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High pressure processing has emerged as a versatile technology for food processor use to ensure food safety and preserve various heat sensitive nutrients and bioactive compounds. By carefully controlling pressure-thermal intensity, the treatment helps to reduce product thermal exposure while simultaneously achieving different treatment effects including pasteurization, sterilization, and shelf-life extension. This opinion paper summarizes scientific advances and future research needs in food process design and development of high pressure-based technologies. Research underway to develop continuous high pressure ultra-shear technology for formulating liquid beverages, sauces, and nano emulsions. Emerging application of high-pressure technology include its use as extraction tool for separating bioactive compounds from various food waste, and as a hyperbaric storage method for reducing energy use during refrigeration storage of foods.

The aim of the presented study was to determine the ability of the high pressure processing (HPP) for extraction of bioactive compounds from black carrot pomace and to optimize treatment conditions (pressure, temperature, processing time) for obtaining the maximum yield of bioactive compounds. Experiments were conducted using pilot scale high pressure food processors and water as the extraction solution. A set of response surface analysis mathematical models were developed and validated for the extraction of bioactive compounds of black carrot pomace, considering total monomeric anthocyanin contents (TMA), total phenolic compounds (TPC) and antioxidant activity (AA). Quality attributes such as total color difference (Delta E*) and polymeric color ratio (PCR) of the samples were also evaluated. The validation results showed that the error values of the obtained models were lower than 10%, which means acceptable error value in modelling study. Combined pressure-thermal treatment at 266.6 MPa, 78.3 degrees C for 13.6 min was identified as the optimal process condition for maximum extraction of bioactive compounds.

The effects of pressure, temperature, shear, and their interactions on selected quality attributes and stability of milk during ultra-shear technology (UST) were investigated. The UST experiments include pressure (400 MPa) treatment of the milk sample preconditioned at 2 different initial temperatures (25°C and 15°C) and subsequently depressurizing it via a shear valve at 2 flow rates (low: 0.15–0.36 g/s; high: 1.11–1.22 g/s). Raw milk, high-pressure processed (HPP; 400 MPa, ~40°C for 0 and 3 min) and thermal treated (72°C for 15 s) milk samples served as the controls. The effect of different process parameters on milk quality attributes were evaluated using particle size, zeta potential, viscosity, pH, creaming, lipase activity, and protein profile. The HPP treatment did not cause apparent particle size reduction but increased the sample viscosity up to 3.08 mPa·s compared with 2.68 mPa·s for raw milk. Moreover, it produced varied effects on creaming and lipase activity depending on hold time. Thermal treatment induced slight reduction in particle size and creaming as compared with raw milk. The UST treatment at 35°C reduced the effective diameter of sample particles from 3,511.76 nm (raw milk) to 291.45 nm. This treatment also showed minimum relative lipase activity (29.93%) and kept milk stable by preventing creaming. The differential effects of pressure, shear, temperature, and their interactions were evident, which would be useful information for equipment developers and food processors interested in developing improved food processes for dairy beverages.

Aeration in beverages, which is manifested as foam or bubbles, increases the sensory preference among consumers. They are either entrapped within the beverage or float at the surface. It is a unique feature that allows the product to garner considerable consumer attention and has been appreciated in hot as well as cold beverages. Recent studies have focused on diverse foam or bubble creation protocols, their mechanism of action, stabilization techniques, and application domains in various beverages. The role of surface-active components in foam formation and its stability are important in food processing. This exposition discusses the important findings on this subject, including methods of creation, sustenance, as well as analysis of foaming or aeration in liquid foods, and attempts to showcase their various dimensions. Recent developments on the various aspects of foam formation in liquid foods are reviewed and presented to aid in future research.

Experiments were conducted to investigate osmotic dehydration of ginger slices suspended in three different osmotic agents at 0.1–600 MPa and 40 °C for various pressure holding times. A Weibull distribution mathematical model was employed to predict the kinetics of moisture and solute transport during osmotic dehydration of ginger. Increased process pressure accelerated the water loss and solid gain and removed significant amount of water within a shorter time period. The effective moisture diffusivity values for glucose, fructose, and sucrose at 0.1 MPa and 40 °C were 0.322 × 10−9, 0.362 × 10−9 and 0.396 × 10−9 m2/s respectively. Pressure treatment at 600 MPa increased these values by approximately by 11–12 folds (3.725 × 10−9, 4.027 × 10−9 and 4.293 × 10−9 m2/s respectively). Among the osmotic agents tested, solute diffusivity was maximum in glucose followed by fructose and sucrose, whereas the moisture diffusivity was greatest in sucrose and lowest in glucose.

A study assessed combined pressure-thermal treatment effect on quality attributes of selected acidified vegetables (banana pepper, red beets and green asparagus) over 30 days storage at 25 °C. Vegetables were acidified by suspending them in pickling liquid either through thermal blanching or 8 h storage at ambient temperature. Subsequently, samples were pressure treated in a pilot scale high pressure processor at 600 MPa, 45° or 65 °C for 5 min and stored at ambient temperature for 30 days. Quality analyses included texture, enzyme activity, color, pH and °Brix. Processed products remained stable during storage (pH Industrial relevance The research documented the quality changes in selected acidified vegetable pickles subjected to various pressure-thermal treatments. By reducing thermal impact, high pressure treatment in combination with modest heat can help preserve quality attributes of acidified vegetable pickles with the extended shelf life. The knowledge from this study could help the food processors in deciding relevance of high pressure processing for industrial manufacturing of acidified low-acid shelf-stable vegetable matrices.

A study was conducted to investigate and model kinetic degradation of ascorbic acid in freshly prepared pineapple juice subjected to various pressure (0.1, 300,450 and 600 MPa)-thermal (30, 75, 85 and 95 °C) treatment combinations. Experiments were conducted using a semi-custom made high pressure kinetic tester as well as an aluminum thermal kinetic tester. Thermal degradation of ascorbic acid was described with simple first order kinetics. The thermal rate constants (k 75 -95 ◦C, 0.1 MPa) and activation energy ( E a ) for ascorbic acid degradation reaction varied in the range of 0.004–0.006 per min and 14.22–29.78 kJ/mol, respectively. Within the experimental conditions of the study (300–600 MPa at 30 °C for holding times up to 15 min) high pressure processing did not alter ascorbic acid content (535.5–564.5 mg/kg). Combined pressure-thermal treatment (300–600 MPa at 75–95 °C) degraded ascorbic acid with increasing thermal intensity and was modeled using first order fractional conversion kinetics model. The lower asymptote value ( [ A ] ∞ [ A ] 0 ), rate constants (k 75 -95 ◦C, 600 MPa) and E a were in the range of 77–85%, 0.108 to 0.138 per min and 17.4–43.8 kJ/mol, respectively. Similarly, pressure sensitivity ( Δ V ≠ ) was ∼0 and −2.99 cm3/mol at 30 and 95 °C, respectively. Knowledge gained from the study can be useful for food processors to optimize high pressure treatment conditions for pineapple juice products.

The mass transfer kinetics during osmotic dehydration of granny smith apple slices in 60 Brix fructose and sucrose solution was studied at atmospheric pressure and at elevated pressure of 2...

The crystallization behavior of a model fat consisting of fully hydrogenated soybean oil (FHSBO) and soybean oil (SBO) is studied under isobaric cooling ( 100 MPa), and atmospheric conditions (0.1 MPa). To monitor the relationship between pressure and the onset of crystallization at both isobaric cooling and adiabatic compression, samples were pressurized until they achieved three different maximum temperatures (70, 80, or 90 °C) under pressure. A lower induction time of crystallization (τ > 2.1 min–1) resulting in smaller crystals was observed during adiabatic compression compared to isobaric cooling (0.4 < τ < 0.9 min–1). Moreover, different crystal size distributions were observed for the different maximum temperatures applied. Using small-angle X-ray scattering analysis, a decrease in nanoplatelet thickness was documented in samples crystallized under high pressure compared to the control samples. The impacts of high pressure processing were also evident in the sample...

Furan, a potential carcinogenic compound, can be formed in array of processed foods. The objective of this study was to conduct kinetic studies in pineapple juice and assess the interactive effects of pressure (0.1 to 600 MPa) and temperature (30 to 120 °C) on furan formation. Additional experiments were carried out in tomato, watermelon, cantaloupe, kale, and carrot juice to understand the influence of matrix and juice pH. Furan was monitored in raw (control) and processed samples by automated headspace gas chromatography mass spectrometry, and quantified by calibration curve method with d4-furan as internal standard. The data were modeled using zero-, first-, and second-order equations. The zero-order rate constants (k T,P ), activation energy (E a ), and Gibbs free energy of activation (ΔG ‡) of furan formation in thermally processed (TP; 90–120 °C) pineapple juice were found to be 0.036–0.55 μg/kg/min, 98–114 kJ/mol, and 173.9–180.5 kJ/mol, respectively. Furan concentration was negligible and close to the detection limit (0.37 μg/kg) after pressure treatment (600 MPa at 30 °C) of juice samples. For similar process temperatures, the rate constants of pressure-assisted thermally processed (PATP; 600 MPa at 105 °C) pineapple juice were lower than that of TP samples. Furan formation was influenced by juice matrix and pH. On the other hand, PATP markedly suppressed furan (0.7 to 1.6 μg/kg) in these selected juices. In conclusion, furan formation increased with process temperature and treatment time, while pressure treatment at ambient temperature did not promote its production. Furan formation in TP fruit juices was also influenced by juice matrix and pH, but these were not the significant factors for PATP-treated juices.

High pressure based technologies are of interest, as they enable the food processors to inactivate harmful and spoilage organisms, extend product shelf life, while having minimal impact on nutrients and fresh like quality attributes of foods. However, simultaneous application of pressure-thermal treatment is required for spore inactivation. Pressure in combination with heat can have synergistic, antagonistic or additive effects on various physical, biochemical and biological reactions in food matrices. It is also important to characterize the engineering properties of foods as influenced by pressure-heat combinations and model the extent of process non-uniformity within processed volume. Suitably controlling the pressure-thermal intensity enables the processors to manufacture various pasteurized, extended shelf-life, and shelf-stable foods. Therefore, this chapter summarizes basic principles associated with food process design and development of high-pressure based technologies, factors governing food safety and quality, and highlight relevant industrial applications.

The objective of this study was to investigate the inactivation kinetics of Enterococcus faecium in peanut butter under different water activities (aw) and superheated steam temperatures. Peanut butters were prepared at 4 different initial water activities (0.19, 0.40, 0.60, and 0.80) and E. faecium was inoculated into the peanut butter (7.4–8.7 log CFU/g). The inoculated peanut butter samples were exposed at 4 different superheated steam temperatures (125 °C, 175 °C, 225 °C, and 250 °C). Survivor data were modelled using Weibull and log-linear models to describe the inactivation kinetics of E. faecium. The decimal reduction times (D-value), temperature sensitivity (zT) and aw sensitivity (zaw) of the D-value were determined from a log-linear model, and inactivation parameters from the Weibull model were also evaluated. An increase in aw of peanut butter and superheated steam temperature decreased the D-value of E. faecium. The zaw-value and zT-value were determined to be 0.60 ± 0.09 and 194.66 ± 40.69 °C, respectively (R2 > 0.89). The inactivation kinetics of E. faecium on surfaces contaminated with peanut butter can provide comprehensive information to superheated steam sanitation treatment which may be applied to environmental surfaces for effective microbial inactivation without the introduction of water.

Understanding the inactivation kinetics of bacterial spores during combined pressure-thermal processing is essential for process design. The knowledge on the influence of pH and water activity (aw) during combined pressure-thermal treatment is limited. Experiments were conducted using Bacillus cereus spores suspended in citrate-phosphate buffers, adjusted to different levels of pH (3.8–7.3) and aw (0.80–0.99). Spores were then treated with a pressure-heat combination (600 MPa, 70 °C) using a laboratory-scale high-pressure kinetic tester. Linear regression and Weibull models were used to fit the experimental data. The kinetic parameters of the spores inactivation estimated from the models were plotted as a function of pH and aw. Results showed that the inactivation kinetic curves were characterized by tailing, particularly at low aw levels. The log reduction of B. cereus spores decreased with the decrease of aw. During pressure-thermal treatment, the changes in acidity values for a given water activity have limited influence on decimal reduction values of the spores. Study findings will be helpful for designing pressure-thermal processes to produce microbially safe products with varying water activity and acidity levels.

The impact of high pressure homogenization (HPH) on physical characteristics and emulsion stability of nutritional formulations were evaluated on a pilot scale HPH unit. Two products of industrial interest were used for these experiments. Manufactured formulations were analyzed using material characterization methods as particle size distribution, microscopy and dynamic mechanical spectra, compared to a control formula manufactured with conventional homogenization and heat treatments. Dynamic rheological measurements as strain and frequency sweeps exhibited increased product stability in parallel to increased homogenization pressures. Homogenization at elevated pressures yielded more shear thinning fluids evidenced by increased viscosities at low shear rates, ten fold greater compared to the control treatment, further evidence to increased physical stability. Experimental findings revealed the existence of a threshold pressure (100–150 MPa) for both formulations exhibiting significant correlation with product quality and physical stability. The study outcomes presents an opportunity for reducing stabilizer concentration in dairy beverages; in addition to shelf life and physical stability improvement for formulations treated at increased homogenization pressures.

Fluid foods are a rapidly growing segment serving the needs of consumers’ healthy life style. Though high-pressure pasteurized beverages have been recently commercialized, the batch nature of the technology has been a hurdle for wider adaptation of the technology for high-throughput commodity-oriented beverage products. Further development of continuous flow through high-pressure processing methods is desired. High-pressure homogenization (HPH) consists of forcing a pressurized fluid to flow through a minute gap, which not only homogenizes the fluid but also increases the fluid’s temperature. HPH offers the possibility of combining homogenization and preservation into a single unit operation. By manipulating initial temperature and applied pressure, HPH treatment can be used to pasteurize or sterilize the product. This work critically examines the efforts in understanding fundamental process engineering aspects of HPH, including pressure-thermal process characterization, valve design (gap size and pressure relation), flow pattern, temperature history, and residence time distribution. This review will also highlight the HPH impact on food quality and bioactive compound retention. Quality aspects examined include particle size distribution and microbial and enzyme inactivation. The insight gained by this review will assist readers to gain a better appreciation of the HPH process design and system scale-up.

This review examines the combined pressure–thermal effects on thermophysical and crystallization properties of lipids. Pressure treatment transiently accelerates the phase transition and shifts the melting temperature of lipids by 10 °C/100 MPa–20 °C/100 MPa. It also transiently alters various thermophysical properties of lipids including density, viscosity, thermal conductivity, and specific heat. The interdependence phase transition of lipids with their corresponding thermophysical properties is highlighted. The magnitude and rate of pressure application influences the mechanism of lipid crystallization under pressure. For example, slow multi-step modest pressure buildup (100–200 MPa) promotes heterogeneous nucleation and slow crystallization which result in stable crystal structures. Increasing the magnitude of pressure by 400–500 MPa accelerates the nucleation rate significantly. On the other hand, rapid single-step pressurization, regardless of pressure level, induces instantaneous volumetric crystallization of less stable crystal structure which is subsequently modified into stable crystal polymorphs during depressurization. High pressure crystallization is also influenced by temperature, pressure holding time, compression rate, compression cycle, and lipid compositions. The effects of pressure treatment are more pronounced in saturated fatty acids compared to unsaturated ones, and it is shown that triglycerides crystallize more slowly under pressure than free fatty acids.

Background A study was conducted to investigate the impact of high pressure (450 and 600 MPa at 30 °C) and thermal (72, 85 and 99 °C at 0.1 MPa) treatments on dispersive and aggregative characteristics of almond milk. Experiments were conducted using a kinetic pressure testing unit and water bath. Particle size distribution, microstructure, UV absorption spectra, pH and color changes of processed and unprocessed samples were analyzed. Results Raw almond milk represented the mono model particle size distribution with average particle diameters of 2 to 3 µm. Thermal or pressure treatment of almond milk shifted the particle size distribution towards right and increased particle size by five- to six-fold. Micrographs confirmed that both the treatments increased particle size due to aggregation of macromolecules. Pressure treatment produced relatively more and larger aggregates than those produced by heat treated samples. The apparent aggregation rate constant for 450 MPa and 600 MPa processed samples were k450MPa,30°C = 0.0058 s(-1) and k600MPa,30°C = 0.0095 s(-1) respectively. Conclusions This study showed that dispersive and aggregative properties of high pressure and heat-treated almond milk were different due to differences in protein denaturation, particles coagulation and aggregates morphological characteristics. Knowledge gained from the study will help food processors to formulate novel plant-based beverages treated with high pressure. © 2015 Society of Chemical Industry.

Pressure-assisted thermal processing (PATP; 500–700 MPa, 90–121 °C) offers new opportunities to sterilize low-acid foods while preserving quality attributes to an extent greater than is possible with traditional thermal processing (TP). This study was conducted to evaluate the possibility of enhancing PATP lethality against the spores of Bacillus amyloliquefaciens , by sensitizing the spores with selected antimicrobial compounds (including emphasis on the use of natural antimicrobials) prior to treatment. A spore crop of B. amyloliquefaciens TMW 2.479 Fad 82, that had previously shown high resistance to combined pressure-heat treatment, was prepared on Nutrient Agar medium supplemented with 10 mg L −1 MnSO 4 ·H 2 O and incubated at 32 °C for 3 d. Spores were inoculated (at ∼10 7 –10 8 CFU mL −1 inoculum level) in HEPES buffer (pH ≤ 7.0) or selected low-acid foods (pH 5.2–5.6) with or without added antimicrobial compounds. The samples were then treated at 600 MPa and 105 °C (PATP) or 0.1 MPa and 105 °C (TP) for various holding times. Among different compounds tested, low-molecular-weight chitosan, and combination of chitosan with some surfactants were most effective ( P

Effect of aqueous extracts of pomegranate peel (PPE) and tamarind pulp (TPE) on lethality of pressure assisted thermal processing (PATP) against Bacillus amyloliquefaciens Fad 82 spores was investigated. B. amyloliquefaciens spores (≈10 8 CFU ml −1 ) were suspended in deionized water (DIW), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer PPE, and TPE (1% w/v in DIW, pH-6) and beef broth with or without PPE and TPE (0.45% w/v). Samples were subjected to pressure assisted thermal processing (PATP, 600 MPa, 105 °C), and thermal processing (TP; 0.1 MPa, 105 °C) for 0 (come-up time), 0.5, 1, 3, and 5 min. Beef broth samples were also pressure treated (HPP; 600 MPa, 35 °C) for 3 and 5 min. Dormant spore survivors were enumerated by spread-plate technique. Heat shock (80 °C for 15 min) was used to enumerate the heat sensitive spores. A 5-min PATP reduced spore survivors counts to below 1-log CFU ml −1 (≈6.5–7.0 log reduction) in PPE and TPE as compared to 2.5-log and 3.1-log in DIW and HEPES buffer, respectively. 3 min PATP treatment reduced the spore survival to 3.58 and 2.1 log CFU ml −1 in beef broth and beef broth + natural extract, respectively. TP and HPP processing could inactivate the spores only by 0.5–1.2 log CFU ml −1 . PPE and TPE are found to enhance the efficacy of PATP.

Alternative food preservation technologies include substitutes to heating methods that may have benefits that include reduction of energy consumption. High-pressure processing (HPP), membrane filtration (MF), pulsed electric fields (PEF), and ultraviolet radiation (UV) are examples of alternative preservation technologies of growing commercial interest. As unit operations these technologies operate in 4 modes of energy transfer: momentum, heat, electromagnetic, or photon transfer. The objectives of this review were: (1) to examine the fundamentals of energy requirements of 4 alternative food processing technologies such as HPP, MF, PEF, UV, and conventional high-temperature short-time (HTST) processing, (2) to establish a basis for comparison of energy consumption between or within technologies, and (3) to evaluate specific energy requirements for the 5 technologies to achieve required safety performance in apple juice. Three levels of energy evaluation for each technology including internal energy, applied energy, and consumed energy were reviewed. The comparison of the specific energy for the 5 technologies was based on information published in scientific papers where the inactivation of Escherichia coli in apple juice was explored. Based on the analysis of energy consumption of these technologies it was concluded that MF and UV have the potential to consume less specific energy than HTST, PEF, and HPP. Differences in energy consumption within each group of technologies were also observed and these could be attributed to differences in the systems. The differences in energy consumption within each group of technologies illustrate that there is potential of improvement in most technologies.

High pressure processing (HPP) has emerged as a commercially viable food manufacturing tool that satisfies consumers' demand for mildly processed, convenient, fresh-tasting foods with minimal to no preservatives. Pressure treatment, with or without heat, inactivates pathogenic and spoilage bacteria, yeast, mold, viruses, and also spores and extends shelf life. Pressure treatment at ambient or chilled temperatures has minimal impact on product chemistry. The product quality and shelf life are often influenced more by storage conditions and packaging material barrier properties than the treatment itself. Application of pressure reduces the thermal exposure of the food during processing, thereby protecting a variety of bioactive compounds. This review discusses recent scientific advances of high pressure technology for food processing and preservation applications such as pasteurization, sterilization, blanching, freezing, and thawing. We highlight the importance of in situ engineering and thermodynamic properties of food and packaging materials in process design. Current and potential future promising applications of pressure technology are summarized.

Effects of high-pressure processing (HPP, 100-600 MPa for 3 min at 30 °C) on the glucosinolate content, conversion to isothiocyanates, and color changes during storage in fresh broccoli sprouts were investigated. A mild heat treatment (60 °C) and boiling (100 °C) were used as positive and negative controls, respectively. Glucosinolates were quantified using liquid chromatography-mass spectrometry, and isothiocyanates were quantified using high-performance liquid chromatography-photodiode array detection. A formation of isothiocyanates was observed in all high-pressure-treated sprouts. The highest degree of conversion (85%) was observed after the 600 MPa treatment. Increased isothiocyanate formation at 400-600 MPa suggests an inactivation of the epithiospecifier protein. During storage, color changed from green to brownish, reflected by increasing a* values and decreasing L* values. This effect was less pronounced for sprouts treated at 100 and 600 MPa, indicating an influence on the responsible enzymes. In summary, HPP had no negative effects on the glucosinolate-myrosinase system in broccoli sprouts.

Effects of surface pasteurization on inactivation of Listeria innocua were investigated. Surface temperature, monitored during post-packaging pasteurization, was used to predict the lethality of L. monocytogenes. Temperatures reached 70°C for lean and fat sausages within 9 min of treatment. An inoculation study validated the efficacy of post-processing and the thermal lethality of L. monocytogenes. Pre-cooked sausage and ham, inoculated with approximately 107 CFU/cm2 of L. innocua, were heated to a surface temperature of 70°C. Numbers of L. innocua were reduced by 7 log on surface-inoculated sausage. Guidelines for safe, ready-to-eat meat products are provided for small scale meat processors.

Influence of high pressure processing (HPP) at 450 and 600 MPa, 30 °C for various holding times (0, 30, 60,180, 300 and 600 s) on almond milk amandin was investigated. The immunoreactivity of pressure treated almond milk was compared with raw and thermally processed (TP) almond milk (72, 85 and 99 °C for 0 to 300 s) using a sandwich enzyme-linked immunosorbent assay (ELISA), Western blot and dot blot. Monoclonal antibodies (mAbs) targeting linear (4F10) and conformational (4C10) epitopes on amandin were used to assess amandin immunoreactivity. To determine the aggregation of almond proteins, almond milk protein solubility was quantified after 300 s of HPP (up to 600 MPa, 30 °C) and TP (at 72, 85 and 99 °C, 0.1 MPa). After HPP (for all holding times), amandin can no longer be detected by the anti-conformational mAb in ELISA while signal generated from the anti-linear epitopes mAb was reduced by half (P 0.05) unless processed at 85 and 99 °C for 300 s. Western blot and dot blot also confirmed the loss of immunoreactivity by both antibodies for HPP almond milk. The reduced band intensity of the 61 and 63 kDa polypeptides and concomitant appearance of high molecular weight polypeptides in Western blot indicated that the observed decrease in immunoreactivity was partly due to the aggregation of amandin. The tested HPP and TP treatments respectively caused a maximum of ~ 70% and ~ 75% reduction in protein solubility. The study demonstrated that the loss of protein solubility, rather than the epitope destruction, may be responsible for the observed decrease in amandin immunoreactivity.

Pressure ohmic thermal sterilization (POTS) involves ohmic heating of foods by applying an electric field under elevated pressure. Experiments were conducted using a custom made POTS apparatus using carrot as the model food. The samples were processed at a target temperature of 105 °C at 600 MPa and treated for 0, 1, 3, and 5 min by regulating the electric field (30 V/cm). POTS treated carrot sample quality attributes were compared against those processed using ohmic heating (0.12 MPa, 30 V/cm, 105 °C) and pressure-assisted thermal processing (PATP; 600 MPa, 0 V/cm, 105 °C). Within the experimental conditions of the study, the thermal come-up time of the POTS, Ohmic and PATP were 1.45 min, 3.58 min and 6.84 min respectively. PATP come-up time also included the pre-heating time (≈6 min). Results indicate the POTS samples had the least textural damage due to minimal thermal exposure. POTS samples had higher crunchiness index (CI) of 0.76 compared to PATP (CI = 0.57) and ohmic heated (CI = 0.62) carrots. All the technologies investigated had minimal impact on product color. This study demonstrates the potential to produce high quality shelf stable low-acid vegetable products using POTS.

This study was carried out to isolate pressure- and heat-resistant indicator spores from selected food matrices (black pepper, red pepper, garlic, and potato peel). Food samples were processed under various thermal (90 to 105°C) and pressure (700 MPa) combination conditions, and surviving microorganisms were isolated. An isolate from red pepper powder, Bacillus licheniformis, was highly resistant to pressure-thermal treatments. Spores of the isolate in deionized water were subjected to the combination treatments of pressure (0.1 to 700 MPa) and heat (90 to 121°C). Compared with the thermal treatment, the combined pressure-thermal treatments considerably reduced the numbers of B. licheniformis spores to less than 1.0 log CFU/g at 700 MPa plus 105°C and at 300 to 700 MPa plus 121°C. The inactivation kinetic parameters of the isolated B. licheniformis spores were estimated using linear and nonlinear models. Within the range of the experimental conditions tested, the pressure sensitivity (zP) of the spores decreased with increasing temperature (up to 121°C), and the temperature sensitivity (zT) was maximum at atmospheric pressure (0.1 MPa). These results will be useful for developing a combined pressure-thermal inactivation kinetics database for various bacterial spores.

BACKGROUND The effect of pressure-assisted thermal processing (PATP) on the inactivation of Geobacillus stearothermophilus spores was determined in deionized water, cooked ground beef, egg patty mince, whole milk and mashed potatoes at 105 °C under 500 and 700 MPa. RESULTS The numbers of G. stearothermophilus spores in deionized water and milk were reduced by more than 6 log CFU mL−1 at 700 MPa and 105 °C, whereas those in cooked beef were reduced by 4.27 log CFU g−1. The inactivation patterns of G. stearothermophilus spores in all food matrices followed nonlinear behavior, showing that Weibull model fitted well to the inactivation curves of G. stearothermophilus spores in low-acid foods. CONCLUSION The complex food matrices caused a protective effect on the inactivation of G. stearothermophilus spores during PATP. The results provide useful information in inactivation kinetics of bacterial spores for validating PATP-processed low-acid foods. © 2014 Society of Chemical Industry

The objective of this work was to study the effect of nisin, alone or combined with sucrose laurate ester (SL), on enhancing Bacillus amyloliquefaciens Fad 82 spores inactivation by pressure-assisted thermal processing (PATP). Spores of B. amyloliquefaciens (108 CFU ml−1) were suspended in sterile phosphate buffer saline (pH 7.6) with concentrations of nisin (0, 100, 200, 1000, 1500 and 2000 IU ml−1) and 1.0% of SL, and combinations of nisin (1000, 1500 and 2000 IU ml−1) and SL (1.1%), and treated by PATP (700 MPa and 105 °C, for 1 min). Nisin did not show any synergetic effect with PATP in all the concentrations tested. Instead, 1.0% of SL alone was effective in enhancing inactivation.

The efficacy of a pressure–ohmic–thermal sterilization (POTS) for Bacillus amyloliquefaciens and Geobacillus stearothermophilus spore inactivation was investigated. Spores (2.5 × 108 cfu/ml) were inoculated in 0.1% NaCl solution (pH 5.0 and 7.0), green pea puree (pH 6.1), carrot puree (pH 5.0) or tomato juice (pH 4.1). Samples were ohmically (50 V/cm) treated at 600 MPa and 105 °C for various holding times using a laboratory-scale high-pressure processor. B. amyloliquefaciens and G. stearothermophilus spores suspended in 0.1% NaCl solution (pH 7.0) were inactivated by 4.6 and 5.6 log, respectively, for a 30-min holding time. B. amyloliquefaciens and G. stearothermophilus spores in tomato juice were reduced by 3.1 and 4.8 log, respectively, for a 10-min holding time. Spore germination was highest in the G. stearothermophilus suspended in 0.1% NaCl solution (pH 7.0). POTS treatment appears to be a potent method for inactivating pressure–thermal resistant bacterial spores. Industrial Relevance Food industry is interested in developing superior quality low-acid shelf-stable foods. This study evaluated the pressure–ohmic–thermal sterilization (POTS) for the inactivation of Bacillus amyloliquefaciens and Bacillus stearothermophilus endospores. The impact of food matrices and acidity on the spore resistance was also investigated. Knowledge gained from the study will help the food processors for understanding the importance of various POTS treatment parameters for sterilization of low-acid foods.

A study was conducted to develop an integrated process lethality model for pressure-assisted thermal processing (PATP) taking into consideration the lethal contribution of both pressure and heat on spore inactivation. Assuming that the momentary inactivation rate was dependent on the survival ratio and momentary pressure–thermal history, a differential equation was formulated and numerically solved using the Runge–Kutta method. Published data on combined pressure–heat inactivation of Bacillus amyloliquefaciens spores were used to obtain model kinetic parameters that considered both pressure and thermal effects. The model was experimentally validated under several process scenarios using a pilot-scale high-pressure food processor. Using first-order kinetics in the model resulted in the overestimation of log reduction compared to the experimental values. When the n th-order kinetics was used, the computed accumulated lethality and the log reduction values were found to be in reasonable agreement with the experimental data. Within the experimental conditions studied, spatial variation in process temperature resulted up to 3.5 log variation in survivors between the top and bottom of the carrier basket. The predicted log reduction of B. amyloliquefaciens spores in deionized water and carrot puree had satisfactory accuracy (1.07–1.12) and regression coefficients (0.83–0.92). The model was also able to predict log reductions obtained during a double-pulse treatment conducted using a pilot-scale high-pressure processor. The developed model can be a useful tool to examine the effect of combined pressure–thermal treatment on bacterial spore lethality and assess PATP microbial safety.

Grapefruit juice treated with high pressure processing (HPP), thermal processing (TP) and control (no treatment) was analyzed for the levels of various bioactive compounds and color, during 21 days of storage at 4 °C. The TP treatment juice had significantly ( P ≤ 0.05) higher L * and b * values than HPP and control juice throughout the storage period. A gradual decline in the level of ascorbic acid was noticed in all the treatments with significantly lower levels in TP treatment as compared to control and HPP during 0 and 7 days of storage analysis. The HPP treatment had no significant ( P ≤ 0.05) effect on the levels of citric acid, flavonoids, limonoids and coumarins, in comparison to the control treatment. The levels of carotenoids were significantly ( P ≤ 0.05) lower among both processing treatments and control at 21 days after storage as compared to the levels present at the initial 0 day after storage. No microbial growth was noticed in both the treatments and control at 28 days after storage. Industrial relevance High pressure processing is an innovative non-thermal processing technique which is applicable for industrial processing of fruit juices. However, its effect on health promoting bioactive compounds present in grapefruit has not been studied. The present study focused on evaluating the effect of HPP and TP techniques on the levels of bioactive compounds and shelf life. Results from this study suggest that HPP treatment maintains the levels of bioactive compounds, color and controls microbial growth as compared to the control treatment. Thus, HPP technique could be applied for providing fresh like grapefruit juice without altering the levels of health beneficial bioactive compounds to consumers.

The efficacy of combined pressure–heat treatment was evaluated for the inactivation of Bacillus coagulans spores in tomato juice. A spore crop of B. coagulans 185A was prepared on nutrient agar plus 500 mg L−1 dextrose and 3 mg L−1 MnSO4·H2O, incubated at 50 °C for 7 d. Spores were suspended (1.7 × 108 CFU mL−1) in tomato juice (pH 4.23) and treated at 600 MPa and process temperatures of 75, 85, 95, 100 and 105 °C, or 0.1 MPa and process temperatures of 100 and 105 °C for ≤15 min. The inactivation data was fitted to estimate kinetic inactivation parameters using selected linear and non-linear models. The models were evaluated using the mean square error, regression coefficient and accuracy factor. Depending upon the process temperature, a combined pressure–heat treatment reduced the spore population by 1.5–3.4 logs during the 30 s pressure come-up time. Pressure holding times of 10, 7, 4 and 3 min and 40 s were sufficient to inactivate the spores to below the detection limit (

A study was conducted to identify optimal ultrasound processing conditions (ultrasound energy density and temperature) to maximize the extraction of anthocyanin colorants from black carrot pomace. The treatment maximized the yield of five different anthocyanin compounds from black carrot pomace with cyanidin-3-xyloside-galactoside-glucoside-ferrulic acid (C3XGGF, 60.85-74.22 mg/L) as the most abundant anthocyanin compound, followed by cyanidin-3-xyloside-galactoside (C3XG, 49.56-70.12 mg/L). The response surface models predicted that if extraction conditions were conducted at 183.1 J/g energy density and 50 degrees C, the yield of various anthocyanin compounds would be maximized from the black carrot pomace. Response surface models were developed correlating anthocyanin yield with ultrasonication treatment parameters. The study showed the synergy of combining ultrasonication and temperature for the extraction of anthocyanin pigments from black carrot pomace. Results of the study also further demonstrate the potential of ultrasonication technology as a tool for the extraction of valuable components waste products from fruits and vegetables juice industry. (C) 2017 Elsevier Ltd. All rights reserved.

Pressure-induced textural changes in selected vegetables (carrot, potato, and red radish) were investigated using in situ electrical conductivity measurement. Electrical conductivity of the vegetables was recorded in situ up to 10 min under elevated pressures (200, 400, 600 MPa at 25 °C) using a custom-fabricated experimental setup. The tissue disintegration index ( Z ) was determined for raw, processed and freeze–thawed samples. The hardness and stiffness of the samples were evaluated using the instrumental texture analyzer. This information was related to the crunchiness index ( CI ). Pressure treatment increased electrical conductivity values of all the samples as a function of pressure and holding time. Beyond a certain threshold of pressure holding time, the electrical conductivity did not change further. In situ electrical conductivity measurement is a useful tool to document the extent of textural changes during high pressure processing.

Role of packaging barrier properties and storage conditions on pressure-assisted thermally processed (PATP) carrot quality were investigated. Samples were packaged in pouches fabricated using three packaging materials (Nylon/EVOH/EVA, Nylon/EVA and MetPET/PE) and processed at 600 MPa and 110 degrees C for 10 minutes. Processed pouches were stored at 25 and 37 degrees C, and withdrawn over 12 weeks. Samples were analyzed for color, beta-carotene and total plate count. Oxygen and water vapor transmission rates (OTR, WVTR), melting point and enthalpy of fusion of the packages were evaluated. PATP treatment resulted in product shelf-stability during storage. Packaging type and storage conditions significantly influenced the product color and beta-carotene content. Nylon/EVOH/EVA package best preserved carrot quality. PATP increased OTR of the MetPET/PE and degraded carrot color and beta-carotene during storage. Raw carrots had 11.13 mg/100g beta-carotene content. PATP treatment followed by 12 weeks storage at 37 degrees C reduced the beta-carotene content of carrots packaged in Nylon/EVOH/EVA, Nylon/EVA and MetPET/PE to 7.19, 0.04 and 0.06 mg/100g, respectively. Similarly, the red color of carrot samples (25.51 for raw carrots) decreased to 19.85, 3.44 and 7.20 for Nylon/EVOH/EVA, Nylon/EVA and MetPET/PE, respectively. The study demonstrated the importance of high barrier packaging materials in preserving PATP-treated carrot quality. (C)2011 Elsevier Ltd. All rights reserved.

Producing a thermally sterilized egg-based product with increased shelf life without losing the sensory and nutritional properties of the freshly prepared product is challenging. Until recently, all commercial shelf-stable egg-based products were sterilized using conventional thermal processing; however, this heat treatment was problematic as quality attributes of the product were negatively affected. Combining high pressure with high temperature is a potential alternative to retorting for the production of shelf-stable egg-based products. This review discusses the challenges of high pressure thermal sterilization as an alternative processing method of producing shelf-stable egg products. Attention is given to product improvement in terms of overall quality through modification of ingredients, formulation, processing and packaging, offering the industry a practical way to produce egg-based products with increased shelf life and appealing quality to the consumer.