Novel Thermal and Non-Thermal Technologies Towards Sustainability and Microbiological Food Safety and Quality

1. Introduction

Ensuring food safety and quality while addressing sustainability challenges remains a cornerstone of modern food systems. Conventional preservation and processing methods, while effective, are increasingly being scrutinised for their energy demands, nutrient degradation, and limited ability to align with consumer expectations for minimally processed, clean-label, and environmentally friendly foods [1]. Conventional food preservation methods use high temperatures to inhibit foodborne pathogens and reduce the microbial load [2], thereby extending the shelf-life of food. However, this process can lead to the loss of essential temperature-sensitive nutrients, alter the texture of food products, and change their sensory characteristics. Pasteurisation, sterilisation, cooking, and drying are currently the main technological approaches for food preservation, which have replaced traditional preservation techniques [3]. These conventional heating techniques primarily depend on producing heat externally to the item being heated, either through burning fuels or using an electric resistive heater. This results in high energy consumption, significant financial costs, and a substantial environmental footprint. Thus, the collaboration between processors and academic institutions to meet consumer demands for high-quality, sustainably produced food, while addressing rising economic standards, has led to the emergence of new technological approaches in food processing. At the same time, the global burden of foodborne illness and spoilage underscores the need for robust technologies capable of achieving reliable microbial inactivation.

Non-thermal technologies are food processing methods that do not rely on high temperatures. They are emerging in the food industry due to their potential to enhance food safety, quality, and sustainability [4]. Some of the most advantageous non-thermal techniques that have emerged, showing notable spoilage inhibition and retention of the sensory properties of foods, are high hydrostatic pressure (HHP), ultrasound, UV radiation (UV-C), ozone, pulsed electric field, and, most recently, cold plasma (CP). Non-thermal technologies can preserve the quality of food and extend its shelf-life by deactivating spoilage microorganisms in various food products, including seafood [5], pork [6], chicken [7], and fresh fruit [8], among others.

This Special Issue, “Novel Thermal and Non-thermal Technologies towards Sustainability and Microbiological Food Safety and Quality”, was launched to address these challenges and to showcase advances in both fundamental research and applied studies. The contributions collectively explore how emerging processing strategies can support safe, high-quality, and sustainable food production, offering insights into microbial inactivation, product functionality, and environmental impact.

2. Overview of Contributions

This Special Issue compiles eight original articles and one review that advance knowledge on novel thermal, non-thermal, and hybrid technologies for safe, high-quality, and sustainable food processing. High-pressure processing (HPP) was extensively investigated as a non-thermal pasteurisation alternative. Shad et al. [9] compared HPP (600 MPa, 4 min) with conventional heat treatment (82 °C, 5 min) for pesto sauces containing 34% and 54% oil and inoculated with Listeria monocytogenes and Salmonella Typhimurium. They observed >4 log pathogen reduction, with no significant effect of oil content on inactivation, and superior preservation of lipid oxidation indices and sensory quality during refrigerated storage.

Hybrid drying methods combining thermal and non-thermal energy inputs were also reported by Mierzwa and Musielak [10]. They showed that microwave-assisted rotary drying of carrots increased drying rates by 112% and microwave–ultrasound combinations by 140%, while reducing specific energy consumption by approximately 30%, with some impact on colour parameters. Similarly, Gondek et al. [11] demonstrated that microwave–convection drying of Moldavian dragonhead leaves drastically shortened the drying time and resulted in higher retention of polyphenols, chlorophyll, and antioxidant activity compared with conventional convection drying—an approach that valorises agricultural by-products.

Two papers addressed the critical link between storage temperature, microbial growth, and sensory acceptance. Frangopoulos et al. [12] modelled aerobic plate count kinetics in pasteurised orange juice under accelerated storage (10–40 °C), reporting shelf-life extension at lower temperatures and rapid spoilage at elevated ones. In a companion sensory study, the same authors [13] found that consumer rejection typically preceded microbiological unsafety by 3 days, reinforcing the need to define shelf-life based on both sensory and safety endpoints.

At the ingredient level, Tsioptsias et al. [14] characterised the thermal behaviour and infrared spectral changes of citric acid monohydrate during dehydration, recrystallisation, and mild heating using Differential Scanning Calorimetry, Thermogravimetric Analysis, and computational modelling, offering insights for formulation stability and potential effects on microbial control in acidified products.

In addition to processing studies, this Special Issue also included contributions that focused on analytical innovations for food quality monitoring. Ekonomou et al. [15] developed a disposable amperometric biosensor based on a screen-printed carbon electrode modified with Meldola’s Blue and coated with glycerol dehydrogenase/NAD⁺, designed for rapid glycerol determination in wine. The biosensor exhibited good linearity in the 1–7.5 mM range, accurate agreement with a reference spectrophotometric method, and required only a small sample volume. Such tools can facilitate on-site monitoring of fermentation and product quality, supporting early decision-making and reducing waste.

Finally, Russell et al. [16] provided a narrative review on the potential of molecular hydrogen (H₂) applications across the farm-to-fork continuum, including postharvest treatment, storage, and processing, where it may act as an antioxidant, delay senescence, and reduce microbial spoilage, thereby contributing to food system sustainability.

Collectively, these studies highlight that novel thermal and non-thermal technologies can deliver effective microbial inactivation while maintaining nutritional and sensory quality. They also stress the importance of optimising process parameters, understanding storage effects, developing real-time monitoring tools, and integrating sustainability considerations, paving the way for wider adoption of such approaches in industry.

3. Conclusions

This Special Issue brings together a diverse set of studies that collectively highlight the potential of novel thermal and non-thermal food processing technologies to enhance microbiological safety, protect food quality, and contribute to sustainability. The breadth of work illustrates the importance of multidisciplinary collaboration among microbiologists, engineers, food technologists, and sustainability scientists.