Non-thermal Processing Research Articles

Dielectric Barrier Discharge Plasma Processing and Sr-Doped ZnO/CNT Photocatalyst Decoration of Cotton Fabrics for Self-Cleaning Application.

Nonthermal plasma processing is a chemical-free and environmentally friendly technique to enhance the self-cleaning activity of nanoparticle-coated cotton fabrics. In this research, Sr-doped ZnO/carbon nanotube (CNT) photocatalysts, namely, S10ZC2, S15ZC2, and S20ZC2 with different Sr doping concentrations, were synthesized using the sol-gel method and coated on plasma-functionalized fabric to perform the self-cleaning tests. The fabrics were treated with dielectric barrier discharge plasma in an open environment for 3 min to achieve a stable coating of nanoparticles. The energy band gap of the photocatalyst decreased with an increase in the level of Sr doping. The band gap of S10ZC2, S15ZC2, and S20ZC2 photocatalysts was estimated to be 2.85, 2.78, and 2.5 eV, respectively. The hexagonal wurtzite structure of ZnO was observed on the fabric surface composited with CNTs and Sr. The S20ZC2 photocatalyst showed better homogeneity and photocatalytic response on the fabric when compared with S10ZC2- and S15ZC2-coated fabrics. The S20ZC2 photocatalyst showed 89% dye degradation efficiency after 4 h of light exposure in methylene blue solution, followed by S15ZC2 (84%) and S10ZC2 (80%) photocatalysts.

Pilot Scale Assessment of High-Pressure Processing (HPP) to Enhance Microbiological Quality and Shelf Life of Fresh Ready-to-Eat (RTE) Blue Crab Meat.

Blue crab (Callinectes sapidus) is a highly valuable wild fishery species of crab native to the waters of the western Atlantic Ocean and the Gulf of Mexico. The annual commercial production of live blue crabs is approximately 50,000 metric tons with a dockside value of USD 200 million. Presently the US blue crab processing industry sells crab meat in three basic forms: fresh crab meat, pasteurized crab meat, and frozen crab meat. By far "Fresh" is the most desirable form of crab meat. However, fresh crab meat has a limited shelf life. This study evaluated the effects of high-pressure processing (HPP) on enhancing the microbiological quality and shelf life of blue crab meat. Live blue crabs were pressure-cooked in a retort (≥115 °C for 4-6 min). The crab meat was handpicked, packed in plastic containers with seals, subjected to HPP treatment, and stored at 4 °C. Container integrity and water leakage issues were examined by observation in addition to weight comparison before and after HPP treatment; the shelf life of crab meat with and without HPP treatments was examined via microbiological tests and sensory evaluations. Results show that polypropylene containers sealed with 10K OTR (oxygen transmission rate) film could withstand high pressure without water leakage issues; HPP treatment at 600 MPa for 3 min could extend the shelf life of fresh, cooked, and handpicked crab meat from 6 days to 18 days based on the strictest APC (aerobic plate account) limit (APC ≤ 100,000 CFU/g). The sensory quality of the HPP-treated crab meat was well accepted throughout the 3-week storage period. The results support the use of HPP as an effective non-thermal processing technology to enhance the microbiological quality and extend the shelf life of fresh RTE blue crab meat.

Effect of non-thermal processing on nutritional and functional properties of milk and milk products- A review

Effect of non-thermal processing on nutritional and functional properties of milk and milk products- A review

The effect of non-thermal hydrodynamic cavitation process on structural and function properties of casein protein

The effect of hydrodynamic cavitation (HC) on protein functionality is an emerging area of interest in the field of non-thermal processing. The effect of HC on Casein protein's physicochemical and functional properties. HC reduced the crystallization temperature from 230.9 °C in CP1 to 223.2 °C in CP2. The initial viscosity increased significantly to 39,080 Pa s from 26,590 Pa s. HC increased the concentration of amino acids following in-vitro digestion from 145.79 ± 5.7 μg/ml to 194.58 ± 6.3 μg/ml. Trypsin inhibitory reduced up to 44 ± 0.02 % in CP3. The solubility increased from 11.21 ± 0.50 μg/ml to 25.70 ± 1.44 μg/ml in CP2. The water holding capacity of the treated sample increased from 1.73 ± 0.19 g/g in CP1 to 2.52 ± 0.0036 g/g. The oil holding capacity of the treated sample decreased from 0.85 ± 0.02 g/g to 0.67 ± 0.03 g/g.

Atmospheric cold plasma reduces Ara h 1 antigenicity in roasted peanuts by altering the protein structure and amino acid profile

Ara h 1 is the major allergen in peanuts. To enhance the unique flavor, peanuts are usually roasted at high temperatures. However, roasting can increase the allergenic potential, owing to glycation of allergens. Atmospheric cold plasma (ACP) is a non-thermal processing technology that generates reactive species, enabling protein structural changes. Herein, glucose was also added to the ACP-treated peanut protein before roasting. The content and antigenicity of the advanced glycation end products were measured. The antigenicity was evaluated by ELISA and in vitro digestion assays. The amino acid profile and secondary and tertiary protein structures were also assessed. The antigenicity of Ara h 1 decreased by 91 % and 76 % after 30 min of air and nitrogen plasma treatment, respectively. The glycation degree and thermal and digestive stabilities were also reduced. These results correlated with the structural changes, denaturation, and aggregation. Therefore, cold plasma may reduce the allergic effects of peanuts.

Evaluating the UV-C sensitivity of Coxiella burnetii in skim milk using a bench-scale collimated beam system and comparative thermal sensitivity study by high-temperature short-time pasteurization

Introduction:Coxiella burnetii is a zoonotic Gram-negative obligate intracellular bacterial pathogen and the causative agent of query (Q) fever in humans. Contamination of milk by C. burnetii, as a consequence of livestock infection, is a significant public health concern. Effective methods to inactivate C. burnetii in milk are a critical aspect of food safety. Implementation of non-thermal UV-C processing technologies in the dairy industry can effectively preserve the sensory and nutritional quality of raw milk products while ensuring their safety, making them a viable alternative to traditional high-temperature short-time (HTST) pasteurization methods.Methods: Optical light attenuation factors, such as the absorption, scattering, and reflection by skim milk (SM) were evaluated using a spectrophotometer. SM inoculated with an avirulent strain of C. burnetii was irradiated using a collimated beam device equipped with a low-pressure UV-C 254 nm lamp at doses from 0 to 12 mJ/cm2. Optical properties were considered for the evaluation of the delivered UV-C dose. The pasteurization treatment was conducted using a lab scale HTST pasteurizer (72°C/15 s). The verification studies were conducted using Escherichia coli ATCC 25922 inoculated in a phosphate buffer (transparent fluid) and humic acid (opaque fluid). Salmonella enterica serovar Muenchen ATCC BAA 1674 inoculated in SM was tested for its suitability as a surrogate for C. burnetii, a bacterium that requires specialized equipment and expertise for experimentation.Results and Discussion: Absorption, reduced scattering coefficient, and the reflectance of SM at 254 nm were measured as 19 ± 0.3/cm, 26 ± 0.5/cm, and 10.6%, respectively. The UV-C results showed a log-linear inactivation of C. burnetii in SM with the UV-C sensitivity (D10) value of 4.1 ± 0.04 mJ/cm2. The results of HTST pasteurization revealed that C. burnetii was heat-sensitive with a D value of 1.75 min. Salmonella Muenchen showed similar UV inactivation kinetics and is, thereby, suggested as a suitable surrogate to C. burnetii for the pilot-scale UV-C processing studies of SM.

Non-thermal processing of watermelon and red grape juices in thin-profile continuous-flow pulsed UV light reactors: Effect on microbiological safety and nutritional value

Herein, we report successful non-thermal pasteurization of fruit juices (watermelon and red grape juices) in a flow-through pulsed light (PL) reactor. Impact of PL reactor configuration (annular/coiled tube), product flow rates (14–75 L/h) and pulse frequency (1–5 Hz) on the inactivation of Escherichia coli ATCC 29055, Listeria innocua ATCC 33090, and Clostridium sporogenes ATCC 7955 in red grape (pH = 3.37) and watermelon juice (pH = 5.02), and changes in quality and nutritional parameters, was explored. >5 and > 7 log10 microbial reductions were achieved in annular and coiled reactor respectively, demonstrating PL's potential in juice pasteurization. Watermelon juice exhibited higher microbial inactivation, while E. coli was found to be most susceptible. The inactivation kinetics using three different models were compared wherein ‘log-linear plus tail model’ showed the best fit. During PL processing, there were minor changes in pH and colour of both juices, whereas nutritional parameters (total anthocyanins, total phenolics, antioxidant capacity, vitamin C, trans-resveratrol, and lycopene content) decreased significantly (p < 0.05) by up to 39.1%, 62.2%, 53.8%, ∼70%, 82%, and 46.8%, respectively, yet at levels lower than conventional thermal pasteurization. These results shall inspire commercialization of PL based fruit beverage pasteurization systems.

Ultrasound-Assisted Enzymatic Protein Hydrolysis in Food Processing: Mechanism and Parameters.

Ultrasound has been widely used as a green and efficient non-thermal processing technique to assist with enzymatic hydrolysis. Compared with traditional enzymatic hydrolysis, ultrasonic-pretreatment-assisted enzymatic hydrolysis can significantly improve the efficiency of enzymatic hydrolysis and enhance the biological activity of substrates. At present, this technology is mainly used for the extraction of bioactive substances and the degradation of biological macromolecules. This review is focused on the mechanism of enzymatic hydrolysis assisted by ultrasonic pretreatment, including the effects of ultrasonic pretreatment on the enzyme structure, substrate structure, enzymatic hydrolysis kinetics, and thermodynamics and the effects of the ultrasonic conditions on the enzymatic hydrolysis results. The development status of ultrasonic devices and the application of ultrasonic-assisted enzymatic hydrolysis in the food industry are briefly described in this study. In the future, more attention should be paid to research on ultrasound-assisted enzymatic hydrolysis devices to promote the expansion of production and improve production efficiency.

Inactivation of microorganisms by high hydrostatic pressure: A literature review

The use of high hydrostatic pressure is intended to perform non-thermal inactivation of microorganisms in food products, to ensure their freshness and to prevent foodborne infections. These infections impact the healthcare system, the food industry, and consumers directly. This study aims to analyse the literature on the effectiveness of high hydrostatic pressure against pathogenic and opportunistic microorganisms transmitted through the consumption of contaminated food. Scientific publications for 2011-2023 were selected for the review. A total of 44 scientific publications were selected, the information from which was critically analysed, systematised and presented in the form of a literature review. The mechanisms of high hydrostatic pressure’s effect on microbial cells are described. To illustrate the effectiveness of high hydrostatic pressure against microorganisms, data from selected publications regarding efficiency and treatment parameters are presented in tables. The inactivation of such clinically important microorganisms as Bacillus cereus, Campylobacter jejuni, Clostridium perfringens, Escherichia coli, Listeria monocytogenes, Salmonella spp., Staphylococcus aureus and Toxoplasma gondii in liquids and food has been demonstrated. High-pressure treatment has been shown to be a non-thermal food processing method, which distinguishes this method from traditional thermal processing methods such as boiling or pasteurization. One of the notable advantages of using high hydrostatic pressure is the non-thermal inactivation of various microorganisms, which preserves the nutritional and flavour properties of the processed product. It is also noted that food products can be processed in the final packaging, which reduces the risk of microbial contamination at the post-processing stages. The main disadvantages are the impossibility of complete inactivation of bacterial spores and the high cost of high-pressure processing equipment. Combining high-pressure treatment with other methods, such as heat treatment, can overcome the limitations of spore inactivation

Research Progress on Biological Accumulation, Detection and Inactivation Technologies of Norovirus in Oysters.

Noroviruses (NoVs) are major foodborne pathogens that cause acute gastroenteritis. Oysters are significant carriers of this pathogen, and disease transmission from the consumption of NoVs-infected oysters occurs worldwide. The review discusses the mechanism of NoVs bioaccumulation in oysters, particularly the binding of histo-blood group antigen-like (HBGA-like) molecules to NoVs in oysters. The review explores the factors that influence NoVs bioaccumulation in oysters, including temperature, precipitation and water contamination. The review also discusses the detection methods of NoVs in live oysters and analyzes the inactivation effects of high hydrostatic pressure, irradiation treatment and plasma treatment on NoVs. These non-thermal processing treatments can remove NoVs efficiently while retaining the original flavor of oysters. However, further research is needed to reduce the cost of these technologies to achieve large-scale commercial applications. The review aims to provide novel insights to reduce the bioaccumulation of NoVs in oysters and serve as a reference for the development of new, rapid and effective methods for detecting and inactivating NoVs in live oysters.

Radiofrequency cold plasma – A novel tool for flavour modification in fresh and freeze-dried strawberries

Cold plasma treatment is an emerging non-thermal food processing tool. This study aimed to identify how cold plasma can improve the aroma of a model space food system (freeze-dried strawberries) by mitigating freeze-drying aroma losses. Cold plasma significantly reduced the negative impact of freeze-drying on aroma; hence, it might be useful as a secondary treatment technique for foods that require extended shelf-life with improved aroma, such as in space travel. “Zero-averaged gravity” (0.004 g), a proxy for non-terrestrial environments, reduced the abundance of two important volatile aroma compounds (methyl butanoate and methyl hexanoate) in the gas phase above strawberries; this loss was mitigated when treated by cold plasma. The impact of cold plasma on aroma was also shown to be matrix and treatment parameter-dependent, and six cold plasma treatment options were subsequently identified as enabling bespoke aroma modifications that ultimately enhanced strawberry aroma compounds.

Structure optimization of pulsed electric field processor and its sterilization effect

Abstract Pulsed electric field (PEF) technology is a highly promising non-thermal processing technique, which holds great potential for sterilizing liquid food. The effectiveness of this treatment depends on two crucial factors: pulse parameters and the structure of the processor. In this study, we focus on optimizing the shape of insulators within the PEF processor to improve the sterilization effect. This research provides a reliable technical reference for designing industrial equipment. The numerical simulation of multi-physics fields was employed to analyze the temperature, electric field, and fluid field distributions for different insulators. Ultimately, the geometric structure of the insulator was optimized by embedding a 0.7-mm arc. Sterilization experiments were then conducted on Escherichia coli and Staphylococcus aureus suspensions with conductivities similar to those of real grapefruit juice. The sterilization effect of the processor with the optimized structure and the maximum applied voltage was examined at the same driving frequency. The results indicate that compared to the original structure, there is an increase in withstanding voltage by 5–10 kV while maintaining significantly improved bactericidal effects at the same applied voltage. Furthermore, we preliminarily discussed the sterilization mechanism by combining electroporation theory with the electroporation threshold of S. aureus.

Effect of plasma processing gas on Ara h 1 in peanut protein extract

Peanut allergen Ara h 1 is one of the most common food allergens in the world, and it is highly allergenic owing to its stable structure. Cold plasma is an emerging non-thermal processing technology that generates reactive radicals that enable the rapid degradation of allergenic protein. In this study, the effectiveness of two plasma treatment gases on the inhibition of the Ara h 1 allergen in peanut protein extract was investigated as the gases were expected to react with the allergen differently. The results revealed that the antigenicity of Ara h 1 decreased by approximately 55% after 13 min of cold plasma treatment. This may be attributed to the destruction of the α-helix structure. In addition, compared to air cold plasma treatment, nitrogen plasma treatment only caused less than one third of oxidative damage to the samples. In summary, air and nitrogen plasmas are both effective in reducing peanut allergen Ara h 1, but the peanut maintained most of its original quality after nitrogen cold plasma treatment. The result of this study demonstrated that nitrogen cold plasma is a great candidate for reducing Ara h 1 for effective food processing.

Numerical study of the effects of pulsed electric field on β-casein

As a non-thermal microbial inactivation technology, pulsed electric field (PEF) treatment can be used in liquid food sterilization. It is necessary to investigate the effects and mechanisms of PEF on the important contents of liquid food. In this study, molecular dynamics (MD) simulation and multiple structural analyses were employed to investigate the effects of PEF on β-casein (BCN) molecule. The investigation focused on examining the impact of PEF on molecular conformation, flexibility, electrostatic properties, and solvent interactions. Results found that high-intensity pulsed electric fields can cause irreversibly complete unfolding of BCN molecule within a picosecond timeframe. The applied PEF changed the dipole moment of BCN molecules, leading to the reorientation of residues towards the direction of the applied electric field. Furthermore, the electric field-induced movement of hydrophobic and hydrophilic residues within the BCN molecules was observed, resulting in concomitant changes in the solvent accessible surface area (SASA) of BCN molecule.Industrial relevance: PEF is an emerging non-thermal processing technology in the food industry. MD simulations were employed to investigate the conformational changes of BCN under different pulse electric fields and exposure times. Our study elucidates the fundamental mechanism of PEF's interaction with protein molecules and may contribute to improving the functional properties of this protein. Analysis at the molecular level can be experimentally validated, providing a theoretical foundation for the widespread application of PEF technology in protein-containing food systems.

The Impact of HPP-Assisted Biocontrol Approach on the Bacterial Communities' Dynamics and Quality Parameters of a Fermented Meat Sausage Model.

Traditional foods are increasingly valued by consumers, whose attention and purchase willingness are highly influenced by other claims such as 'natural', 'sustainable', and 'clean label'. The purpose of the present study was to evaluate the impact of a novel non-thermal food processing method (i.e., HPP-assisted biocontrol combining mild high hydrostatic pressure, listeriophage Listex, and pediocin PA-1 producing Pediococcus acidilactici) on the succession of bacterial communities and quality of a fermented sausage model. A comparative analysis of instrumental color, texture, and lipid peroxidation revealed no significant differences (p > 0.05) in these quality parameters between non- and minimally processed fermented sausages throughout 60-day refrigerated storage (4 °C). The microbiota dynamics of biotreated and untreated fermented sausages were assessed by 16S rRNA next-generation sequencing, and the alpha and beta diversity analyses revealed no dissimilarity in the structure and composition of the bacterial communities over the analyzed period. The innovative multi-hurdle technology proposed herein holds valuable potential for the manufacture of traditional fermented sausages while preserving their unique intrinsic characteristics.

200-W short-pulse operation of photonic-crystal lasers based on simultaneous absorptive and radiative Q-switching.

Short-pulse high-peak-power lasers are crucial laser sources for various applications such as non-thermal ultrafine material processing and eye-safe high-resolution remote sensing. Realizing such operation in a single semiconductor laser chip without amplifiers or external resonators is expected to contribute to the development of compact, affordable laser sources for such applications. In this paper, we demonstrate short-pulse high-peak-power photonic-crystal surface-emitting lasers based on simultaneous absorptive and radiative Q-switching. The proposed device induces an instantaneous and simultaneous decrease in both absorptive and out-of-plane radiation losses due to saturable absorption and self-evolution of the photonic band, respectively, which results in drastic Q-switching operation of the device. Based on this concept, we experimentally demonstrate short-pulse generation with 200-W-class peak power and a pulse width of < 30 ps. In addition, via pulse compression with dispersion compensation, we achieve an even higher peak power of ∼300 W with a shorter pulse width of ∼10 ps.

Effect of pulsed light on curcumin chemical stability and antioxidant capacity.

Curcumin is the major bioactive component in turmeric with potent antioxidant activity. Little is known about how pulsed light (PL) technology (an emerging non-thermal food processing technology relying on high intensity short duration flashes of light) can affect the chemical stability and antioxidant capacity of curcumin. This study found that PL treatment of fluence levels from 0 to 12.75 J/cm2 produced a fluence-dependent reduction in curcumin content. These results paralleled the production of a tentative curcumin dimer, identified as a potential photochemical transformation product. PL-treated curcumin at relatively higher fluence levels decreased chemical-based ORAC and ABTS antioxidant capacity, relative to control (P < 0.05). This contrasted the effect observed to increase coincidently both intracellular antioxidant capacity (e.g., DCFH-DA (P < 0.05)) and GSH/GSSG ratio (P < 0.05), respectively, in cultured differentiated Caco-2 cells. In conclusion, the application of PL on curcumin results in photochemical transformation reactions, such as dimerization, which in turn, can enhance biological antioxidant capacity in differentiated Caco-2 cells.

Quality evaluation of ozone-processed Kinnow (Citrus reticulata Blanco) juice at ambient temperature

ABSTRACT Non-thermal processing has been developed to increase the quality and storage life of fruit juices in response to consumer desire. Ozonation is a recently developed method that generates volatile oxygen atoms that can eliminate a broad spectrum of microbes and extend the shelf stability of food products. The present research was intended to investigate the ozone processing on the physicochemical characteristics, microbiological quality, sensory attributes, and antioxidant potential of Kinnow juice. In this study, Kinnow juice was processed to 150 mg/h of ozone gas at a constant concentration for 5, 10, and 15 min. The sample was then taken in a plastic container and stored at 35°C ± 2 for three months. The results revealed that ozone processing had a significant (p˂0.05) effect on the total phenolics (TP) contents, total flavonoids (TF) contents, total soluble solids (TSS), acidity, total antioxidant activity (TAA) and DDPH radical scavenging activity of Kinnow juice. In addition, the ozonation application also significantly (p˂0.05) decreased the population of the microbes when the ozone time was increased from 5–15 min. Among the treatments, it was observed that T3 had the highest TSS, acidity, TF contents, TAA, and DDPH radical scavenging activity values and the lowest mold and plate counts. Regarding sensory qualities, T0+ showed the highest sensory score during storage. Thus, it may be concluded from the findings of our study that ozone application improved the quality of Kinnow juice by increasing TSS, phytochemicals and decreasing the microbial population, thereby prolonging their shelf life.

Cold plasma as an emerging nonthermal technology for food processing: A comprehensive review

Cold plasma, a partially ionized gas maintained at low temperatures, has emerged as a promising nonthermal food processing technique with various applications, including food sterilization and improved agricultural output. By generating reactive species such as ions, radicals, and photons, cold plasma interacts with and modifies the surfaces of materials or living cells. This comprehensive review focuses on the microbial decontamination capabilities of cold plasma and its impact on a wide range of food products, including cereals, milk, fruits, vegetables, and meat. Cold plasma treatment offers distinct advantages over traditional methods such as heat treatment, chemical treatment, and irradiation. It effectively eliminates pathogenic microbes from food surfaces while preserving the quality, flavor, and nutritional content of the food. By sterilizing food surfaces and packaging materials, cold plasma significantly reduces the risk of harmful microorganism contamination. Moreover, it extends the shelf life of food products by eliminating germs, viruses, and other hazardous microbes. This review critically assesses the qualitative impact of plasma treatment, emphasizing the importance of selecting the appropriate cold plasma technology for various food products. To ensure the safety and effectiveness of cold plasma technology for commercial implementation, this review investigates the properties of cold plasma treatment for different food products. It examines the molecular connections between dietary components and cold plasma species, highlighting potential avenues for future research.

Low Energy Twist Defects in Pentatwinned Silver Nanowires

Transmission electron microscopy investigation of networks of pentatwinned silver nanowires has identified the presence of nanoscale defects within individual wires, showing narrow regions of banded contrast normal to the nanowire axis (bamboo faults). Structural analysis using machine learning decomposition of scanning precession electron diffraction data identifies these bamboo faults as a pair of twist boundaries normal to the wire axis creating low energy coincident site lattices between the faulted region and the parent nanowire. This leads to a conservation of the relative misorientation of the twinned structure within the faulted region, leading to an apparent local rotation of the nanowire. Their presence after spraying and nonthermal processing suggests that they may form during nanowire synthesis. However, examination of the networks before and after cyclic straining finds an increase in the density of the defects, indicating that they may also form as a result of mechanical deformation.