Pulsed electric field-assisted extraction of hesperidin from tangerine peel and its technological optimization through response surface methodology.

BACKGROUND: Tangerine peel is rich in flavonoids, particularly hesperidin, which has anti-inflammatory, antioxidant and anticancer biological activities. However, it is often wasted during citrus processing. The current common extraction method for hesperidin is solvent extraction, which has the characteristics of low extraction rate and high contamination. The aim of this study was to investigate the effect of pulsed electric field-assisted alkali dissolution extraction, followed by an acidification precipitation method, on the extraction rate and structure of hesperidin from tangerine peel. RESULTS: The results showed that the selected factors (material/liquid ratio, electric field intensity and pulse number) had a significant effect on the extraction yield. An optimum condition of 66.00 mL g-1, 4.00 kV cm-1 and 35.00 pulses gave the maximum amount (669.38 µg mL-1), which was consistent with the theoretically predicted value by software (672.10 µg mL-1), indicating that the extraction process was feasible. In addition, the purified extract was further identified as hesperidin from UV and NMR spectra. CONCLUSION: An appropriate strength of pulsed electric field-assisted alkali dissolution extraction followed by an acidification precipitation method can effectively improve the extraction rate of orange peel, and the purity of the extracted orange peel is higher. Compared with the traditional extraction, the pulsed electric field-assisted extraction method may be a potential technology for hesperidin extraction, which is beneficial for the high-value utilization of citrus resources. © 2024 Society of Chemical Industry.

Advances in the Study of Probiotics for Immunomodulation and Intervention in Food Allergy.

Food allergies are a serious food safety and public health issue. Soybean, dairy, aquatic, poultry, and nut products are common allergens inducing allergic reactions and adverse symptoms such as atopic dermatitis, allergic eczema, allergic asthma, and allergic rhinitis. Probiotics are assumed as an essential ingredient in maintaining intestinal microorganisms' composition. They have unique physiological roles and therapeutic effects in maintaining the mucosal barrier, immune function, and gastrointestinal tract, inhibiting the invasion of pathogenic bacteria, and preventing diarrhea and food allergies. Multiple pieces of evidence reveal a significant disruptive effect of probiotics on food allergy pathology and progression mechanisms. Thus, this review describes the allergenic proteins as an entry point and briefly describes the application of probiotics in allergenic foods. Then, the role of probiotics in preventing and curing allergic diseases by regulating human immunity through intestinal flora and intestinal barrier, modulating host immune active cells, and improving host amino acid metabolism are described in detail. The anti-allergic role of probiotics in the function and metabolism of the gastrointestinal tract has been comprehensively explored to furnish insights for relieving food allergy symptoms and preventing food allergy.

A review of bacterial biofilm control by physical strategies.

Biofilms are multicellular communities of microorganisms held together by a self-produced extracellular matrix, which contribute to hygiene problems in the food and medical fields. Both spoilage and pathogenic bacteria that grow in the complex structure of biofilm are more resistant to harsh environmental conditions and conventional antimicrobial agents. Therefore, it is important to develop eco-friendly preventive methodologies to eliminate biofilms from foods and food contact equipment. The present paper gives an overview of the current physical methods for biofilm control and removal. Current physical strategies adopted for the anti-biofilm treatment mainly focused on use of ultrasound power, electric or magnetic field, plasma, and irradiation. Furthermore, the mechanisms of anti-biofilm action and application of different physical methods are discussed. Physical strategies make it possible to combat biofilm without the use of biocidal agents. The remarkable microbiocidal properties of physical strategies are promising tools for antimicrobial applications.

Applications of Innovative Non-Thermal Pulsed Electric Field Technology in Developing Safer and Healthier Fruit Juices.

The deactivation of degrading and pectinolytic enzymes is crucial in the fruit juice industry. In commercial fruit juice production, a variety of approaches are applied to inactivate degradative enzymes. One of the most extensively utilized traditional procedures for improving the general acceptability of juice is thermal heat treatment. The utilization of a non-thermal pulsed electric field (PEF) as a promising technology for retaining the fresh-like qualities of juice by efficiently inactivating enzymes and bacteria will be discussed in this review. Induced structural alteration provides for energy savings, reduced raw material waste, and the development of new products. PEF alters the α-helix conformation and changes the active site of enzymes. Furthermore, PEF-treated juices restore enzymatic activity during storage due to either partial enzyme inactivation or the presence of PEF-resistant isozymes. The increase in activity sites caused by structural changes causes the enzymes to be hyperactivated. PEF pretreatments or their combination with other nonthermal techniques improve enzyme activation. For endogenous enzyme inactivation, a clean-label hurdle technology based on PEF and mild temperature could be utilized instead of harsh heat treatments. Furthermore, by substituting or combining conventional pasteurization with PEF technology for improved preservation of both fruit and vegetable juices, PEF technology has enormous economic potential. PEF treatment has advantages not only in terms of product quality but also in terms of manufacturing. Extending the shelf life simplifies production planning and broadens the product range significantly. Supermarkets can be served from the warehouse by increasing storage stability. As storage stability improves, set-up and cleaning durations decrease, and flexibility increases, with only minor product adjustments required throughout the manufacturing process.

High-pressure processing of fish and shellfish products: Safety, quality, and research prospects.

Seafood products have been one of the main drivers behind the popularity of high-pressure processing (HPP) in the food industry owing to a high demand for fresh ready-to-eat seafood products and food safety. This review provides an overview of the advanced knowledge available on the use of HPP for production of wholesome and highly nutritive clean label fish and shellfish products. Out of 653 explored items, 65 articles published during 2016-2021 were used. Analysis of the literature showed that most of the earlier work evaluated the HPP effect on physicochemical and sensorial properties, and limited information is available on nutritional aspects. HPP has several applications in the seafood industry. Application of HPP (400-600 MPa) eliminates common seafood pathogens, such as Vibrio and Listeria spp., and slows the growth of spoilage microorganisms. Use of cold water as a pressure medium induces minimal changes in sensory and nutritional properties and helps in the development of clean label seafood products. This technology (200-350 MPa) is also useful to shuck oysters, lobsters, crabs, mussels, clams, and scallops to increase recovery of the edible meat. High-pressure helps to preserve organoleptic and functional properties for an extended time during refrigerated storage. Overall, HPP helps seafood manufacturers to maintain a balance between safety, quality, processing efficiency, and regulatory compliance. Further research is required to understand the mechanisms of pressure-induced modifications and clean label strategies to minimize these modifications.

The increasing hunger concern and current need in the development of sustainable food security in the developing countries.

Background: COVID-19 has affected millions of people worldwide. Recently, international agencies have revealed that poverty and hunger could kill more people than COVID-19 victims. Many global workforces have lost their jobs during this pandemic situation. In developing countries, most of the workers and their families live hand to mouth, depending on daily wage, and loss of income would be a hunger pandemic. Globally, the proportion of undernourished and hungry people have been on an upswing due to climate changes and violent conflicts. The millions of people are facing chronic malnourishment and COVID-19 menaces undermining the endeavour of philanthropic and food security. COVID-19 has increased the risk of livelihood by the shortage of food and distraction of the supply chain especially in the developing countries where rural expanses depend on agriculture production and seasonal jobs. So, if they are forced to limit their activities, their livelihoods will be demolished. Scope and approach: COVID-19 is increasing the jeopardy of food prices over the world, which would prompt a crisis in several developing countries. The government organizations in developing countries are doing well to protect people from the current pandemic. But they are also in critical situation regarding food supply chains and are facing difficulties in providing nutrient-rich foods. The susceptible people are fraught to secure household income and manage their food. In this review, we have explored the food security approach, food supply chain and risk of food shortage. Every country in the world needs to implement effective interventions to maintain open trade and food supply chains, ensure access to nutrients for all at affordable prices and develop co-operation to preserve the flexibility of universal food markets.

Identification of Potent Natural Resource Small Molecule Inhibitor to Control Vibrio cholera by Targeting Its Outer Membrane Protein U: An In Silico Approach.

Vibrio cholerae causes the diarrheal disease cholera which affects millions of people globally. The outer membrane protein U (OmpU) is the outer membrane protein that is most prevalent in V. cholerae and has already been recognized as a critical component of pathogenicity involved in host cell contact and as being necessary for the survival of pathogenic V. cholerae in the host body. Computational approaches were used in this study to screen a total of 37,709 natural compounds from the traditional Chinese medicine (TCM) database against the active site of OmpU. Following a sequential screening of the TCM database, we report three lead compounds-ZINC06494587, ZINC85510056, and ZINC95910434-that bind strongly to OmpU, with binding affinity values of -8.92, -8.12, and -8.78 kcal/mol, which were higher than the control ligand (-7.0 kcal/mol). To optimize the interaction, several 100 ns molecular dynamics simulations were performed, and the resulting complexes were shown to be stable in their vicinity. Additionally, these compounds were predicted to have good drug-like properties based on physicochemical properties and ADMET assessments. This study suggests that further research be conducted on these compounds to determine their potential use as cholera disease treatment.

Cinnamaldehyde inhibit Escherichia coli associated with membrane disruption and oxidative damage.

In this study, the antimicrobial mechanism of cinnamaldehyde (CIN) against Gram-negative Escherichia coli ATCC 25922 (E. coli) based on membrane and gene regulation was investigated. Treatment with low concentration (0, 1/8, 1/4, 3/8 MIC) of CIN can effectively suppress the growth of E. coli by prolonging its lag phase and Raman spectroscopy showed obvious distinction of the E. coli after being treated with these concentration of CIN. The determination of relative conductivity indicated that CIN at relatively high concentration (0, 1, 2, 4 MIC) can increase the cell membrane permeability, causing the leakage of cellular content. Besides, the content of malondialdehyde (MDA) and the activity of total superoxide dismutase (SOD) of E. coli increased with increasing treatment concentration of CIN, implying that CIN can cause oxidative damage on E. coli cell membrane and induce the increase of total SOD activity to resist this oxidative harm. Moreover, quantitative real-time RT-PCR (qRT-PCR) analysis revealed the relationship between expression of antioxidant genes (SODa, SODb, SODc) and treatment CIN concentration, suggesting that SOD, especially SODc, played a significant role in resistance of E. coli to CIN. The underlying inactivation processing of CIN on E. coli was explored to support CIN as a potential and natural antimicrobial agent in food industry.

Dihydromyricetin: A review on identification and quantification methods, biological activities, chemical stability, metabolism and approaches to enhance its bioavailability.

BACKGROUND: Dihydromyricetin (DMY) is an important plant flavonoid, which has received great attention due to its health-benefiting activities, including antioxidant, antimicrobial, anti-inflammatory, anticancer, antidiabetic and neuroprotective activities. DMY capsules have been sold in US as a nutraceutical supplement to prevent alcoholic hangovers. The major disadvantage associated with DMY is its chemical instability and poor bioavailability caused by the combined effects of its low solubility and poor membrane permeability. This limits its practical use in the food and pharmaceutical fields. SCOPE AND APPROACH: The present paper gives an overview of the current methods for the identification and quantification of DMY. Furthermore, recent findings regarding the main biological properties and chemical stability of DMY, the metabolism of DMY as well as different approaches to increase DMY bioavailability in both aqueous and lipid phases are discussed. KEY FINDINGS AND CONCLUSIONS: Current trends on identification and quantification of DMY have been focused on spectral and chromatographic techniques. Many factors such as heat, pH, metal ions, could affect the chemical stability of DMY. Despite the diverse biological effects of DMY, DMY faces with the problem of poor bioavailability. Utilization of different delivery systems including solid dispersion, nanocapsule, microemuslion, cyclodextrin inclusion complexes, co-crystallization, phospholipid complexes, and chemical or enzymatic acylation has the potential to improve both the solubility and bioavailability. DMY digested in laboratory animals undergoes reduction, dehydroxylation, methylation, glucuronidation, and sulfation. Novel DMY delivery systems and basic pharmacokinetic studies of encapsulated DMY on higher animals and humans might be required in the future.

Fish Protein and Lipid Interactions on the Digestibility and Bioavailability of Starch and Protein from Durum Wheat Pasta.

This research focussed on the utilisation of salmon protein and lipid to manipulate pasta's glycaemic index and protein digestibility. Salmon fish (Oncorhynchus tschawytscha) powder (SFP) supplemented pasta flour in amounts from 5% to 20% (w/w). Inclusion of SFP lead to a significant reduction in starch digestibility and hence the potential glycaemic values of pasta (experimental pasta being up to 143% lower than control values). SFP addition to pasta increased the release of phenolic compounds from pasta during both gastric digestion (179%) and pancreatic digestion (133%) in comparison to the control sample. At the same time, the antioxidant activity of the digested pasta was increased by up to 263% (gastric) and 190% (pancreatic) in comparison to durum wheat pasta alone. Interestingly, although protein levels increased with incorporation of SFP, the digestibility values of the protein decreased from 86.41% for the control pasta to 81.95% for 20% SFP pasta. This may indicate that there are interactions between phenols and protein in the pasta samples which affect overall protein digestibility levels.

Sugar profile, volatile compounds, composition and antioxidant activity of Sukkari date palm fruit.

The target of this research was to determine sugar profile, volatile compounds, minerals content and antioxidant properties of the Sukkari date flesh as methanolic and ethanolic extracts. Sukkari date showed sugar 78.32% (dry weight), while fibre, crude protein, ash and crude fat were 3.15, 3.01, 2.30 and 0.56, respectively. Glucose (51.80%), fructose (47.50%), while small amount sucrose, fucose and galacturonic acid were also detected. Potassium, calcium and magnesium were observed to be the predominant. Twenty-two components were identified; 5-Hydroxymethylfurfural was present in the highest amount (27.25%), followed by 4H-Pyran-4-one,2,3-dihydro-3,5-dihydroxy-6-methyl (9.45%). Total phenolic and flavonoid content of methanolic extract were 62.50 mg GAE/100 g and 3.20 mg CE/100 g, respectively, against 60.25 mg GAE/100 g and 2.90 mg CE/100 g respectively, for ethanolic extracts. Three assays including DPPH, reducing power and ABTS radical scavenging activities showed a good antioxidant activity of date palm extract. Sukkari date was observed to have good nutritional and antioxidant characteristics and can be utilize as potential nutrition.

Quality characteristics of the processed dates vinegar under influence of ultrasound and pulsed electric field treatments.

This research aimed to evaluate the influences of the pulsed electric field (PEF), ultrasound (US), and combination between them (PEF + US) on the quality of vinegar processed from date palm fruits compared with untreated vinegar (UT). Physicochemical properties, free amino acids (FAA), volatile components, organic acids, total phenolics and flavonoids, and sensory analysis were determined. The results showed that there were no significant differences in pH, total titratable acidity, ethanol content, and total sugar in all treated vinegar compared with UT. However, the values were found to be decreased (PEF + US < PEF < US < UT). Twenty-eight compounds were identified in the vinegar treated by PEF + US as the highest number of components, followed by PEF and US (23 and 22 components, respectively), compared with 19 compounds identified in UT. Compared with UT, there was a significant increase (p < 0.05) in the total FAA in dates vinegar among all treated samples (UT < US < PEF < PEF + US). Total phenolic and flavonoids contents results indicated that there was a significant increase (p < 0.05) in the treated vinegar compared with UT. Sensory analysis results indicated that no significant difference (p < 0.05) in all the parameters, except for a quite significant difference (p < 0.05) in the overall acceptability between the treated vinegar. In this study, vinegar was successfully produced from date palm fruits. Therefore, PEF + US are capable not only in enhancing the extraction process but also in the production of vinegar with good quality.

Combined impact of pulsed electric field and ultrasound on bioactive compounds and FT-IR analysis of almond extract.

The aim of this paper is to investigate the combined impact of pulsed electric field (PEF) and ultrasound (US) to evaluate the physicochemical, bioactive compounds and chemical structure of almond extract. Almond extract was first treated with PEF and then with US. Combined treatment (PEF-US) has attained the highest value of total phenolics, total flavonoids, condense tannins, anthocyanin contents and antioxidant activity in DPPH, reducing power and metal chelating activity than all other treatments. Among all those treatments, there was slightly visible difference in the color. Moreover, FT-IR spectra indicate that the effect of PEF-US on almond extract did not produce new carbonyl compounds, but led to the higher concentration of these compounds. This study demonstrated that the PEF-US could be useful for the extraction of bioactive compounds as well as improving the stability of volatile compounds.

Impact of pulsed electric field treatment on drying kinetics, mass transfer, colour parameters and microstructure of plum.

The aim of the present study was to scrutiny the impact of pulsed electric field (PEF) as a pre-treatment method on the convective drying kinetics, cell disintegration, colours and microstructural changes of fresh plums. In this study, the PEF intensities of 1-3 kV/cm, pulses number 30 and 70 °C drying temperature was applied to detect the drying kinetics. The specific energy consumption generated by PEF treatment was 10-90 kJ/kg. It was explored that the cell disintegration index increased from 0.147 to 0.572 with increased electric field intensity from 1 to 3 kV/cm. Further, we found that high cell disintegration leads to increase in drying rate and shorten drying time. The rates of water diffusion coefficient also increase with increasing PEF intensity from 0.27 to 16.47 × 10-9 m2/s. PEF pre-treatment followed by convective drying results in enhanced lightness and chroma as compared to untreated plum. Furthermore, the microscopic analysis by scanning electron microscopy at 200 × revealed that the PEF treatment at 3 kV/cm had caused shrinkage in the plum tissues which might be responsible for higher diffusion rate of water in the plum. In this work was investigated that drying kinetics and mass transfer after PEF treatment to improve quality of dried plum.

Modification of membrane properties and fatty acids biosynthesis-related genes in Escherichia coli and Staphylococcus aureus: Implications for the antibacterial mechanism of naringenin.

In this work, modifications of cell membrane fluidity, fatty acid composition and fatty acid biosynthesis-associated genes of Escherichia coli ATCC 25922 (E. coli) and Staphylococcus aureus ATCC 6538 (S. aureus), during growth in the presence of naringenin (NAR), one of the natural antibacterial components in citrus plants, was investigated. Compared to E. coli, the growth of S. aureus was significantly inhibited by NAR in low concentrations. Combination of gas chromatography-mass spectrometry with fluorescence polarization analysis revealed that E. coli and S. aureus cells increased membrane fluidity by altering the composition of membrane fatty acids after exposure to NAR. For example, E. coli cells produced more unsaturated fatty acids (from 18.5% to 43.3%) at the expense of both cyclopropane and saturated fatty acids after growth in the concentrations of NAR from 0 to 2.20mM. For S. aureus grown with NAR at 0 to 1.47mM, the relative proportions of anteiso-branched chain fatty acids increased from 37.2% to 54.4%, whereas iso-branched and straight chain fatty acids decreased from 30.0% and 33.1% to 21.6% and 23.7%, respectively. Real time q-PCR analysis showed that NAR at higher concentrations induced a significant down-regulation of fatty acid biosynthesis-associated genes in the bacteria, with the exception of an increased expression of fabA gene. The minimum inhibitory concentration (MIC) of NAR against these two bacteria was determined, and both of bacteria underwent morphological changes after exposure to 1.0 and 2.0 MIC.

Temperature-mediated variations in cellular membrane fatty acid composition of Staphylococcus aureus in resistance to pulsed electric fields.

Effects of growth temperature on cell membrane fatty acid composition, fluidity and lethal and sublethal injury by pulsed electric fields (PEF) in Staphylococcus aureus ATCC 43300 (S. aureus) in the stationary phase were investigated. Analysis of the membrane fatty acids by gas chromatography-mass spectrometry (GC-MS) revealed that branched chain fatty acids (iso C14:0, iso C15:0, anteiso C15:0 and anteiso C17:0) and straight chain fatty acids (C12:0, C14:0, C16:0, C17:0 and C18:0) were primary constituents in the membrane. The S. aureus changed its membrane fatty acid composition and its overall fluidity when exposed to different temperatures. The PEF lethal and sublethal effects were assessed, and results suggested that the degree of inactivation depended on the cell membrane structure, electric field strength and treatment time. The PEF inactivation kinetics including lethal and sublethal injury fractions were fitted with non-linear Weibull distribution, suggesting that inactivation of the first log cycle of S. aureus population was significantly affected by growth temperature, and the membrane of cells became more fluid, and easier to induce electroportion in low temperatures. Moreover, the morphology of S. aureus cells were investigated by electron microscopy, showing that various temperature-modified cells were distorted to differing extents and some even collapsed due to deep irreversible electroporation after PEF treatment.

An in vitro investigation of the inhibitory mechanism of ß-galactosidase by cinnamaldehyde alone and in combination with carvacrol and thymol.

BACKGROUND: Some antibacterial agents exert their antimicrobial action by targeting the cytoplasmic macromolecules, such as proteins or nucleic acids, to disturb the properties of macromolecules that may deeply influence their biological activities and functions. Cinnamaldehyde (CIN) is a natural antibacterial ingredient found in the bark and leaves of cinnamon trees. METHODS: The inhibitory mechanism of a typical enzyme, ß-galactosidase by CIN was investigated by UV-visible, fluorescence, 3-D spectroscopy, circular dichroism, atomic force microscopy and molecular modeling studies. RESULTS: CIN decreased the activity of ß-galactosidase by competitive inhibition through a multiphase kinetic process. 3-D spectroscopy and circular dichroism showed that the binding of CIN to ß-galactosidase resulted in changes in micro-environment of tryptophan and tyrosine residues, and conformation of ß-galactosidase. The molecular recognition was also analyzed through modeling which indicated that CIN was inserted into the active site pocket of ß-galactosidase and interacted with amino acid residues, such as Met502, Trp568, Phe601 and Trp999. Atomic force microscopy showed that a serious destabilization of the native conformation of ß-galactosidase occurred after binding with CIN, e.g., morphological changes and increased dimensions of the ß-galactosidase molecule. Moreover, it was found that the combinations of CIN, carvacrol and thymol exposure displayed synergistic effects on the inhibition of ß-galactosidase. GENERAL SIGNIFICANCE: This study exhibits a comprehensively understanding about the action mechanism of CIN that affects the conformation and activity of ß-galactosidase in biochemical processes and provides some new insights into the possible intracellular targeting behaviors of CIN at a molecular level.

Combination of microbiological, spectroscopic and molecular docking techniques to study the antibacterial mechanism of thymol against Staphylococcus aureus: membrane damage and genomic DNA binding.

Thymol (2-isopropyl-5-methylphenol) is a natural ingredient used as flavor or preservative agent in food products. The antibacterial mechanism of thymol against Gram-positive, Staphylococcus aureus was investigated in this work. A total of 15 membrane fatty acids were identified in S. aureus cells by gas chromatography-mass spectrometry. Exposure to thymol at low concentrations induced obvious alterations in membrane fatty acid composition, such as decreasing the proportion of branched 12-methyltetradecanoic acid and 14-methylhexadecanoic acid (from 22.4 and 17.3% to 7.9 and 10.3%, respectively). Membrane permeability assay and morphological image showed that thymol at higher concentrations disrupted S. aureus cell membrane integrity, which may decrease cell viability. Moreover, the interaction of thymol with genomic DNA was also investigated using multi-spectroscopic techniques, docking and atomic force microscopy. The results indicated that thymol bound to the minor groove of DNA with binding constant (K a) value of (1.22 ± 0.14) × 104 M-1, and this binding interaction induced a mild destabilization in the DNA secondary structure, and made DNA molecules to be aggregated. Graphical Abstract Thymol exerts its antibacterial effect throught destruction of bacterial cell membrane and binding directly to genomic DNA.

Applications of Computer Vision for Assessing Quality of Agri-food Products: A Review of Recent Research Advances.

With consumer concerns increasing over food quality and safety, the food industry has begun to pay much more attention to the development of rapid and reliable food-evaluation systems over the years. As a result, there is a great need for manufacturers and retailers to operate effective real-time assessments for food quality and safety during food production and processing. Computer vision, comprising a nondestructive assessment approach, has the aptitude to estimate the characteristics of food products with its advantages of fast speed, ease of use, and minimal sample preparation. Specifically, computer vision systems are feasible for classifying food products into specific grades, detecting defects, and estimating properties such as color, shape, size, surface defects, and contamination. Therefore, in order to track the latest research developments of this technology in the agri-food industry, this review aims to present the fundamentals and instrumentation of computer vision systems with details of applications in quality assessment of agri-food products from 2007 to 2013 and also discuss its future trends in combination with spectroscopy.

Effect of Pulsed Electric Field on Membrane Lipids and Oxidative Injury of Salmonella typhimurium.

Salmonella typhimurium cells were subjected to pulsed electric field (PEF) treatment at 25 kV/cm for 0-4 ms to investigate the effect of PEF on the cytoplasmic membrane lipids and oxidative injury of cells. Results indicated that PEF treatment induced a decrease of membrane fluidity of Salmonella typhimurium (S. typhimuriumi), possibly due to the alterations of fatty acid biosynthesis-associated gene expressions (down-regulation of cfa and fabA gene expressions and the up-regulation of fabD gene expression), which, in turn, modified the composition of membrane lipid (decrease in the content ratio of unsaturated fatty acids to saturated fatty acids). In addition, oxidative injury induced by PEF treatment was associated with an increase in the content of malondialdehyde. The up-regulation of cytochrome bo oxidase gene expressions (cyoA, cyoB, and cyoC) indicated that membrane damage was induced by PEF treatment, which was related to the repairing mechanism of alleviating the oxidative injury caused by PEF treatment. Based on these results, we achieved better understanding of microbial injury induced by PEF, suggesting that micro-organisms tend to decrease membrane fluidity in response to PEF treatment and, thus, a greater membrane fluidity might improve the efficiency of PEF treatment to inactivate micro-organisms.