Food Decontamination Research Articles

A Honeycomb Film Template-Based Method for High-Throughput Preparation of Anti-Salmonella typhimurium 14,028 Phage Microgels

Developing efficient anti-microbials for thoroughly addressing Salmonella contamination is essential for the improvement of food safety. Phage-built materials have shown great potential for biocontrol in environments. Due to challenges in delivery and stability, their widespread use has remained unattainable. Here, we have developed a honeycomb film template-based method for the high-throughput preparation of phage microgels. The honeycomb film template can be simply fabricated in a humid chamber based on a well-established breath figure method. The bacteriophage microgels can be further manufactured by dropping a pre-gelation solution containing bacteriophages into a honeycomb film template. This method can produce over 210,000 phage microgels in every square centimeter template with each microgel containing 1.04 × 107 phages. They can kill 99.90% of the contaminated S. typhimurium 14,028 on chicken samples. This simple, heat-free, and solvent-free method can maintain the strong anti-bacterial efficiency of phages, which can expand the wide application of phage-built microgels for food decontamination.

Experimental Investigation of Bacterial Inactivation of Beef Using Indirect Cold Plasma in Cold Chain and at Room Temperature.

Pathogen contamination is a severe problem in maintaining food safety in the cold chain. Cold plasma (CP) is a novel non-thermal disinfection method that can be applied for the bacterial inactivation of food in appropriate contexts. Currently, research on CP used on food at cold chain temperatures is rare. This work investigated the bacterial inactivation effect of CP on beef at typical cold storage temperatures of 4 and -18 °C and room temperature (25 °C). The reactive species in CP were indirectly tested by evaluating O3, NO3- and NO2- in cold plasma-activated water (PAW), which indicated the highest concentrations of reactive species in CP at 25 °C and the lowest at -18 °C. The bactericidal efficacy of CP treatment against beef inoculated with Escherichia coli at -18 °C, 4 °C, and 25 °C was 30.5%, 60.1%, and 59.5%, respectively. The 4 °C environment was the most appropriate treatment for CP against beef, with the highest bactericidal efficacy and a minor influence on beef quality. The indirect CP treatment had no significant effect on the texture, color, pH, or cooking loss of beef at -18 °C. CP shows significant potential for the efficient decontamination of food at cold chain temperatures.

Sustainable processing technologies (pulsed light, electrolysed water and ozonation) for microbial decontamination of muscle foods

Considering the high perishable nature of muscle foods (fish, poultry and red meat) and wide diversity in spoilage microorganisms responsible for spoilage, the prevalence of pathogenic microorganisms in muscle food spoilage is significant. There has been extensive coverage on the emergence of antibiotic resistance in food spoilage microbes in recent years. Chemical preservatives have been extensively employed for the preservation of muscle foods although they have been found to cause toxicity and are not environmentally sustainable. Nevertheless, the scientific community has shown a growing interest in recent breakthroughs in the utilization of innovative clean-label technologies for the preservation of muscle meals, owing to their sustainable characteristics. Among them pulsed light, electrolysed water and ozonation have been under wide exploration. The evaluated sustainable technologies have been found to effectively inhibit the microbial spoilage and reduce the development of antimicrobial resistance. This review discusses potentiality of sustainable technologies in preserving muscle foods with minimal deteriorative impact.

Oxygen and air cold plasma for the inactivation of Bacillus cereus in low-water activity soy powder

Cold plasma (CP) technology is a promising alternative to thermal treatments for the microbial decontamination of foods with low-water activity. The aim of this work is study the application of low-pressure CP (0.35 mbar) for the inactivation of Bacillus cereus in a soybean powder matrix using O₂ and synthetic air as ionizing gases. The parameters tested were an input power of 100, 200 and 300 W and an exposure time of 10 to 30 min. The excited reactive species formed were monitored by optical emission spectroscopy, and survival data were analyzed using the Weibull mathematical model. Treatments with both gases were effective in inactivating B. cereus. Air plasma resulted in a maximum 3.71-log reduction in bacterial counts at 300 W and 30 min, while O2 plasma showed the strongest inactivation ability, achieving levels higher than 5 log cycles at 300 W and > 25 min. This is likely due to the strong antimicrobial activity of oxygen-derived radicals together with carbon monoxide as an oxidation by-product. In addition, the Weibull distribution function accurately modeled the inactivation of B. cereus. Cold plasma technology is a promising approach for the decontamination of bacteria in low-water activity foods.

Recent Advances in Non-Contact Food Decontamination Technologies for Removing Mycotoxins and Fungal Contaminants.

Agricultural food commodities are highly susceptible to contamination by fungi and mycotoxins, which cause great economic losses and threaten public health. New technologies such as gamma ray irradiation, ultraviolet radiation, electron beam irradiation, microwave irradiation, pulsed light, pulsed electric fields, plasma, ozone, etc. can solve the problem of fungal and mycotoxin contamination which cannot be effectively solved by traditional food processing methods. This paper summarizes recent advancements in emerging food decontamination technologies used to control various fungi and their associated toxin contamination in food. It discusses the problems and challenges faced by the various methods currently used to control mycotoxins, looks forward to the new trends in the development of mycotoxin degradation methods in the future food industry, and proposes new research directions.

Micellar-type aggregates of HP-β-CD/GML inclusion complex: Increased water-solubility and effective antibacterial capabilities

The inclusion complex (IC) was successfully obtained by encapsulating glycerol monolaurate (GML) into the cavity of hydroxypropyl-β-cyclodextrin (HP-β-CD). Compared with solubility of pure GML <80 μg/mL in water, and the water-solubility of encapsulated GML was significantly improved and reached to 270,000 μg/mL. IC can form nanoparticles by self-assembly, probably assigned to its strong capability to form micellar-type aggregates. A Higuchi's AL-type phase-solubility diagram indicated the strong interaction between host and guest molecules with the formation of 1:1 GML/HP-β-CD complex and the stability constant at 6248 L/mol. Compared with pure GML, encapsulated GML at the same concentration can also show good antibacterial capabilities against S. aureus and E. coli in sterile water, and the effective preservative capabilities towards beef meatballs. The boosted enhancement in water-solubility of GML and the effective antibacterial capabilities endowed IC with potential in the application of food decontamination.

Inactivation of Salmonella Typhimurium and Listeria monocytogenes in dairy systems: Effect of fat and food matrix structure under radio frequency heating

The effect of two food intrinsic factors (fat content, matrix structure) on the radio frequency (RF) inactivation of Salmonella Typhimurium and Listeria monocytogenes was investigated in dairy model systems: i.e., liquids with 0.08% and 5.9% fat and gels with 0.08% and 5.9% fat. In the liquid, higher fat content resulted in higher inactivation for both microorganisms. In gels, inactivation rate was higher with the lower fat content, while opposite behaviour occurred for L. monocytogenes above 70 °C. A gel matrix resulted in higher inactivation of S. Typhimurium, while complex temperature-dependent behaviour was present for L. monocytogenes. Sublethal injury was most significant for L. monocytogenes at 5.9% fat content and high temperatures. Overall, fat content and matrix structure impacted the microbial inactivation during RF heating and should be taken into account when designing novel RF heating food decontamination strategies. Industrial relevanceRadio frequency (RF) heating as a food processing technology has seen increased industrial application in recent years. The technology allows a more homogeneous heating of food products and also enables the treatment of low-moisture foods. The increased knowledge on the influence of fat content and food structure on RF thermal inactivation will lead to the development of improved and more efficient treatments.

High-throughput fabrication of antimicrobial phage microgels and example applications in food decontamination.

Engineered by nature, biological entities are exceptional building blocks for biomaterials. These entities can impart enhanced functionalities on the final material that are otherwise unattainable. However, preserving the bioactive functionalities of these building blocks during the material fabrication process remains a challenge. We describe a high-throughput protocol for the bottom-up self-assembly of highly concentrated phages into microgels while preserving and amplifying their inherent antimicrobial activity and biofunctionality. Each microgel is comprised of half a million cross-linked phages as the sole structural component, self-organized in aligned bundles. We discuss common pitfalls in the preparation procedure and describe optimization processes to ensure the preservation of the biofunctionality of the phage building blocks. This protocol enables the production of an antimicrobial spray containing the manufactured phage microgels, loaded with potent virulent phages that effectively reduced high loads of multidrug-resistant Escherichia coli O157:H7 on red meat and fresh produce. Compared with other microgel preparation methods, our protocol is particularly well suited to biological materials because it is free of organic solvents and heat. Bench-scale preparation of base materials, namely microporous films (the template for casting microgels) and pure concentrated phage suspension, requires 3.5 h and 5 d, respectively. A single production run, that yields over 1,750,000 microgels, ranges from 2 h to 2 d depending on the rate of cross-linking chemistry. We expect that this platform will address bottlenecks associated with shelf-stability, preservation and delivery of phage for antimicrobial applications, expanding the use of phage for prevention and control of bacterial infections and contaminants.

Assessment of lipid oxidation and microbial decontamination of sardine (Sardina pilchardus) fillets processed by plasma-activated water (PAW)

Plasma activated water (PAW) is emerging as a mild and environmentally friendly technology for microbial and chemical decontamination of food. The aim of this work was to evaluate the degree of oxidation of lipids of sardine tissue treated by PAW generated with a pulsed corona discharge. The effect of PAW on the natural microflora of the fish was also evaluated. Under the adopted experimental conditions, PAW was able to reduce the number of mesophilic aerobes and Pseudomonas spp. by 0.22 and 0.20 log units, respectively, but no increase in shelf life was observed at chilling temperatures compared to water washing. A loss of polyunsaturated fatty acids (PUFAs) and an increase in volatile oxidation products derived from the cleavage of PUFA hydroperoxides were observed at the longest treatment duration. Twelve cholesterol oxidation products (COPs) were identified in sardine lipids, but no significant differences in total COPs content were observed between PAW processed and control samples. Free radical mediated oxidation pathways led to the most abundant COPs, but a significant contribution of non-radical pathways was also observed. Further studies are needed to better understand the low efficiency of PAW in microbial decontamination of proteinaceous materials.

On the evaluation of the antimicrobial effect of grape seed extract and cold atmospheric plasma on the dynamics of Listeria monocytogenes in novel multiphase 3D viscoelastic models

The demand for products that are minimally processed and produced in a sustainable way, without the use of chemical preservatives or antibiotics have increased over the last years. Novel non-thermal technologies such as cold atmospheric plasma (CAP) and natural antimicrobials such as grape seed extract (GSE) are attractive alternatives to conventional food decontamination methods as they can meet the above demands. The aim of this study was to investigate the microbial inactivation potential of GSE, CAP (in this case, a remote air plasma with an ozone-dominated RONS output) and their combination against L. monocytogenes on five different 3D in vitro models of varying rheological, structural, and biochemical composition. More specifically, we studied the microbial dynamics, as affected by 1 % (w/v) GSE, CAP or their combination, in three monophasic Xanthan Gum (XG) based 3D models of relatively low viscosity (1.5 %, 2.5 % and 5 % w/v XG) and in a biphasic XG/Whey Protein (WPI) and a triphasic XG/WPI/fat model. A significant microbial inactivation (comparable to liquid broth) was achieved in presence of GSE on the surface of all monophasic models regardless of their viscosity. In contrast, the GSE antimicrobial effect was diminished in the multiphasic systems, resulting to only a slight disturbance of the microbial growth. In contrast, CAP showed better antimicrobial potential on the surface of the complex multiphasic models as compared to the monophasic models. When combined, in a hurdle approach, GSE/CAP showed promising microbial inactivation potential in all our 3D models, but less microbial inactivation in the structurally and biochemically complex multiphasic models, with respect to the monophasic models. The level of inactivation also depended on the duration of the exposure to GSE. Our results contribute towards understanding the antimicrobial efficacy of GSE, CAP and their combination as affected by robustly controlled changes of rheological and structural properties and of the biochemical composition of the environment in which bacteria grow. Therefore, our results contribute to the development of sustainable food safety strategies.

Reduction of Staphylococcus aureus in vitro and in milk by photodynamic inactivation using riboflavin and curcumin as photosensitizers: Cell damage and effects on product quality

Foodborne bacterial pathogens such as Staphylococcus aureus (S. aureus) are a threat due to the progressive resistance of microorganisms to multiple drugs. In this sense, photodynamic therapy (PDT) is an innovative food decontamination technique based on the combination of a photosensitizer compound (PS), light of adequate wavelength, and molecular oxygen. The reactive oxygen species (ROS) produced are responsible for non-specific cell damage and make the development of resistance unlikely. The objective was to determine the cell viability of S. aureus ATCC 25923 submitted to PDT mediated by Riboflavin (RIB) and Curcumin (CUR) in vitro and in fluid milk. The structural damage responsible for the death of the bacteria was investigated. In milk, lighting was tested by two methods: thin layers and constant agitation. The effects of the treatments on the composition, oxidation, and color of the product were also investigated. The blue light emitting diode (LED) inhibits S. aureus even in the absence of PS. CUR and RIB demonstrated synergistic antimicrobial activity, increasing the efficiency of PDT. CUR was more efficient than RIB, inhibiting 7 log CFU/mL at concentrations above 62.50 μg/mL in vitro. PDT caused cell death through oxidation and disruption of the bacterial membrane. Despite the considerable photoinhibition in milk (1.63 log CFU/mL), the physiological environment of this matrix impaired the efficiency of the technique. Both lighting methods reduced the bacteria counts. There was no change in macronutrients composition and protein oxidation. However, light caused lipid peroxidation and PS pigmented the milk. Therefore, PDT is efficient to inhibit bacterial pathogens and can be used as a complement to traditional food preservation technologies.

APPLICATION OF ULTRAVIOLET LED SYSTEMS IN THE GRAIN PROCESSING AND COMPOUND FEED INDUSTRIES

The materials of the article outline the features of the use of ultraviolet LED systems in industry, and propose a solution for their use in the grain processing and compound feed industry. Ultraviolet light (UV) is a well-researched and widely used means of decontamination and disinfection of surfaces, air, water, and food. Usually, far ultraviolet radiation (or ultraviolet C, UVC) with a wavelength of 254 nm is used, which corresponds to the peak absorption of wave energy by the DNA of a living cell. There is a mathematical mechanism for calculating the parameters of radiation in relation to its effect on microorganisms: a curve describing the microbial death depending on the increase in the radiation dose received by the bacteria and formulae for the relationship between the three main parameters (dose, radiation flux and exposure duration). Ultraviolet lamps (tubes) are commonly used, on the basis of which a large number of emitters have been developed for different needs. There are also emitters for grain and feed disinfection in use, but only outside of industrial production lines. Ultraviolet irradiation is not used directly on manufacturing lines so far. However, it can be used to reduce the microbial burden of a feed or food product prior to packaging the finished product. For this purpose, ultraviolet light-emitting diodes (LEDs) available on the world market today can be used. However, their use faces difficulties: ultraviolet LEDs emit wavelengths longer than lamps (at about 275 nm or more), which requires an increase in the duration of irradiation, which is undesirable for industrial processing of products directly on the line. However, the small size of the UVC LEDs will allow them to be installed in grain processing and feed mills inside equipment (magnetic separators, gravity feeders, etc.) with appropriate protection against damage by moving material. In addition, suspended emitters of any configuration can be placed above belt conveyors that move material at a certain speed. This approach will require certain measures to control the efficiency of irradiation (requires microbiological studies) and to protect personnel from the harmful effects of ultraviolet rays (means of personal and collective protection, measurement of radiation intensity).

Poly(vinyl alcohol) antibacterial films containing cross‐linked chitosan‐citric and photosensitive curcumin

AbstractComposite films PVA‐CS‐Curx (x = 0, 0.01, 0.06 and 0.12%) were successfully obtained by using vacuum‐drying at 80°C. The occurrence of nonenzymatic browning and cross‐linking of chitosan‐citric improved the thermal stability, water‐resistance, and mechanical property of films. Under the same humidity, the oxygen permeability of PVA‐CS‐Curx showed the dependence of test temperature and curcumin concentration (P &lt; 0.05). Relative to other films, the oxygen permeability (10−14 cc μm cm−2 s−1 Pa−1) of PVA‐CS‐Cur0.12 was 3.47 ± 0.55, 4.72 ± 0.94, and 7.29 ± 0.45 at 23, 30, and 40°C, respectively, showing gentle upward trend as temperature increased. Under white light irradiation, excellent antibacterial capability of PVA‐CS‐Curx demonstrated that polycationic chitosan‐citric complex and curcumin immobilized in films played the roles as synergistic antibacterial agents. Upon white irradiation of 20 min at 60 mW cm−2, the bactericidal rate of PVA‐CS‐Cur0.12 reached to 94.0 ± 3.09%. The excellent decontamination in meat preservation endowed films with the possibility in application of food decontamination.

Plasma-Activated Water: Physicochemical Properties, Generation Techniques, and Applications

Plasma-activated water (PAW) is water that has been treated with atmospheric pressure plasma. Due to the presence of reactive oxygen and nitrogen species (RONS), PAW can be used in various applications such as (1) surface disinfection and food decontamination, (2) enhancement in seed germination, and (3) enhancement in surface cooling in the nucleate boiling regime. Briefly, for surface disinfection, the reactive species in PAW can induce oxidative stress on microbes; for enhancement of seed germination, the reactive species in PAW can trigger seed germination and provide nutrients; for enhancement in surface cooling, the reactive species cause a reduction in the surface tension of PAW, facilitating the phase-change heat transfer and, quite unexpectedly, minimizing the surface oxidation. Here, we review the physicochemical properties of PAW, the three commonly used techniques (plasma jet, dielectric barrier discharge, and corona discharge) for generating atmospheric pressure plasma, and the use of PAW for the above three applications. In particular, we review the recent development of the miniaturization of the plasma generator integrated with an acoustic neutralizer to produce plasma-activated aerosols, elimination of the need for storage, and the interesting physicochemical properties of PAW that lead to cooling enhancement.

Influence of diluent on antimicrobial activity of cinnamon bark essential oil vapor against Staphylococcus aureus and Salmonella enterica on a laboratory medium and beef jerky

The influence of chemical diluents on the antimicrobial activity of plant essential oil (EO) vapors was evaluated. We first determined if vapors generated from 22 chemical diluents not containing EO had antimicrobial activities. Ethyl ether vapor retarded the growth of S. aureus. The minimal inhibitory concentrations (MICs) and the minimal lethal concentrations (MLCs) of cinnamon bark EO vapor, which was diluted in and generated from 21 diluents, against S. aureus and S. enterica were determined. Cinnamon bark EO vapor showed significantly (P ≤ 0.05) lower MICs against S. aureus when diluted in dimethyl sulfoxide (DMSO), ethanol, ethyl acetate, or jojoba oil, and against S. enterica when diluted in DMSO, ethanol, or jojoba oil, compared to those in other diluents. We compared antimicrobial activities of cinnamon bark EO vapor diluted in DMSO, ethanol, ethyl acetate, or jojoba oil against S. aureus and S. enterica on beef jerky as a food model. Antimicrobial activity was significantly (P ≤ 0.05) higher when vaporized from DMSO. These results indicate that antimicrobial activity of cinnamon bark EO vapor may vary significantly (P ≤ 0.05) depending on the type of diluent from which it is vaporized. These observations provide basic information when developing food and food-contact surface decontamination strategies using EO vapors.

Influence of cold atmospheric pressure plasma treatment of Spirulina platensis slurry over biomass characteristics

Cold atmospheric pressure plasma (CAPP) technique is an innovative non-thermal approach for food preservation and decontamination. This study aimed to evaluate the effect of CAPP power density on microorganism inactivation and quality of Spirulina platensis (S. platensis) slurry. 91.31 ± 1.61% of microorganism were inactivated within 2.02 ± 0.11 min by 26.67 W/g CAPP treatment under 50 ℃. Total phenolic, Chlorophyll-a (Chl-a), and carotenoids contents were increased by 20.51%, 63.55%, and 70.04% after 20.00 W/g CAPP treatment. Phycobiliproteins (PBPs), protein, intracellular polysaccharide, and moisture content of S. platensis was decreased, while vividness, lightness, color of yellow and green, antioxidant activity, Essential Amino Acid Index were enhanced after CAPP treatment. The nutrient release and filaments breakage of CAPP-treated S. platensis improved its bio-accessibility. The findings provided a deep understanding and insight into the influence of CAPP treatment on S. platensis, which were meaningful for optimizing its sterilization and drying processing condition.

The simultaneous influence of ultraviolet rays and cold plasma on the physicochemical attributes and shelf life of dried pistachios during the storage period

AbstractThis investigation aimed to assess the simultaneous impact of ultraviolet (UV) and cold plasma (CP) on the quality and microbial attributes of dried pistachios during the storage period. Currently, novel nonthermal technologies exhibit high potential as a low‐cost, efficient, additive‐free, and nonpolluting strategies for fungi deactivation and mycotoxins degradation in foods. Over recent years, the combination of CP with other procedures, such as ultraviolet (UV) irradiation, ultrasound, ozone, and so forth, has been proposed and attracted lots of attention. For this purpose, in this study, the simultaneous effects of ultraviolet rays and cold plasma on dried pistachios artificially contaminated with aflatoxigenic fungi were assessed. The physicochemical attributes and surface morphology of pistachios were evaluated as well. The concentration of aflatoxin produced was investigated via high‐performance liquid chromatography. Artificially contaminated pistachios were treated with cold plasma at 80 W constant power level at both 10 and 15 min. Following the plasma treatment, pistachio samples were treated by ultraviolet rays at 354 nm wavelength and current intensity in 0.25 A at the same time. The results of this study revealed the fungal deactivation rate achieved by UV‐CP treatment was greater than the sum of the deactivation rates of distinct UV and CP treatments, as maximum reduction of Aspergillus oryzae count (3.7 CFU/g) observed after simultaneous UV‐CP treatment for 15 min (p &lt; 0.05). Moreover, no substantial modifications were detected in the investigation of pH and DPPH radical scavenging activity of samples treated with UV‐CP (p &gt; 0.05). The results of this study confirm the effectiveness of the simultaneous application of UV rays and CP in nuts to maintain quality and increase useful life, along with an alternative method for thermal treatments.Practical applicationsUsually, nonthermal procedures lead to their destruction by changing the chemical structure of mycotoxins. Ultraviolet (UV) radiation being a nonthermal technology, the benefits of its usage are various: the least loss of nutrients and sensorial quality of foods, no toxic residues, and low energy consumption compared with other thermal treatments normally applied for food decontamination. The latter is the main purpose of this technique due to its effectiveness in the inactivation of pathogenic microorganisms and spoilage. Besides this, Cold plasma (CP) technology has been displayed to overcome many of the insufficiency of regular decontamination strategies in the food industry, with slight damage to the quality of products and high efficiency. Although several physical procedures have shown acceptable results in the decontamination of fungi and degradation of mycotoxins in many foods, to date there are few published works on the effects of simultaneous application of UV radiation and CP on foods, particularly pistachios in is available. Hence, the intention of this investigation was to assess the effect of combination of UV radiation and CP on the physicochemical attributes and shelf life of dried pistachios during the storage period.

Inhibition of Fungal Growth and Aflatoxin B1 Synthesis in Aspergillus flavus by Plasma-Activated Water.

The gaseous reactive oxygen/nitrogen species (RONS) generated by cold atmospheric plasma (CAP) can effectively inactivate Aspergillus flavus (A. flavus) and prolong the shelf-life of food. Plasma-activated water (PAW) is the extension of cold plasma sterilization technology. Without the limitation of a plasma device, PAW can be applied to more scenarios of food decontamination. However, the efficacy of PAW as a carrier of RONS for eradicating A. flavus or inhibiting its growth remains unclear. In this study, the immediate fungicidal effect and long-term inhibitory effect of PAW on A. flavus were investigated. The results demonstrated that 60-min instant-prepared PAW could achieve a 3.22 log reduction CFU/mL of A. flavus and the fungicidal efficacy of PAW gradually declined with the extension of storage time. Peroxynitrite (ONOO-/ONOOH) played a crucial role in this inactivation process, which could damage the cell wall and membrane structure, disrupt intracellular redox homeostasis, and impair mitochondrial function, ultimately leading to fungal inactivation. In addition to the fungicidal effect, PAW also exhibited fungistatic properties and inhibited the synthesis of aflatoxin B1 (AFB1) in A. flavus. By analyzing the cellular antioxidant capacity, energy metabolism, and key gene expression in the AFB1 synthesis pathway, it was discovered that PAW can significantly reduce ATP levels, while increasing SOD and CAT activity during 5-d cultivation. Meanwhile, PAW effectively suppressed the expression of genes related to AFB1 synthesis.

Applications of curcumin loaded nanoemulsions in photoinactivation of Aspergillus niger spores

AbstractBackgroundAspergillus niger is one of the most common fungal contaminants of food products, leading to several economic losses on fruit, vegetables and other food products during storage. Over the years, several new techniques have been developed to control fungal growth, including photodynamic inactivation, in which excitation of a photosensitizer in the right wavelength leads to ROS production and microbial death.ResultsOn this paper, curcumin was used as a natural photosentitizer against A. niger spores. Nanoemulsions were used in order to encapsulated curcumin and increase its water solubility. Results showed that spores inhibition could reach up to 80% after 3 min of irradiation while values for un‐encapsulated curcumin were around 30%.ConclusionResults presented show that nanoemulsions could be use to enhance the photoinactivation properties of curcumin, against fungal spores from A. niger. This type of process can be use for food decontamination and preservation.

Developing effective radio frequency and ultraviolet combination technology based on evaluating quality characteristics of buckwheat

Radio frequency (RF) heating and ultraviolet (UV) radiation are widely used in food processing. In this study, effects of RF and UV treatment alone and in combination on quality characteristics of buckwheat were investigated and compared under the operational parameters used for effective food decontamination. Results showed that RF heating at the high temperature (H-RF, 105 °C) led to significant changes on physicochemical properties of buckwheat, including an increase in water absorption capacity (WAC), and decreases in swelling power (SP), emulsifying capability (EC), foaming capacity (FC), viscosity capability, gelatinization enthalpy (ΔH), and rheological property. Correspondingly, intermolecular hydrogen bonds were broken, short-range order degree (ratio of 1047/1022 cm−1 and 995/1022 cm−1), crystallinity degree, and SH group contents were reduced. The changes of these parameters were mitigated by RF treatment at the low temperature (L-RF, 90 °C). While the UV radiation only affected the FC, EC, viscosity capability, and rheological property. Especially, UV radiation at low intensity (L-UV, 2.25 mW/cm2) alone did not significantly influence the multi-scale structures and physicochemical properties of buckwheat. Meanwhile, buckwheat treated by L-RF alone or in combination with L-UV performed the similar properties, implying that the UV treatment after RF heating could not further alter the quality of buckwheat. These results would provide basic information for the selection of suitable treatment to meet the needs of developing an effective treatment process.