Comparative study on color,viscosity and related enzymes of tomato juice treated by high-intensity pulsed electric fields or heat

The effects of high intensity pulsed electric fields (HIPEF) processing (35 kV/cm for 1,500 μs using bipolar 4-μs pulses at 100 Hz) on color parameters and viscosity, as well as peroxidase (POD), pectin methylesterase (PME) and polygalacturonase (PG), were evaluated during 77 days of storage at 4 °C and compared to thermal treatments at 90 °C for 1 min or 30 s for unprocessed tomato juice. HIPEF-treated tomato juice showed higher values of lightness than the thermally processed and the untreated juice throughout storage time (P < 0.05). Viscosity of HIPEF-treated tomato juice was also greater than both thermally treated and untreated for the first 35 days of storage. POD of HIPEF-treated tomato juice was inactivated by 97% whereas in the case of the thermally treated, 90 and 79% inactivation was achieved after 1 min and 30 s, respectively. The highest PME inactivation in tomato juice was obtained by PEF (82%) and heat treatment at 90 °C for 1 min (96%). PG of PEF-treated tomato juice was inactivated by 12% whereas thermal treatments at 90 °C for 1 min or 30 s achieved 44 and 22%, respectively. Despite the low rates of PG inactivation obtained, the pattern followed in the residual activity along the storage time was similar in the tomato juice treated by HIPEF than the thermally processed.     

Effect of thermosonication on quality improvement of tomato juice

Inactivation of pectinmethylesterase (PME) and polygalacturonase (PG) is required to minimize quality loss in tomato products. Tomato juice was subjected to thermosonication (TS) (24 kHz), at amplitudes of 25, 50 and 75 μm at 60, 65 and 70 °C or heat only treatments. The TS treatment at 60 °C, 65 °C and 70 °C for 41.8, 11.7 and 4.3 min exposure, respectively reduced PME activity by 90%. The heat only treatment at 60 °C, 65 °C and 70 °C for 90.1, 23.5 and 3.5 min, respectively inactivated PME by 90%. TS treatments with 25–75 μm amplitude had no significant impact on the inactivation efficiency between 60 and 70 °C. After TS the average particle size decreased noticeably (< 30 μm) and viscosity increased 2–4 fold, compared to the heat treated or untreated juice (180 μm)_. These results suggest that TS at 60 and 65 °C could be useful to obtain tomato juice with a low residual PME activity and high viscosity.Industrial relevanceThe processed tomato industry is constantly in search for potential alternative processes to conventional “cold break” and “hot break” treatments that could inactivate the pectic enzymes of importance. The findings of this study would help the industry to inactivate pectinmethylesterase (PME) enzyme at a lower temperature range and also achieve a higher viscosity due to the mechanical effects of thermosonication. Low temperature treatment would enable the retention of fresh-like properties of tomato juice. Based on the findings of this study, thermosonication could be considered as a potential alternative to conventional “cold break” and “hot break” treatments of tomato juice.     

Evaluation of processing qualities of tomato juice induced by thermal and pressure processing

Effects of processing conditions including hot-break processing (92 °C for 2 min), cold-break processing (60 °C for 2 min) and hydrostatic pressure treatments (100-500 MPa) at different temperatures (4, 25 and 50 °C) for 10 min on quality aspects of tomato juice were investigated. Both hot- and cold-break processing induced significant changes in color, viscosity and radical-scavenging capacity of tomato juice compared with control (fresh tomato juice); moreover, hot-break processing induced a specific range of reduction of pectin methylesterase (PME) and polygalacturonase (PG) activities. Pressure treatments at and below 200 MPa at 4 and 25 °C maintained the color, extractable total carotenoids and lycopene, and radical-scavenging capacity; further, those at 500 MPa at 4 and 25 °C improved all the quality attributes the most except inactivation of PME in this study. The residual activity of PME showed the lowest after treating by 200 MPa at 25 °C; however, the PME activity was enhanced by treatments at 300-500 MPa and various temperatures. The residual activity of PG decreased gradually to 72% with pressure elevated from 100 to 400 MPa at 4 and 25 °C, further, that declined quickly to 10% after 500 MPa treatments. This research clearly shows that it is possible to selectively produce good tomato juice products by high pressure processing at ambient temperature.     

Thermal and High-Pressure Stability of Pectinmethylesterase, Polygalacturonase, β-Galactosidase and α-Arabinofuranosidase in a Tomato Matrix: Towards the Creation of Specific Endogenous Enzyme Populations Through Processing

The thermal and pressure stability of tomato pectinmethylesterase (PME), polygalacturonase (PG), β-galactosidase (β-Gal), and α-arabinofuranosidase (α-Af) were investigated in situ. Enzyme inactivation by thermal and high-pressure processing (respectively 5 min at 25–95 °C at 0.1 MPa and 10 min at 0.1–800 MPa at 20 °C) was monitored by measuring the residual activity in crude enzyme extracts of treated tomato purée samples. PME was completely inactivated after a 5-min treatment at 75 °C. Only 30 % of the pressure stable PME was inactivated after a treatment at 800 MPa (20 °C, 10 min). A 5-min treatment at 95 °C and a treatment at 550 MPa (20 °C, 10 min) caused complete PG inactivation. β-Gal and α-Af activities were already reduced significantly by thermal treatments at 42.5–52.5 °C and 45–60 °C, respectively. These enzymes were, however, rather pressure resistant: treatments at respectively 700 and 600 MPa were necessary to reduce the activity below 10 % of the initial value. Assuming that first-order, fractional conversion or biphasic inactivation models could be applied to the respective enzyme inactivation data, inactivation rate constants and their temperature or pressure dependence for the different enzymes were determined. Based on differences in process stability of the enzymes, possibilities for the creation of specific “enzyme populations” in tomato purée by selective enzyme inactivation were identified. For industrially relevant process conditions, the enzyme inactivation data obtained for tomato purée were shown to be transferable to intact tomato tissue.     

Inactivation kinetics of polygalacturonase in tomato juice

The inactivation kinetics of polygalacturonase (PG) in tomato juice was studied during thermal and high-pressure/thermal processing. In the temperature range of 55–70 °C the thermal inactivation of polygalacturonase in tomato juice followed a fractional conversion model, with a thermostable fraction of approximately 14%. Under conditions of combined high-pressure/thermal processing, 200–550 MPa/5–50 °C, PG inactivation presented first order kinetics. A mathematical model to describe the inactivation rate constant as a function of pressure and temperature was formulated. Industrial relevance: Polygalacturonase is responsible for the decrease of viscosity in tomato-based products. However, little research on thermal and high pressure/thermal inactivation kinetics of tomato Polygalacturonase has been reported. This research clearly shows that it is possible to selectively inactivate PG by high pressure/thermal processing without applying high temperatures. This leads to tomato-based products with improved functional properties while other quality attributes (color, flavor, nutritional value) are maintained.     

Thermal and high-pressure stability of purified polygalacturonase and pectinmethylesterase from four different tomato processing varieties

Polygalacturonase (PG) and pectinmethylesterase (PME) were extracted and purified from four tomato varieties (Galeón, Malpica, Perfectpeel and Soto) used in the processing industry. The processing stability (thermal and high pressure) of PG and PME from the four varieties was analyzed, and they all showed the same behavior. PG was present in two isoforms, PG1 (inactivated at 90 °C, 5 min) and PG2 (inactivated at 65 °C, 5 min). In contrast, PG1s and PG2s showed the same pressure stability, both can be inactivated at room temperature in the pressure range of 300–500 MPa. On the other hand, purified PMEs could be thermally inactivated (5 min, 70 °C) but 50% of its activity remained after high-pressure treatment (850 MPa, 15 min, 25 °C). High pressure processing can thus be used for selective inactivation of PG in tomato processing (while keeping PME intact). This fact could open prospectives for improving texture/rheology of processed tomato based products; however further research in the texture/rheology area is needed.     

Evaluation of heat and oxidative damage during storage of processed tomato products. II. Study of oxidative damage indices

Tomato products (pulp, puree and paste) submitted to accelerated aging (30, 40 and 50 °C for 3 months) were studied to evaluate variations in the kinetics of the degradation of antioxidants and antioxidant activity. The carotenoids lycopene and β‐carotene, ascorbic acid, rutin and total phenolics were analysed. The antioxidant activity was measured using (a) the xanthine oxidase (XOD)/xanthine system, which generates superoxide radicals and hydrogen peroxide, and (b) the linoleic acid/CuSO₄ system, which promotes lipid peroxidation. The ascorbic acid content decreased even at 30 °C, following pseudo‐first‐order kinetics, with an activation energy of 105 200 J mol^?1 for tomato pulp and 23 600 J mol^?1 for tomato paste. The lower the initial ascorbic acid content, the higher was the degradation rate. Variations in phenolic compounds occurred at 40 °C and higher, following pseudo‐zero order kinetics. The antioxidant activity of the hydrophilic fraction of the tomato products depended on both antioxidant degradation and the Maillard reaction and could not be described by a kinetic model. The β‐carotene content decreased even at 30 °C, whereas the lycopene content was stable in all samples. The antioxidant activity of the lipophilic fraction of the tomato products decreased following pseudo‐first order kinetics, with an activation energy of 22 200 J mol^?1 for tomato pulp and 20 200 J mol^?1 for tomato paste. It is concluded that significant ‘oxidative damage’ can occur in tomato products during their commercial shelf‐life. Copyright © 2003 Society of Chemical Industry     

The kinetics of inactivation of pectin methylesterase and polygalacturonase in tomato juice by thermosonication

The ultrasonic inactivation kinetics of polygalacturonase (PG) and pectin methylesterase (PME) in tomato juice were studied at a frequency of 20 kHz, amplitude of 65 μm and temperatures between 50 and 75 °C. Thermal treatments at the same temperatures were conducted to separate the effects of heat and ultrasound. The thermal inactivation of PG was described by a fractional conversion model with PG 1 remaining stable, whereas the inactivation of PG by combined ultrasonic and heat treatment (thermosonication) was best described by first order biphasic kinetics, with both PG1 and PG2 inactivated at different rates. The thermal and thermosonication inactivation of PME was described well by first order kinetics. The inactivating effect of combined ultrasound and heat was synergistic. Thermosonication enhanced the inactivation rates of both PME and PG. The inactivation rate of PME was increased by 1.5–6 times and the inactivation rate of PG2 by 2.3–4 times in the temperature range 60–75 °C, with the highest increase corresponding to the lowest temperature.     

Comparison of the application of high pressure and pulsed electric fields technologies on the selective inactivation of endogenous enzymes in tomato products

Application of novel technologies such as high pressure (HP) or pulsed electric fields (PEF) on the remaining activity of endogenous tomato pectinolytic enzymes such as Pectinmethylesterase (PME) and Polygalacturonase (PG), responsible for tomato products texture was studied. HP combined with temperature (200–800 MPa @ 55–75 °C), PEF (5.5–12.5 kV/cm, 0–12 ms treatment time) and thermally treated (55–75 °C) samples were studied. After thermal treatment, PG appeared to be more resistant than PME. Opposite behavior was observed for HP treated samples. For PME inactivation more intense P-T process conditions were necessary compared to PG. For PEF treatment, 98% inactivation was observed at 12.5 kV/cm and 6 ms for PME, and at 5.5 kV/cm and 11 ms for PG. PME appeared to be more HP and PEF resistant compared to PG. The results support the potential application of HP and PEF to selectively inactivate PG while partially retaining PME in tomato juices, aiming in improved tomato products' textural characteristics.Industrial relevanceThe aim of the tomato industry is to produce tomato products of desired textural and sensorial characteristics while increasing the yield by decreasing the evaporated water. This can be achieved by applying novel technologies such as high pressure (HP) processing or pulsed electric fields (PEF) that affect the remaining activity of the endogenous pectinolytic enzymes such as Pectinmethylesterase (PME) and Polygalacturonase (PG), responsible for the final texture leading to products with improved quality characteristics such as viscosity, color and consistency. However, HP treatment is a batch process and makes it difficult for the treatment of large quantities (production of small quantities of superior products could be the target of the application of HP technology), while PEF technology could be applied in line with the typical production flow of that kind of products before the cold break step.     

Effect of UV-LED irradiation processing on pectolytic activity and quality in tomato (Solanum lycopersicum) juice

The aim of this research was to analyze pectolytic activities (pectinmethylesterase “PME” and polygalacturonase “PG”) and physical qualities in tomato juice treated by UV-LED, Hot Break (HB), and Cold Break (CB) processing. Tomato juice treated by UV-LED (117 mJ/cm²) obtained a residual PME activity similar to that of CB, and tomato juice treated by UV-LED (351 mJ / cm²) had a residual PME activity 28.3% lower than HB (p < 0.05). The effect of UV-LED on PG activity was similar to HB and 49% lower than CB (p < 0.05). Furthermore, UV-LED processing caused a decrease in pH and total acidity and a significant increase in total lycopene content. Antioxidant activity and viscosity for UV-LED processing were similar to CB, total polyphenol content and °Brix were similar to HB (p > 0.05). Therefore, this study provides a promising application of UV-LED technology for controlling enzymatic activity in tomato juice, and an alternative to heat treatment.Industrial relevanceNowadays, the tomato industry uses heat treatments to inactivate pectolytic enzymes. UV-LED technology could have an industrial appreciation, as it was efficient in decrease the activity of these enzymes, in addition, preserved and increased some bioactive compounds. Therfore, it is proposed as an efficient method for processing fruit and vegetable juices. Nevertheless, further studies are needed to clarify the effect of this technology on pectolytic enzymes and quality parameters in liquid fruit and vegetable foods.     

Inactivation of tomato pectic enzymes by manothermosonication

 The resistance of tomato pectic enzymes to manothermosonication (MTS), a combined treatment of heat and ultrasound under moderate pressure, was studied. Pectinmethylesterase (PMF) and polygalacturonases (PG) I and II were inactivated much more efficiently by MTS than by simple heating. In MTS inactivation of these enzymes, the effect of heat and ultrasonic waves was synergistic. D values [the time required for the (original) enzyme activity to decrease by 90%] for PME heat inactivation at 62.5  °C were reduced 52.9-fold by MTS and those for PG I at 86  °C and PG II at 52.5  °C, 85.8-fold and 26.3-fold, respectively. Received: 23 January 1998 / Revised version: 23 March 1998     

Inactivation of tomato pectic enzymes by manothermosonication

 The resistance of tomato pectic enzymes to manothermosonication (MTS), a combined treatment of heat and ultrasound under moderate pressure, was studied. Pectinmethylesterase (PMF) and polygalacturonases (PG) I and II were inactivated much more efficiently by MTS than by simple heating. In MTS inactivation of these enzymes, the effect of heat and ultrasonic waves was synergistic. D values [the time required for the (original) enzyme activity to decrease by 90%] for PME heat inactivation at 62.5  °C were reduced 52.9-fold by MTS and those for PG I at 86  °C and PG II at 52.5  °C, 85.8-fold and 26.3-fold, respectively. Received: 23 January 1998 / Revised version: 23 March 1998     

High hydrostatic pressure treatment and storage of carrot and tomato juices: Antioxidant activity and microbial safety

The application of high hydrostatic pressure (HHP) (250 MPa, 35 °C for 15 min) and thermal treatment (80 °C for 1 min) reduced the microbial load of carrot and tomato juices to undetectable levels. Different combinations of HHP did not cause a significant change in the ascorbic acid content of either juice (P > 0.05). Both heat treatments (60 °C for 5–15 min and 80 °C for 1 min) resulted in a significant loss (P < 0.05) in the free‐radical scavenging activity as compared to untreated samples. HHP‐treated juices showed a small loss of antioxidants (below 10%) during storage. The ascorbic acid content of pressurized tomato and carrot juices remained over 70 and 45% after 30 days of storage, respectively. However, heat treatment caused a rapid decrease to 16–20%. Colour changes were minor (ΔE = 10) for pressurised juices but for heat‐pasteurised samples it was more intense and higher as a result of insufficient antioxidant activity. HHP treatment (250 MPa, 35 °C for 15 min) led to a better product with regard to anti‐radical scavenging capacity, ascorbic acid content and sensory properties (colour, pH) of the tomato and carrot juices compared to conventional pasteurisation. Therefore, HHP can be recommended not only for industrial production but also for safe storage of fresh juices, such as tomato and carrot, even at elevated storage temperatures (25 °C). Copyright © 2007 Society of Chemical Industry     

Investigation and kinetic evaluation of furan formation in tomato paste and pulp during heating

Due to its high ascorbic acid content and acidic environment, tomato is susceptible for furan formation during heat treatment. In this study, kinetics of furan formation was analyzed in order to have an understanding of the reactions taking place in tomato pulp during heating. Also several tomato paste samples were investigated in terms of their furan and hydroxymethylfurfural (HMF) concentrations, and the possible furan precursors. Paste samples were found to contain 3.3–13 ng/g furan and 0.9–39.4 μg/g HMF (dry weight basis). Freshly prepared tomato pulps were heated at 70, 80, and 90 °C for different times, and analyzed for ascorbic acid, dehydroascorbic acid, and furan concentrations. The formation rates of furan in the very first 5 min of heating at 70, 80, and 90 °C were 0.0071, 0.0130, and 0.0168 nmol/g·min, respectively. Rate constants related to reactions taking place during furan formation were estimated by multi-response kinetic modeling. The results revealed that ascorbic acid oxidation is the critical step in furan formation reaction mechanism during heating of tomato pulp, and prevention of oxidation during processing might help to limit furan formation.     

Enhanced inactivation of pectin methyl esterase in orange juice using modified supercritical carbon dioxide treatment

The aim of the study is to quantify the effect of ethanol addition and exposure surface on the inactivation of pectin methyl esterase (PME), a juice clarifying enzyme, in orange juice using supercritical carbon dioxide (SC‐CO₂). Addition of ethanol to the SC‐CO₂ at 2% (v/v) caused greater inactivation than SC‐CO₂ alone, with a maximum reduction of PME activity of 97% at 30 MPa and 40 °C for 60 min. As the surface area to volume ratio was increased, the rate of inactivation of PME increased. Analysis of first‐order reaction kinetic data revealed that D values were greatly influenced by ethanol addition and agitation. With the addition of 2% ethanol, the D value reduced by half, that is, 56 min from 109 min. With impeller agitation of the sample at 1100 ± 100 rpm, the D value for PME was further reduced to 43 and 30 min without and with ethanol, respectively. The activity of PME treated with SC‐CO₂ remained unchanged after 14 days of storage at 4 °C. Treatment did not significantly change pH or colour, but did significantly increase the cloud values of the juice, resulting in a cloud stabilised juice with similar qualities to fresh juice.     

Effect of rotating tray drying on antioxidant components,color and rehydration ratio of tomato saladette slices

A rotating tray drier was built and controlled for drying of tomato slices at different temperatures (45, 50 and 60 °C) and air velocities (0.6 and 1.2 m s^?1) with and without tray rotation. Drying curves were fitted using the Page mathematical model. Effective diffusivities for the different drying conditions correlated well with the chemical composition variables; lycopene, ascorbic acid and total polyphenols (TPP). The effect of drying conditions over quality of dried tomato slices was evaluated by quantifying their contents of lycopene, ascorbic acid and TPP, and measuring their color and rehydration ratio. The best drying conditions were 60 °C drying temperature and 0.6 m s^?1 air velocity with the use of tray rotation. These conditions minimized the degradation of lycopene (2.9%), ascorbic acid (17.3%) and TPP (2.1%) during drying. Tray rotation has a contribution on the a* color value, as well as on the lycopene and ascorbic acid concentrations (5% significance level).     

Shelf‐Life Study of an Orange Juice–Milk Based Beverage after PEF and Thermal Processing

ABSTRACT: The effect of thermal and pulsed electric field (PEF) processing on the shelf life of an orange juice–milk beverage (OJMB) was studied. The intensities of the treatments were selected to produce similar inactivation of pectin methyl esterase (PME), an enzyme responsible for the jellification and loss of fresh juice cloudiness. Physical properties (pH, °Brix, and color), microbial population, PME activity, and volatile compounds of the product were analyzed during a 4‐wk storage at 8 to 10 °C. The pH was not affected by any treatment but decreased during the storage in the untreated sample. The °Brix values were decreased by the 2 treatments. The thermal and PEF treatments initially inactivated PME activity by 90%. During storage, the PME activity remained constant in the 2 treated samples and decreased slightly in the untreated sample. The reductions in bacterial as well as yeast and mold counts were similar after the 2 treatments (4.5 and 4.1 log CFU/mL for thermal against 4.5 and 5 log CFU/mL for PEF). Based on the initial bacterial counts of the control, it was estimated that the shelf lives of the OJMB treated with thermal and PEF processing stored at 8 to 10 °C were 2 and 2.5 wk, respectively. Differences were observed in the color parameters of the OJMB between the 2 treatments in comparison with the control, with a higher difference observed in the thermally processed samples. The relative concentration of volatile compounds was higher in OJMB processed by PEF treatment than that in the thermally processed sample. During storage, the loss of volatile compounds was lower in the PEF sample while thermal and control samples had a similar rate of loss. For an OJMB, treatment with PEF achieved the same degree of microbial and enzyme inactivation as the thermal treatment, but better preserved color and volatile compounds.     

Effects of industrial tomato paste processing on ascorbic acid, flavonoids and carotenoids and their stability over one-year storage

BACKGROUND : The effects of industrial tomato paste processing and long‐term (12 months) ambient storage on the content and stability of quercetin, kaempferol, ascorbic acid (AA), dehydroascorbic acid (DHAA), β‐carotene and lycopene were evaluated in a commercially produced tomato paste. RESULTS : The initial thermal treatment (hot break; 93 °C for 5 min) resulted in significant reductions in quercetin (54%), kaempferol (61%), AA (63%) and β‐carotene (30%), whereas subsequent processing steps (e.g. evaporation and sterilization) did not result in marked changes in these compounds. Lycopene was stable during hot break but decreased by 20% through evaporation and sterilization. The ratio of DHAA:vitamin C increased during hot break to 23%, whereas the ratio of DHAA:vitamin C remained relatively low in subsequent processing steps, indicating that AA was not oxidized. AA decreased with prolonged storage, with only 13% remaining at 12 months. The carotenoids and quercetin remained stable through 12 months of ambient storage. CONCLUSIONS : Tomato pomace contained significant amounts of carotenoids and flavonoids, indicating that it may be an underutilized processing byproduct. Copyright © 2011 Society of Chemical Industry     

Chemical Characterization of Tomato Juice Fermented with Bifidobacteria

Abstract: The objective of this research was to characterize the chemical properties of tomato juice fermented with bifidobacterial species. Tomato juice was prepared from fresh tomatoes and heated at 100 °C prior to fermentation. Bifidobacterium breve, Bifidobacterium longum, and Bifidobacterium infantis were inoculated in tomato juice and kept at 35 to 37 °C for up to 6 h. Fructooligosaccharide (FOS) was added to tomato juice prior to fermentation. The analyses for brix, total titratable acidity (TTA), pH, color, and lycopene content were conducted to characterize tomato juices fermented with bifidobacterial species. Heat treatment of tomato juice did not cause any significant changes in brix, pH, and TTA. Only the redness of tomato juice was significantly increased, as the heating time increased to 30 min. The tomato juices fermented with B. breve and B. longum exhibited significant decreases in pH (3.51 and 3.80, respectively) and significant increases in TTA (13.50 and 12.50, respectively) (P < 0.05). B. infantis did not cause any significant change in the chemical properties of tomato juice. The addition of FOS further improved the fermentation of tomato juice by bifidobacterial species. The lycopene contents of tomato juice were significantly increased from 88 to 113 μg/g by heat treatment at 100 °C (P < 0.05), however did not exhibit any significant change after fermentation with bifidobacterial species.     

Selection of Process Conditions for High Pressure Pasteurization of Sea Buckthorn Juice Retaining High Antioxidant Activity

Sea buckthorn berries juice is a nutritious beverage, rich in vitamin C and carotenoids with high antioxidant activity. The main requirements for a freshly squeezed sea buckthorn juice production are the cloud stability and antioxidant activity retention after processing. Appropriate process technologies and conditions have to be applied in order to inactivate pectin methyl esterase (PME), responsible for cloud loss, while maintaining the nutritional characteristics and antioxidant activity of the juice. The objectives of the present work were to study and model the effect of thermal treatment and high pressure (HP) processing on the inactivation kinetics of endogenous PME and on total antioxidant activity alteration. Thermal treatment significantly affected PME inactivation and residual antioxidant activity. Processing even at mild process conditions (60 °C for 1 min) resulted in 2.5-fold antioxidant activity reduction and 50 % PME inactivation compared to untreated sample. Pressure and temperature acted synergistically for PME inactivation that followed first-order kinetics with a residual PME activity at all pressure–temperature combinations used (200–600 MPa and 25–35 °C). The effect of temperature and pressure on the inactivation rate constants was expressed through the activation energy and activation volume, respectively. Values of 163 kJ/mol and ?17 mL/mol at reference pressure of 600 MPa and reference temperature of 35 °C were estimated, respectively. Antioxidant activity of the samples was expressed through the determination of the effective concentration (EC₅₀). A slight increase in sea buckthorn antioxidant activity when applying pressures (200–600 MPa) at ambient temperature (25 °C) was observed compared to the corresponding value of untreated juice. Processing at higher temperatures did not significantly alter the total antioxidant activity of sea buckthorn juice. For sample treated at 600 MPa–35 °C for 5 min, a 5 % reduction of total antioxidant activity was observed. These conditions are proposed as effective process conditions for sea buckthorn juice cold pasteurization, based on the higher antioxidant activity retention and simultaneous PME inactivation.