Comparing the Effects of Ultra‐High‐Pressure Homogenization and Conventional Thermal Treatments on the Microbiological,Physical, and Chemical Quality of Almond Beverages

The effects of ultra‐high‐pressure homogenization (UHPH) at 200 and 300 MPa, in combination with different inlet temperatures (55, 65, and 75 °C) on almond beverages with lecithin (AML) and without lecithin (AM), were studied. UHPH‐treated samples were compared with the base product (untreated), pasteurized (90 °C, 90 s), and ultra‐high‐temperature (UHT, 142 °C, 6 s) samples. Microbiological analysis, physical (dispersion stability, particle size distribution, and hydrophobicity), and chemical (hydroperoxide index) parameters of special relevance in almond beverages were studied. Microbiological results showed that pressure and inlet temperature combination had a significant impact on the lethal effect of UHPH treatment. While most UHPH treatments applied produced a higher quality of almond beverage than the pasteurized samples, the combination of 300 MPa and 65 and/or 75 °C corresponded to a maximum temperature after high pressure valve of 127.7 ± 9.7 and 129.3 ± 12.6 °C, respectively. This temperature acted during less than 0.7 s and produced no bacterial growth in almond beverages after incubation at 30 °C for 20 d. UHPH treatments of AML samples caused a significant decrease in particle size, resulting in a high physical stability of products compared to conventional heat treatments. UHPH treatment produced higher values of hydroperoxide index at day 1 of production than heat‐treated almond beverage. Hydrophobicity increased in AML‐UHPH‐treated samples compared to AM and conventional treatments. Practical Application: Ultra‐high‐pressure‐homogenization (UHPH) is an emerging technology, a potential alternative to conventional heat treatments. It is a simple process consisting of single step. When liquid food (almond beverage in this study) passes through the high‐pressure valve, a very good stability and reduction of microorganisms is achieved, both effects due to the particle breakdown. Specific UHPH conditions could produce commercial sterilization of almond beverage.     

High-Pressure Destruction Kinetics of E. coli(29055) in Apple Juice

High‐pressure (HP) destruction of Escherichia coli (29055) in apple juice was evaluated (150 to 400 MPa; 0 to 80 min at 25 °C) based on a dual destruction behavior consisting of pressure pulse and pressure hold (first order rate) effects. Enumeration was carried out in brain‐heart infusion agar (BHIA) and violet‐red bile agar (VRBA) to differentiate between surviving cells with and without injury. A pressure pulse at 400 MPa destroyed the entire population (10⁸ CFU/mL) of E. coli. During pressure‐hold, D values (decimal reduction time) of E. coli decreased with an increase in pressure, and D values from BHIA (survivors including injured cells) were higher than from VRBA (survivors excluding injured cells). Thus, an increasing number of cells were initially injured than killed with HP treatment until finally killed. Pressure dependency of D was described by z‐value model with associated z_p values (pressure range to result in a decimal change in D values) of 126 and 140 MPa on BHIA and VRBA.     

Effects of Rigor Status during High‐Pressure Processing on the Physical Qualities of Farm‐Raised Abalone (Haliotis rufescens)

High‐pressure processing (HPP) is used to increase meat safety and shelf‐life, with conflicting quality effects depending on rigor status during HPP. In the seafood industry, HPP is used to shuck and pasteurize oysters, but its use on abalones has only been minimally evaluated and the effect of rigor status during HPP on abalone quality has not been reported. Farm‐raised abalones (Haliotis rufescens) were divided into 12 HPP treatments and 1 unprocessed control treatment. Treatments were processed pre‐rigor or post‐rigor at 2 pressures (100 and 300 MPa) and 3 processing times (1, 3, and 5 min). The control was analyzed post‐rigor. Uniform plugs were cut from adductor and foot meat for texture profile analysis, shear force, and color analysis. Subsamples were used for scanning electron microscopy of muscle ultrastructure. Texture profile analysis revealed that post‐rigor processed abalone was significantly (P < 0.05) less firm and chewy than pre‐rigor processed irrespective of muscle type, processing time, or pressure. L values increased with pressure to 68.9 at 300 MPa for pre‐rigor processed foot, 73.8 for post‐rigor processed foot, 90.9 for pre‐rigor processed adductor, and 89.0 for post‐rigor processed adductor. Scanning electron microscopy images showed fraying of collagen fibers in processed adductor, but did not show pressure‐induced compaction of the foot myofibrils. Post‐rigor processed abalone meat was more tender than pre‐rigor processed meat, and post‐rigor processed foot meat was lighter in color than pre‐rigor processed foot meat, suggesting that waiting for rigor to resolve prior to processing abalones may improve consumer perceptions of quality and market value.     

Effects of High‐Hydrostatic Pressure on Inactivation of Human Norovirus and Physical and Sensory Characteristics of Oysters

The purpose of the study was to determine the effect of high‐hydrostatic pressure (HHP) on inactivation of human norovirus (HuNoV) in oysters and to evaluate organoleptic characteristics of oysters treated at pressure levels required for HuNoV inactivation. Genogroup I.1 (GI.1) or Genogroup II.4 (GII.4) HuNoV was inoculated into oysters and treated at 300 to 600 MPa at 25 and 0 °C for 2 min. After HHP, viral particles were extracted by porcine gastric mucin‐conjugated magnetic beads (PGM‐MBs) and viral RNA was quantified by real‐time RT‐PCR. Lower initial temperature (0 °C) significantly enhanced HHP inactivation of HuNoV compared to ambient temperature (25 °C; P < 0.05). HHP at 350 and 500 MPa at 0 °C could achieve more than 4 log₁₀ reduction of GII.4 and GI.1 HuNoV in oysters, respectively. HHP treatments did not significantly change color or texture of oyster tissue. A 1‐ to 5‐scale hedonic sensory evaluation on appearance, aroma, color, and overall acceptability showed that pressure‐treated oysters received significantly higher quality scores than the untreated control (P < 0.05). Elevated pressure levels at 450 and 500 MPa did not significantly affect scores compared to 300 MPa at 0 °C, indicating increasing pressure level did not affect sensory acceptability of oysters. Oysters treated at 0 °C had slightly lower acceptability than the group treated at room temperature on day 1 (P < 0.05), but after 1 wk storage, no significant difference in sensory attributes and consumer desirability was observed (P > 0.05).     

High‐Pressure Inactivation of Enzymes: A Review on Its Recent Applications on Fruit Purees and Juices

In the last 2 decades high‐pressure processing (HPP) has established itself as one of the most suitable nonthermal technologies applied to fruit products for the extension of shelf‐life. Several oxidative and pectic enzymes are responsible for deterioration in color, flavor, and texture in fruit purees and juices (FP&J). The effect of HPP on the activities of polyphenoloxidase, peroxidase, β‐glucosidase, pectinmethylesterase, polygalacturonase, lipoxygenase, amylase, and hydroperoxide lyase specific to FP&J have been studied by several researchers. In most of the cases, partial inactivation of the target enzymes was possible under the experimental domain, although their pressure sensitivity largely depended on the origin and their microenvironmental condition. The variable sensitivity of different enzymes also reflects on their kinetics. Several empirical models have been established to describe the kinetics of an enzyme specific to a FP&J. The scientific literature in the last decade illustrating the effects of HPP on enzymes in FP&J, enzymatic action on those products, mechanism of enzyme inactivation during high pressure, their inactivation kinetics, and several intrinsic and extrinsic factors influencing the efficacy of HPP is critically reviewed in this article. In addition, process optimization of HPP targeting specific enzymes is of great interest from an industrial approach. This review will give a fair idea about the target enzymes specific to FP&J and the optimum conditions needed to achieve sufficient inactivation during HPP treatment.     

Microbial Inactivation Kinetics during High‐Pressure Carbon Dioxide Treatment: Nonlinear Model for the Combined Effect of Temperature and Pressure in Apple Juice

ABSTRACT: Isobaric and isothermal semi‐logarithmic survival curves of natural microflora in apple juice treated with high‐pressure carbon dioxide at 7, 13, and 16 MPa pressures and 35, 50, and 60 °C temperatures were fitted with a nonlinear equation to find the values of the coefficient b(P ), b(T ), n(P ), and n(T ). Profiles of the model parameters were obtained as a function of pressure and temperature. The model fitted with good agreement (R² > 0.945), the survival curves. An empirical equation was proposed to describe the combined effects of pressure and temperature. The equation, derived from a power law model, was written in the form: . The proposed model fitted the experimental data well. At 7 MPa and 50 and 60 °C, 13 MPa and 35 and 60 °C, 16 MPa and 35 °C, the model provided log₁₀ reduction residual values (observed value – fitted value) lower than 0.284 showing a good agreement between the experimental and the predicted survival levels.     

High‐Pressure Thermal Sterilization: Food Safety and Food Quality of Baby Food Puree

The benefits that high‐pressure thermal sterilization offers as an emerging technology could be used to produce a better overall food quality. Due to shorter dwell times and lower thermal load applied to the product in comparison to the thermal retorting, lower numbers and quantities of unwanted food processing contaminants (FPCs), for example, furan, acrylamide, HMF, and MCPD‐esters could be formed. Two spore strains were used to test the technique; Geobacillus stearothermophilus and Bacillus amyloliquefaciens, over the temperature range 90 to 121 °C at 600 MPa. The treatments were carried out in baby food puree and ACES‐buffer. The treatments at 90 and 105 °C showed that G. stearothermophilus is more pressure‐sensitive than B. amyloliquefaciens. The formation of FPCs was monitored during the sterilization process and compared to the amounts found in retorted samples of the same food. The amounts of furan could be reduced between 81% to 96% in comparison to retorting for the tested temperature pressure combination even at sterilization conditions of F₀‐value in 7 min.     

Two Kaempferol Glycosides Separated from Camellia Oleifera Meal by High‐Speed Countercurrent Chromatography and Their Possible Application for Antioxidation

Recently, kaempferol and its glycosides have attracted considerable attention owing to their potentially health‐benefitting properties including protection against chronic diseases. Here, a microwave‐assisted extraction (MAE) method was developed for the extraction of total flavonoid glycosides (FG) from Camellia oleifera meal, a major agrifood waste largely generated as a byproduct from the Camellia oil processing industry. Compared with traditional extraction methods, MAE enables more efficient extraction of FG. High‐speed countercurrent chromatography was then applied to separate FG from MAE extract, and two major compounds were successfully separated with purities above 90.0% as determined by HPLC. These two compounds were further identified by UV, FT‐IR, ESI‐MS, ¹H‐NMR, and ¹³C‐NMR as kaempferol 3‐O‐[α‐L‐rhamnopyranosyl‐(1→6)‐β‐D‐glucopyranosyl]‐7‐O‐β‐D‐glucopyranoside and kaempferol 3‐O‐[β‐D‐glucopyranosyl‐(1→4)‐α‐L‐rhamnopyranosyl]‐7‐O‐α‐L‐rhamnopyranoside, which were for the first time separated from C. oleifera meal. The results of antioxidant activity assay demonstrated that both compounds had excellent scavenging activity for DPPH radical, and exhibited protective effects against H₂O₂‐induced oxidative damage of vascular endothelial cells. The findings of this work suggest the possibility of employing C. oleifera meal as an attractive source of health‐promoting compounds, and at the same time facilitate its high‐value reuse and reduction of environmental burden.     

Contribution of High‐Pressure‐Induced Protein Modifications to the Microenvironment and Functional Properties of Rabbit Meat Sausages

Rabbit meat batters were subjected to high pressure (HP, 100 to 300 MPa for 3, 9, or 15 min) to elucidate their effects on proteins structures, the microenvironment, and the resulting functionalities of the subsequently heated products. To determine these effects, we investigated structural and microenvironmental changes using Raman spectroscopy and also expressible moisture content, textural characteristics, and dynamic rheological properties of batters during heating (20 to 80 °C). Untreated samples served as controls. Analysis of specific Raman spectral regions demonstrated that applications of HP to rabbit meat batters tended to induce the transformation of the all‐gauche S‐S conformation to gauche‐gauche‐trans in the batter system. HP treatment higher than 100 MPa for 9 min promoted secondary structural rearrangements, and molecular polarity enhancement in the proteins prior to cooking. Also, increases of O–H stretching intensities of rabbit meat sausages were obtained by HP treatment, denoting the strengthening of water‐holding capacity. These HP‐induced alterations resulted in improved texture and, perhaps, improved juiciness of rabbit meat sausages (P < 0.05), however they had relatively poorer rheological properties than the controls. Nevertheless, HP treatment, especially 200 MPa for 9 or 15 min, was an effective technique for improving the functionalities of gel‐type products through modification of meat proteins.     

High‐Throughput Isolation of Bacteriocin‐Producing Lactic Acid Bacteria,with Potential Application in the Brewing Industry

Lactic acid bacteria (LAB) were isolated from malted cereals by means of a high‐throughput screening approach and investigated for antimicrobial activity against a range of beer‐spoiling bacteria. Putative bacteriocin‐producing strains were identified by 16S rRNA analysis and the inhibitory compounds were partially characterized. Following determination of the inhibitory spectra of the strains, an unspeciated Lactobacillus sp. UCC128, with inhibitory activity against a range of beer‐spoiling strains was subjected to further characterization. A bacteriocin was purified from this strain and analyzed by mass spectrometry to determine the weight of the protein. The result indicated that the bacteriocin was highly similar to pediocin AcH/PA‐1 from Pediococcus acidilactici. The bacteriocin‐producers identified in this study have the potential to be used in the brewing industry to enhance the microbiological stability of beer in conjunction with hurdles already in place in the brewing process.     

高压CO2杀灭大肠杆菌的杀菌机理研究

通过检测大肠杆菌体内H+-ATP酶的活性、利用氨基酸自动分析仪测定萃取物的氨基酸成分、扫描电镜对处理前后的大肠杆菌进行观察,比较考察高压CO2对大肠杆菌菌粉和菌悬液的杀菌效果。结果表明:高压CO2杀灭大肠杆菌不是由某一机理单独作用的,而是由机械破裂致死机制、萃取机制和酸化机制共同作用的结果。     

Characterization of Physicochemical Properties and IgE‐Binding of Soybean Proteins Derived from the HHP‐Treated Seeds

The aim of this work was to evaluate the characterization of physicochemical properties and IgE‐binding of soybean proteins derived from the high hydrostatic pressure (HHP) treated seeds. Soybean seeds were treated by HHP at different pressures, and changes in the physicochemical properties of soybean proteins were characterized by proteins solubility, free sulfhydryl (SH) content, surface hydrophobicity, and secondary structures. Sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE) and enzyme‐linked immunoabsorbent assay (ELISA) were used to define the proteins patterns and IgE‐binding ability. The results showed that HHP treatment in the ranges of 0 to 500 MPa led to a slight but gradual decline in free SH content. The solubility and hydrophobicity of soybean proteins increased sharply from 100 to 200 MPa, and gradually decreased upon the further increase of pressure. The α‐helix and β‐sheets contents of soybean proteins decreased, while the random coil content increased. The SDS‐PAGE showed that HHP treatment of 100 to 200 MPa could dissociate the proteins, breaking the aggregates into smaller units, while the treatment ranging from 300 to 500 MPa could induce the proteins aggregation into larger units. Moreover, the ELISA revealed that the IgE‐binding of soybean proteins after HHP treatment at 200 MPa decreased 61.7% compared to the untreated group. Our findings suggested that HHP processing could not only modify the physicochemical properties of soybean proteins, but also significantly reduce its IgE‐binding at an appropriate pressure level.     

Coalho Cheese Made with Protease from Thermomucor indicae‐seudaticae N31: Technological Potential of the New Coagulant for the Production of High‐Cooked Cheese

The aim of this study was to explore the use of a new coagulant from Thermomucor indicae‐seudaticae N31 for the manufacture of a high‐cooked starter‐free cheese variety, by evaluating its physicochemical and functional characteristics in comparison to cheeses made with a traditional commercial coagulant. Coalho cheese was successfully produced with the new protease as it exhibited comparable characteristics to the one produced using the commercial enzyme: pH behavior during manufacture; cheese composition; protein and fat recovery; and cheese yield. In addition, during storage, melting was low and not affected by storage time; the increase of TCA 12% soluble nitrogen (% of total nitrogen) was lower than half of that of pH 4.6 soluble nitrogen (% of total nitrogen); concentration of β‐CN significantly decreased, whereas α_s1‐CN concentration was not affected by storage time.     

The use of mechanical analyses,scanning electron microscopy and ultrasonic imaging to study the effects of high‐pressure processing on multilayer films

The effects of high‐pressure processing (HPP) on the mechanical and physical characteristics of eight high‐barrier multilayer films were investigated. These films were PET/SiO_x/LDPE, PET/Al₂O₃/LDPE, PET/PVDC/nylon/HDPE/PP, PE/nylon/EVOH/PE, PE/nylon/PE, metallised PET/EVA/LLDPE, PP/nylon/PP and PET/PVDC/EVA. In addition, PP was evaluated as a monolayer film for comparison purposes. Pouches made from these films were filled with distilled water, sealed, then pressure processed at 600 and 800 MPa for 5, 10 and 20 min at a process temperature of 45 °C. Pouches kept at atmospheric pressure were used as controls. Prior to and after HPP, all films were tested for tensile strength, percentage elongation and modulus of elasticity (at 50 cm min^?1) and imaged by scanning electron microscopy (SEM) and C‐mode scanning acoustic microscopy (C‐SAM). Results showed no significant changes in tensile strength, elongation and modulus of elasticity of all films after HPP. However, significant physical damage to metallised PET (MET‐PET) was identified by SEM and C‐SAM. Thus it could be concluded that MET‐PET is not suitable for batch‐type high‐pressure‐processed food packaging. It can also be concluded that the other materials investigated during this study are suitable for batch‐type high‐pressure‐processed food packaging. Copyright © 2003 Society of Chemical Industry     

High‐pressure recovery of anthocyanins from grape skin pomace (Vitis vinifera cv. Teran) at moderate temperature

The objective was to evaluate the influences of the high hydrostatic pressure extraction parameters on the recovery of anthocyanins from the grape skin pomace extracts (Vitis vinifera cv. Teran) under moderate temperatures. Studied parameters were: solvents (methanol and ethanol); solvent concentrations (30, 50, and 70%); pressures (300, 400, and 500 MPa); times (3, 6.5, 10 min); and temperatures (22, 26, 30 °C). Predominant anthocyanins in all extracts were malvidins (malvidin‐3‐glucoside as the main compound) representing 55.77% of overall anthocyanin content. The type of solvent did not significantly influence anthocyanin extraction yield, while decreased solvent concentration (increased solvent‐to‐water ratio) significantly improved extraction of anthocyanins. Increase of pressure enhanced extraction yield of the anthocyanins but temperature showed stronger impact on the anthocyanins recovery. This investigation evidenced that the best conditions for HHPE of anthocyanins from grape pomace were extraction time 3.39 min, extraction temperature 29.48 °C, pressure 268.44 MPa and solvent concentration 70%.

Practical applications

Due to increased interest for the use of cheap winery byproducts as a source of expensive polyphenols for functional food production, skins from grape pomace became valuable raw material. Therefore, there is a need to evaluate the influence of HHPE innovative extraction technology on its nutritive value during processing. Optimizing parameters for polyphenolic recovery from grape pomace is directly related with nutritional value and economics of food engineering during industrial processing. Obtained results showed that the HHPE under lower temperatures is suitable for the extraction process of anthocyanins from grape skin pomace, but more research is needed to identify other food‐grade solvents with their corresponding concentrations that are useful for the extraction assisted with high hydrostatic pressure.