Thermodynamics, transport phenomena, and electrochemistry of external field-assisted nonthermal food technologies

Delivery to the gut microbiota: A rapidly proliferating research field

The post genomic era has brought breakthroughs in our understanding of the complex and fascinating symbiosis we have with our co-evolving microbiota, and its dramatic impact on our physiology, physical and mental health, mood, interpersonal communication, and more. This fast "proliferating" knowledge, particularly related to the gut microbiota, is leading to the development of numerous technologies aimed to promote our health via prudent modulation of our gut microbiota. This review embarks on a journey through the gastrointestinal tract from a biomaterial science and engineering perspective, and focusses on the various state-of-the-art approaches proposed in research institutes and those already used in various industries and clinics, for delivery to the gut microbiota, with emphasis on the latest developments published within the last 5 years. Current and possible future trends are discussed. It seems that future development will progress toward more personalized solutions, combining high throughput diagnostic omic methods, and precision interventions.

In-package decontamination of chicken breast using cold plasma technology: Microbial, quality and storage studies

Atmospheric cold plasma (ACP) is a promising non-thermal technology for controlling food spoilage. In this study, ACP treatment at 100 kV for 1, 3 and 5 min was applied to chicken breast samples. Approximately 2 log CFU/g reduction in natural microflora of chicken was achieved within 5 min of treatment and 24 h of storage. The observed reduction was attributed to the reactive oxygen and nitrogen species in cold plasma. For shelf-life study, control and ACP treated samples (100 kV for 5 min) were analysed for the population of mesophiles, psychrotrophs and Enterobacteriaceae as well as sample colour and pH over a storage period of 24 days. On day 24, the population of mesophiles, psychrotrophs and Enterobacteriaceae in treated chicken was respectively 1.5, 1.4 and 0.5 log lower than the control. These results suggest that in-package ACP is an effective technology to extend the shelf-life of poultry products.

Effects of heating or ultrasound treatment on the enzymolysis and the structure characterization of hempseed protein isolates

The effects of heating (90 °C/30 min) or ultrasound (200/400/600 W) treatment on antioxidant and angiotensin-converting enzyme inhibitory (ACEI) activity of hydrolysates from hempseed protein isolates (HPI) were studied. The secondary structure, surface hydrophobicity, intrinsic fluorescence, scanning electron microscopy (SEM) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of HPI treated by heating or ultrasound were measured. The results showed that hydrolysate from HPI treated with ultrasound at 200 W showed higher hydrolysis degree, proportion of lower molecular mass components (1.0-3.0 kDa), antioxidant and ACEI activity than those from heating or high-power treated. The changes in secondary structure, surface hydrophobicity and intrinsic fluorescence indicated the unfolding of HPI after ultrasound. The SEM results showed that HPI treated with ultrasound at 200 W exhibited decrease in particle size and deformation and further increased in power caused the aggregates of HPI. In conclusion, the ultrasound treatment at low-power was superior to 90 °C/30 min treatment in facilitating enzymatic release of antioxidant and ACEI peptides from HPI.

High voltage atmospheric cold air plasma control of bacterial biofilms on fresh produce

Atmospheric cold plasma (ACP) offers great potential for decontamination of food borne pathogens. This study examined the antimicrobial efficacy of ACP against a range of pathogens of concern to fresh produce comparing planktonic cultures, monoculture biofilms (Escherichia coli, Salmonella enterica, Listeria monocytogenes, Pseudomonas fluorescens) and mixed culture biofilms (Listeria monocytogenes and Pseudomonas fluorescens). Biotic and abiotic surfaces commonly occurring in the fresh food industry were investigated. Microorganisms showed varying susceptibility to ACP treatment depending on target and process factors. Bacterial biofilm populations treated with high voltage (80 kV) ACP were reduced significantly (p < 0.05) in both mono- and mixed species biofilms after 60 s of treatment and yielded non-detectable levels after extending treatment time to 120 s. However, an extended time was required to reduce the challenge mixed culture biofilm of L. monocytogenes and P. fluorescens inoculated on lettuce, which was dependent on biofilm formation conditions and substrate. Contained treatment for 120 s reduced L. monocytogenes and P. fluorescens inoculated as mixed cultures on lettuce (p < 0.05) by 2.2 and 4.2 Log10 CFU/ml respectively. When biofilms were grown at 4 °C on lettuce, there was an increased resistance to ACP treatment by comparison with biofilm grown at temperature abuse conditions of 15 °C. Similarly, L. monocytogenes and P. fluorescens exposed to cold stress (4 °C) for 1 h demonstrated increased tolerance to ACP treatment compared to non-stressed cells. These finding demonstrates that bacterial form, mono versus mixed challenges as well as environmental stress conditions play an important role in ACP inactivation efficacy.

Cold Plasma for Effective Fungal and Mycotoxin Control in Foods: Mechanisms, Inactivation Effects, and Applications

Cold plasma treatment is a promising intervention in food processing to boost product safety and extend the shelf-life. The activated chemical species of cold plasma can act rapidly against micro-organisms at ambient temperatures without leaving any known chemical residues. This review presents an overview of the action of cold plasma against molds and mycotoxins, the underlying mechanisms, and applications for ensuring food safety and quality. The cold plasma species act on multiple sites of a fungal cell resulting in loss of function and structure, and ultimately cell death. Likewise, the species cause chemical breakdown of mycotoxins through various pathways resulting in degradation products that are known to be less toxic. We argue that the preliminary reports from cold plasma research point at good potential of plasma for shelf-life extension and quality retention of foods. Some of the notable food sectors which could benefit from antimycotic and antimycotoxin efficacy of cold plasma include, the fresh produce, food grains, nuts, spices, herbs, dried meat and fish industries.

Three Pillars of Novel Nonthermal Food Technologies: Food Safety, Quality, and Environment

This review gives an overview of the impact of novel nonthermal food technologies on food safety, on quality, and on the environment. It confirms that research in this field is mainly focused on analyzing microbial and/or chemical aspects of food safety. However, recent research shows that in spite of various food safety benefits, some negative (quality oriented) features occur. Finally, this paper shows the necessity of analyzing the environmental dimension of using these technologies.

Cold atmospheric plasma manipulation of proteins in food systems

Plasma processing has been getting a lot of attention in recent applications as a novel, eco-friendly, and highly efficient approach. Cold plasma has mostly been used to reduce microbial counts in foodstuff and biological materials, as well as in different levels of packaging, particularly in cases where there is thermal sensitivity. As it is a very recent application, the impact of cold plasma treatment has been studied on the protein structures of food and pharmaceutical systems, as well as in the packaging industry. Proteins, as a food constituent, play a remarkable role in the techno-functional characteristics of processed foods and/or the physico-chemical properties of protein-based films. At the same time, some proteins are responsible for reduction in quality and nutritional value, and/or causing allergic reactions in the human body. This study is a review of the influences of different types of plasma on the conformation and function of proteins with food origin, especially enzymes and allergens, as well as protein-made packaging films. In enzyme manipulation with plasma, deactivation has been reported to be either partial or complete. In addition, an activity increase has been observed in some cases. These variations are caused by the effect of different active species of plasma on the enzyme structure and its function. The level and type of variations in the functional properties of food proteins, purified proteins in food, and plasma-treated protein films are affected by a number of control factors, including treatment power, time, and gas type, as well as the nature of the substance and the treatment environment.