Microbial Control in Clean Label Products

Originally Published: March 29, 2018
Last Updated: February 4, 2021
An image of swiss chard - a potential clean label replacement for nitrite in cured meats.

March 29, 2018 — Although our industry and government remain mostly focused on pathogen control, “spoilage control is a more difficult challenge to address,” said Peter Taormina, Ph.D., President, Etna Consulting Group. “Pathogens are the primary culprits in food safety; they are the organisms identified by companies in their hazard analyses and critical control points (HACCP), and are addressed through formulation and process controls.” However, added Taormina, spoilage organisms also pose significant hazards to manufacturers in the form of product viability and corporate brand image.

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2018 CLC/Peter Taormina - Microbial Control in Clean Label Products

Water activity is one of multiple hurdles to consider when controlling pathogenic and spoilage microorganisms.

New, clean label ingredients can be problematic, because not much is known about them yet. “For example, the non-proteolytic, psychrotolerant Clostridium botulinum is one pathogen that keeps me up at night, because it lacks a proteolytic effect that makes growth in the product evident,” said Taormina. The group II, non-proteolytic C. botulinum are mostly associated with aquatic environment sources and, given that some clean label ingredients are derived from aquatic environments, food safety scientists must ask whether they come bearing spores of these organisms.

Formulating to control pathogenic and spoilage microorganisms requires a “big picture” approach that anticipates establishing multiple hurdles to microorganism outgrowth, including formulation, packaging and post-lethality treatments. “Antimicrobial hurdles used in product development and processing include processing temperature, water activity (aw), pH, reduction-oxidation potential (REDOX) and preservative application,” said Taormina.

“Preservatives should pose the last hurdle. However, we would rather that pH and aw hurdles are great enough so that REDOX and preservative hurdles aren’t challenged, as some microbes can grow at very low pH and aw.” And, whereas salt is the “best preservative we have, public resistance to salt consumption limits its use in clean label products,” he added.

For clean label preservatives, we want to avoid -ics, -ates and –ites, or anything with an “x” or a “y,” noted Taormina. Unfortunately, that describes many of the most effective preservatives available, but some of these also exist in natural sources, such as acetic acid in vinegar; benzoic acid in cranberries; and propionic acid from Swiss cheese.
Plant-derived antimicrobials that could qualify as clean label ingredients include glucosinolates (cruciferous vegetables), lignans (flax seed), saponins (yucca, asparagus), catechins (green tea) and spices…whether as essential oils or as extracts.

Microbial preservatives provide another option, such as microbially derived antimicrobials including bacteriocins (e.g., nisin), competitive bacteria (e.g. Lactobacilli) and phages (viruses that infect bacteria). Celery, Swiss chard or acerola cherry powders represent clean label-friendly sources of nitrites for cured meats.

Processing can boost or supplement preservative ingredients in formulations. One relatively new method, high-pressure processing (HPP), is well along in commercialization. Each process poses its own spoilage challenges, however: HPP may allow for the survival of spore-forming bacteria concomitant with the destruction of otherwise competitive microbial strains. A number of spore-forming bacteria can survive heating processes and grow-out under refrigeration temperatures, even at relatively low pH.

This is especially problematic for low-acid products, such as nut milks, noted Taormina.
“When considering extended shelf-life, there is always risk. Pathogen control is well-researched, and one can always find a lot of good data in peer-reviewed research,” said Taormina. That is not the case with spoilage microorganisms. “Their risk continuum looks very different than that for pathogens,” he added.

For example, traditional spoilage inhibitors for ready-to-eat packaged meats include sodium or potassium lactates, plus sodium diacetate or acetate. Alternative clean label inhibitors include vinegar, fruit-extract vinegar blends and cultured sugar. “A problem arises, however, when, for clean label reasons, dextrose is replaced with sucrose. (The result is that common Leuconostoc sp. bacteria will cleave the sucrose disaccharide, producing a slimy film on the meat.) I see this over and over again,” emphasized Taormina.

Spoilage is the result of an accumulation of factors and, unfortunately, much less information is publicly available about spoilage microorganisms than about pathogens, Taormina noted.Therefore, companies should do their research and seek outside help well in advance of new product launches—before real damage is done to the product and the company’s reputation.

“Microbial Control in Clean Label Products,” Peter Taormina, Ph.D., President, Etna Consulting Group

This presentation was given at the 2018 Clean Label Conference. To download presentations from this event, go to https://cleanlabel.globalfoodforums.com/category/clean-label-rd-academy/

See past and future Clean Label Conference Events at https://cleanlabel.globalfoodforums.com/clean-label-events/