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From 2012, the preservation of food products under pressure has been increasingly studied and the knowledge acquired has enlarged since several food products have been studied at different storage conditions. This new food preservation methodology concept called Hyperbaric Storage (HS) has gain relevance due to its potential as a replacement or an improvement to the conventional cold storage processes, such as the traditional refrigeration (RF), or even frosting, from the energetic savings to the reduction of the carbon foot-print. Briefly, HS is capable to inhibit the microbial proliferation or its inactivation which results in the extension of the shelf-life of several food products when compared to RF. Moreover, the overall quality parameters seem not to be affected by HS, being the differences detected on samples over storage similar to lower when compared to the ones stored at RF. This review paper aims to gather data from all studies carried out so far regarding HS performance, mainly at room temperature on fruit juices, meat and fisheries, as well on dairy products and ready-to-eat meals. The HS advantages as a new food preservation methodology are presented and explained, being also discussed the industrial viability and environmental impact of this methodology, as well its limitations.

Extracts from fruit processing by-products usually present high amounts of bioactive compounds with several important activities such as antioxidant and antimicrobial capacities. In this work we studied (i) the cytotoxicity profile of pomegranate peel extract and (ii) safety and quality aspects after incorporating this extract in carrot juice - a beverage with low antioxidant potential and highly prone to microbial growth. The extract was obtained by high-pressure extraction and was non-cytotoxic towards the Caco-2 cell line after in vitro digestion. The non-cytotoxic pomegranate peel extract was added to carrot juice in a concentration of 5 mg mL-1. Fortified juices were processed by high-pressure and conventional heat and stored under refrigeration. On the 28th day of storage, microbial counts in PPE-fortified juices were reduced by 1.0 log10 CFU mL-1 and the pressurized juices showed significantly fewer counts than the thermal-treated ones. Just after processing, phenolic and flavonoid contents, as well as ABTS and FRAP antioxidant capacities, increased 3.6, 3.5, 8.2, and 9.4-fold, respectively in the fortified juices. The extract addition did not affect any colour parameter and all studied physicochemical parameters i.e. total soluble solids, pH, colour, total phenolics, flavonoids, hydrolysable tannins, and antioxidant capacity remained constant throughout storage. These findings could pave the way towards the development of safe beverages with improved bioactive properties.

Lipid stability, physical properties and volatiles profile of vacuum-packaged fresh Atlantic salmon (Salmo salar) loins were evaluated after hyperbaric storage at low temperature (HS/LT: 60 MPa/10 °C) and compared to atmospheric pressure and conventional refrigeration (AP/5 °C) after 5, 15 and 30 days, and at low temperature (AP/10 °C), after 5 and 15 days. No variations in drip loss and water holding capacity were observed for HS/LT samples. Compared to AP, HS/LT caused lower changes on muscle fibres, visible by scanning electron micrographs, and a decrease of resilience property (only after 30 days). In addition, myofibrillar fragmentation index did not change at HS/LT. Fatty acids were generally not affected by the different storage conditions, while the polyene index at HS/LT was similar to fresh samples during the 30 days of storage, confirmed by the lower lipid oxidation state of these samples, compared to AP. According to the volatile profile (SPME-GC/MS), HS samples showed to be more similar to the fresh ones, retaining fresh-like alcohols and aldehydes, generally not detected in AP samples after 15 days, the latter presenting spoilage-related compounds probably derived from microbial activity. According to these results, HS/LT represents a promising preservation methodology for fresh salmon loins (and fish in general), retaining better important physicochemical properties for 30 days, when compared to the conventional refrigeration., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Edible flowers, such as pansies, have a short shelf-life. Crystallization is a treatment used to prolong the shelf-life of fruits and vegetables. So, the aim of the present work was to investigate the effect of crystallization in the physicochemical, microbial and antioxidant properties of pansies ( Viola×wittrockiana ) during room temperature storage (7, 15, 30, 60 and 90 days). Comparing fresh and crystallized pansies, significant differences were detected. After 90 days of storage, crystallized pansies kept similar appearance to those immediately after treatment. A significant decrease in water activity, moisture, ash and protein contents was observed between 0 and 90 days of storage for crystallized pansies. Some bioactive compounds, such as flavonoids and monomeric anthocyanins, showed a significant decrease after 90 days of storage, while hydrolysable tannins increased. Concerning phenolic compounds, these maintained constant along storage. The microbial load of crystallized pansies during all storage time was lower than fresh ones. So, crystallization can be an effective method for pansies preservation, being some nutritional and bioactive compounds, little affected during storage. However, crystallization contributed to a high increase in sugar content and energy values compared to fresh pansies.

The long-term effect of thermal pasteurization (TP) and high-pressure processing (HPP) of orange juices stored under refrigeration, on the bioactive components and antioxidant activity, was compared. Total phenolic content (TPC), flavonoid, anthocyanin, and carotenoid contents, the individual content of major phenolic components, and the antioxidant activity, were evaluated in TP- and HPP-treated juices over a 36-day period. At day 0, no significant differences in TPC, and a decrease in carotenoid content after both treatments, were observed. TP caused a decrease of flavonoid and anthocyanin contents, while HPP increased flavonoid content. Three major phenolic components were identified: apigenin-6,8-di- C -glucoside, naringenin-7- O -rutinoside, and hesperetin-7- O -rutinoside, the latter increasing ca. 45% immediately after HPP. During storage, a decrease in TPC, and in the anthocyanin and carotenoid contents of both treated juices was observed, with higher anthocyanin and phenolic contents in HPP juices. A significant increase of hesperetin-7- O -rutinoside content was observed in HPP juice. Both treatments caused a decrease (26% and 13%, respectively) of antioxidant activity. Most of the kinetic profiles followed zero-order patterns, with HPP juices showing a considerably higher half-life than TP ones. These results clearly demonstrate the advantages of HPP for orange juice preservation allowing, also, their nutritional benefits to be enhanced by increasing the content of some bioactive components.

Fish freshness is lost by autolytic degradation produced by endogenous enzymes. Frozen storage is one of the most used methods to preserve fish properties. However, protein denaturation has shown to be a major problem for frozen European hake (Merluccius merluccius), leading to texture losses and off-odour development. The aim of this work was to study the changes produced by high-pressure processing (HPP) before freezing on quality of frozen European hake stored at -21 °C for 12 months. The effect of HPP (150-450 MPa) on mechanical properties and expresible water was evaluated in raw and cooked fish samples. The effect on colour (L*, a* and b*) was assessed only in raw fish. Results showed that HPP before freezing is beneficial to maintain expresible water in good levels up to 6 months. The luminosity significantly increased with pressure level. Textural profile of raw samples showed that HPP increased hardness, adhesiveness and springiness of frozen hake. Cooked samples were also affected by HPP, being the best results obtained at 300 MPa for 6 months of frozen storage. Overall, results showed that HPP improves the quality of frozen hake., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The effect of hyperbaric storage on Bacillus subtilis endospores, as a new food preservation methodology with potential to replace the conventional refrigeration processes, was assessed and compared to refrigeration. To do so, three different matrices (McIlvaine buffer, carrot juice and brain-heart infusion broth, BHI-broth) were inoculated with B. subtilis endospores and stored at 25, 50 and 100 MPa at variable/uncontrolled room temperature (18-23 °C), under refrigeration (4 °C), and room temperature at atmospheric pressure (0.1 MPa), up to 60 days. Two different quantification procedures were performed to assay both vegetative and endospores (unheated samples) and endospores (heated samples), to assess germination under pressure. The results showed that hyperbaric storage yielded pronounced endospore loads reductions in carrot juice and BHI-broth at 50 and 100 MPa, while in McIlvaine buffer, lower endospore loads reductions were observed. At 25 MPa, the endospores germinated and outgrew in carrot juice. Under refrigeration conditions, both carrot juice and BHI-broth underwent endospore germination and outgrowth after 60 and 9 days of storage, respectively, while in McIlvaine buffer there were no endospore outgrowth. These results suggest that hyperbaric storage at room temperature might not only be a feasible preservation procedure regarding endospores, but also that the food product (matrix characteristics) seems to influence the microbial inactivation that occurs during hyperbaric storage., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Hyperbaric storage (HS) of raw watermelon juice, up to 10days at 50, 75, and 100MPa at variable/uncontrolled room temperature (18-23°C, RT) was studied and compared with storage at atmospheric pressure (AP) under refrigeration (4°C, RF) and RT, being evaluated microbiological (endogenous and inoculated), physicochemical parameters, and enzymatic activities. Ten days of storage at 50MPa resulted in a microbial growth evolution similar to RF, while at 75/100MPa were observed microbial load reductions on endogenous and inoculated microorganisms (Escherichia coli and Listeria innocua, whose counts were reduced to below the detection limit of 1.00 log CFU/mL), resulting in a shelf-life extension compared to RF. The physicochemical parameters remained stable at 75MPa when compared to the initial raw juice, except for browning degree that increased 1.72-fold, whilst at 100MPa were observed higher colour variations, attributed to a lycopene content decrease (25%), as well as reductions on peroxidase residual activity (16.8%) after 10days, while both polyphenol oxidase and pectin methylesterase residual activities were similar to RF. These outcomes hint HS as a reliable alternative to RF as a new food preservation methodology, allowing energy savings and shelf-life extension of food products. This is the first paper studying the effect of HS on inoculated microorganisms and on a broad number of physicochemical parameters and on endogenous enzymatic activities, for a preservation length surpassing the shelf-life by RF., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Hyperbaric storage at room temperature (without temperature control) of raw bovine meat was studied and compared to refrigeration. Samples were first stored for 12h at 50, 100 and 150MPa, and in a second set of experiments, for a longer period of 10days at 50MPa. For the 12h storage, refrigeration and 50MPa had a similar microbial growth inhibition effect and, at 100 and 150MPa an additional microbial inactivation effect was found. For the longer experiment (10days at 50MPa) results pointed for a shelf-life increase of raw beef compared to samples stored under refrigeration. For both tests (12h and 10days) samples preserved under pressure showed no detrimental effect on physicochemical parameters comparatively to the initial and refrigerated samples. These results indicate that hyperbaric storage at room temperature not only allows high energy savings, but additionally has potential to extend the shelf-life of a perishable food product compared to refrigeration., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The impact of high hydrostatic pressure (HHP) treatments on volatile composition of sulphur dioxide-free wines during bottle storage was studied. For this purpose, white and red wines were produced without sulphur dioxide (SO2) and, at the end of the alcoholic fermentation, the wines were pressurised at 500 MPa and 425 MPa for 5 min. Wine with 40 ppm of SO2 and a wine without a preservation treatment were used as controls. More than 160 volatile compounds, distributed over 12 chemical groups, were identified in the wines by an advanced gas chromatography technique. The pressurised wines contained a higher content of furans, aldehydes, ketones, and acetals, compared with unpressurised wines after 9 months of storage. The changes in the volatile composition indicate that HHP treatments accelerated the Maillard reaction, and alcohol and fatty acid oxidation, leading to wines with a volatile composition similar to those of faster aged and/or thermally treated wines., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Hyperbaric storage (8h) of melon juice (a highly perishable food) at 25, 30 and 37°C, under pressure at 25-150 MPa was compared with atmospheric pressure storage (0.1 MPa) at the same temperatures and under refrigeration (4°C). Comparatively to the refrigerated condition, hyperbaric storage at 50/75 MPa resulted in similar or lower microbial counts (total aerobic mesophiles, enterobacteriaceae, and yeasts/moulds) while at 100/150 MPa, the counts were lower for all the tested temperatures, indicating in the latter case, in addition to microbial growth inhibition, a microbial inactivation effect. At 25 MPa no microbial inhibition was observed. Physicochemical parameters of all samples stored under pressure (pH, titratable acidity, total soluble solids, browning degree and cloudiness) did not show a clear variation trend with pressure, being the results globally similar to refrigeration storage. These results show the potential of hyperbaric storage, at and above room temperature and with potential energy savings, comparatively to refrigeration., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The changes in microbiological, physiochemical, and textural properties in fresh cheeses made from either cow or goat milk were observed under hyperbaric storage (HS, 50–100 MPa) at room temperature (RT) and compared with refrigerated storage under normal atmospheric pressure for 60 days. An initial microbial growth inhibition was observed for both cheese types, as well as a considerable inactivation of all endogenous microbiota under HS/RT (75–100 MPa/RT). This contributed to a higher stability of pH and color values, especially at the higher pressure at room temperature (100 MPa/RT) throughout 60 days storage. A compression effect occurred during HS/RT, resulting in higher whey loss, reduction in moisture content, and textural changes. Such changes tended to decrease over time, to values closer to the initial ones, with hardness values at the 60th day of storage at 75/RT similar to those observed for refrigeration on the 7th day and 1.4‐fold higher than those observed at 100/RT. Overall, HS/RT reduced the microbial populations load during storage (≥5 log units in some cases), with minimal effects on most of the evaluated quality parameters. These results point to a considerable shelf‐life extension of HS fresh cheeses, without temperature control, pinpointing HS as a more sustainable preservation strategy than refrigeration, with great potential for industrial application. Practical Application: The results presented in this study point to increased microbial stability of fresh cheeses when stored under hyperbaric storage without temperature control, leading possibly to an increased shelf‐life, of up to 60 days. This kind of new food preservation strategy may be suitable for longer transportation of foods, where energy may not be handily and widely available, while additionally contributing to increased shelf‐life and safety. Also, hyperbaric storage could be applied throughout the food storage, improving shelf‐life with a lower carbon footprint than refrigeration. [ABSTRACT FROM AUTHOR]

Edible flowers are a new gourmet product; however, they are not always available all years. Thus, it is essential to find out technologies to guarantee this product for a longer time. Flowers of four species (borage [Borago officinalis], heartsease [Viola tricolor], kalanchoe [Kalanchoe blossfeldiana], and dandelion [Taraxacum officinale]) were subjected to freezing (in their natural form and in ice cubes) and analyzed in terms of visual appearance, the content of flavonoids, hydrolysable tannins, phenolics, antioxidant activity (2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging activity and reducing power), and microbial quality after storage for 1 and 3 months. Flowers in ice cubes showed similar appearance to fresh ones during the 3 months of storage, whereas frozen flowers were only equivalent up to 1 month with the exception of kalanchoe. Even though flowers in ice cubes showed good appearance after 3 months of storage, they had the lowest values of bioactive compounds and antioxidant activity. On the contrary, when frozen, the content of bioactive compounds maintained or even increased up to 1 month of storage compared to fresh flowers, except for borage. Furthermore, in both freezing treatments, the microorganisms' counts decreased or maintained when compared to fresh samples, except in dandelion. In general, both treatments may allow keeping the flowers after their flowering times. Practical Application: The market of edible flowers is increasing, although they are a very perishable product with short shelf‐life. Edible flowers are stored in the cold (frozen or in ice cubes); however, the effect on the bioactive compounds and microbial quality that this treatment may have on borage (Borago officinalis), heartsease (Viola tricolor), kalanchoe (Kalanchoe blossfeldiana), and dandelion (Taraxacum officinale) flowers is unknown. So, the present study was conducted to increase the knowledge about the changes that freezing treatments may have in different edible flowers. The results of the present study underline that each flower has different behavior at frozen and ice cubes storage. However, freezing flowers maintain/increase the contents of bioactive compounds, while ice cubes not. Both treatments are effective in protecting flowers from microorganism growth. So, suggesting that both freezing treatments can be used as a preservative method and may allow keeping the flowers after their flowering times. [ABSTRACT FROM AUTHOR]

Hyperbaric Storage (HS) is a food preservation methodology that stores foods for long periods inside vessels at pressure levels above atmospheric pressure. HS has been studied for different perishable products, showing good results for food safety and quality and shelf-life extension, frequently at uncontrolled room temperature. Studies reported HS's ability to control microbial growth and cause microbial inactivation during storage. This review seeks to investigate the inactivation of different microorganisms observed in HS studies at variable storage conditions (pressure level, storage duration and temperature). The maximum inactivation seen in these studies is presented and discussed, along with an examination of how those variables and other factors (food composition, pH and water activity (a W)) impact inactivation. Additionally, the potential of a novel pressure pasteurization method, moderate pressure pasteurization (MPP), is discussed. In HS studies, microbial inactivation frequently reached levels below the detection limit, including reductions of over 6 log units. Varying storage conditions impacts the inactivation as, typically, increasing the pressure level and the temperature results in higher and/or quicker reductions. Storage duration depends on HS purpose, but studies range from hours up to one year with considerable inactivation results. Other possible impacting factors include the type of microorganism, as Gram-negative bacteria appear to be less pressure resistant; the food composition; and the pH and a W : a low pH and high a W often facilitate inactivation. Inactivation results exceeding 5 log units after storage at moderate pressure levels for a few hours highlighted MPP as a potential novel nonthermal pasteurization methodology. • Hyperbaric Storage can control microbial growth and cause inactivation • Inactivation by Hyperbaric Storage at room temperature can reach over 5 log units • Food composition, pH and water activity can impact microbial inactivation • Low pH and high a W can be advantageous for microbial inactivation • Hyperbaric Storage has potential as novel nonthermal pasteurization process [ABSTRACT FROM AUTHOR]

Requeijão, a Portuguese whey cheese, was selected as a case study of a highly perishable dairy product and stored at 0.1 (AP) and 100 MPa (HS) at variable room temperature (RT) (≈17-21° C) and compared with refrigeration (RT) (4° C), during two storage periods, 24 hr and 10 days. After 24 hr at AP/RT, Requeijão presented microbial counts above 6.00 log CFU/g, while after HS, total aerobic mesophiles and Enterobacteriaceae growth was inhibited. For lactic acid bacteria and yeasts and molds, HS showed an additional microbial inactivation effect, decreasing approximately 1.5 and 3.5 log CFU/g, to values below the detection limit (<1.0 log CFU/g) during the 24 hr experiment. In the second storage experiment (10 days), HS allowed to achieve counts below the detection limit, maintaining them throughout the storage period, and also the physicochemical parameters were unaffected. Thus, HS results clearly point to Requeijão shelf-life extension compared to RF. Practical applications Hyperbaric storage (HS) at room temperature (RT) is emerging as a new food preservation methodology that acts by microbial growth inhibition similarly to refrigeration. However, HS allows significant energetic costs reduction, since it only implies energy costs during compression/decompression phases (few minutes), and no additional energy is needed to control the temperature or to maintain the product under pressure for long periods as opposed to refrigeration. This is undoubtedly a great advantage for HS, since energy savings implied will greatly reduce costs throughout the storage period. As a consequence, HS also becomes an environmentally friendlier technology, with a carbon footprint estimated to be about 26-fold lower compared to refrigeration storage. This is one of the few studies concerning HS on solid foods and the first work that stored foods for longer storage periods (up to 10 days). [ABSTRACT FROM AUTHOR]

Hyperbaric storage (HS), storage under pressure at 25°C and 30°C, of a ready-to-eat (RTE) soup was studied and compared with refrigeration. Soup was stored at different time (4 and 8 h), temperature (4°C, 25°C, and 30°C), and pressure (0.1, 100, and 150 MPa) conditions, to compare microbial loads and physicochemical parameters. HS resulted in similar (microbial growth inhibition) to better (microbial inactivation) results compared to refrigeration, leading to equal and lower microbial loads, respectively, at the end of storage. Lower/higher pressure (100 vs. 150 MPa) and shorter/longer storage times (4 vs. 8 h) resulted in more pronounced microbial growth inhibition/microbial inactivation. Aerobic mesophiles showed less susceptibility to HS, compared to Enterobacteriaceae and yeast and molds. HS maintained generally the physicochemical parameters at values similar to refrigeration. Thus, HS with no need for temperature control throughout storage and so basically energetically costless, is a potential alternative to refrigeration. [ABSTRACT FROM AUTHOR]

This research focuses on biochemical changes related to quality losses observed in Atlantic mackerel ( Scomber scombrus) muscle stored under commercial frozen storage conditions (9 months, −18 °C) when subjected to high-hydrostatic pressure (HHP) treatments (125, 150, 175, and 200 MPa for 0 min) before freezing. After freezing, free fatty acid (FFA) formation (lipid hydrolysis assessment) showed a marked inhibition in HHP-treated fish and during frozen storage of samples treated at 175 MPa. Fluorescence ratio (FR) assessment of tertiary lipid oxidation showed a partial inhibitory effect during the 0-9-month period for samples treated at 175 and 200 MPa. After a 3-month storage of samples treated at these pressure levels, one-dimensional SDS-PAGE analysis of the sarcoplasmic protein fraction revealed the disappearance of a band; additionally, samples treated at 150 MPa showed the same effect at month 9. After gel excision, trypsin digestion, tandem mass spectrometry (MS/MS), and sequence database analysis, the band was identified as phosphoglycerate mutase 2 (28.7 kDa). On the other hand, HHP processing did not show a significant effect on trimethylamine (TMA) values, primary and secondary lipid oxidation, PUFA levels, 1-D myofibril protein pattern, and the activity of acid phosphatase and cathepsins B and D. Biochemical quality indices such as FFA, TMA, and FR and the activity of acid phosphatase and cathepsin B showed a progressive increase throughout the frozen storage of all samples. [ABSTRACT FROM AUTHOR]

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The assessment of enzymatic activity on Atlantic horse mackerel ( Trachurus trachurus) during frozen storage was carried out in samples pre-treated by high-pressure processing (HPP) combinations of 150, 300 and 450 MPa with 0-, 2.5- and 5-min holding time (untreated samples were used as controls). The activities of four enzymes (acid phosphatase, cathepsins B and D, and lipase) in fish muscle were quantified during accelerated storage conditions (up to 3 months at −10 °C). The experimental data were fitted to second-order polynomial models to determine the effect of pressure level, holding time and frozen storage time on these enzyme activities and to identify conditions of maximum/minimal enzyme inactivation. Acid phosphatase and cathepsin (B and D) activities were significantly ( p < 0.05) influenced by HPP, showing behaviours during frozen storage different from control samples. Acid phosphatase and cathepsin B activities decreased ( p < 0.05) with HPP treatments, being this effect more intense for cathepsin B, particularly at 450 MPa. Regarding cathepsin D, the activity increased ( p < 0.05) at intermediate pressure (300 MPa) and decreased ( p < 0.05) at higher pressure (450 MPa). During frozen storage, cathepsin D enzymatic activity tended to increase over time indicating activity recovery of these enzymes. Although a predictive model for its activity was not acceptable, the increase in lipase activity during storage was the most pronounced trend observed. [ABSTRACT FROM AUTHOR]

Hyperbaric storage at naturally variable room temperature (RT) conditions (18-21 °C) and above (30 °C) was evaluated as a possible new food preservation method, regardless of temperature. Preservation of watermelon juice (used as a case study of a highly perishable food) at RT and 5 °C at atmospheric pressure was compared to preservation under 100 MPa at RT. After 8 h of hyperbaric storage at 100 MPa, the initial microbial loads of the watermelon juice were reduced by 1 log unit for total aerobic mesophiles, and 1-2 log units for Enterobacteriaceae and yeasts and moulds, to levels of about 3 log units for the former and below the detection limit for the latter, and remained thereafter unchanged up to 60 h. Similar results were obtained at 30 °C at 100 MPa after 8 h. At atmospheric pressure at RT (24 h) and 30 °C (8 h), microbial levels were already above quantification limits and unacceptable for consumption. Furthermore, pressure attenuated the increase in titratable acidity verified at atmospheric pressure, but caused higher colour changes, especially a higher lightness and a lower browning degree. Post-hyperbaric storage at 5 °C revealed an extended shelf life, as an additional benefit of hyperbaric storage. These results show that hyperbaric storage is a very promising food preservation methodology. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we studied the effect of high-pressure processing (HPP) pre-treatments (150, 300 and 450MPa for 0, 2.5 and 5min) on key enzyme activities in Atlantic mackerel (Scomber scombrus) during frozen storage (3months of accelerated storage, −10°C). Except for a minor decrease from treatment at 450MPa, no substantial effect on acid phosphatase activity was observed. In contrast, cathepsins B and D and lipase were affected by HPP and frozen storage. Increasing the pressure reduced cathepsin B and lipase activities. Generally, increasing the holding time at 150MPa increased the activity of cathepsin B and lipase (except at month 1), while increasing the holding time at 300MPa reduced the lipase activity, and no effect was observed at 450MPa. Overall, cathepsin D activity increased with frozen storage time and for treatments at 300MPa but decreased at 450MPa. This work provides novel information of HPP pre-treatments application, lowering enzyme activity during frozen storage of Atlantic mackerel. Industrial relevance: The activity of fish endogenous enzymes has an important role in its deterioration during frozen storage, limiting its commercialisation. This research presents valuable information concerning the employment of high-pressure processing pre-treatments to reduce deteriorative enzymatic activities during the subsequent frozen storage of Atlantic mackerel (Scomber scombrus). High-pressure processing pre-treatments can so be of interest for fish processors to enhance the frozen storage of these fish species and possibly of others. [Copyright &y& Elsevier]

This work studied the effect of high pressure processing ( HPP) at 400, 500 and 600 MPa during 10, 5 and 3 min, respectively, on samples ewe cheese manufactured from raw milk, during storage (100 days) at 5 °C. Total aerobic mesophilic and lactic acid bacteria were slightly affected, decreasing by about 1.0 and 0.82 log CFU g−1, respectively, immediately after HPP treatment at 600 MPa for 3 min, while Enterobacteriaceae, yeasts and moulds, and Listeria innocua were reduced to below the quantification limits. Lactic acid bacteria decreased further during storage, showing increasing inactivation as the pressure level increased. Physicochemical parameters (water activity, moisture content, pH and titratable acidity) were generally not affected by HPP, while lipid oxidation increased throughout storage, with HPP samples showing lower values (50-66%) at 100 days of storage. The results indicated that HPP has potential to improve cheese microbial safety and shelf-life, with a lower lipid oxidation level than nonpressurised cheese. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of high-pressure processing (HPP) on the quality of fresh sea bass fillets using two pressure levels (250 and 400 MPa; 5 min pressure holding time). Vacuum-packed fillets were used as control samples, and all fillets were stored under refrigerated conditions for 18 days. The microbiological, chemical, physical, and sensory parameters were followed. Both HPP treatments increased the microbiological shelf life of sea bass fillets. In day 14, control samples reached the upper acceptability limit (7 log colony-forming units (CFU) g), while fillets treated at 250 and 400 MPa had 3.2 and 1.4 log CFU g, respectively. In general, hydrogen sulphide-producing bacteria and Enterobacteriaceae loads were below the detection limit in HPP treatments. Results from nucleotide analysis indicate that HPP treatments reduced the conversion of inosine 5′-monophosphate to inosine. HPP also influenced fillet sensory characteristics. The most evident changes in fillets were the increase in whiteness, the loss of translucency, and a firmer consistency. The effect was more pronounced in the treatment at 400 MPa. Lipid oxidation increased in HPP-treated samples, being more accentuated in the treatment at 400 MPa. Instrumental smell intensity increased in both HPP treatments, though the sensory panel did not detect any rancid or other unpleasant odours. No effect was observed in the amount of volatile bases or in pH values. In conclusion, HPP treatments showed potential application for new fish product development with increased microbiological safety and shelf life, longer freshness, and unique characteristics (e.g. firmer and whitish). [ABSTRACT FROM AUTHOR]

Abstract: Frozen storage of horse mackerel (Trachurus trachurus) is limited by lipid damage causing sensory quality losses. This work deals with changes in functional and sensory properties during frozen storage of horse mackerel treated by high hydrostatic pressure processing (HPP) prior to freezing. Three levels of pressure (150, 300, and 450MPa), pressure holding time (0.0, 2.5, and 5.0min), and frozen storage time (0, 1, and 3months) were studied. Expressible water, colour parameters, mechanical texture parameters and sensory parameters were evaluated in raw and cooked samples. The texture profile analysis of raw and cooked HPP samples suggested that a product texture similar or close to fresh muscle is possible. The sensory analysis showed that a 150MPa treatment yielded high acceptability values. Although acceptability decreased during frozen storage, values remained close to those of fresh samples. Industrial relevance: Frozen storage of fatty fish species is known to be strongly limited by the lipid damage development, being this an important drawback for its commercialisation as such or for its further employment as raw material in other kinds of processing (canneries, smoking, etc.). Present research provides novel and valuable information concerning the employment of high hydrostatic pressure technology applied before freezing and frozen storage to improve some functional and sensory properties in horse mackerel muscle indicating that it can be a useful alternative for fish processors seeking to better utilise this resource. [Copyright &y& Elsevier]

Industrial drying of salted fish is an extremely common practice in the Portuguese industry of codfish processing. The present study aims to obtain sorption isotherms of codfish, which will be useful in designing drying processes and prediction of storage conditions for this product. The equilibrium moisture contents (wet basis) were determined for salted codfish at 15, 18, 20, and 23ºC at relative humidities ranging from 40 to 70%. Experiments were also carried out for fresh codfish at the temperature of 20ºC for the same values of relative humidity. The sorption capacity of codfish decreased with an increase in temperature at constant relative humidity. Thirteen models were used to correlate the experimental data analysis of salted codfish: modified BET, Cauri, Chung-Pfost, modified Chung-Pfost, GAB, modified GAB, Halsey, modified Henderson, Kuhn, Oswin, modified Oswin, Smith, and modified Smith. Based on the mean relative percentage deviation, standard error of estimate, randomness of residual, and coefficient of determination, experimental data were well described by all the models. The equilibrium moisture content of salted codfish was best predicted using the modified GAB model, with a coefficient of determination of 0.99. [ABSTRACT FROM AUTHOR]

In this study, we found that pressure treatments of 100 MPa applied for 5 and 10 min inhibited the sprouting of potato tubers that were stored for 3 months before the pressure treatments, for at least 6 weeks at 18 °C. Less intense pressure treatments of 30 and 50 MPa for 5 and 10 min did not inhibit sprouting, but hindered sprout development, evaluated by sprout length, elongation rate and mass. Pressure treatments caused a higher inhibition of sprouting, when applied to tubers after 5 months of storage, before the application of the pressure treatments. For these tubers, pressure treatments at 50 and 100 MPa for 5 and 10 min inhibited sprouting for at least 6 weeks at 18 °C. For the same tubers, a pressure treatment at 30 MPa for 10 min already showed some inhibitory effect on sprouting and hindered sprout development. Pressure treatments show great potential to be used, as a nonthermal and chemical-free method, to control sprouting of potato tubers. [ABSTRACT FROM AUTHOR]

Marketing issues of small-sized meagre can be overcome with the development of fish hams. This study aimed to test high pressure processing (HPP) to promote gelation of meagre hams, as an alternative to the heat processing. It was also aimed to reduce microbial transglutaminase (MTGase) from the formulation of HPP hams. Meagre hams were subjected to HPP varying different pressure parameters. The water holding capacity (WHC) and folding properties of hams were not affected by HPP, compared with heat processed hams. Whiteness was lower in HPP hams, and values increased with pressure level. The best results were obtained at 350 and 500 MPa at 30 °C, which also enhanced the textural properties of hams. Meagre hams prepared with different contents of MTGase (0–5.0 g/kg) were subjected to HPP. This enzyme did not affect the WHC and the folding properties of hams within each condition tested. HPP hams can be prepared with lower levels of MTGase (2.5 g/kg), without compromising the textural properties of hams. The results showed that it is possible to produce meagre hams with good textural properties and to reduce the MTGase content using HPP, validating the use of this technology as an alternative to the heat-induced gelation. [ABSTRACT FROM AUTHOR]

Hyperbaric storage (HS; 50–75 MPa) at room temperature (25–37 °C) was evaluated using Atlantic salmon ( Salmo salar ), and compared to refrigeration (4 °C, RF). HS at 75 MPa caused a reduction of about 3.5 log units of initial microbial counts, leading to an increase of the microbial shelf-life of at least 25 days, compared to RF (3 days) and HS at 50 MPa, while at 60 MPa a microbial growth slowdown was observed, increasing the microbial shelf-life to at least 6 days. Additionally, at 75 MPa no changes in colour was detected during the 25 days. However, HS/RT enhanced an increase in primary and secondary lipid oxidation products compared to RF, while for atmospheric pressure at room temperature, tertiary lipid oxidation increased. HS may represent an interesting methodology for fresh fish shelf-life extension by microbial growth inhibition and microbial reduction, with additional energy saving when compared to RF. Industrial relevance Hyperbaric storage at room temperature (HS/RT) has shown a shelf-life extension of fresh fish salmon, as well as possible energy savings, when compared to conventional refrigeration. HS/RT only involves energy consumption during the compression and decompression phases, not requiring additional energy to control the temperature or maintain the product under pressure. However, before industrial implementation, more research is needed to clarify the effect of these storage conditions on mechanisms implied in fish quality degradation. [ABSTRACT FROM AUTHOR]

Hyperbaric storage (HS) of raw watermelon juice, at 50, 62.5 and 75 MPa, at temperatures of 10, 15 and ≈25 °C (room temperature, RT), was studied to evaluate shelf-life comparatively to refrigeration (RF, 4 °C). Generally, RF caused an increase of microbial loads to values ≥6.0 log CFU/mL after 7 days of storage. Contrarily, HS at 62.5/75 MPa (15 °C) showed a reduction of initial loads, by at least 2.5 log CFU/mL, up to 58 days, while pH and colour values did not changed under these HS conditions. Additionally, the combination of a lower temperature with HS has beneficial effects to control microbial development, particularly for the lower pressure studied (50 MPa/10 °C). In conclusion, HS increased watermelon juice shelf-life for at least 58 days, indicating a great potential for future RF replacement. [ABSTRACT FROM AUTHOR]

Hyperbaric storage (HS) at room temperature is a new approach for food preservation. It was studied for the first time, here, for two ready-to-eat (RTE) pre-cooked food commercial products and using an industrial-scale pressure equipment. Caldo verde and Bacalhau com natas were stored for 12 h at 0.1, 50, 100 and 150 MPa, at uncontrolled naturally variable room temperature (~ 21 °C). The results showed that HS caused microbial growth inhibition at 100 MPa for all the studied microorganisms. Moreover, an additional inactivation effect at 150 MPa resulted in values below the detection limit for Enterobacteriaceae and yeasts and moulds, resulting in equal to better results when compared to refrigeration. Regardless of HS conditions no changes were verified in physico-chemical parameters when compared to refrigeration storage. Therefore, HS has the potential to substitute refrigeration as a quasi-energetically costless and carbon foot-printless preservation methodology. Industrial relevance Hyperbaric storage (HS) is a very promising technique for microbial proliferation inhibition at room-like temperatures, allowing natural temperature fluctuations. HS has several advantages when compared to refrigeration namely, it is nearly energetically costless (it only requires energy costs during compression to reach the required pressure level and virtually no additional energy is necessary to maintain the product under pressure along the storage), and so it is also basically carbon foot-printeless. This is the first work to study HS of two commercial highly perishable ready-to-eat food products at room temperature conditions and to assess its effect on fatty acid content, using an industrial high pressure equipment. [ABSTRACT FROM AUTHOR]

Several studies have demonstrated the feasibility of pulsed electric fields (PEF) for different applications in food industry. PEF technology is therefore a valuable tool that can improve functionality, extractability, and recovery of nutritionally valuable compounds as well as the bioavailability of micronutrients and components in a diverse variety of foods. Additionally, other studies have shown the potential of PEF treatments to reduce food processing contaminants and pesticides. This opens the doors to new PEF applications in the food industry. This review focused on some of the most renowned traditional and emerging PEF applications for improvement of osmotic dehydration, extraction by solvent diffusion, or by pressing, as well as drying and freezing processes. The impact of PEF on different products of biological origin including plant tissues, suspension of cells, by-products and wastes will be analyzed in detail. In addition, recent examples of PEF-assisted biorefinery application will be presented, and finally, the main aspects of PEF-assisted cold pasteurization of liquid foods will also be described. [ABSTRACT FROM AUTHOR]