Effects of high-pressure processing on the physicochemical properties and glycemic index of fruit puree in a hyperglycemia mouse model.

BACKGROUND: In this study, the duration of high-pressure processing (HPP) required to achieve a 5 log reduction of Escherichia coli O157:H7 in fruit purees was evaluated. Banana, cantaloupe, and dragon fruit purees were subjected to HPP at 600 MPa for 300, 270, and 270 s, respectively, and their physicochemical properties and enzyme activities were then analysed. Diabetic mice were fed fresh and HPP-treated purees to observe their effects on the glycemic index (GI) and postprandial blood glucose response. RESULTS: Compared with their fresh counterparts, the HPP-treated banana and dragon fruit purees exhibited significantly higher viscosities, lower glucose concentrations, and higher glucose dialysis retardation indices and showed disrupted sucrose invertase and polygalacturonase activities. The GI and postprandial blood glucose response were not significantly different between the fresh and HPP-treated cantaloupe purees. By contrast, the peak time of glucose response (Tmax ) was delayed from 30 min to 60 min, and the area under the receiver operating characteristic curve was reduced by 40% in the mice fed HPP-treated banana and dragon fruit purees. The GIs of the HPP-treated banana and dragon fruit purees (were 50.3 and 44.8, respectively) were significantly lower than those of their fresh counterparts (85.1 and 75.2, respectively). CONCLUSION: HPP can change the physicochemical properties of fruit purees, resulting in stabilized blood glucose levels and lower GIs after consumption. Therefore, purees processed in this manner would benefit consumers and patients with diabetes/pre-diabetes who need to maintain stable blood glucose levels (Fig. S1). © 2022 Society of Chemical Industry.

Evaluation of microbiological safety, physicochemical and aromatic qualities of shiikuwasha (Citrus depressa Hayata) juice after high pressure processing.

This study evaluated high pressure processing (HPP) for achieving greater than 5-log reduction of Escherichia coli O157:H7 in shiikuwasha (Citrus depressa Hayata) juices and compare quality parameters, including microbiological safety, total phenolic content (TPC), total flavanones (TFC), and polymethoxylated flavones, browning, volatile aromatic, and physicochemical properties of HPP-treated juice with those of high-temperature short-time pasteurized juice. A HPP of 600 MPa for 150 s was identified capable of achieving greater than 5.15-log reductions of E. coli O157:H7 in shiikuwasha juice. The microbiological shelf life of the juices were at least 28 days when processed at HPP for 600 MPa/150 s or HTST for 90 °C/60 s. The color, aromatic, and antioxidant contents (TPC, TFC, Tangeletin, Nobiletin) were well preserved after HPP, however, HTST resulted in a significant (p < 0.05) loss of antioxidant content (TPC (8.8%), Tangeletin (6.8%)), and negatively impacted the juice color. By the end of storage, the amount of these aroma relevant volatiles appears to still be higher in HPP pasteurized juices compared to their conventional counterparts. This study demonstrated that under optimal conditions of HPP can attain the same level of microbiological safety as thermal pasteurization and preserved the acceptable quality of shiikuwasha juice.

Inactivation Mechanism of Aspergillus flavus Conidia by High Hydrostatic Pressure.

This study investigated the inactivation mechanism of Aspergillus flavus conidia by high hydrostatic pressure (HHP). Activity counts, scanning electron microscopic (SEM) analysis, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were used to study the effects of the HHP treatment on the morphology and protein composition of A. flavus spores. The results showed that that a 3-min-lasting 600 MPa treatment could completely abolish 107 colony-forming units/mL of live fungi. Furthermore, we also observed that lower spore viability corresponded to a higher Propidium Iodide absorption rate. The SEM images revealed that HHP disrupted the spore morphology and resulted in pore formation that led to the release of intracellular molecules, such as nucleic acids and proteins. The nucleic acid and protein concentration in the spore suspension increased in parallel with the increasing treatment pressure. The SDS-PAGE analysis showed that there were differences in the protein bands between the HHP-treated and untreated A. flavus spores, as the HHP treatment caused partial protein degradation and extracellular release. Therefore, the results of this study proved that high pressure could induce a morphological disruption in the internal and external cellular structures and degrade intracellular and extracellular proteins leading to an inactive state in A. flavus.

The effect of high-pressure processing on reducing the glycaemic index of atemoya puree.

BACKGROUND: This study investigated the effects of high-pressure processing (HPP) on the glycaemic index (GI) of atemoya puree (AP) in rats. Sprague-Dawley rats were fed with unprocessed and high-pressure processed atemoya puree (HPP-AP), and the GIs for the unprocessed AP and HPP-AP were calculated from changes in blood glucose concentrations within 2 h after meals. The physicochemical properties of AP were analysed to understand the mechanism affecting its GI. RESULTS: The results showed that HPP (600 MPa for 15 min) could delay increase in postprandial blood glucose levels, decrease the peak value of postprandial blood glucose by 76.1%, and significantly decrease the GI of AP to 49.8 in the experimental group compared to 65.4 in the control group. HPP did not exert a significant effect on the glucose and pectin contents of AP, but it increased the viscosity of the puree and its dietary fibre content and delayed the time of peak glucose response. In the analysis of enzymes of the puree, we found that HPP significantly decreased the activities of sucrose invertase, pectin methylesterase and polygalacturonase, thereby decreasing the rate of glucose generation in the puree and stabilizing the pectin structure, which decreased the absorption of glucose by the small intestine, thus decreasing the GI value. CONCLUSION: Our findings suggest that HPP technology could effectively delay increase in postprandial blood glucose levels and decrease the GI value of AP, thus having a potential application in developing atemoya puree products with low GI. © 2020 Society of Chemical Industry.

Microbial Shelf-Life, Starch Physicochemical Properties, and in Vitro Digestibility of Pigeon Pea Milk Altered by High Pressure Processing.

This study examined the effects of high-pressure processing (HPP) on microbial shelf-life, starch contents, and starch gelatinization characteristics of pigeon pea milk. HPP at 200 MPa/240 s, 400 MPa/210 s, and 600 MPa/150 s reduced the count of Escherichia coli O157:H7 in pigeon pea milk by more than 5 log CFU/mL. During the subsequent 21-day refrigerated storage period, the same level of microbial safety was achieved in both HPP-treated and high-temperature short-time (HTST)-pasteurized pigeon pea milk. Differential scanning calorimetry and scanning electron microscope revealed that HPP at 600 MPa and HTST caused a higher degree of gelatinization in pigeon pea milk, with enthalpy of gelatinization (∆H) being undetectable for both treatments. In contrast, HPP at 400 MPa led to an increase in the onset temperature, peak temperature, and conclusion temperature, and a decrease in ∆H, with gelatinization percentages only reaching 18.4%. Results of an in vitro digestibility experiment indicate that maximum resistant starch and slowly digestible starch contents as well as a decreased glycemic index were achieved with HPP at 400 MPa. These results demonstrate that HPP not only prolongs the shelf-life of pigeon pea milk but also alters the structural characteristics of starches and enhances the nutritional value.

Effects of high-pressure processing and thermal pasteurization on quality and microbiological safety of jabuticaba (Myrciaria cauliflora) juice during cold storage.

The aims of this study were to investigate the effects of high-pressure processing (HPP) on jabuticaba juice characteristics including microbial levels, phenolic compounds, antioxidant activity, and physicochemical properties during 28 days of storage at 4 °C and to perform a sensory evaluation. Juice samples were pressurized at 200, 400, or 600 MPa for 5 min. During thermal processing, juice was treated in a water bath at 90 °C for 60 s. Elevated aerobic plate counts, coliforms, psychrotrophs and yeasts/molds, were not detected in the HPP-400, HPP-600, or thermal-processed (TP) juices and further cold storage showed at least a shelf life of 28 days at 7 °C. All HPP-treated juice had significantly higher antioxidant capacities, higher total phenolic, flavonoid, and monomeric anthocyanin content, and lower browning degrees, compared with the TP. The soluble solid content, titratable acidity and pH were not significantly different in the HPP-400, HPP-600, and TP after 28 days. The ΔE values were significantly increased in all juice samples. Sensory analysis indicated that the HPP-treated juices had higher acceptance and lower bitter perception. In conclusion, HPP treatments above 400 MPa were effective in ensuring microbiological safety, maintaining the overall quality parameters, extending the shelf life, and achieving consumer acceptance.

Antimicrobial Effects and Mechanisms of Ethanol Extracts of Psoralea corylifolia Seeds Against Listeria monocytogenes and Methicillin-Resistant Staphylococcus aureus.

Psoralea corylifolia seeds contain many bioactive compounds commonly used in traditional Chinese medicine. In this study, the antibacterial activity and possible mechanism of P. corylifolia seed ethanol extract (PCEE) against foodborne pathogens were investigated. Both methicillin-resistant Staphylococcus aureus (MRSA) and Listeria monocytogenes had similar minimum inhibitory concentrations and minimum bactericidal concentrations of PCEE at 50 and 100 µg/mL, respectively. Furthermore, elevated OD260, protein concentration, and electric conductivity indicated irreversible damage to the cytoplasmic membranes of PCEE-treated cells. Indeed, the treated cells displayed disrupted membranes, incomplete and deformed shapes, and rupture as visualized by scanning electron microscopy. Multidrug-resistance efflux pump gene expression was also analyzed by quantitative reverse transcription PCR. Although the mdrL, mdrT, and lde genes of L. monocytogenes and the mepA gene of MRSA were upregulated, there was no significant difference that indicated an attempt by the efflux pumps to discharge PCEE. MRSA norA expression and abcA expression were significantly downregulated (p < 0.05). A possible mechanism for PCEE may be to cause an energy depletion, either by inhibiting adenosine triphosphate binding or by disturbing the proton gradient, resulting in membrane damage.

Extraction of bioactive ingredients from fruiting bodies of Antrodia cinnamomea assisted by high hydrostatic pressure.

The aim of this study was to use high hydrostatic pressure treatment to enhance the extraction efficiency of the active components from the fruiting bodies of Antrodia cinnamomea, and compare with those obtained by shake and ultrasonic extraction methods. The conditions of high pressure extraction (HPE) at 600 MPa, a liquid/solid ratio of 40:1, and 3 min of treatment yielded triterpenoids and adenosine concentrations of 410.41 mg/100 mL and 0.47 mg/100 mL, respectively, which did not differ significantly from those with the two other treatments-shake extraction at 180 rpm for 8 h and ultrasonic extraction at 50 Hz for 60 min. The HPE extracts significantly attenuated reactive oxygen species, nitric oxide and prostaglandin E2 production in lipopolysaccharide-stimulated RAW 264.7 cells than shake extracts did. SEM micrographs revealed that high-pressure caused physical morphological damage to the mycelium of fruiting bodies, such as distortion and disruption of mycelial cells, and increased the mass-transfer effectiveness of the solvent and solute. HPE can be employed as an efficient extraction technique for production of bioactive ingredients that might have a potential application in food and related industries.

Effects of high pressure extraction on the extraction yield, phenolic compounds, antioxidant and anti-tyrosinase activity of Djulis hull.

The hulls of Djulis (Chenopodium formosanum) are a type of agricultural waste. Using 70% ethanol as the extraction solvent, this study compared the extraction yields of high-pressure-assisted extraction (HPE) and conventional oscillation extraction (CE) for Djulis hulls (DH). The total phenolic and flavonoid contents, and antioxidant, anti-inflammatory and anti-tyrosinase activities were also compared. Our findings indicated that 600 MPa/5 min of HPE resulted in higher total phenolic (567-642 mg GAE/g) and flavonoid (47.2-57.2 mg QU/g) concentrations; gallic acid (44.5-53.2 µg/g) and rutin (26.8-34.2 µg/g) were the main phenolic and flavonoid compounds. When the extraction pressure was greater than 450 MPa, HPE extracts showed stronger antioxidant capacity and anti-tyrosinase activity than CE extracts. In a LPS-induced RAW 264.7 cell model of inflammation, HPE extracts had significant inhibitory effects on the cumulative concentrations of nitric oxide and prostaglandin E2. These results indicate that HPE had a better extraction yield, and required a shorter time for the extraction of functional ingredients from DH. Hence, DH could be a potential source for natural antioxidants for the food and biotechnology industries.

Influence of high-pressure processing on the generation of γ-aminobutyric acid and microbiological safety in coffee beans.

BACKGROUND: The aim of this study was to investigate the influence of high-pressure processing (HPP) on γ-aminobutyric acid (GABA) content, glutamic acid (Glu) content, glutamate decarboxylase (GAD) activity, growth of Aspergillus fresenii, and accumulated ochratoxin A (OTA) content in coffee beans. RESULTS: The results indicated that coffee beans subjected to HPP at pressures ≥50 MPa for 5 min increased GAD activity and promoted the conversion of Glu to GABA, and showed a significantly doubling of GABA content compared with unprocessed coffee beans. Additionally, investigation of the influence of HPP on A. fresenii growth on coffee beans showed that application ≥400 MPa reduced A. fresenii concentrations to <1 log. Furthermore, during a 50-day storage period, we observed that a processing pressure of 600 MPa completely inhibited A. fresenii growth, and on day 50 the OTA content of coffee beans subjected to processing pressures of 600 MPa was 0.0066 µg g-1 , which was significantly lower than the OTA content of 0.1143 µg g-1 in the control group. CONCLUSION: This study shows that HPP treatment can simultaneously increase GABA content and inhibit the growth of A. fresenii, thereby effectively reducing the production and accumulation of OTA and maintaining the microbiological safety of coffee beans. © 2018 Society of Chemical Industry.

Comparison of high pressure and high temperature short time processing on quality of carambola juice during cold storage.

This study validated high hydrostatic pressure processing (HPP) for achieving greater than 5-log reductions of Escherichia coli O157:H7 in carambola juice and determined shelf life of processed juice stored at 4 °C. Carambola juice processed at 600 MPa for 150 s was identified capable of achieving greater than 5.15-log reductions of E. coli O157:H7, and the quality was compared with that of high temperature short time (HTST)-pasteurized juice at 110 °C for 8.6 s. Aerobic, psychrotrophic, E. coli/coliform, and yeasts and moulds in the juice were reduced by HPP or HTST to levels below the minimum detection limit (< 1.0 log CFU/mL), and showed no outgrowth after refrigerated storage of 40 days. There were no significant differences in pH and titratable acidity between the untreated, HPP, and HTST juices. However, HTST treatment significantly changed the color of juice, while no significant difference was observed between the control and HPP samples. HPP and HTST treatments reduced the total soluble solids in the juice, but maintained higher sucrose, glucose, fructose, and total sugar contents than untreated juice. The total phenolic and ascorbic acid contents were higher in juice treated with HPP than untreated and HTST juice, but there was no significant difference in the flavonoid content. Aroma score analysis showed that HPP had no effect on aroma, maintaining the highest score during cold storage. The results of this study suggest that appropriate HPP conditions can achieve the same microbial safety as HTST, while maintaining the quality and extending the shelf life of carambola juice.

Quality changes in high hydrostatic pressure and thermal pasteurized grapefruit juice during cold storage.

This study evaluated the effects of high hydrostatic pressure (HHP) and thermal pasteurization (TP) on microbial counts, physicochemical properties, antioxidant characteristics, naringin and naringenin contents, and naringinase activity of grapefruit juice during 21 days cold storage period. Results showed that HHP and TP significantly decreased the total microbial, coliform, and yeast counts. No significant differences between HHP-treated grapefruit juice (600 MPa/5 min) and untreated fruit juice with respect to physicochemical properties such as total titratable acidity, pH, and total soluble solids was observed after 21 days of storage. Although HHP affected the colour and antioxidant characteristics of grapefruit juice, the extent of effect was significantly lower than that for TP-treated fruit juice. This demonstrated that HHP could better maintain the original flavour and quality of grapefruit juice compared to TP. In addition, 92% naringinase activity was maintained in HHP-600 group on Day 21, which increased the degradation of bitter naringin into non-bitter naringenin during the cold storage of grapefruit juice. In summary, HHP can simultaneously maintain the microbiological safety of grapefruit juice along with its original quality characteristics. HHP can effectively extend the storage period and safety during cold chain transport, and hence highly applicable in the grapefruit juice industry.

Effect of high-pressure processing and thermal pasteurization on overall quality parameters of white grape juice.

BACKGROUND: The aim of this study was to investigate the microbial levels, physicochemical and antioxidant properties and polyphenol oxidase (PPO) and peroxidase (POD) activities as well as to conduct a sensory analysis of white grape juice treated with high-pressure processing (HPP) and thermal pasteurization (TP), over a period of 20 days of refrigerated storage. RESULTS: HPP treatment of 600 MPa and TP significantly reduced aerobic bacteria, coliform and yeast/mold counts. At day 20 of storage, HPP-600 juice displayed no significant differences compared with fresh juice in terms of physicochemical properties such as titratable acidity, pH and soluble solids, and retained less than 50% PPO and POD activities. Although significant differences were observed in the color, antioxidant contents and antioxidant capacity of HPP-treated juice, the extent of these differences was substantially lower than that in TP-treated juice, indicating that HPP treatment can better retain the quality of grape juice. Sensory testing showed no significant difference between HPP-treated juice and fresh juice, while TP reduced the acceptance of grape juice. CONCLUSION: This study shows that HPP treatment maintained the overall quality parameters of white grape juice, thus effectively extending the shelf life during refrigerated storage. © 2016 Society of Chemical Industry.

Recent Advances in Food Processing Using High Hydrostatic Pressure Technology.

High hydrostatic pressure is an emerging non-thermal technology that can achieve the same standards of food safety as those of heat pasteurization and meet consumer requirements for fresher tasting, minimally processed foods. Applying high-pressure processing can inactivate pathogenic and spoilage microorganisms and enzymes, as well as modify structures with little or no effects on the nutritional and sensory quality of foods. The U.S. Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA) have approved the use of high-pressure processing (HPP), which is a reliable technological alternative to conventional heat pasteurization in food-processing procedures. This paper presents the current applications of HPP in processing fruits, vegetables, meats, seafood, dairy, and egg products; such applications include the combination of pressure and biopreservation to generate specific characteristics in certain products. In addition, this paper describes recent findings on the microbiological, chemical, and molecular aspects of HPP technology used in commercial and research applications.

Inactivation of pathogenic Listeria monocytogenes in raw milk by high hydrostatic pressure.

The aim of this work was to investigate the mechanisms underlying the inactivation of Listeria monocytogenes in raw milk under high hydrostatic pressure (HHP). The results showed that a 450-MPa treatment for 5 min could completely eliminate 108 colony-forming units/mL of viable bacteria, as indicted by increased uptake of propidium iodide. Morphological damage to the cell wall, cell membrane, and cytoplasmic components by HHP treatments was observed on scanning and transmission electron micrographs. The protein bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels differed between HHP-treated and untreated L. monocytogenes, in that HHP decreased the protein content and caused partial protein degradation. Therefore, our results indicate that HHP inactivates L. monocytogenes by causing morphological changes in the internal and external cellular structures, as well as through membrane damage, cell wall rupture, and membrane protein degradation.

Potential Utility of High-Pressure Processing to Address the Risk of Food Allergen Concerns.

High-pressure processing (HPP) technology is a novel, nonthermal processing technology for food. This special processing method can inactivate microorganisms and enzymes in food at room temperature using ultra-high pressures of above 100 MPa, while the original flavor and nutritional value of the food are maintained, with an extended refrigerated shelf-life of the food in distribution. In recent years, because of the rising prevalence of food allergies, many researchers have actively sought processing methods that reduce the allergenicity of food allergens. This study describes the effects of the current HPP technology on allergen activity. Our main goal was to provide an overview of the current research achievements of the application of HPP to eliminate the allergenicity of various foods, including legumes, grains, seafood, meat, dairy products, fruits, and vegetables. In addition, the processing parameters, principles, and mechanisms of HPP for allergen destruction are discussed, such as the induction of protein denaturation, the change in protein conformation, allergen removal using the high-pressure extraction technology, and the promotion of enzymatic hydrolysis to alter the sensitization of the allergens. In the future, the application of HPP technology as a pretreatment step for raw food materials may contribute to the development of food products with low or no allergenic ingredients, which then can effectively reduce the concern for consumers with allergies, reduce the risk of mistaken ingestion, and reduce the overall incidence of allergic reactions from food.

Halomonas beimenensis sp. nov., isolated from an abandoned saltern.

A Gram-staining negative, motile, non-spore-forming, short rod-shaped (0.8-1.5 × 1.5-2.0 µm), halophilic bacterium, designated strain NTU-107(T), was isolated from brine samples collected from the abandoned Beimen saltern in southern Taiwan. The novel strain grew with 0-15% (w/v) NaCl (optimum between 5% and 10%), at 15-55 °C (optimum 40 °C) and at pH 5.5-9.5 (optimum pH 7.5). The major cellular fatty acids were C(18:1)ω7c, C(16:0) and C(19:0 )cyclo ω8c, the genomic DNA G+C content was 66.5 mol%, and the predominant ubiquinone was Q-9. The major polar lipids included phosphatidylglycerol, diphosphatidylglycerol and phosphatidylethanolamine. In a phylogenetic analysis based on 16S rRNA gene sequences, strain NTU-107(T) clustered with members of the genus Halomonas. In hybridization experiments, however, the levels of DNA-DNA relatedness between strain NTU-107(T) and the type strains of its closest phylogenetic neighbours (Halomonas koreensis, H. organivorans and H. ventosae) were all found to be less than 40 %. Based on the phenotypic, chemotaxonomic and genetic data, strain NTU-107(T) represents a novel species within the genus Halomonas, for which the name Halomonas beimenensis sp. nov. is proposed. The type strain is NTU-107(T) ( = BCRC 17999(T) = KCTC 22876(T) = JCM 16084(T)).

High hydrostatic pressure treatment induced microstructure changes and isothiocyanates biosynthesis in kale.

Effects of high-pressure processing (HPP) on the myrosinase activity, glucosinolate (GLS) content, isothiocyanate (ITC) conversion rate, color, and bacterial count of kale leaves were investigated. Thermal process at 100 °C were used as negative control groups. The sample processed at 600 MPa exhibited the highest myrosinase activity and ITC conversion rate of 70.4%, while the GLS content was significantly lower than those in the raw and the thermally processed samples. However, processing of the samples at elevated temperatures results in gradual loss of myrosinase activity. SEM images showed that HPP induces irregular crushing damage to the veins, edges, and surfaces of the leaves, thereby promoting the conversion process in the myrosinase-GLS-ITC system. Additionally, HPP caused less significant color change of the kale leaves than thermal treatment. HPP achieved the same level of pasteurization as thermal treatment in terms of bacterial count.

Effect of high pressure pretreatment on myrosinase-glucosinolate system, physicochemical and bacterial properties during fermentation of brine-pickled radishes.

The myrosinase-glucosinolate system, physicochemical properties, and bacterial community were profiled during fermentation of high hydrostatic pressure (HHP) pretreated brine-pickled radishes; traditionally brine-pickled radishes were utilised as the control. Scanning electron microscopy (SEM) analysis revealed that 300 MPa pretreatment promoted brine infiltration in radish cells and damaged cellular microstructures, which activated the myrosinase-glucosinolate system. The conversion of glucosinolate (GLs) to isothiocyanates (ITC) increased and significantly enhanced the raphasatin and sulforaphene contents of pickled radish. However, 600 MPa pretreatment suppressed myrosinase activity. HHP pretreatment altered the natural radish bacterial communities by reducing the total bacterial and lactic acid bacteria counts. Lactobacillus spp. became the dominant bacterial genus within 15 d of fermentation. However, the destruction of cellular structures by HHP pretreatment also significantly decreased hardness and caused the dissolution of amino acids and TTA into brine. This caused reduced amino acid and TTA contents compared to the control group, as well as decreases in pH. HHP pretreatment suppressed the growth of spoilage bacteria (e.g. Pseudomonas, Staphylococcus, and Shewanella genera). This study provides new insight into the potential applications of HHP treatment in pickling, as it demonstrates that HHP can increase the ITC conversion rate of pickled radish, modify its physiochemical characteristics, and decrease microbial risk. Therefore, HHP is a promising preprocessing technique to be used for pickle manufacturing industry.