods

Managing microbial risks in plant-based dairy and meat alternatives: from raw material variability to effective processing and hygiene strategies across the supply chain.

 

 

Introduction  

Consumers are increasingly opting for plant-based alternatives to dairy and meat, driven by environmental concerns, lifestyle choices, and health considerations. An expanding range and diversity of plant-based products is being introduced to the market including alternatives for milk, cheese, yoghurt, dairy desserts, meat burgers and deli-meats. Among others, cereals (oats, rice), pseudo-cereals (quinoa), legumes (soybeans, faba beans, peas, lentils), seeds (sesame and sunflower), and nuts (almonds, cashew, coconuts) make the most common sources and take the biggest share of plant-based proteins (Bocker and Silva 2022; Kovačević et al. 2024). Plant-based foods are often assumed to be microbiologically safe; however, foodborne outbreaks have highlighted the need to reassess this perception. Many of these products are complex formulations made from a variety of ingredients, which can increase the challenges of ensuring food safety throughout production. The diversity of raw materials and processing steps in novel plant-based foods requires careful attention to microbial risks across the entire supply chain.

 

Foodborne outbreaks and recalls  

Contamination with bacterial pathogens can occur at various stages of the food supply chain, including production, processing, and packaging. When pathogens are present, there is a risk of foodborne illness, particularly in ready-to-eat (RTE) plant-based foods that do not undergo further heat treatment before consumption. Figure 1 provides an overview of recalls and outbreaks linked to plant-based meat and dairy alternatives, or their ingredients (e.g. nuts), primarily reported over the past decade. The main pathogens associated with these food safety incidents include Salmonella spp., Listeria monocytogenes, and enterotoxin-producing strains of the Bacillus cereus group. Additionally, similar to concerns with milk-based infant formula, Cronobacter sakazakii warrants attention in plant-based alternatives intended for vulnerable populations.

Figure 1: Foodborne outbreaks and recalls linked to plant-based meat or dairy alternatives or ingredients.

 

Pathogen contamination routes  

Raw materials used in plant-based foods can become contaminated with pathogens through various routes. Preventing contamination begins with the implementation of good agricultural practices during primary production. Ingredients such as cereals, legumes, nuts, seeds, and dried herbs and spices, the latter often used for seasoning in plant-based cheeses, are sourced globally and have been reported to be occasionally contaminated with Salmonella or other pathogens (Bourdoux et al. 2016). Notably, Salmonella is well-adapted to survive in dry or high-fat, low-moisture foods (water activity < 0.85), and outbreaks have been linked to products such as nuts, peanut butter, and sesame-based items (Figure 1). While peanut butter is not typically a base ingredient in plant-based milks, it is commonly used in plant-based yogurts, ice creams, and cheese spreads to enhance flavor and texture, though it remains a common allergen.  

Other pathogens of c