Application of ultrasound technology in processing of ready-to-eat fresh food: A review

Advances in prepared dish processing using efficient physical fields: A review

Prepared dishes are increasingly popular convenience food that can be eaten directly from hygienic packaging by heating. Physics field (PF) is food processing method built with physical processing technology, which has the characteristics of high efficiency and environmental safety. This review focuses on summarizing the application of PFs in prepared dishes, evaluating and comparing PFs through quality changes during processing and storage of prepared dishes. Currently, improving the quality and extending the shelf life of prepared dishes through thermal and non-thermal processing are the main modes of action of PFs. Most PFs show good potential in handing prepared dishes, but may also react poorly to some prepared dishes. In addition, the difficulty of precise control of processing conditions has led to research mostly at the laboratory stage, but as physical technology continues to break through, more PFs and multi-physical field will be promoted for commercial use in the future. This review contributes to a deeper understanding of the effect of PFs on prepared dishes, and provides theoretical reference and practical basis for future processing research in the development of various enhanced PFs.

Relationship between Biofilm Formation and Antibiotic Resistance and Adherence Genes in Staphylococcus aureus Strains Isolated from Raw Cow Milk in Shahrekord, Iran

The production of biofilms by S. aureus contributes significantly to treatment failures. The present study aims to establish the relationship between biofilm formation and antibiotic resistance and adhesion genes in Staphylococcus aureus strains isolated from raw cow milk in Shahrekord, Iran. A total of 90 samples of raw cow's milk were collected. Presumptive S. aureus strains were obtained using Baird-Parker plates after enrichment in tryptone soy broth, and final colonies were selected from brain heart infusion. Additional tests such as coagulase were done, and the identification was confirmed by the detection of the aroA gene. Biofilm producing strains were screened using a spectrophotometry method applied to microplates. Crystal violet staining was used to quantify the formation of biofilm. An antibiotic susceptibility test was performed using the Kirby-Bauer disc diffusion method. PCR was used to detect several biofilm and antibiotics resistance related genes. The chi-square test and Fisher's exact test were used to establish a statistically significant relationship between biofilm reaction and antibiotic resistance (p value <0.05). Results show a moderate (38.88%) recovery rate of S. aureus in milk and 65.71% of the isolates were strong biofilm producers. Antibiotic susceptibility tests show an alarming rate of resistance to beta-lactam antibiotics, especially penicillin (100%), ampicillin (91.42%), and oxacillin (71.42%). This finding correlates with antibiotic resistance gene detection, in which the gene blaZ was most found (71.42%), followed by mecA and Aac-D (42.85%). Detection of biofilm-related genes shows that all the genes targeted were found among S. aureus isolates. Statistical tests show a significant correlation between biofilm production and antibiotic resistance in S. aureus. This study revealed that there is a significant correlation between biofilm production and antibiotic resistance in S. aureus isolated from raw milk. These results highlight the need for regular surveillance of the occurrence of S. aureus strains in milk and milk products in Iran.

Synergistic antibacterial mechanism of different essential oils and their effect on quality attributes of ready-to-eat pakchoi (Brassica campestris L. ssp. chinensis)

The mixture of garlic essential oil (GEO), ginger essential oil (GIEO) and litsea cubeba essential oil (LCEO) was prepared and its effect on the antibacterial activity of E. coli, S. aureus and P. aeruginosa, as well as properties of ready-to-eat pakchoi during storage were assessed. GEO, GIEO or LCEO treatment significantly enhanced the accumulation of reactive oxygen species (ROS) levels, resulting in disruption of the permeability of cell membrane, the leakage of cytoplasmic contents, and the alteration of the secondary structure of bacterial proteins. Meanwhile, GEO, GIEO or LCEO treatment repressed the key enzyme in tricarboxylic acid (TCA) and Hexose monophosphate pathway (HMP) cycle of E. coli, S. aureus and P. aeruginosa. Essential oil treatments (p < 0.05) could significantly prolong the shelf life of pakchoi, total bacterial count (TBC) values and chlorophyll content of GEO/GIEO/LCEO sample were 3.47 log cfu/g and 0.82 mg/g, respectively, after storage for 7 days. E. coli, S. aureus and P. aeruginosa counts in GEO/GIEO/LCEO samples decreased by 56.76 %, 70.10 %, 73.95 % compared to CK (no essential oil) samples. The comprehensive results from the sensory (flavor and color) and microbial analysis (especially TBC) showed that GEO/GIEO/LCEO could extend the shelf life of ready-to-eat pakchoi from 4 d to 7 d. As compared with GEO, GIEO or LCEO individually, the combination of GEO, GIEO and LCEO exhibited synergistic effect and more pronouncedly antibacterial activity to improve quality of ready-to-eat pakchoi.

Recent advances in essential oil complex coacervation by efficient physical field technology: A review of enhancing efficient and quality attributes

Although complex coacervation could improve the water solubility, thermal stability, bioavailability, antioxidant activity and antibacterial activity of essential oils (EOs). However, some wall materials (such as proteins and polysaccharides) with water solubility and hydrophobic nature limited their application in complex coacervation. In order to improve the properties of EO complex coacervates, some efficient physical field technology was proposed. This paper summarizes the application and functional properties of EOs in complex coacervates, formation and controlled-release mechanism, as well as functions of EO complex coacervates. In particular, efficient physical field technology as innovative technology, such as high pressure, ultrasound, cold plasma, pulsed electric fields, electrohydrodynamic atomization and microwave technology improved efficient and quality attributes of EO complex coacervates are reviewed. The physical fields could modify the gelling, structural, textural, emulsifying, rheological properties, solubility of wall material (proteins and polysaccharides), which improve the properties of EO complex coacervates. Overall, EOs complex coacervates possess great potential to be used in the food industry, including high bioavailability, excellent antioxidant capacity and gut microbiota in vivo, masking the sensation of off-taste or flavor, favorable antimicrobial capacity.

Quantitative proteomic analysis provides insight into the survival mechanism of Salmonella typhimurium under high-intensity ultrasound treatment

The survival mechanism of Salmonella treated with high-intensity ultrasound (HIU) should be explored to further enhance the bactericidal efficacy of HIU. In this study, culturable Salmonella was reduced by applying HIU. Electron microscope imaging revealed that HIU caused the disintegration of cell structure and leakage of intracellular substances. For the Salmonella after the HIU treatment, key enzymes of the tricarboxylic acid [TCA] cycle were significantly downregulated, which led to a reduced ATP content (45.25%–75.00%), although ATPase activity was augmented by 33.82%–60.64% in the Salmonella. Accordingly, surviving Salmonella could have tolerated the stress of HIU by upregulating their environmental sensing (two-component system), chemotaxis (bacterial chemotaxis), substance uptake (ABC transporter), and ATP production (oxidative phosphorylation). Therefore, synergistically blocking the ATP production, signal transduction, or substance intake of Salmonella offer promising potential strategies to improve the bactericidal effect of HIU in industrial food processing.

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Cell damage and substances leakage were observed in ultrasound treated Salmonella.

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Ultrasonic treatments caused 1017 differentially expressed proteins in Salmonella.

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Ultrasound inhibited tricarboxylic acid cycle and reduced adenosine triphosphate content in Salmonella.

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Salmonella tolerated ultrasound by upregulating two-component system, ABC transport, and bacterial chemotaxis.

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These altered pathways could be potential targets to enhance the lethality of ultrasound.

Understanding the effects of ultrasound processng on texture and rheological properties of food

The demand for the production of high quality and safe food products has been ever increasing. Consequently, the industry is looking for novel technologies in food processing operations that are cost-effective, rapid and have a better efficiency over traditional methods. Ultrasound is well-known technology to enhance the rate of heat and mass transfer providing a high end-product quality, at just a fraction of time and energy normally required for conventional methods. The irradiation of foods with ultrasound creates acoustic cavitation that has been used to cause desirable changes in the treated products. The technology is being successfully used in various unit operations such as sterilization, pasteurization, extraction, drying, emulsification, degassing, enhancing oxidation, thawing, freezing and crystallization, brining, pickling, foaming and rehydration, and so forth. However, the high pressure and temperature associated with the cavitation process is expected to induce some changes in the textural and rheological properties of foods which form an important aspect of product quality in terms of consumer acceptability. The present review is aimed to focus on the effects of ultrasound processing on the textural and rheological properties of food products and how these properties are influenced by the process variables.

Valorization of mushroom by-products: a review

With the rapid growth of the global economy and the global population, the production of solid waste has increased remarkably. Mushrooms are gaining popularity among researchers for their ability to turn waste into nutrients. However, a large number of by-products are produced during the industrial processing of mushrooms. Traditional waste management, focusing on the utilization and disposal of mushroom by-products, has attracted the attention of researchers. Meanwhile, the circular economy has become a multidisciplinary research field, and the valorization of mushroom by-products is a very important part of circular economy research. Various mushroom by-products of mushroom are reviewed in this paper. By-products are used in food as raw materials or functional components, in livestock and poultry feed after grinding/fermentation, and as electrochemical materials and papermaking materials. The by-products can also be used to produce ethanol and other biological sources of energy, as absorbing substances in sewage treatment, and as fertilizer in soil amendment. Mushroom processing by-products can be applied in various fields. To improve production efficiency, new extraction technology (including supercritical fluid technology and microwave extraction technology) can be adopted to increase the bioactive substance content in the by-products. Choosing appropriate processing temperature, time, and other processing conditions can also enhance product quality. Finally, more research is needed on the cost-effective utilization of the by-products and the feasibility of industrialization. © 2022 Society of Chemical Industry.

Ultrasound-Assisted Extraction and the Encapsulation of Bioactive Components for Food Applications

Various potential sources of bioactive components exist in nature which are fairly underutilized due to the lack of a scientific approach that can be sustainable as well as practically feasible. The recovery of bioactive compounds is a big challenge and its use in food industry to develop functional foods is a promising area of research. Various techniques are available for the extraction of these bioactives but due to their thermolabile nature, there is demand for nonthermal or green technologies which can lower the cost of operation and decrease operational time and energy consumption as compared to conventional methods. Ultrasound-assisted extraction (UAE) is gaining popularity due to its relative advantages over solvent extraction. Thereafter, ultrasonication as an encapsulating tool helps in protecting the core components against adverse food environmental conditions during processing and storage. The review mainly aims to discuss ultrasound technology, its applications, the fundamental principles of ultrasonic-assisted extraction and encapsulation, the parameters affecting them, and applications of ultrasound-assisted extraction and encapsulation in food systems. Additionally, future research areas are highlighted with an emphasis on the energy sustainability of the whole process.

Protective Effect of Ultrasound-Processed Amazonian Sapota-do-Solimões (Quararibea cordata) Juice on Artemia salina Nauplii

Juice processing by non-thermal technology has been extensively studied, aiming at microbial inactivation and quality improvement. However, the knowledge about the possible toxic effects that those technologies can produce in foodstuffs due to the production of reactive oxygen species is still unknown. In this study, sapota-do-Solimões juice processed by ultrasound (2, 6, and 10 min) was evaluated by a toxicity test and protective effect through stress biomarkers (catalase, superoxide dismutase, and lipid peroxidation) using Artemia salina nauplii. The non-thermal processed juice was nontoxic to A. salina. However, the juice fibers imparted some damage to the animal’s body. The ultrasound-processed juice (2 and 6 min) decreased the A. salina mortality to 30% compared to the control assay with H2O2 where mortality was 80% after 48 h of exposure. However, after 72 h of exposure, the A. salina was entirely degraded by H2O2-induced toxicity. Furthermore, the catalase and superoxide dismutase presented the highest activity after A. salina was exposed to the unprocessed juice. Thus, sapota-do-Solimões juice processed by the ultrasound could promote a protective effect on A. salina, revealing this technology’s potential to enhance juice features without toxicity.

Garlic essential oil microcapsules prepared using gallic acid grafted chitosan: Effect on nitrite control of prepared vegetable dishes during storage

In order to lower the nitrite content in prepared vegetable dishes (PVDs) within a week, microcapsules loaded with garlic essential oils (GEO) were prepared using modified chitosan (CS) with different mass ratios of gallic acid (GA) to CS, and their physicochemical properties were determined. The effects of GEO alone and of microcapsules made using native CS and GA-CS (GA-grafted CS) with the highest conjugation degree on the nitrite content in PVD_S were measured quantitatively. Also, the reasons for the differences were identified. The results showed that the microcapsules prepared using GA-CS (at a mass ratio of 0.5:1) presented the best physicochemical properties, including antioxidant activity, encapsulation efficiency, sustained release, etc. GA-CS microcapsules enhanced growth inhibition of bacteria producing nitrites, thus showing its excellent ability to inhibit nitrites, compared to GEO alone and microcapsules made using native CS. GA-CS encapsulation is a new option to lower the nitrite content in PVDs.

Assessment of ultrasound-assisted vacuum impregnation as a method for modifying cranberries' quality

Combined vacuum impregnation and ultrasound was proposed as an alternative method to improve the infusion of ascorbic acid in berry fruit. The effect of ultrasound application at different stages of impregnation - vacuum, relaxation, and both stages - on the qualitative characteristics of impregnated cranberries was investigated. The quality assessment was based on porosity, color, antioxidant capacity, anthocyanin, polyphenol and structure compound content. Ultrasound-assisted vacuum impregnation contributed to higher ascorbic acid content, smaller relative color difference, and greater antioxidant properties. It was found that the degree of impregnation varies considerably and depends on the stage of using ultrasound. Due to more favorable quality attributes, the conclusion was reached that ultrasound should be applied during the relaxation stage of vacuum impregnation.

Changes in Textural Quality and Water Retention of Spiced Beef under Ultrasound-Assisted Sous-Vide Cooking and Its Possible Mechanisms

The present study investigated the effects of ultrasound (28 kHz, 60 W at 71 °C for 37 min) combined with sous-vide cooking (at 71 °C for 40, 60, 80, 100, 120 min) on the textural quality, water distribution, and protein characteristics of spiced beef. Results showed that the spiced beef treated with conventional cooking (CT) had the highest cooking loss (41.31%), but the lowest value of shear force (8.13 N), hardness (55.66 N), springiness (3.98 mm), and chewiness (64.36 mJ) compared to ultrasound-assisted sous-vide (USV) and sous-vide cooking (SV) groups. Compared with long-time thermal treatment, USV heating within 100 min enhanced the water retention of spiced beef by maintaining the lower values of cooking loss (16.64~25.76%), T₂ relaxation time (242.79~281.19 ms), and free water content (0.16~2.56%), as evident by the intact muscle fibers. Moreover, the USV group had relatively lower carbonyl content, but higher sulfhydryl content compared to CT and SV groups. More protein bands coupled with a minor transformation from α-helixes to β-turns and random coils occurred in USV40~USV80. In conclusion, these results indicated that USV treatment within 100 min positively affected the textural quality and water retention of spiced beef by moderate protein oxidation.

Transcriptome and proteome analysis of ultrasound pretreated peanut sprouts

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It was first time to combined transcriptomic and proteome analyses to investigate the ultrasound pretreated peanut sprouts.

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A total of 1104 DEGs and 399 DEPs between ultrasound pretreated and nontreated peanut sprouts.

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Ultrasound upregulated three key genes that could have increased the content of resveratrol via phenylpropanoid biosynthesis.

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The genes and proteins related to phenylpropanoid biosynthesis, flavonoids biosynthesis, and lipid metabolism.

Combined transcriptomic and proteome analyses were carried out to investigate the influence of ultrasound pretreatment on peanut sprouts. In total, 1104 differentially expressed genes (upregulated:538, downregulated:521) and 399 differentially accumulated proteins (upregulated: 197, downregulated: 202) were identified between ultrasound pretreated and nontreated peanut sprouts. These genes and proteins were related to a series of crucial biomolecular processes, including the metabolism of carbohydrates, terpenoids, and polyketides. The most enriched pathways were further analyzed in each category. Importantly, ultrasound upregulated three key genes namely the arahy. Tifrunner. gnm1.ann1.DXZI51, arahy.Tifrunner.gnm1.ann1.VGN2GE, and arahy.Tifrunner.gnm1.ann1.Y23DM6 that could have increased the content of resveratrol via phenylpropanoid biosynthesis. Furthermore, this study shows that B3, MYB transcription factor-like families play a significant role in response to ultrasound treatment. Overall, this study provides useful transcriptomics and proteomics information highlighting the molecular mechanisms that influence nutritional differences in peanut sprouts.

Application of Electrolyzed Water in the Food Industry: A Review

Electrolyzed water is a novel disinfectant and cleaner that has been widely utilized in the food sector for several years to ensure that surfaces are sterilized, and that food is safe. It is produced by the electrolysis of a dilute salt solution, and the reaction products include sodium hydroxide (NaOH) and hypochlorous acid. In comparison to conventional cleaning agents, electrolyzed water is economical and eco-friendly, easy to use, and strongly effective. Electrolyzed water is also used in its acidic form, but it is non-corrosive to the human epithelium and other organic matter. The electrolyzed water can be utilized in a diverse range of foods; thus, it is an appropriate choice for synergistic microbial control in the food industry to ensure food safety and quality without damaging the organoleptic parameters of the food. The present review article highlights the latest information on the factors responsible for food spoilage and the antimicrobial potential of electrolyzed water in fresh or processed plant and animal products.

Evaluation of effects of ultrasound-assisted saucing on the quality of chicken gizzards

The purpose of this study was to evaluate the effects of ultrasound-assisted saucing on the quality of chicken gizzards. The results showed that with the prolonging of the saucing time, the yield, water holding capacity (WHC), lightness (L*), redness (a*) and springiness of chicken gizzards significantly decreased, while the shear force, hardness and chewiness significantly increased (P < 0.05). When the saucing time was the same, the yield, WHC, springiness and tenderness of the ultrasound group were significantly higher than those of the non-ultrasound group (P < 0.05). In particular, when the saucing time was 30 min, the yield, WHC and springiness of the ultrasound group increased by 2.13%, 0.97% and 10.53%, and the shear force decreased by 21.22% compared with those of the non-ultrasound group, respectively. Besides, ultrasound pretreatment increased the content of aromatic compounds, short-chain alkanes, alcohols, aldehydes and ketones, and the principal component analysis displayed that C-50 (saucing for 50 min without ultrasound pretreatment) and U-30 (saucing for 30 min with ultrasound pretreatment) were similar in flavor. Therefore, ultrasound pretreatment is a potential way to improve the quality of saucing chicken gizzards and shorten the processing time.

Improving the poor texture and technological properties of chicken wooden breast by enzymatic hydrolysis and low-frequency ultrasound

Abstract

Wooden breast (WB) is a recurrent myopathy in fast‐growing birds, which alters the appearance, functionality, and the texture of the breast muscle. The objectives of this study were (i) to evaluate the effect of a combined use of papain enzyme and ultrasound on the texture of WB chicken using response surface methodology and (ii) to assess the effect of marinating on the quality of WB chicken meat. Full factorial experimental design method was used to obtain the ideal conditions to soften the WB meat. The independent variables were the concentration of papain (0.1%–0.3%) and the time in ultrasonic bath (10–30 min); shear force (SF) was the dependent variable. The optimum results were obtained at a concentration of 0.2% papain and 20 min on ultrasound. Papain enzyme had a great influence on the texture of WB meat, reducing its hardness. However, the effect of the ultrasound time on the SF response was not observed. The marinated WB meat showed similar SF values and texture profile than those from normal (N) meat, with reduction in the parameters of protein and lipid oxidation. The use of papain without ultrasound bath proved to be an efficient means for improving the tenderness of WB breasts.

Practical Application

This study shows the efficiency of the application of two technological procedures (enzymatic treatment and ultrasound) to improve the texture profile and technological properties of chicken breasts affected by the wooden breast myopathy. The economic loss caused by the world‐wide occurrence of wooden breast is enormous, and the application of papain has been found to counteract the impaired properties of this abnormal chicken breasts. Since papain is already widely used in the food industry to tenderize meat, its application in improving the quality of WB meat is straightforward.

Effect of Ultrasound Treatment on Barrier Changes of Polymers before and after Exposure to Food Simulants

In this study, we investigated the impact of ultrasound treatment on barrier properties of linear low-density polyethylene (LLDPE) and acrylic/poly(vinylidene chloride) polypropylene (PPAcPVDC)-coated pouches intended for food packaging before and after exposure to food simulants. Packaging pouches were filled with two food simulants, namely ethanol (10% (v/v)) and acetic acid (3% (w/v)), in order to simulate food−packaging interaction and possible compound migration from packaging materials. Samples were subjected to an ultrasound water bath treatment for 5 min, 15 min, and 30 min at 60 °C (±2 °C) and with an amplitude of 100% as an equivalent to the heat-treatment conditions combined with an ultrasound effect. Furthermore, the effect of temperature on the polymer barrier (water vapour and oxygen permeability) properties was tested at 20 °C, 40 °C, and 60 °C. Results showed that PPAcPVDC possessed better properties of water vapour permeability and oxygen permeability properties to LLDPE. Statistical analyses showed a significant (p < 0.001) impact of ultrasound treatment on the overall migration value, regardless of the food simulant used.

Advances, Applications, and Comparison of Thermal (Pasteurization, Sterilization, and Aseptic Packaging) against Non-Thermal (Ultrasounds, UV Radiation, Ozonation, High Hydrostatic Pressure) Technologies in Food Processing

Nowadays, food treatment technologies are constantly evolving due to an increasing demand for healthier and tastier food with longer shelf lives. In this review, our aim is to highlight the advantages and disadvantages of some of the most exploited industrial techniques for food processing and microorganism deactivation, dividing them into those that exploit high temperatures (pasteurization, sterilization, aseptic packaging) and those that operate thanks to their inherent chemical–physical principles (ultrasound, ultraviolet radiation, ozonation, high hydrostatic pressure). The traditional thermal methods can reduce the number of pathogenic microorganisms to safe levels, but non-thermal technologies can also reduce or remove the adverse effects that occur using high temperatures. In the case of ultrasound, which inactivates pathogens, recent advances in food treatment are reported. Throughout the text, novel discoveries of the last decade are presented, and non-thermal methods have been demonstrated to be more attractive for processing a huge variety of foods. Preserving the quality and nutritional values of the product itself and at the same time reducing bacteria and extending shelf life are the primary targets of conscious producers, and with non-thermal technologies, they are increasingly possible.

Extraction of functional extracts from berries and their high quality processing: a comprehensive review

Berry fruits have attracted increasing more attention of the food processing industry as well as consumers due to their widely acclaimed advantages as highly effective anti-oxidant properties which may provide protection against some cancers as well as aging. However, the conventional extraction methods are inefficient and wasteful of solvent utilization. This paper presents a critical overview of some novel extraction methods applicable to berries, including pressurized-liquid extraction, ultrasound-assisted extraction, microwave-assisted extraction, supercritical fluid extraction, enzyme-assisted extraction as well as some combined extraction methods. When combined with conventional methods, the new technologies can be more efficient and environmentally friendly. Additionally, high quality processing of the functional extracts from berry fruits, such as refined processing technology, is introduced in this review. Finally, progress of applications of berry functional extracts in the food industry is described in detail; this should encourage further scientific research and industrial utilization.

What Do Consumers Think about Foods Processed by Ultraviolet Radiation and Ultrasound?

This study aimed to investigate Brazilian consumers’ perception concerning foods processed by ultraviolet (UV) radiation and ultrasound (US) and define consumer segments considering their socioeconomic characteristics and eating habits towards industrialized products through free word association tasks answered by 1004 participants via an online platform. UV- and US-treated foods were more frequently related to unfamiliar words/terms (21.51 and 36.95%) and negative associations (36.25 and 26.70%) than positive ones (29.89 and 24.20%), respectively. Unfamiliarity and health risk concerns were more reported for US-treated foods by women aged 18–25 and ≥46 with low income, and low and frequent industrialized products consumption, as well as for UV-treated foods by consumers ≤35 years old with low and medium income, and low and frequent industrialized products consumption. This indicates that more clear and trustworthy information is needed before introducing these products in the Brazilian market, mainly for potential target consumer groups identified in this study.

In vitro and in silico approaches to investigate antimicrobial and biofilm removal efficacies of combined ultrasonic and mild thermal treatment against Pseudomonas fluorescens

A combined ultrasonic and thermal (US-TM) treatment was developed in this study to achieve a high efficacy of P. fluorescens biofilm control. The present study demonstrated that combined a moderate ultrasound treatment (power ≥ 80 W) and a mild heat (up to 50 °C) largely destroyed biofilm structure in 15 min and removed>65.63% of biofilm from a glass slide where cultivated the P. fluorescens biofilm. Meanwhile, the viable cell count was decreased from 10.72 to 6.48 log₁₀CUF/mL. Differences in biofilm removal and lethal modes of US-TM treatment were confirmed through microscopies analysis in vitro. The ultrasound first contributed to releasing the bacteria in the biofilm to the environment and simultaneously exposing inner bacteria at the deep layer of biofilm depending on shear force, shock waves, acoustic streaming, etc. When the biofilm structure was destroyed, US-TM treatment would synergistically inactivate P. fluorescens cells. In silico studies adopted COMSOL to simulate acoustic pressure and temperature distribution in the bioreactor; both of them were significantly influenced by various factors, such as input power, sonotrode position, materials and volume of container, etc. Facing the biofilm issue existing on the surface of container, boundary conditions were exported and thereby pointing out potential "dead ends" where the ultrasound may not be effectively transduced. Both in vitro and in silico results may inspire the food industry to adopt US-TM treatment to achieve biofilm control.

Low frequency ultrasound treatment enhances antibrowning effect of ascorbic acid in fresh-cut potato slices

Ascorbic acid (AsA) is generally used as an antibrowning agent for fresh-cut potato (FCP). However, its browning inhibitory effect is temporary because of its rapid consumption during redox processes. In this study, the effect of browning inhibition in FCP slices was evaluated using low frequency ultrasound (LFU; 40 kHz, 200 W, 3 min) and AsA (0.2%, w/v) treatments alone or in combination. The results showed that LFU combined with AsA (LFU-AsA) treatment could achieve a better antibrowning effect than either treatment alone (higher L*, lower a* and ΔE*), and there was no adverse effect on texture properties. LFU-AsA treatment not only inhibited the activity of PPO more effectively than AsA treatment, but also enhanced the antibrowning effect by retaining higher AsA content. Moreover, it also maintained membrane integrity by limiting lipid peroxidation and solute migration during storage. Overall, LFU-AsA treatment would be a promising method in food preservation industries.

Recent Advances in the Application of Enzyme Processing Assisted by Ultrasound in Agri-Foods: A Review

The intensification of processes is essential for the sustainability of the biorefinery concept. Enzyme catalysis assisted by ultrasound (US) may offer interesting opportunities in the agri-food sector because the cavitation effect provided by this technology has been shown to improve the efficiency of the biocatalysts. This review presents the recent advances in this field, focused on three main applications: ultrasound-assisted enzymatic extractions (UAEE), US hydrolysis reactions, and synthesis reactions assisted by US for the manufacturing of agri-food produce and ingredients, enabling the upgrading of agro-industrial waste. Some theoretical and experimental aspects of US that must be considered are also reviewed. Ultrasonic intensity (UI) is the main parameter affecting the catalytic activity of enzymes, but a lack of standardization for its quantification makes it unsuitable to properly compare results. Applications of enzyme catalysis assisted by US in agri-foods have been mostly concentrated in UAEE of bioactive compounds. In second place, US hydrolysis reactions have been applied for juice and beverage manufacturing, with some interesting applications for producing bioactive peptides. In last place, a few efforts have been performed regarding synthesis reactions, mainly through trans and esterification to produce structured lipids and sugar esters, while incipient applications for the synthesis of oligosaccharides show promising results. In most cases, US has improved the reaction yield, but much information is lacking on how different sonication conditions affect kinetic parameters. Future research should be performed under a multidisciplinary approach for better comprehension of a very complex phenomenon that occurs in very short time periods.

Effects of ultrasound-assisted low-concentration chlorine washing on ready-to-eat winter jujube (Zizyphus jujuba Mill. cv. Dongzao): Cross-contamination prevention, decontamination efficacy, and fruit quality

Wash water is circulated for use in the minimal processing industry, and inefficient disinfection methods can lead to pathogen cross-contamination. Moreover, few disinfection strategies are available for ready-to-eat fruits that do not need to be cut. In this study, the use of chlorine and ultrasound, two low-cost disinfection methods, were evaluated to disinfect winter jujube, a delicious, nutritious, and widely sold fruit in China. Ultrasound treatment (28 kHz) alone could not decrease the cross-contamination incidence of Escherichia coli O157:H7, non-O157 E. coli, and Salmonella Typhimurium, and free chlorine treatment at 10 ppm decreased the incidence from 55.00% to 5.00% for E. coli O157:H7, 65.00% to 6.67% for non-157 E. coli, and 70.00% to 6.67% for S. Typhimurium. The cross-contamination incidence was completely reduced (pathogens were not detected in sample) when the treatments were combined. The counts of aerobic mesophiles, aerobic psychrophiles, molds, yeasts, and three pathogens in the group subjected to combination treatment (28 kHz ultrasound + 10 ppm free chlorine) were significantly lower than those in the control, chlorine-treated, and ultrasound-treated groups during storage (0-7 d at 4 °C). Analysis of weight loss, sensory quality (crispness, color, and flavor), instrument color (a*/b*), soluble matter contents (total soluble solids, reducing sugar, total soluble sugar, and titratable acid), and nutritional properties (ascorbic acid and polyphenolic contents) indicated that treatment with ultrasound, chlorine, and their combination did not lead to additional quality loss compared with properties of the control. Additionally, the activities of phenylalanine ammonia-lyase and polyphenol oxidase were not significantly increased in the treatment group, consistent with the quality analysis results. These findings provide insights into disinfection of uncut ready-to-eat fruits using a minimum dose of disinfectant for cross-contamination prevention under ultrasonication. The use of ultrasound alone to decontaminate fresh produce is accompanied by a high risk of pathogen contamination, and the use of sanitizers to decrease cross-contamination incidence is recommended.

Effects of ultrasound pretreatment on the drying kinetics, water status and distribution in scallop adductors during heat pump drying

BACKGROUND

A material's physical and chemical properties during drying are influenced by water status and distribution. However, merely overall water removal is reported in many investigations, which hinders clarification of the drying mechanism. Therefore, the effects of ultrasound (US) pretreatment (0 W, CK; 90 W, US-90; 180 W, US-180) on the drying kinetics and quality of heat pump drying (HPD) scallop adductors was performed based on low-field nuclear magnetic resonance (LF-NMR).

RESULTS

Compared with CK, effective moisture diffusion coefficient was increased by 12.43% and 23.35% for US-90 and US-180, respectively. The Weibull model satisfactorily described the drying characteristics with a high r² (> 0.998), low rmse (< 0.0120) and χ² (< 0.00008). LF-NMR revealed that the immobilized water was predominant in scallop adductors. As drying proceeded, the relaxation time of free and immobilized water was decreased sharply, whereas the relaxation time of bound water scarcely changed. The time required to reduce approximately two-fifths of the original peak area of immobilized water was 720, 630 and 540 min for CK, US-90 and US-180, respectively. The amplitude of immobilized water was decreased and bound water increased significantly, although free water was kept constant (ranging 1-2%). US pretreatment reduced total color difference and hardness, but enhanced the toughness of dried scallop adductors. However, US had no significant influence on the product rehydration rate and shrinkage rate.

CONCLUSION

LF-NMR was successfully employed to evaluate the drying degree of scallop adductors. US facilitated the conversion of immobilized water to free water and, consequently, promoted water removal during HPD. © 2021 Society of Chemical Industry.

Hybrid high-intensity ultrasound and microwave treatment: A review on its effect on quality and bioactivity of foods

With the growing of consumer's demand for products ready to eat that can be elaborated with greener technologies without affecting to their organoleptic characteristics, the application of ultrasound combined with microwaves has been widely studied on food preservation treatments (drying, frying), extraction of high-value added compounds and enzymatic hydrolysis of proteins. This review presents a complete picture of current knowledge on the ultrasound combined with microwaves including the mechanisms, influencing factors, advantages and drawbacks, emphasising in several synergistic effects observed in different processes of strong importance in the food industry. Recent research has shown that this hybrid technology could not only minimise the disadvantages of power US for drying and frying but also improve the product quality and the efficiency of both cooking processes by lowering the energy consumption. Regarding extraction, current studies have corroborated that the combined method presents higher yields in less time, in comparison with those in the respective ultrasound and microwave separately. Additionally, recent results have indicated that the bioactive compounds extracted by this combined technology exhibit promising antitumor activities as well as antioxidant and hepatoprotective effects. Remarkably, this hybrid technology has been shown as a good pre-treatment since the structural changes that are produced in the molecules facilitate the subsequent action of enzymes. However, the combination of these techniques still requires a proper design to develop and optimized conditions are required to make a scale process, and it may lead to a major step concerning a sustainable development and utilization of bioactive compounds from natural products in real life.

Sonoprocessing: From Concepts to Large-Scale Reactors

Intensification of ultrasonic processes for diversified applications, including environmental remediation, extractions, food processes, and synthesis of materials, has received attention from the scientific community and industry. The mechanistic pathways involved in intensification of ultrasonic processes that include the ultrasonic generation of cavitation bubbles, radical formation upon their collapse, and the possibility of fine-tuning operating parameters for specific applications are all well documented in the literature. However, the scale-up of ultrasonic processes with large-scale sonochemical reactors for industrial applications remains a challenge. In this context, this review provides a complete overview of the current understanding of the role of operating parameters and reactor configuration on the sonochemical processes. Experimental and theoretical techniques to characterize the intensity and distribution of cavitation activity within sonoreactors are compared. Classes of laboratory and large-scale sonoreactors are reviewed, highlighting recent advances in batch and flow-through reactors. Finally, examples of large-scale sonoprocessing applications have been reviewed, discussing the major scale-up and sustainability challenges.

Mechanism of low-frequency and high-frequency ultrasound-induced inactivation of soy trypsin inhibitors

In this study, the effect of ultrasonic frequency and power on the inactivation of soy trypsin inhibitors (TIs) was investigated to explore the ultrasound-induced inactivation mechanism. It was observed that 20 kHz and 355 kHz ultrasound have better inactivation efficiency than 1056 kHz. First-order rate constants for the inactivation process were obtained, which increased with increasing ultrasonic power at both 20 kHz and 355 kHz. For 20 kHz ultrasound, the formation of TI aggregates resulting from the physical effects of acoustic cavitation decreased the interactions between the active sites of TIs and trypsin, thus reducing the TI activity. For 355 kHz ultrasound, most of the methionine in the TIs was oxidised within 5 mins, resulting in a faster reduction of TI activity. Subsequent aggregation of TIs resulted in further TI inactivation. SDS-PAGE showed that neither disulphide bonds nor CC coupling were involved in the formation of aggregates.

Effects of ultrasound and gamma irradiation on quality maintenance of fresh Lentinula edodes during cold storage

Microbial infection, senescence and water losses result in serious quality deterioration of postharvest mushrooms. The aim of this study was to investigate the impact of ultrasound treatment (US), gamma irradiation treatment (GI) and their combination on quality maintenance of fresh Lentinula edodes during storage. The results showed that US + GI was the most effective approach to maintaining the quality of mushrooms. US + GI reduced natural microflora present on L. edodes, such as total number of colonies, molds, yeasts, Pseudomonas and Enterobacteriaceae. Furthermore, US + GI stimulated phenylalanine ammonia lyase, maintained the highest level of total phenolic content (733.63 mg GAE/kg on Day 4), and postponed the occurrence of reduced ascorbic acid (33.7% retention relative to the control), which contributed to strengthening the antioxidant capacity. Additionally, US + GI retarded water mobility and loss. In brief, the US + GI in this study is an effective hurdle technology for preserving the quality of fresh L. edodes during storage.

Effect of biofilm on the survival of Staphylococcus aureus isolated from raw milk in high temperature and drying environment

Microbial contamination in dairy products is a momentous factor affecting food safety. Studies have shown that Staphylococcus aureus, which is an important causative agent of a range of infectious and foodborne diseases, may remain in raw milk after a series of complex processing processes. Although most S. aureus possess biofilm formation capacity, there are few studies concerning the role of biofilm formation of this bacterium in stress tolerance and longtime survival in the dairy products. In this study, we selected 5 S. aureus (RMSA1, RMSA2, RMSA3, RMSA4 and RMSA5) isolates from raw milk and investigated their virulence and biofilm characteristics. Results from biofilm assays showed that all 6 S. aureus strains (5 dairy isolates and 1 human-derived model strain NCTC8325) could form complete biofilms in vitro. The reverse transcription-PCR experiments confirmed that multiple genes related to virulence factors and biofilm formation were expressed in the 6 strains. Furthermore, we simulated the high temperature (at 60 °C for 30 min) and drying pressure (at 37 °C for 24 h) during dairy processing to detect the survival rate of strains culturedunderbiofilm or planktonic condition. The data showed that under high temperature and dry conditions, the survival rates of strains cultured under biofilm conditions were much higher than that of strains cultured under planktonic conditions. In addition, the adversity resistance associated with biofilm formation was more obvious in the milk-isolated strains compared with strain NCTC8325. This study provides evidence regarding the mechanisms of stress resistance of S. aureus strains isolated from raw milk and contribute to prevention of dairy product contamination caused by this bacterium.

Greener organic synthetic methods: Sonochemistry and heterogeneous catalysis promoted multicomponent reactions

Ultrasound is an essential technique to improve organic synthesis from the point of view of green chemistry, as it can promote better yields and selectivities, in addition to shorter reaction times when compared to the conventional methods. Heterogeneous catalysis is another pillar of sustainable chemistry being the recycling and reuse of the catalysts one of its great advantage. In the other hand, multicomponent reactions provide the synthesis of structurally diverse compounds, in a one-pot fashion, without isolation and purification of intermediates. Thus, the combination of these protocols has proved to be a powerful tool to obtain biologically active organic compounds with lower costs, time and energy consumption. Herein, we provide a comprehensive overview of advances on methods of organic synthesis that have been reported over the past ten years with focus on ultrasound-assisted multicomponent reactions under heterogeneous catalysis. In particular, we present pharmacologically important N- and O-heterocyclic compounds, considering their synthetic methods using green solvents, and catalyst recycling.

Low-intensity ultrasound enhances the antimicrobial activity of neutral peptide TGH2 against Escherichia coli

In recent years, foodborne diseases caused by Escherichia coli are a major threat to the food industry and consumers. Antimicrobial peptides (AMPs) and ultrasound both have good inhibitory effects on E. coli. In this work, the mechanism of action and synergistic effect of an in silico predicted AMP, designated as TGH2 (AEFLREKLGDKCTDRHV), from the C-terminal sequence of Tegillarca granosa hemoglobin, combined with low-intensity ultrasound was explored. The minimal inhibitory concentration (MIC) of TGH2 on E. coli decreased by 4-fold to 31.25 μg/mL under 0.3 W/cm² ultrasound treatment, while the time kill curve analysis showed that low-intensity ultrasound combined with peptide TGH2 had an enhanced synergistic bactericidal effect after 0.5 h. The permeability on E. coli cell membrane increased progressively during combined treatment with peptide TGH2 and low-intensity ultrasound, resulting in the leakage of intracellular solutes, as shown by transmission electron microscopy (TEM). Structural analysis using circular dichroism (CD) revealed that peptide TGH2 has an α-helical structure, showing a slight untwisting effect under 0.3 W/cm² ultrasound treatment for 0.5 h. The findings here provide new insight into the potential application of ultrasound and AMPs combination in food preservation.

Applications of novel processing technologies to enhance the safety and bioactivity of milk

Bioactive compounds in food can have high impacts on human health, such as antioxidant, antithrombotic, antitumor, and anti-inflammatory activities. However, many of them are sensitive to thermal treatments incurred during processing, which can reduce their availability and activity. Milk, including ovine, caprine, bovine, and human is a rich source of bioactive compounds, including immunoglobulins, vitamins, and amino acids. However, processing by various novel thermal and non-thermal technologies has different levels of impacts on these compounds, according to the studies reported in the literature, predominantly in the last 10 years. The reported effect of these technologies either covers microbial inactivation or the bioactive composition; however, there is a lack of comprehensive compilation of studies that compare the effect of these technologies on bioactive compounds in milk (especially, caprine and ovine) to microbial inactivation at similar settings. This research gap makes it challenging to conclude on the specific processing parameters that could be optimized to achieve targets of microbial safety and nutritional quality at the same time. This review covers the effect of a wide range of thermal and non-thermal processing technologies including high-pressure processing, pressure-assisted thermal sterilization, pulsed-electric field treatment, cold plasma, microwave-assisted thermal sterilization, ultra-high-pressure homogenization, ultrasonication, irradiation on the bioactive compounds as well as on microbial inactivation in milk. Although a combination of more than one technology could improve the reduction of bacterial contaminants to meet the required food safety standards and retain bioactive compounds, there is still scope for research on these hurdle approaches to simultaneously achieve food safety and bioactivity targets.

Ultrasound, infrared and its assisted technology, a promising tool in physical food processing: A review of recent developments

Traditional food processing techniques can no longer meet the ever increasing demand for high quality food across the globe due to its low process efficiency, high energy consumption and low product yield. This review article is focused on the mechanism and application of Infrared (IR) and ultrasound (US) technologies in physical processing of food. We herein present the individual use of IR and US (both mono-frequency and multi-frequency levels) as well as IR and US supported with other thermal and non-thermal technologies to improve their food processing performance. IR and US are recent thermal and non-thermal technologies which have now been successfully used in food industries to solve the demerits of conventional processing technologies. These environmentally-friendly technologies are characterized by low energy consumption, reduced processing time, high mass-transfer rates, better nutrient retention, better product quality, less mechanical damage and improved shelf life. This work could be, with no doubt, useful to the scientific world and food industries by providing insights on recent advances in the use of US and IR technology, which can be applied to improve food processing technologies for better quality and safer products.