Microbial decontamination of porous model food powders by Vacuum-Steam-Vacuum treatment

The objective of this work was to study the systematic inactivation of immobilized heat-resistant, validated wild-type bacteria (sporulated Bacillus subtilis D2 and vegetative Cronobacter sakazakii H30) in porous enlarged model food powder particles using the Vacuum-Steam-Vacuum (VSV) process. Developed bacterial sensors allowed a local contamination of model particles at a defined intraparticle position. Contradicting previous studies, a spore inactivation of 4 log ₁₀ CFU in high depths of up to 10 mm (particle core) was possible by VSV treatment despite a noticeable intraparticle attenuation. To mimic inactivation in smaller food powder particles, similar-sized bacterial sensors were treated and showed slightly curve-linear kinetics explained by a short warm-up phase (lag time). Measured inactivation was lower than that predicted by traditional capillary (z = 8.0  ^∘ C) treatment of suspensions due to non-linearity in the high temperature regime. This could be described by twice as high z values of 15.4 °C (no lag time) and 17.2 °C (lag time), respectively.Industrial relevance of present workThe emerging Vacuum-Steam-Vacuum (VSV) decontamination process aims at efficient heat transfer on solid surfaces and pores using saturated steam as the heat-transferring fluid. VSV was already used for treating vegetables, fruits, meats and spices. This work describes use of VSV for dry porous solids.     

Microbial decontamination of black pepper by ozone and the effect of the treatment on volatile oil constituents of the spice

The use of ozone as a substitute for ethylene oxide to decontaminate whole black peppercorn and ground black pepper and the effects of ozone on the volatile oil constituents of the spice were studied. Black peppercorns were immersed in water and sparged with ozonised air (ozone concentration, 6·7 mg litre^?1) for 10 min at an air flow rate of 6 litre min^?1. This treatment reduced the microbial population of peppercorn by 3–4 log numbers. Ground black pepper with various moisture levels was sparged with ozonised air for up to 6 h. This treatment reduced the microbial population by 3–6 log numbers, depending on the moisture content of the spice. Higher moisture content led to a greater reduction in microbial load. The volatile oil constituents of the spice with and without ozone treatment were extracted with isopropyl ether and analysed by gas chromatography and gas chromatography-mass spectrometry. Ozone treatment of ground black pepper resulted in the oxidation of certain volatile oil constituents while the treatment had no significant effect on the volatile oil constituents of whole peppercorn.     

Mandarin preservation by microwave-powered cold plasma treatment

Cold plasma treatment (CPT) was investigated as a nonthermal method for inhibiting Penicillium italicum and improving storability of mandarins (Citrus unshiu Marc.). Whole mandarin fruits or the peels were treated with cold plasma at 0.7 kPa using a microwave CPT system. The treatment variables were plasma-forming gases, plasma generation power, and treatment time. Nitrogen (N₂)-CPT at 900 W for 10 min, resulted in the highest inhibition of P. italicum (84% reduction in disease incidence), significantly increased the total phenolic content and antioxidant activity of mandarin peel after the treatment (p < 0.05), but did not significantly affect CO₂ generation, weight loss, content of soluble solids, titratable acidity, pH, ascorbic acid concentration (flesh), or surface color during storage at 4 and 25 °C. These results demonstrate the potential for CPT application as a postharvest technology for preserving mandarins, increasing the total phenolic content and antioxidant activity of mandarin peel.     

Continuous in-line decontamination of food-processing surfaces using cold atmospheric pressure air plasma

This study assessed a continuous in-line decontamination system for food contact surfaces and processing equipment that utilized cold atmospheric pressure plasma (CAP) generated from ambient air. The plasma system was evaluated against two common foodborne pathogens (Salmonella Typhimurium, Listeria monocytogenes) on stainless steel surfaces and against S Typhimurium on commercial poly[ether]-thermoplastic poly[urethane] (PE-TPU) conveyor belts, under simulated conditions of a food-processing facility. A significant level of microbial inactivation was achieved, up to 3.03 ± 0.18 and 2.77 ± 0.71 logCFU/mL reductions of L. monocytogenes and S. Typhimurium respectively within 10 s total treatment on stainless steel surfaces, and a 2.56 ± 0.37 logCFU/mL reduction of S. Typhimurium within 4 s total treatment on the PE-TPU material, according to a procedure based on the well-established EN 13697:2015 industrial protocol. CAP exposure was shown to have a minor impact on the morphology and composition of the treated surfaces. The results indicated that CAP can be applied for effective and continuous disinfection against common foodborne pathogens in food-processing facilities.Industrial relevanceLow temperature plasmas have shown great promise for microbial decontamination, yet industrial uptake of the technology has been limited due to scaling limitations. In this study, a prototype conveyor-based CAP decontamination system was developed and tested under realistic conditions expected within a food-processing facility. The results showed a high level of antimicrobial action against two common foodborne pathogens within a few seconds of CAP exposure, a timescale in line with industrial line processing speeds. Our findings demonstrated that CAP shows great promise for the continuous in-situ decontamination of food contact surfaces, with the potential to mitigate against the costly downtimes incurred in current production line practices implementing chemical disinfectants.     

High voltage atmospheric cold plasma decontamination of Salmonella enteritidis on chicken eggs

Salmonella enteritidis (SE) accounts for more than 70% of Salmonella spp. infections in humans with a primary source being chicken eggs, that can result from post-lay SE cross-contamination of the shell from contaminated equipment or the environment. The objective of this study was to apply a HVACP treatment that can achieve a minimum 5-log reduction in SE on the surface of artificially inoculated shell eggs with an initial bacterial load of 10⁸ CFU/egg, after a previous disinfection. Optimized HVACP treatment conditions were an indirect treatment with air at 60% humidity at 100 kV for one minute treatment and six hours post-treatment or alternatively, five minutes of treatment and four hours post-treatment. Egg quality parameters of Haugh unit (HU), pH, color, and vitelline membrane and shell strength were tested under the optimized conditions and showed no significant difference (p > 0.05) between treated and untreated eggs.Industrial relevance: Missing information for a possible scale up of a cold plasma system for egg surface decontamination has been addressed by an optimization of HVACP treatment focused on treatment and post-treatment time, essential parameters to have into account in the food industry. These results demonstrate that HVACP is an effective decontamination method for SE on chicken shell eggs and provides a baseline for a future scale up of the process, showing that different combinations of treatment variables can achieve the desired decontamination without affecting to key quality parameters of the egg such as Haugh Unit or vitelline membrane strength.     

Survey of aflatoxins in retail samples of whole and ground black and white peppercorns

A total of 126 local and imported samples of commercial white and black pepper in Malaysia were analysed for aflatoxins B₁, B₂, G₁ and G₂ (AFB1, AFB2, AFG1, AFG2) content using high-performance liquid chromatography (HPLC) with a fluorescence detector (FD). An acetonitrile–methanol–water (17 : 29 : 54; v/v) mixture was used as a mobile phase and clean-up was using an immunoaffinity column (IAC). Seventy out of 126 (55.5%) samples were contaminated with total aflatoxins, although only low levels of aflatoxins were found ranging from 0.1 to 4.9 ng g^?1. Aflatoxin B₁ showed the highest incidence of contamination and was found in all contaminated samples. There was a significant difference between type of samples and different brands (p < 0.05). The results showed black peppers were more contaminated than white peppers.     

The inactivation of Salmonella by cold atmospheric plasma treatment

The need to fulfill consumer demand for fresh products without compromising microbial food safety and quality has increased the interest of the food industry in low-temperature innovative processes for food preservation. Compared to thermal processing, these emerging technologies rely on physical processes, such as high hydrostatic pressure, ionizing radiation, ultrasonication, pulsed electric fields, ultraviolet radiation and cold plasmas that are able to inactivate microorganisms at ambient or sublethal temperatures. This latter treatment is one of the more promising food preservation technologies. In this review we survey the main factors affecting the sensitivity and resistance of Salmonella to cold atmospheric gas plasmas. A more complete understanding of the factors involved in inactivation by this emerging technology will enhance its implementation in food preservation.     

Effects of packaging parameters on the microbial decontamination of Korean steamed rice cakes using in-package atmospheric cold plasma treatment

Food Science and Biotechnology - The effects of packaging materials, package shape, and secondary packaging on the inactivation of indigenous mesophilic aerobic bacteria in Korean steamed rice...     

绿色等离子遇到黑色纤维——等离子活化环境友好碳纤维

碳纤维复合材料(CFRP)质量轻,强度高,在机械制造业可代替钢板,是一种有前途的材料。尽管钢板很重,但在当前仍是最先进的材料。目前,CFRP生产不是为了获得轻质量的终端产品,而是旨在符合航天工程的标准规范(部分已经过时)。这意味着,除其他问题,纤维与基体之间的黏结性能没有得到优化。表面黏附的最优化可以进一步降低能量消耗,从而产生积极的环境影响,尤其是交通工程应用中。通过开发"绿色加工"达到节约能源的"绿色目标",使这项研究工作更有价值。介绍了通过等离子体处理活化碳纤维表面的方法。     

Optimization of decontamination conditions for Aspergillus flavus inoculated to military rations snack and physicochemical properties with atmospheric cold plasma

In this study, the effectiveness of ACP in inactivating Aspergillus flavus inoculated to military rations snack using response surface methodology (RSM) was investigated. Additionally, the effect of this treatment on the total count and yeast–mold count, as well as some quality properties of military rations snack, was examined. RSM was applied to study the voltage effects (5–15 kV), the distance between ACP emitter and sample (3–7 cm), and different treatment time (2–10 min) on the physicochemical properties of the military rations snack. Increasing voltage and time, together with reducing distance, caused a decrease in A. flavus, total count, yeast and mold count, total aflatoxin, as well as color difference. The peroxide value also increased with increasing voltage levels. The optimum conditions for treated military rations snack by ACP are as follows: a system voltage of 9 kV, a distance of 3 cm between the sample and the emitter, and a time of 6 min. Under these conditions, the responses, including the utmost reduction of 4.31 log CFU/g for the total count, 4.64 log CFU/g for yeast–mold count, and 2.98 log CFU/g for A. flavus were found from starting level of 5.2, 2, and 3.1 log CFU/g, respectively. It was found that snack samples had a 3.66% decrease in moisture content, 76.13% decrease in total aflatoxin, 3.01% increase in color difference, and 0.22 meq O₂.kg/oil increase in peroxide value as a result of ACP application. ACP has the potential to increase microbiological safety by maintaining desirable quality properties in military rations snack.     

Investigation of a large gap cold plasma reactor for continuous in-package decontamination of fresh strawberries and spinach

The aim of this work was to investigate the efficacy of a large gap atmospheric cold plasma (ACP) generated with an open-air high-voltage dielectric barrier discharge (DBD) pilot-scale reactor, operated in either static (batch) or continuous mode for produce decontamination and quality retention. Significant reductions in the bacterial populations inoculated on the strawberries and spinach were obtained after the static mode of ACP treatment with 2.0 and 2.2 log₁₀ CFU/ml reductions for E. coli and 1.3 and 1.7 log₁₀ CFU/ml reductions for L. innocua, respectively. Continuous treatment was effective against L. innocua inoculated on strawberries, with 3.8 log₁₀ CFU/ml reductions achieved. No significant differences in colour, firmness, pH or total soluble solids (TSS) was observed between control and ACP-treated samples with the effects of treatment retained during the shelf-life period. The pilot-scale atmospheric air plasma reactor retained the strawberry quality characteristics in tandem with useful antimicrobial efficacy.Industrial relevanceThis in-package plasma technology approach is a low-power, water-free, non-thermal, post-package treatment. Generating cold plasma discharges inside food packages achieved useful antimicrobial effects on fresh produce. Depending on the bacterial type, produce and mode of ACP treatment significant reductions in the populations of pathogenic microorganisms attached to the fresh produce was achieved within 2.5 min of treatment. The principal technical advantages include contaminant control, quality retention, mitigation of re-contamination and crucially the retention of bactericidal reactive gas molecules in the food package volume, which then revert back to the original gas.     

生猪屠宰加工过程中微生物的污染及减菌措施

为确保屠宰加工肉类产品的安全和卫生,主要对生猪在屠宰加工过程中微生物污染和减菌措施进行了总结,旨在对屠宰行业在预防和减少屠宰线上胴体污染方面提供参考。     

Impact of ultrasonication,ultraviolet and atmospheric cold plasma processing on quality parameters of tomato-based beverage in comparison with thermal processing

The aim of the study was to develop a tomato-based beverage and to investigate the effect of thermal (pasteurization) and non-thermal (ultrasonication, ultra-violet (UV), atmospheric cold plasma (ACP)) processing on the quality of a tomato-based beverage. The ultrasonication and ACP processing for 10 min put significant effect on L* and a* color values of the tomato beverage. All the processing techniques applied degraded ascorbic acid but maximum retention (95%) of ascorbic acid was found in ACP processed beverage. Furthermore, ACP processing of 10 min also had significant (p ≥ 0.05) effect on bioactive compounds like chlorogenic acid, sinapic acid and gallic acid in comparison to thermal and other non-thermal processing. Moreover, ACP for 10 min and ultrasonication for 15 min was found equivalent to thermal processing in microbial reduction and ACP processing for 10 min was found equivalent to pasteurization in reduction of yeast and mold count. Both thermal and non-thermal processing had insignificant (p ≥ 0.05) effects on pH, TSS and sugars of developed beverage. In summary, ACP processing for 10 min has emerged as the best processing method for retaining as well as improving the quality of the developed beverage.     

冷等离子处理对玉米籽粒外观及结构的影响

控制冷等离子处理仪的频率参数,处理高水分玉米籽粒60s,通过扫描电子显微镜观察各组玉米样品外观及内部结构形态。结果表明,经冷等离子体处理的实验组相比未经处理的对照组籽粒表面产生明显褶皱及刻蚀,且冷等离子处理仪功率越高,表面褶皱越明显;实验组玉米胚乳结构中,原本排列致密有序的淀粉颗粒经冷等离子处理后间距增大,颗粒间基质蛋白会裸露甚至断裂,而等离子处理对胚部结构无显著影响。冷等离子处理可破坏玉米表面蜡质层,有助于玉米内部水分向外扩散,本研究为冷等离子预处理加快玉米干燥速率提供了一定的参考。     

Enhanced hydration properties and antioxidant activity of peanut protein by covalently binding with sesbania gum via cold plasma treatment

A cold plasma (CP) assisted Maillard reaction (MR) is innovatively proposed to improve the hydration property and antioxidant activity of high-denatured peanut protein isolate (HPPI) which is limited in the food industry due to poor solubility. The physicochemical properties (hydration, rheological, thermal and antioxidant properties) and the structure of CP-induced glycosylation products were investigated. The results showed that the CP treatment facilitated the degree of grafting and browning. With CP treatment, the solubility (from 610.0 g/L to 1580.0 g/L), the bound water content and the hydrophilic -OH content increased. The HPPI exposed more active amino groups and interacted with sesbania gum molecules with covalent bonding. Those changes were conducive to the formation of the hydrophilic surface of glycosylation products and gel network structure. The antioxidant activity of glycosylation product was significantly increased. The CP-assisted MR may be an efficient and energy-saving approach to improve the functional properties of HPPI in the food industry.