Ultrasound assisted thermal inactivation of spores in foods: Pathogenic and spoilage bacteria, molds and yeasts

Inactivation effects of combined thermosonication and potassium sorbate treatments on Bacillus subtilis spores

This study aimed to investigate the inactivation effect of combined TS (thermosonication) and PS (potassium sorbate) treatments on Bacillus subtilis spores. The inactivation effect and potential mechanisms were examined using plate counts, OD600 values, nucleic acid leakage, DPA (dipicolinic acid) leakage, flow cytometry, and FTIR (Fourier transform infrared spectroscopy). The results showed that, after TS + PS treatments, the integrity of the inner membrane was lost, the permeability of the inner membrane to water molecules was increased, and the intraspore substances leaked. Furthermore, the OD600 value was reduced, indicating that the spore core hydration was enhanced. Spores proportion with damaged inner membrane was significantly increased to 66%, the ordered secondary structure of the protein was changed into a disordered structure and nucleic acid was fragmented after TS + PS treatment. The results indicated that the combined TS and PS treatments may be a useful method for inactivating bacterial spores in food processing and sterilization.

The postbiotic potential of Aspergillus oryzae - a narrative review

The filamentous fungus Aspergillus oryzae has a long tradition in East Asian food processing. It is therefore not surprising that in recent years fermentation products of A. oryzae have attracted attention in the emerging field of postbiotics. This review aims to provide a comprehensive summary of the potential postbiotic effects of fermentation products from A. oryzae, by discussing possible mechanisms of action against the background of the molecular composition determined so far. In particular, cell wall constituents, enzymes, extracellular polymeric substances, and various metabolites found in A. oryzae fermentation preparations are described in detail. With reference to the generally assumed key targets of postbiotics, their putative beneficial bioactivities in modulating the microbiota, improving epithelial barrier function, influencing immune responses, metabolic reactions and signaling through the nervous system are assessed. Drawing on existing literature and case studies, we highlight A. oryzae as a promising source of postbiotics, particularly in the context of animal health and nutrition. Challenges and opportunities in quality control are also addressed, with a focus on the necessity for standardized methods to fully harness the potential of fungal-based postbiotics. Overall, this article sheds light on the emerging field of A. oryzae-derived postbiotics and emphasizes the need for further research to fully realize their therapeutic potential.

High-frequency ultrasound modulation of Zn2+ release from nanoclay supported ZnO antibacterial composites

Bacterial infections pose considerable health risks, emphasising the critical need for effective and biocompatible antibacterial drugs. Considerably, we developed an efficient antimicrobial system incorporating the combined potential of high-frequency ultrasound and antimicrobial drugs against bacterial infections. A ZnO-kaolinite (Kaol) composite with antibacterial properties was synthesised by growing ZnO on the Kaol nano-clay surface using the co-precipitation method. High-frequency ultrasound efficiently promotes the release of Zn2+, which enhances the antibacterial properties. Furthermore, in-depth in vitro antibacterial studies and bacterial live/dead staining experiments validate the exceptionally high antibacterial performance of the composite. Therefore, owing to the synergistic effects of high-frequency ultrasound and antibacterial properties, the as-prepared novel antibacterial composite is a promising potential substitute for conventional antibacterial agents.

Applications of high-intensity ultrasound on shrimp: Potential, constraints, and prospects in the extraction and retrieval of bioactive compounds, safety, and quality

The global shrimp market holds substantial prominence within the food industry, registering a significant USD 24.7 billion in worldwide exportation in 2020. However, the production of a safe and high-quality product requires consideration of various factors, including the potential for allergenic reactions, occurrences of foodborne outbreaks, and risks of spoilage. Additionally, the exploration of the recovery of bioactive compounds (e.g., astaxanthin [AX], polyunsaturated fatty acids, and polysaccharides) from shrimp waste demands focused attention. Within this framework, this review seeks to comprehend and assess the utilization of high-intensity ultrasound (HIUS), both as a standalone method and combined with other technologies, within the shrimp industry. The objective is to evaluate its applications, limitations, and prospects, with a specific emphasis on delineating the impact of sonication parameters (e.g., power, time, and temperature) on various applications. This includes an examination of undesirable effects and identifying areas of interest for current and prospective research. HIUS has demonstrated promise in enhancing the extraction of bioactive compounds, such as AX, lipids, and chitin, while concurrently addressing concerns such as allergen reduction (e.g., tropomyosin), inactivation of pathogens (e.g., Vibrio parahaemolyticus), and quality improvement, manifesting in reduced melanosis scores and improved peelability. Nonetheless, potential impediments, particularly related to oxidation processes, especially those associated with lipids, pose a hindrance to its widespread implementation, potentially impacting texture properties. Consequently, further optimization studies remain imperative. Moreover, novel applications of sonication in shrimp processing, including brining, thawing, and drying, represent a promising avenue for expanding the utilization of HIUS in the shrimp industry.

Ultrasonic processing: effects on the physicochemical and microbiological aspects of dairy products

Dairy products that are contaminated by pathogenic microorganisms through unhygienic farm practices, improper transportation, and inadequate quality control can cause foodborne illness. Furthermore, inadequate storage conditions can increase the microflora of natural spoilage, leading to rapid deterioration. Ultrasound processing is a popular technology used to improve the quality of milk products using high-frequency sound waves. It can improve food safety and shelf life by modifying milk protein and fats without negatively affecting nutritional profile and sensory properties, such as taste, texture, and flavor. Ultrasound processing is effective in eliminating pathogenic microorganisms, such as Salmonella, Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes. However, the efficiency of processing is determined by the type of microorganism, pH, and temperature of the milk product, the frequency and intensity of the applied waves, as well as the sonication time. Ultrasound processing has been established to be a safe and environmentally friendly alternative to conventional heat-based processing technologies that lead to the degradation of milk quality. There are some disadvantages to using ultrasound processing, such as the initial high cost of setting it up, the production of free radicals, the deterioration of sensory properties, and the development of off-flavors with lengthened processing times. The aim of this review is to summarize current research in the field of ultrasound processing and discuss future directions.

Enhancement of microbicidal efficacy of chemical disinfectants when combined with ultrasound technology

AIMS

This study investigated the antimicrobial efficacy of ultrasound technology (US) in combination with two different disinfectants (Disinfectant A and Disinfectant B), containing peracetic acid (PAA) and quaternary ammonium compounds (QACs), respectively, against two sporigenic pathogens, Aspergillus brasiliensis and Bacillus subtilis.

METHODS AND RESULTS

The microbicidal activity of the coupled treatment was compared with the use of the disinfectants alone, and the efficacy of the disinfection strategies was evaluated by the log reduction of the population of the microorganism inoculated onto stainless-steel surface. The combination treatment resulted in a log reduction of 5.40 and 3.88 (Disinfectant A + US) against A. brasiliensis and B. subtilis, at 850 and 500 ppm PAA, compared to 265 and 122 (Disinfectant A only). For Disinfectant B, in combination with US, showed a logarithmic reduction of 5.04 and 4.79 against A. brasiliensis and B. subtilis at 078% v v-1 and 392% v v-1 QACs, respectively, vs. 1.58 and 1.64 (Disinfectant B only). Moreover, no colonies or not statistically significant growth was observed within the US bath containing the disinfectant.

CONCLUSIONS

The antimicrobial efficacy of the two disinfectants was greatly enhanced when used in combination with US, and this also makes it possible to avoid the overuse of chemicals for disinfection.

Ultrasonics and sonochemistry: Editors' perspective

Ultrasonic waves can induce physical and chemical changes in liquid media via acoustic cavitation. Various applications have benefitted from utilizing these effects, including but not limited to the synthesis of functional materials, emulsification, cleaning, and processing. Several books and review articles in the public domain cover both fundamental and applied aspects of ultrasonics and sonochemistry. The Editors of the Ultrasonics Sonochemistry journal possess diverse expertise in this field, from theoretical and experimental aspects of acoustic cavitation to materials synthesis, environmental remediation, and sonoprocessing. This article provides Editors' perspectives on various aspects of ultrasonics and sonochemistry that may benefit students and early career researchers.

Application progress of ultrasonication in flour product processing: A review

Flour products played a vital role in the global diet structure. With the increasing demand for dietary health and food standardization, the staple food of flour products made from coarse grains due to its unique flavor and rich nutrition has become a trend and is favored by consumers. However, the lack of gluten protein in the raw materials prevented the formation of a stable gluten network structure, leading to the deterioration of the quality of flour products. Ultrasonic treatment, as an innovative food processing technology, generated energy during the action of ultrasonic waves that had a positive impact on the texture, organizational structure, or flavor characteristics of food. That was of great significance for improving food production efficiency, improving food processing quality, and extending food shelf life. This article applied ultrasonic technology to the processing of flour products from the perspective of promoting fermentation and improving production efficiency of flour products. The cavitation effect of ultrasound promoted the formation of gluten network structure, improved the rheology properties of dough and the quality of flour products by promoting protein cross-linking, improving the foaming and emulsifying stability of gluten protein, and promoting the growth and reproduction of yeast. All reviewed studies indicate that ultrasound would be a promising technology for producing high-quality surface products under appropriate conditions.

Trends in Food Pathogens Risk Attenuation

Foodborne pathogens represent one of the most dangerous threats to public health along the food chain all over the world. Over time, many methods were studied for pathogen inhibition in food, such as the development of novel packaging materials with enhanced properties for microorganisms' growth inhibition (coatings, films) and the use of emerging technologies, like ultrasound, radio frequency or microwave. The aim of this study was to evaluate the current trends in the food industry for pathogenic microorganisms' inhibition and food preservation in two directions, namely technology used for food processing and novel packaging materials development. Five technologies were discussed in this study, namely high-voltage atmospheric cold plasma (HVACP), High-Pressure Processing (HPP), microwaves, radio frequency (RF) heating and ultrasound. These technologies proved to be efficient in the reduction of pathogenic microbial loads in different food products. Further, a series of studies were performed, related to novel packaging material development, by using a series of antimicrobial agents such as natural extracts, bacteriocins or antimicrobial nanoparticles. These materials proved to be efficient in the inhibition of a wide range of microorganisms, including Gram-negative and Gram-positive bacteria, fungi and yeasts.

Mechanism of ultrasonic combined with different fields on protein complex system and its effect on its functional characteristics and application: A review

In recent years, new food processing technologies (such as ultrasound, high-pressure homogenization, and pulsed electric fields) have gradually appeared in the public 's field of vision. These technologies have made outstanding contributions to changing the structure and function of protein complexes. As a relatively mature physical field, ultrasound has been widely used in food-related fields. However, with the gradual deepening of related research, it is found that the combination of different fields often makes some characteristics of the product better than the product under the action of a single field, which will not only lead to a broader application prospect of the product, but also make the product a better solution in some special fields. There are usually synergistic and antagonistic effects when multiple fields are combined, and these effects will also gradually enlarge the interaction between different components of the protein complex system. In this paper, while explaining the mechanism of ultrasonic combined with other fields affecting the steric hindrance and shielding site of protein complex system, we will further explain the effect of this effect on the function and application of protein complex system.

Microbial decontamination assisted by ultrasound-based processing technologies in food and model systems: A review

Ultrasound (US) technology is recognized as one of the emerging technologies that arise from the current trends for improving nutritional and organoleptic properties while providing food safety. However, when applying the US alone, higher power and longer treatment times than conventional thermal treatments are needed to achieve a comparable level of microbial inactivation. This results in risks, damaging food products' composition, structure, or sensory properties, and can lead to higher processing costs. Therefore, the US has often been investigated in combination with other approaches, like heating at mild temperatures and/or treatments at elevated pressure, use of antimicrobial substances, or other emerging technologies (e.g., high-pressure processing, pulsed electric fields, nonthermal plasma, or microwaves). A combination of US with different approaches has been reported to be less energy and time consuming. This manuscript aims to provide a broad review of the microbial inactivation efficacy of US technology in different food matrices and model systems. In particular, emphasis is given to the US in combination with the two most industrially viable physical processes, that is, heating at mild temperatures and/or treatments at elevated pressure, resulting in techniques known as thermosonication, manosonication, and manothermosonication. The available literature is reviewed, and critically discussed, and potential research gaps are identified. Additionally, discussions on the US's inactivation mechanisms and lethal effects are included. Finally, mathematical modeling approaches of microbial inactivation kinetics due to US-based processing technologies are also outlined. Overall, this review focuses only on the uses of the US and its combinations with other processes relevant to microbial food decontamination.

Exploring the Power of Thermosonication: A Comprehensive Review of Its Applications and Impact in the Food Industry

Thermosonication (TS) has been identified as a smart remedy for the shortcomings of heat treatment, which typically requires prolonged exposure to high temperatures. This technique combines moderate heat treatment with acoustic energy to eliminate harmful microorganisms and enzymes in food products. Unlike conventional heat treatment, thermosonication utilizes short holding times, allowing for the preservation of food products’ phytochemical compounds and sensory characteristics. The benefits and challenges of this emerging technology, such as equipment cost, limited availability of data, inconsistent results, high energy consumption, and scale-up challenges, have been assessed, and the design process for using ultrasound in combination with mild thermal treatment has been discussed. TS has proven to be a promising technique for eliminating microorganisms and enzymes without compromising the nutritional or sensory quality of food products. Utilizing natural antimicrobial agents such as ascorbic acid, Nisin, and ε-polylysine (ε-PL) in combination with thermosonication is a promising approach to enhancing the safety and shelf life of food products. Further research is required to enhance the utilization of natural antimicrobial agents and to acquire a more comprehensive comprehension of their impact on the safety and quality of food products.

Food safety and food security through predictive microbiology tools: a short review

This article discusses the issues of food safety and food security as a matter of global health. Foodborne illness and deaths caused by pathogens in food continue to be a worldwide problem, with a reported 600 million cases per year, leading to around 420,000 deaths in 2010. Predictive microbiology can play a crucial role in ensuring safe food through mathematical modelling to estimate microbial growth and behaviour. Food security is described as the social and economical means of accessing safe and nutritious food that meets people's dietary preferences and requirements for an active and healthy life. The article also examines various factors that influence food security, including economic, environmental, technological, and geopolitical challenges globally. The concept of food safety is described as a science-based process or action that prevents food from containing substances that could harm human health. Food safety receives limited attention from policymakers and consumers in low- and middle-income countries, where food safety issues are most prevalent. The article also highlights the importance of detecting contaminants and pathogens in food to prevent foodborne illnesses and reduce food waste. Food and Agriculture Organization (FAO), an institution belonging to World Health Organization (WHO) presented calls to action to solve some of the emerging problems in food safety, as it should be a concern of all people to be involved in the pursue of safer food. The guarantee of safe food pertaining to microbiological contamination, as there are different types of active microorganisms in foods, could be obtained using predictive microbiology tools, which study and analyse different microorganisms' behaviour through mathematical models. Studies published by several authors show the application of primary, secondary, or tertiary models of predictive microbiology used for different food products.

Thermosonication as a pretreatment of raw milk for Minas frescal cheese production

Minas frescal cheese is extremely popular in Brazil, with high perishability and acceptability. Among emerging technologies, ultrasound stands out for its satisfactory results regarding microbiological safety and technological and sensory aspects. The combined mild temperature application, called thermosonication, can generate even more promising results. In this study, a high-intensity ultrasound system combined with thermal heating (TS, thermosonication) was applied for the treatment of raw milk to produce Minas Frescal cheese. US energy was delivered to raw milk samples using a probe operating at a 20 kHz of frequency and nominal power of 160, 400, and 640 W. The TS system was compared with conventional pasteurization (HTST, high-temperature short-time pasteurization) at 72 to 75 °C and 15 s. Soft cheeses were prepared with different samples: (a) raw milk (control), b)conventionally pasteurized milk (HTST), and c) TS treat milk in different nominal power (TS160, TS400, and TS640). The produced cheeses were evaluated for microbiological behavior, rheology, color parameters, and bioactive compounds. TS treatment in milk resulted in higher microbial inactivation and stability during storage, improved color parameters (higher lightness (L*), and whiteness index (WI). TS treatment also showed a higher generation of bioactive compounds (higher antioxidant, and inhibitory activities of α-amylase, α-glucosidase, and angiotensin-converting enzymes) than HTST. The impact of TS on rheological properties was similar to HTST, resulting in more brittle and less firm products than the cheese produced with raw milk. The positive effects were more prominent using a nominal power of 400 W (TS400). Therefore, TS proved to be a promising process for processing milk for Minas Frescal cheese production.

Application and potential of multifrequency ultrasound in juice industry: Comprehensive analysis of inactivation and germination of Alicyclobacillus acidoterrestris spores

The majority of acidic fruits are perishable owing to their high-water activity, which promotes microbial activity, thus exhibiting metabolic functions that cause spoilage. Along with sanitary practices, several treatments are used during processing and/or storage to inhibit the development of undesirable bacteria. To overcome the challenges caused by mild heat treatment, juice manufacturers have recently increased their involvement in developing novel non-thermal processing procedures. Ultrasonication alone or in combination with other hurdle technologies may be used to pasteurize processed fruit juices. Multifrequency ultrasound has gained popularity due to the fact that mono-frequency ultrasound has less impact on bacterial inactivation and bioactive compound enhancement of fruit juice. Here, we present and discuss the fundamental information and technological knowledge of how spoilage bacteria, specifically Alicyclobacillus acidoterrestris, assemble resistant spores and inactivate and germinate dormant spores in response to nutrient germinants and physical treatments such as heat and ultrasound. To the authors' knowledge, no prior review of ultrasonic inactivation and germination of A. acidoterrestris in fruit juice exists. Therefore, this article aims to provide a review of previously published research on the inactivation and germination of A. acidoterrestris in fruit juice by ultrasound and heat.

Non-thermal Processing Technologies for Dairy Products: Their Effect on Safety and Quality Characteristics

Thermal treatment has always been the processing method of choice for food treatment in order to make it safe for consumption and to extend its shelf life. Over the past years non-thermal processing technologies are gaining momentum and they have been utilized especially as technological advancements have made upscaling and continuous treatment possible. Additionally, non-thermal treatments are usually environmentally friendly and energy-efficient, hence sustainable. On the other hand, challenges exist; initial cost of some non-thermal processes is high, the microbial inactivation needs to be continuously assessed and verified, application to both to solid and liquid foods is not always available, some organoleptic characteristics might be affected. The combination of thermal and non-thermal processing methods that will produce safe foods with minimal effect on nutrients and quality characteristics, while improving the environmental/energy fingerprint might be more plausible.

Salmonella spp. in low water activity food: Occurrence, survival mechanisms, and thermoresistance

The occurrence of disease outbreaks involving low-water-activity (a_w ) foods has gained increased prominence due in part to the fact that reducing free water in these foods is normally a measure that controls the growth and multiplication of pathogenic microorganisms. Salmonella, one of the main bacteria involved in these outbreaks, represents a major public health problem worldwide and in Brazil, which highlights the importance of good manufacturing and handling practices for food quality. The virulence of this pathogen, associated with its high ability to persist in the environment, makes Salmonella one of the main challenges for the food industry. The objectives of this article are to present the general characteristics, virulence, thermoresistance, control, and relevance of Salmonella in foodborne diseases, and describe the so-called low-water-activity foods and the salmonellosis outbreaks involving them.

Application of High-Intensity Ultrasound to Improve Food Processing Efficiency: A Review

The use of non-thermal processing technologies has grown in response to an ever-increasing demand for high-quality, convenient meals with natural taste and flavour that are free of chemical additions and preservatives. Food processing plays a crucial role in addressing food security issues by reducing loss and controlling spoilage. Among the several non-thermal processing methods, ultrasound technology has shown to be very beneficial. Ultrasound processing, whether used alone or in combination with other methods, improves food quality significantly and is thus considered beneficial. Cutting, freezing, drying, homogenization, foaming and defoaming, filtration, emulsification, and extraction are just a few of the applications for ultrasound in the food business. Ultrasounds can be used to destroy germs and inactivate enzymes without affecting the quality of the food. As a result, ultrasonography is being hailed as a game-changing processing technique for reducing organoleptic and nutritional waste. This review intends to investigate the underlying principles of ultrasonic generation and to improve understanding of their applications in food processing to make ultrasonic generation a safe, viable, and innovative food processing technology, as well as investigate the technology's benefits and downsides. The breadth of ultrasound's application in the industry has also been examined. This will also help researchers and the food sector develop more efficient strategies for frequency-controlled power ultrasound in food processing applications.

Resistance of Eupenicillium javanicum mold spores to the light-emitting diode (LED), LED-assisted thermal and thermal processing in strawberry and apple juices

The use of light-emitting diode (LED) technology for the non-thermal processing of foods is a major topic of interest among various research groups. This study is aimed at inactivating the Eupenicillium javanicum ascospores present in strawberry and apple juices using a combination of a visible LED (vis-LED, 430–630 nm, 216–420 J/cm²) and 90 °C thermal treatment, as well as to compare the findings with the inactivation done using thermal-processes alone. The results showed that violet-blue LEDs within the range of 430 and 460 nm with an energy between 300 and 420 J/cm² were better for the inactivation of E. javanicum ascospores than the green and red LEDs which were within the 550–630 nm region with an energy range from 216 to 264 J/cm². Furthermore, the inactivation process conducted using vis-LED was affected by the juice's soluble solid contents and the calculated D_LED-values were within the range of 116.3 J/cm² to 277.8 J/cm² in juices with a Brix scale value of 10–20°. Finally, the inactivation rate obtained from combining a violet-blue LED with a 90 °C thermal treatment was similar to the rate of using the thermal treatment alone.

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Effect of visible (vis-) LED treatment on inactivation E. javanicum spores was studied.

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Maximum log reduction was obtained with LED in the violet-blue region.

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E. javanicum spores showed higher LED resistance in apple juice than in strawberry juice.

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Soluble solid has an effect on E. javanicum inactivation by vis-LED.

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Similar thermal inactivation rates were observed between vis-LED + heat and heat alone.

A review of recent advances in the decontamination of mycotoxin and inactivation of fungi by ultrasound

Innovative technologies for the pasteurization of food products have increased due to the global demand for higher-quality food products. In this regard, the current article aimed to provide an overview regarding the latest research on US application in the decontamination of fungi in food products and highlight the parameters influencing the effectiveness of this method. Therefore, the related article with inactivation of fungi and mycotoxins by ultrasound among last four years (2018-2021) by using terms such as 'mycotoxin,' 'inactivation,' 'ultrasound,' 'decontamination' among some international databases such as PubMed, Web of Science, Embase and Google Scholar" was retrieved. Ultrasound (US) is considered a non-thermal decontamination method for food products. In US, the release of energy due to the acoustic phenomenon destroys microorganisms. This technology is advantageous as it is inexpensive, eco-friendly, and does not negatively affect food products' food structure and organoleptic properties. The influence of the US on food structure and organoleptic properties dramatically depends on the intensity and energy density applied In addition, it can preserve higher levels of ascorbic acid, lycopene, and chlorophyll in sonicated food products. The treatment conditions, including frequency, intensity, duration, temperature, and processing pressure, influence the effectiveness of decontamination. However, US displays synergistic or antagonistic effects on bacteria, yeasts, molds, and mycotoxins when combined with other types of decontamination methods such as chemical and thermal approaches. Thus, further research is needed to clarify these effects. Overall, the application of US methods in the food industry for decreasing the microbial content of food products during processing has been applied. However, the use of US with other techniques needs to be studied further.

Ultrasound and heat treatment effects on Staphylococcus aureus cell viability in orange juice

Ultrasounds are being considered an excellent alternative technology in juice preservation. Yet, when combined with heat treatment, the process seems to be further intensified. This work aimed to evaluate and compare the impact of ultrasounds and heat treatments, when applied alone or in combination, on Staphylococcus aureus survival in orange juice. Inoculated commercial pasteurized orange juice was treated at different times at 20, 30, 40, 50 and 60 °C. SEM analyses were applied to identify morphological changes in S. aureus cells appearance. The microbial inactivation data were fitted using two mathematical models, depending on the behaviour observed. Sonication at 20, 30, and 40 °C induced 4.02 ± 0.52, 3.80 ± 0.49 and 4.30 ± 0.74 log cycles reduction of S. aureus after treatments of 90, 60 and 60 min, respectively. The heat treatments at the same temperatures had no impact on S. aureus survival. When 50 and 60 °C were applied, more than 5-log reductions were attained for both thermosonication and heat treatments alone. A synergistic effect was observed between sonication and high temperatures. At 50 °C, the thermosonication reduced the treatment time from 60 to 35 min and the microbial load from 5.14 ± 0.08 to 10.76 ± 0.28 log cycles reduction, compared to heat treatment alone. Results from SEM images showed that cells undergo membrane damage during sonication exposure. This was observed by collapsed cells, cell disruption, and holes in the cell's membrane. Thermosonication proved to be a viable alternative to thermal pasteurization of orange juice since milder treatments can be safely applied, improving the final product quality.

Emerging Non-Thermal Technologies as Alternative to SO2 for the Production of Wine

SO₂ is an antioxidant and selective antimicrobial additive, inhibiting the growth of molds in the must during the early stages of wine production, as well as undesirable bacteria and yeasts during fermentation, thus avoiding microbial spoilage during wine production and storage. The addition of SO₂ is regulated to a maximum of 150–350 ppm, as this chemical preservative can cause adverse effects in consumers such as allergic reactions. Therefore, the wine industry is interested in finding alternative strategies to reduce SO₂ levels, while maintaining wine quality. The use of non-thermal or cold pasteurization technologies for wine preservation was reviewed. The effect of pulsed electric fields (PEF), high pressure processing (HPP), power ultrasound (US), ultraviolet irradiation (UV), high pressure homogenization (HPH), filtration and low electric current (LEC) on wine quality and microbial inactivation was explored and the technologies were compared. PEF and HPP proved to be effective wine pasteurization technologies as they inactivate key wine spoilage yeasts, including Brettanomyces, and bacteria in short periods of time, while retaining the characteristic flavor and aroma of the wine produced. PEF is a promising technology for the beverage industry as it is a continuous process, requiring only microseconds of processing time for the inactivation of undesirable microbes in wines, with commercial scale, higher throughput production potential.