Dry surface biofilms in the food processing industry: An overview on surface characteristics, adhesion and biofilm formation, detection of biofilms, and dry sanitization methods

Abstract

Bacterial biofilm formation in low moisture food processing (LMF) plants is related to matters of food safety, production efficiency, economic loss, and reduced consumer trust. Dry surfaces may appear dry to the naked eye, however, it is common to find a coverage of thin liquid films and microdroplets, known as microscopic surface wetness (MSW). The MSW may favor dry surface biofilm (DSB) formation. DSB formation is similar in other industries, it occurs through the processes of adhesion, production of extracellular polymeric substances, development of microcolonies and maturation, it is mediated by a quorum sensing (QS) system and is followed by dispersal, leading to disaggregation. Species that survive on dry surfaces develop tolerance to different stresses. DSB are recalcitrant and contribute to higher resistance to sanitation, becoming potential sources of contamination, related to the spoilage of processed products and foodborne disease outbreaks. In LMF industries, sanitization is performed using physical methods without the presence of water. Although alternative dry sanitizing methods can be efficiently used, additional studies are still required to develop and assess the effect of emerging technologies, and to propose possible combinations with traditional methods to enhance their effects on the sanitization process. Overall, more information about the different technologies can help to find the most appropriate method/s, contributing to the development of new sanitization protocols. Thus, this review aimed to identify the main characteristics and challenges of biofilm management in low moisture food industries, and summarizes the mechanisms of action of different dry sanitizing methods (alcohol, hot air, UV‐C light, pulsed light, gaseous ozone, and cold plasma) and their effects on microbial metabolism.

Customizing Sanitization Protocols for Food-Borne Pathogens Based on Biofilm Formation, Surfaces and Disinfectants—Their Two- and Three-Way Interactions

“…Biofilm formation is affected by factors such as bacterial species, the characteristics of the surfaces, and the surrounding medium/environment [79,80]. In the food-processing industry, surface features are also very important for biofilm formation because they influence initial cell attachment [81]. Additionally, it has been observed that a critical surface tension value promotes bacterial adhesion [82,83].…”

Engineered Sustainable Omniphobic Coatings to Control Liquid Spreading on Food-Contact Materials

“…71,180,181 The adhesion of sticky food debris to these surfaces can encourage the attachment and colonization of bacteria. 34,182 Once bacteria establish biofilms, given their strong recalcitrance, they become notoriously difficult to remove. Thus, they may persist on food-processing machinery for months despite the frequent use of sanitation.…”

“…32 Standard testing methodologies to evaluate the durability and mechanical robustness of coated surfaces include sandpaper scratch testing, tape peeling, falling-sand abrasion, and blade scratching. Although a few studies have evaluated the strength and durability of certain coated surfaces using an ASTM standardized Taber test, 33,34 many others have adopted diverse nonstandardized custom-made abrading techniques. The random choice of abrasive sandpaper materials with different grit sizes, abrasion speed, weight load, and abrasion duration can make it difficult to accurately judge the overall performance between two surfaces.…”

“… A key reason that fuels the widespread occurrence of food-borne outbreaks is the poor sanitation and hygiene of food-contact surfaces. Many such surfaces used in food-processing facilities, such as conveyor belts, transportation and/or storage vessels, rollers, and metal benches, may not be properly cleaned and sanitized, causing the transmission of unwanted microorganisms to the food products. ,, The adhesion of sticky food debris to these surfaces can encourage the attachment and colonization of bacteria. , Once bacteria establish biofilms, given their strong recalcitrance, they become notoriously difficult to remove. Thus, they may persist on food-processing machinery for months despite the frequent use of sanitation .…”

Comparative assessment of UV-C radiation and non-thermal plasma for inactivation of foodborne fungal spores suspension in vitro

“…Dry sanitation techniques 7 or no-touch methods, including hot air, UV-C light, pulsed light, gaseous ozone (O 3 ), and NTP, have the potential to enhance the effectiveness of traditional methods (chlorine-based solutions), leading to more efficient sanitization processes. 5,8,9 Additionally, these approaches are environmentally friendlier than conventional wet methods, as they do not generate toxic waste such as acids and hydroxides usually employed in CIP processes, thus mitigating their environmental footprint.…”