Thermal Processing Of Foods Research Articles

Revisiting Non-Thermal Food Processing and Preservation Methods-Action Mechanisms, Pros and Cons: A Technological Update (2016-2021).

The push for non-thermal food processing methods has emerged due to the challenges associated with thermal food processing methods, for instance, high operational costs and alteration of food nutrient components. Non-thermal food processing involves methods where the food materials receive microbiological inactivation without or with little direct application of heat. Besides being well established in scientific literature, research into non-thermal food processing technologies are constantly on the rise as applied to a wide range of food products. Due to such remarkable progress by scientists and researchers, there is need for continuous synthesis of relevant scientific literature for the benefit of all actors in the agro-food value chain, most importantly the food processors, and to supplement existing information. This review, therefore, aimed to provide a technological update on some selected non-thermal food processing methods specifically focused on their operational mechanisms, their effectiveness in preserving various kinds of foods, as revealed by their pros (merits) and cons (demerits). Specifically, pulsed electric field, pulsed light, ultraviolet radiation, high-pressure processing, non-thermal (cold) plasma, ozone treatment, ionizing radiation, and ultrasound were considered. What defines these techniques, their ability to exhibit limited changes in the sensory attributes of food, retain the food nutrient contents, ensure food safety, extend shelf-life, and being eco-friendly were highlighted. Rationalizing the process mechanisms about these specific non-thermal technologies alongside consumer education can help raise awareness prior to any design considerations, improvement of cost-effectiveness, and scaling-up their capacity for industrial-level applications.

Non-thermal Technologies for Food Processing.

Food is subjected to various thermal treatments during processes to enhance its shelf-life. But these thermal treatments may result in deterioration of the nutritional and sensory qualities of food. With the change in the lifestyle of people around the globe, their food needs have changed as well. Today's consumer demand is for clean and safe food without compromising the nutritional and sensory qualities of food. This directed the attention of food professionals toward the development of non-thermal technologies that are green, safe, and environment-friendly. In non-thermal processing, food is processed at near room temperature, so there is no damage to food because heat-sensitive nutritious materials are intact in the food, contrary to thermal processing of food. These non-thermal technologies can be utilized for treating all kinds of food like fruits, vegetables, pulses, spices, meat, fish, etc. Non-thermal technologies have emerged largely in the last few decades in food sector.

Small Intestinal Bacterial Overgrowth Syndrome Is Not Associated With Thermal Food Processing Pattern

Abstract Objectives To compare the patterns of thermal food processing methods in patients with and without the syndrome intestinal bacterial overgrowth (SIBO). Methods It was retrospective single-center study. Data of patients with lactulose breath test GastroCheck Gastrolyser (Bedfont, UK) and diet assessment (24-hours dietary recall) were enrolled. Those with excessive production of hydrogen, methane, both or neither gases were identified. All dishes and products consumed by a patient we divided to 6 categories depending on thermal food processing method: those that were not processed (raw) (Cat-r), boiled (Cat-bl), fried (Cat-f), stewed (Cat-s), baked (Cat-bk) in the oven or grilled (Cat-g). To analyze the structure of thermal food processing, we divided the weight of all products or dishes that underwent specific method of processing to the total weight of the food consumed. The pattern of thermal food processing within each group was obtained as a quotient of the total percentage (by weight) of the food processed with the certain method by the number of patients in the group. Results The data of 1200 patients were available for the final analysis: 640 patients in the SIBO-H2 group, 162 in the SIBO-CH4 group, 270 in the SIBO-CH4-H2 group, and 128 patients in the control group. The distribution of thermal food processing categories was as follows: in patients with SIBO-H2 (Cat-r: 45.3 ± 17.2%, Cat-bl: 31.8 ± 15.6%, Cat-s: 3.5 ± 7.7%, Cat-f: 6.5 ± 10.5%, Cat-bk: 12.4 ± 10.3%, Cat-g 0.3 ± 3.3%); with SIBO-CH4 (Cat-r: 47.2 ± 16.6%, Cat-bl: 29.5 ± 15.1%, Cat-s: 4.3 ± 7.4%, Cat-f: 5.8 ± 10.0%, Cat-bk: 12.4 ± 10.3%, Cat-g: 0,4 ± 3,9%); with SIBO-CH4-H2 (Cat-r: 45.5 ± 16.3%, Cat-bl: 31.0 ± 16.1%, Cat-s: 4.0 ± 8.0%, Cat-f: 5.4 ± 9.9%, Cat-bk: 13.4 ± 11.0%, Cat-g: 0.3 ± 2.2%); in the control group (Cat-r: 44.8 ± 16.8%, Cat-bl: 32.4 ± 16.4%, Cat-s: 3.0 ± 6.5%, Cat-f: 5.2 ± 7.7%, Cat-bk 14.1 ± 10.4%, Cat-g: 0.2 ± 1.9%). No significant difference was found between the study groups and the control group by mean percentage of raw, boiled, stewed, fried, baked and grilled food intake. Conclusions We found no association between thermal food processing patterns and SIBO. Funding Sources The study was supported by Russian Scientific Foundation grant No. 19-76-30014.

Inhibition Kinetics and Mechanism of Glutathione and Quercetin on Acrylamide in the Low-Moisture Maillard Systems

The inhibition kinetics of glutathione (GSH) and quercetin on acrylamide (AA) formation in the low-moisture Maillard systems were investigated at 180°C. The inhibition rates in an equal-molar asparagine-glucose (Asn-Glc) system were higher than those in an asparagine-fructose (Asn-Fru) system, and the maximum inhibition rates for AA were 57.75% with 10-2 mol L-1 GSH and 51.38% with 10-1 mol L-1 quercetin. The Logistic-Index dynamic model and two consecutive simplified first-order kinetic models were well fitted to the changes of AA in the Asn-Glc system. The kinetics results suggested that the predominant inhibition effect of GSH on AA could be attributed to the competitive reaction between GSH and Asn for the consumption of Glc. The kinetic results and high-pressure liquid chromatography-tandem mass spectrometry analysis of the inhibitory effect of quercetin on AA indicated that quercetin might mitigate AA through the binding reaction of quercetin decomposition products and Maillard intermediate products. These experimental results provide theoretical data that may be useful to control the formation of AA during food thermal processing.

On optimum dynamic temperature profiles for thermal inactivation kinetics determination.

Determination of inactivation kinetics, associated with thermal processing of foods and obtained from dynamic temperature experiments, requires carefully designed experiments, the primary element being the selection of the appropriate temperature profile along with a carefully planned sampling schedule. In the present work, a number of different dynamic temperature profiles were investigated in terms of their ability to generate accurate kinetic parameters with low confidence intervals (CIs). Although alternative models have been also tested, our work was concentrated on thermal inactivation kinetics that could be described by the classical D-z values. A pair of D and z values was assumed, and for each temperature profile tested, concentration data at different processing times were generated through the appropriate models. Next, an error (up to ±2.5% or ±5%) was introduced on these theoretical values to generate pseudo-experimental data, and the back-calculation of the assumed kinetic parameters by non-linear regression was performed. The accuracy and the 95% CIs of the estimated kinetic parameters were evaluated; joint confidence regions were also constructed to investigate parameters correlation. The effect of temperature profile pattern, level of error, number of experimental points, and reference temperature was assessed. A stepwise increasing and a single triangle-pattern temperature profile were the best profiles among those tested. As a general observation, based on different kinetic models investigated, temperature profiles and sampling intervals that result in concentration versus time diagrams having shapes as suggested by the primary model used when isothermally applied are not considered appropriate for parameter estimation.

Sub-chronic exposure to PhIP induces oxidative damage and DNA damage, and disrupts the amino acid metabolism in the colons of Wistar rats

Heterocyclic amines (HCAs) are a group of mutagenic compounds produced during thermal processing of protein-rich foods. One of the most abundant HCAs, 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP) has potential carcinogenic and mutagenic effects on human organs, especially the colon. This study aimed to explore the toxic effects of PhIP on amino acid metabolism in the colon of Wistar rats using RNA-seq and LC-MS/MS. Exposure to PhIP for 4 weeks induced oxidative damage and DNA damage in the colons, and disrupted the expression of related genes involved in tryptophan metabolism, beta(β)-alanine metabolism, valine, leucine, and isoleucine degradation, and glutathione metabolic pathways. Moreover, the levels of fecal metabolites related to amino acid metabolism were affected by PhIP. Cumulatively, these results indicate that PhIP can induce colonic oxidative injury and disorders related to amino acid metabolism, thereby providing a new theoretical basis for the study of PhIP toxicity.

Proteomic Analyses of 3-Monochloropropanediol 1-Monooleate and 1-Monostearate Induced Testicular Toxicity in a 90 Day Sprague-Dawley Rats' Study.

3-Monochloropropane 1,2-diol (3-MCPD) esters are toxicants formed during food thermal processing, and their testicular toxicities were widely reported. In this 90 day in vivo study, Sprague-Dawley rats were treated with 3-MCPD 1-monooleate at 10 and 100 mg/kg body weight (bw)/day or 1-monostearate at 15 and 150 mg/kg bw/day. Histological results indicated that testicular impairment was observed, and the level of serum testosterone was decreased dose dependently, while the levels of serum transforming growth factor beta and interferon-γ in rats' serum were increased dose dependently. To address the molecular mechanisms leading to testicular toxicities of 3-MCPD esters, testes samples were investigated with a mass spectrometry proteomic approach. The deregulated proteins affected by 3-MCPD esters include many enzymes related with the inflammatory necrosis pathways. While verifying the results in cellular level, 3-MCPD 1-monooleate and 3-MCPD 1-monostearate showed almost similar testicular cytotoxicity, and they could activate RIPK1 and MLKL pathways at the cellular level. All of these results showed the possible mechanisms about the toxicity of 3-MCPD esters in rats' testes and play a vital role in understanding the toxic effects of 3-MCPD esters both in vivo and in vitro.

Adverse Effects of Thermal Food Processing on the Structural, Nutritional, and Biological Properties of Proteins.

Thermal processing is one of the most important processing methods in the food industry. However, many studies have revealed that thermal processing can have detrimental effects on the nutritional and functional properties of foods because of the complex interactions among food components. Proteins are essential nutrients for humans, and changes in the structure and nutritional properties of proteins can substantially impact the biological effects of foods. This review focuses on the interactions among proteins, sugars, and lipids during thermal food processing and the effects of these interactions on the structure, nutritional value, and biological effects of proteins. In particular, the negative effects of modified proteins on human health and strategies for mitigating these detrimental effects from two perspectives, namely, reducing the formation of modified proteins during thermal processing and dietary intervention in vivo, are discussed.

A fluorescence biosensor based on single-stranded DNA and carbon quantum dots for acrylamide detection

As a potential carcinogen produced in food thermal processing, acrylamide (AM) can cause irreversible harm to human health. For the detection of AM in food products, a simple fluorescent biosensor based on single-stranded DNA (ssDNA) and carbon quantum dots (CQDs) was developed. Reduced fluorescence intensity of CQDs at 445 nm (excitation at 350 nm) was induced by the attachment of ssDNA. In the presence of AM, ssDNA was preferentially bound to AM by hydrogen bonding and the degree of fluorescence reduction was smaller than that without AM. Under optimized conditions, results showed that the sensing approach for detecting AM had a low detection limit of 2.41 × 10−8 M in the standard solution, and a linear relationship ranging from 5 × 10−3 to 1 × 10−7 M with the determination coefficient (R2) of 0.9895 was obtained. Furthermore, a good recovery percentage (91.36–98.11%) in bread crust showed the potential for practical applications of this proposed biosensor.

Formation of furan in baby food products: Identification and technical challenges

Furan is generally produced during thermal processing of various foods including baked, fried, and roasted food items such as cereal products, coffee, canned, and jarred prepared foods as well as in baby foods. Furan is a toxic and carcinogenic compound to humans and may be a vital hazard to infants and babies. Furan could be formed in foods through thermal degradation of carbohydrates, dissociation of amino acids, and oxidation of polyunsaturated fatty acids. The detection of furan in food products is difficult due to its high volatility and low molecular weight. Headspace solid-phase microextraction coupled with gas chromatography/mass spectrometer (GC/MS) is generally used for analysis of furan in food samples. The risk assessment of furan can be characterized using margin of exposure approach (MOE). Conventional strategies including cooking in open vessels, reheating of commercially processed foods with stirring, and physical removal using vacuum treatment have remained unsuccessful for the removal of furan due to the complex production mechanisms and possible precursors of furan. The innovative food-processing technologies such as high-pressure processing (HPP), high-pressure thermal sterilization (HPTS), and Ohmic heating have been adapted for the reduction of furan levels in baby foods. But in recent years, only HPP has gained interest due to successful reduction of furan because of its nonthermal mechanism. HPP-treated baby food products are commercially available from different food companies. This review summarizes the mechanism involved in the formation of furan in foods, its toxicity, and identification in infant foods and presents a solution for limiting its formation, occurrence, and retention using novel strategies.

Event-based dynamic optimization for food thermal processing: High-quality food production under raw material variability

Industrial canneries are subject to perturbations that may compromise food safety requirements. In such cases, plant operators typically increase the processing time, leading to undesirable large processing cycles and excessive quality degradation. In addition, differences among the items in a batch lead to variability in terms of quality and safety which, if not explicitly considered in the processing strategy, forces the use of conservative operation policies.In this work, we present an event-based dynamic optimization approach that combines available plant measurements and mathematical model predictions to anticipate the effect of plant perturbations on food safety. A safety software sensor is build upon an on-line predictive simulation and a previous food-variability characterization such that, if any perturbation during the sterilization compromises food safety, a new processing strategy that optimizes a trade off among quality, uniformity and processing time is recomputed and implemented. Such multi-objective dynamic optimization problem under food product variability is efficiently addressed by taking advantage of the monotonicity and convexity properties of the food quality/safety dynamics.

Effect of methylglyoxal on the alteration in structure and digestibility of α-lactalbumin, and the formation of advanced glycation end products under simulated thermal processing.

α‐Dicarbonyl compounds (α‐DCs) are a class of compounds generated during the thermal processing of food. Due to the high reactivity, α‐DCs were endowed with the ability to react with food components thus lowering nutrition value and even leading to a potential risk for food safety. In this study, methylglyoxal (MG), the most abundant α‐DCs, was selected to investigate the alteration effects on the structure and digestibility of α‐lactalbumin (αLA) under thermal processing (60–100°C). The results showed that the modification degree of αLA by MG increased with the rise of processing temperature, accompanied by the significant changes in molecular weight, intrinsic fluorescence, and secondary structures of αLA. High‐resolution mass spectrometry analysis identified that lysine (Lys) and arginine (Arg) are the modification sites, and Nε‐(carboxyethyl)‐L‐lysine is the main modification type. Since the Lys and Arg are also the cleavage sites of trypsin, the digestibility of MG modified αLA (MG‐αLA) by trypsin correspondingly decreased with an increase of processing temperature. The reacted Lys and Arg residues, and the protein‐bound AGEs were quantified, and the contents were found to be highly dependent on the temperature.

Internet of Nonthermal Food Processing Technologies (IoNTP): Food Industry 4.0 and Sustainability

With the introduction of Industry 4.0, and smart factories accordingly, there are new opportunities to implement elements of industry 4.0 in nonthermal processing. Moreover, with application of Internet of things (IoT), smart control of the process, big data optimization, as well as sustainable production and monitoring, there is a new era of Internet of nonthermal food processing technologies (IoNTP). Nonthermal technologies include high power ultrasound, pulsed electric fields, high voltage electrical discharge, high pressure processing, UV-LED, pulsed light, e-beam, and advanced thermal food processing techniques include microwave processing, ohmic heating and high-pressure homogenization. The aim of this review was to bring in front necessity to evaluate possibilities of implementing smart sensors, artificial intelligence (AI), big data, additive technologies with nonthermal technologies, with the possibility to create smart factories together with strong emphasis on sustainability. This paper brings an overview on digitalization, IoT, additive technologies (3D printing), cloud data storage and smart sensors including two SWOT analysis associated with IoNTPs and sustainability. It is of high importance to perform life cycle assessment (LCA), to quantify (En)—environmental dimension; (So)—social dimension and (Ec)—economic dimension. SWOT analysis showed: potential for energy saving during food processing; optimized overall environmental performance; lower manufacturing cost; development of eco-friendly products; higher level of health and safety during food processing and better work condition for workers. Nonthermal and advanced thermal technologies can be applied also as sustainable techniques working in line with the sustainable development goals (SDGs) and Agenda 2030 issued by United Nations (UN).

Trapping of Acrolein by Curcumin and the Synergistic Inhibition Effect of Curcumin Combined with Quercetin.

Acrolein (ACR) is a toxic unsaturated aldehyde that is formed during different steps of thermal food processing. Here, we explored the kinetics of curcumin and ACR and elucidated the pathway of curcumin trapping ACR by preparing a mono-adduct of ACR (CMA-1) conjugated with curcumin. The synergistic scavenging effect and mechanism of curcumin combined with quercetin on ACR was analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Comparing the uses of curcumin and quercetin both individually and in combination, we found that quercetin in combination resulted in more curcumin being transformed into CMA-2, while curcumin in combination made the amount of di-ACR conjugated to quercetin (QDA) increase. We also added combined curcumin and quercetin into grilled chicken wings to demonstrate that curcumin and quercetin could scavenge ACR by forming their own ACR adducts and antioxidant activity during the process. Our results have noted a new strategy, in which some combinations of dietary polyphenols might contribute to the removal of toxic ACR produced during thermal food processing.

Innovative Infrared Heating Technologies for Food and Agricultural Processing

Food and agricultural industries have an increasing need to develop and adopt novel and sustainable processing technologies with high processing and energy efficiency and less water usage and waste-water generation while, at the same time, delivering safe, high-quality processed food and agricultural products. The use of infrared (IR) radiation heating for food and agricultural processing represents a novel approach for various food thermal processing operations, including drying, blanching, disinfestation, disinfection, and stabilization. Relevant attributes of IR heating technology include high heat delivery rate, lack of need for a heating medium, reduced processing time, improved energy efficiency, and enhanced product quality and safety with a minimal environmental footprint. The author and his research team recently conducted systematic and innovative research on IR heating for food and agricultural product processing, which resulted in an advancement in the scientific knowledge of IR heating in food science and engineering and the development and commercialization of a series of patented processing technologies. The novel IR heating technologies improved food healthfulness, quality, and safety while saving energy and water. The focus of this article is the review of several innovative IR heating-based processing technologies that were developed, including IR dry-peeling, dry-blanching, and dehydration technologies for fruits and vegetables; IR heating technology for drying and roasting of tree nuts; and effective IR heating for simultaneously achieving multiple goals in rice postharvest processing.

Acrylamide inhibits autophagy, induces apoptosis and alters cellular metabolic profiles

Acrylamide (ACR) is generated during thermal processing of carbohydrate-rich foods at high temperature and can directly enter the body through ingestion, inhalation and skin contact. The toxicity of ACR has been widely studied. The main results of these studies show that exposure to ACR can cause neurotoxicity in both animals and humans, and show reproductive toxicity and carcinogenicity in rodent animal models. However, the mechanism of toxicity of ACR has not been studied by metabolomics approaches, and the effect of ACR on autophagy remains unknown. Here, U2OS cell were treated with ACR 6 and 24 h and collected for further study. We have demonstrated that ACR inhibited autophagic flux, and increased ROS content. Accumulation of ROS resulted in increase of apoptosis rates and secretion of inflammatory factors. In addition, significant differences in metabolic profiles were observed between ACR treated and control cells according to multiple analysis models. A total of 73 key differential metabolites were identified. They were involved in multiple metabolic pathways. Among them, exposure to ACR caused glycolysis/gluconeogenesis attenuation by decreasing levels of glycolytic intermediates, reduced the rate of the TCA cycle, while elevating levels of several amino acid metabolites and lipid metabolites. In summary, our study provides useful evidence of cytotoxicity caused by ACR via metabolomics and multiple bioanalytic methods.

Introduction to the Special Issue: New Frontiers in Acrylamide Study in Foods—Formation, Analysis and Exposure Assessment

Acrylamide is a chemical contaminant that naturally originates during the thermal processing of many foods. Since 2002, worldwide institutions with competencies in food safety have promoted activities aimed at updating knowledge for a revaluation of the risk assessment of this process contaminant. The European Food Safety Authority (EFSA) ruled in 2015 that the presence of acrylamide in foods increases the risk of developing cancer in any age group of the population. Commission Regulation (EU) 2017/2158 establishes recommended mitigation measures for the food industry and reference levels to reduce the presence of acrylamide in foods and, consequently, its harmful effects on the population. This Special Issue explores recent advances on acrylamide in foods, including a novel insight on its chemistry of formation and elimination, effective mitigation strategies, conventional and innovative monitoring techniques, risk/benefit approaches and exposure assessment, in order to enhance our understanding for this process contaminant and its dietary exposure.

Plasma-activated water: Physicochemical properties, microbial inactivation mechanisms, factors influencing antimicrobial effectiveness, and applications in the food industry.

Novel nonthermal inactivation technologies have been increasingly popular over the traditional thermal food processing methods due to their capacity in maintaining microbial safety and other quality parameters. Plasma-activated water (PAW) is a cutting-edge technology developed around a decade ago, and it has attracted considerable attention as a potential washing disinfectant. This review aims to offer an overview of the fundamentals and potential applications of PAW in the agri-food sector. A detailed description of the interactions between plasma and water can help to have a better understanding of PAW, hence the physicochemical properties of PAW are discussed. Further, this review elucidates the complex inactivation mechanisms of PAW, including oxidative stress and physical effect. In particular, the influencing factors on inactivation efficacy of PAW, including processing factors, characteristics of microorganisms, and background environment of water are extensively described. Finally, the potential applications of PAW in the food industry, such as surface decontamination for various food products, including fruits and vegetables, meat and seafood, and also the treatment on quality parameters are presented. Apart from decontamination, the applications of PAW for seed germination and plant growth, as well as meat curing are also summarized. In the end, the challenges and limitations of PAW for scale-up implementation, and future research efforts are also discussed. This review demonstrates that PAW has the potential to be successfully used in the food industry.

Effect of microwave-assisted processing on polyphenol oxidase and peroxidase inactivation kinetics of açai-berry (Euterpe oleracea) pulp

Microwave heating has been considered a promising technology for continuous flow thermal processing of fluid foods due to better retention of quality. Considering the importance of açai-berry pulp and its perishability, the inactivation kinetics of peroxidase (POD) and polyphenol oxidase (PPO) were investigated under conventional and microwave heating. First-order two-component model was well fitted to the data, indicating the presence of at least two fractions with different resistances. POD was more thermally resistant (90% inactivation for 40 s at 89 °C) and could be considered as a processing target. Inactivation curves dependency on heating technology suggests specific effects of microwaves on the protein structure. Additionally, the dielectric properties of açai-berry pulp were evaluated at 915 and 2,450 MHz for temperatures up to 120 °C. Power penetration depth dropped with temperature at 915 MHz (from 29 to 11 mm), but was less affected at 2,450 MHz (between 8 and 11 mm).

Effect of Microwave Heating on the Acrylamide Formation in Foods

Acrylamide (AA) is a neurotoxic and carcinogenic substance that has recently been discovered in food. One of the factors affecting its formation is the heat treatment method. This review discusses the microwave heating as one of the methods of thermal food processing and the influence of microwave radiation on the acrylamide formation in food. In addition, conventional and microwave heating were compared, especially the way they affect the AA formation in food. Available studies demonstrate differences in the mechanisms of microwave and conventional heating. These differences may be beneficial or detrimental depending on different processes. The published studies showed that microwave heating at a high power level can cause greater AA formation in products than conventional food heat treatment. The higher content of acrylamide in microwave-heated foods may be due to differences in its formation during microwave heating and conventional methods. At the same time, short exposure to microwaves (during blanching and thawing) at low power may even limit the formation of acrylamide during the final heat treatment. Considering the possible harmful effects of microwave heating on food quality (e.g., intensive formation of acrylamide), further research in this direction should be carried out.