Summary
The effect of different ultra‐high pressure homogenisation (UHPH) treatments on physicochemical and sensorial properties of orange juice was studied in comparison with thermal pasteurisation ...(90 °C, 1 min). UHPH treatments consisted on combinations of two inlet temperatures (10 or 20 °C) and three pressures (100, 200 and 300 MPa). Effect of treatments was assessed on general quality parameters (colour, pH, °Brix, titratable acidity, reducing sugars and non‐enzymatic browning index), particle size distribution and cloud stability. None of the UHPH treatments caused significant differences in the °Brix, reducing sugars, pH and non‐enzymatic browning index with respect of fresh or pasteurised juice. Only titratable acidity was significantly lower when inlet temperature of UHPH treatments was 20 °C. UHPH treatments significantly reduced the particle size and in consequence the cloudiness and the total colour value (∆E*) increased. The overall consumer acceptability of UHPH and pasteurised juices was similar.
UHPH improves the appearance of orange juice by decreasing the size of the particles, resulting in high stability and turbidity, both characteristics desired in orange juice.
Ultra-high pressure homogenization (UHPH) is a high pressure technique in which a fluid is pressurized by pumping at higher than 200 MPa and instantaneously depressurized at atmospheric pressure ...across a special valve. The full process takes <0.2 s and the in-valve time is <0.02 s. In the valve, extremely intense impacts and shear forces produce the nanofragmentation of biological tissue at a range of 100–300 nm. The antimicrobial effect is highly effective, reaching easily inactivation levels higher than 6-log cycles even at low in-valve temperatures. At in-valve temperatures of 140–150°C (0.02 s) the destruction of thermoresistant spores is possible. Even when the temperature in-valve can be elevated (70–150°C), it can be considered a gentle technology because of the tremendously short processing time. It is easy to get outlet temperatures after valve of 20–25°C by the expansion and assisted by heat exchangers. Thermal markers as hydroxymethylfurfural (HMF) are not formed, nor are deleterious effects observed in sensitive compounds as terpenes or anthocyanins, probably because of the low effect in covalent bonds of small molecules of the high-pressure techniques compared with thermal technologies. Additionally, intense inactivation of oxidative enzymes is observed, therefore protecting the sensory and nutritional quality of fruit juices and avoiding or reducing the use of antioxidants as sulphites. UHPH can be consider a powerful and highly effective continuous and sterilizing technology without thermal repercussions, able to keep fresh juices with most of their initial sensory and nutritional quality and allowing high-quality and natural fermented derivatives as wine.
Although, the High Hydrostatic Pressure (HHP) technology has been gaining gradual popularity in food industry since last two decades, intensive research is needed to explore the missing information. ...Bacterial inactivation in food by using HHP applications can be enhanced by getting deeper insights of the process. Some of these aspects have been already studied in detail (like pressure, time, and temperature, etc.), while some others still need to be investigated in more details (like pH, rates of compression, and decompression, etc.). Selection of process parameters is mainly dependent on type of matrix and target bacteria. This intensive review provides comprehensive information about the variety of aspects that can determine the bacterial inactivation potential of HHP process indicating the fields of future research on this subject including pH shifts of the pressure treated samples and critical limits of compression and decompression rates to accelerate the process efficacy.
•Elimination of vegetative cells of yeast, molds and bacteria by UHPH in must.•Strong inactivation of oxidative enzymes: PPO.•Absence of thermal degradation markers. No detection of HMF.•Higher ...antioxidant activity in UHPH processed must.•UHPH is a powerful tool to reduce SO2 in white wines.
The use of UHPH sterilization in the absence of SO2 has been used to eliminate wild microorganisms and inactivate oxidative enzymes. A white must of the Muscat of Alexandria grape variety was continuously processed by UHPH at 300 MPa (inlet temperature: 23–25 °C). The initial microbial load of the settled must was 4-log CFU/mL for both yeast and moulds, and slightly lower for bacteria. After UHPH processing, no microorganisms were detected in 1 mL. UHPH musts remain without fermentative activity for more than 60 days. Concentrations of the thermal markers indicated the absence of thermal damage in the UHPH-treated musts, since 5-hydroxymethylfurfural was not detected. In addition, the must treated by UHPH keeps terpene concentrations similar to those of the untreated controls. A strong inactivation of the oxidative enzymes was observed, with no browning at room temperature for more than 3 days. The antioxidant value of the UHPH-treated must was 156% higher than the control.
The effect of ultra high pressure homogenization (UHPH) at 200 and 300MPa in combination with different inlet temperatures (55, 65 and 75°C) on soymilk was studied. UHPH-treated soymilk was compared ...with the base product (untreated), with pasteurized (95°C for 30s) and with ultra high temperature (UHT; 142°C for 6s) treated soymilks. Microbiological (total aerobic meshophilic bacteria, aerobic spores, and Bacillus cereus), physical (dispersion stability and particle size distribution) and chemical (lipoxygenase activity, hydroperoxide index and trypsin inhibitor activity) parameters of special relevance in soymilk were studied. Microbiological results showed that pressure and inlet temperature combination had a significant impact on the lethal effect of UHPH treatment. While most of UHPH treatments applied produced high quality of soymilks better than that pasteurized, the combination of 300MPa and 75°C produced a commercially sterile soymilk. UHPH treatments caused a significant decrease in particle size resulting in a high physical stability of samples compared with conventional heat treatments. UHPH treatment produced lower values of hydroperoxide index than heat treated soymilks although trypsin inhibitor activity was lower in UHT-treated products.
► UHPH at 200 and 300MPa at inlet temperature of 55, 65 and 75°C on soymilk was studied. ► Microbial quality, physical stability, oxidation and trypsin inhibitor activity were evaluated. ► UHPH treatment produced high physical stability soymilk and reached commercial sterility at 300MPa and 75°C. ►UHPH showed lower oxidation compared to heat treatments and considerable inactivation of the trypsin inhibitors.
Ultra high pressure homogenization (UHPH) was applied on soymilk to produce an aseptically packaged beverage. UHPH-treated soymilk (300MPa, 80°C inlet temperature and 144°C/0.7s at the homogenization ...valve) was compared with samples treated by ultra high temperature (UHT) at 142°C for 6s. After treatment, soymilk samples were aseptically packaged in coated paperboard cartons of 200mL Tetra Brik containers. Tetra Brik containers were stored for 6months at room temperature and analyzed at different days. Microbiological (total mesophilic aerobic bacteria, aerobic spores, Bacillus cereus, and enterobacteria counts), physical (dispersion stability and particle size distribution), chemical (hydroperoxide index and volatile profile evolution) and sensory analyses were performed on soymilks. Both UHPH and UHT soymilks did not present microbiological growth during storage. UHPH soymilk presented high colloidal stability and relevant decrease in hydroperoxide index during storage. On the other hand, almost all of the compounds associated to off-flavors were detected in the volatile profile of soymilk. Sensory results indicated that UHPH treatment did not produce changes in soymilk which could affect the panel perception for different UHT and UHPH soymilks and for selecting their preference.
Soymilk constitutes one of the food industry sectors with the highest worldwide growth and its consumption has experienced a noticeable increase in the last years. The growing consumer demand for safe products, environmentally friendly processes and high quality nutritional foods has challenged the food industry to adapt the technological processes. This tendency impacts directly on traditional technologies, like heat treatments. In this sense, UHPH technology has been applied as an alternative to those thermal treatments. This research paper presents a comparative study between soymilk treated by UHPH and by UHT to produce a product stored at room temperature for 6months. Results showed stable levels of oxidation, high physical stability, no microbial growth and a positive trend of sensory response during the period analyzed for UHPH soymilk. Moreover, the UHPH system was designed to work at continuous flow, allowing its application in several industrial food processes.
•UHPH and UHT soymilks did not present microbial growth over 180days of storage.•UHPH soymilks showed high physical stability during storage at room temperature.•UHPH soymilks presented relevant decrease in hydroperoxide index during storage.•Hexanal values showed important decrease during storage of UHPH soymilks.•Panelist was not able to identify the differences between UHT and UHPH treatments.
The use of high-pressure technologies is a hot topic in food science because of the potential for a gentle process in which spoilage and pathogenic microorganisms can be eliminated; these ...technologies also have effects on the extraction, preservation, and modification of some constituents. Whole grapes or bunches can be processed by High Hydrostatic Pressure (HHP), which causes poration of the skin cell walls and rapid diffusion of the anthocyanins into the pulp and seeds in a short treatment time (2–10 min), improving maceration. Grape juice with colloidal skin particles of less than 500 µm processed by Ultra-High Pressure Homogenization (UHPH) is nano-fragmented with high anthocyanin release. Anthocyanins can be rapidly extracted from skins using HHP and cell fragments using UHPH, releasing them and facilitating their diffusion into the liquid quickly. HHP and UHPH techniques are gentle and protective of sensitive molecules such as phenols, terpenes, and vitamins. Both techniques are non-thermal technologies with mild temperatures and residence times. Moreover, UHPH produces an intense inactivation of oxidative enzymes (PPOs), thus preserving the antioxidant activity of grape juices. Both technologies can be applied to juices or concentrates; in addition, HHP can be applied to grapes or bunches. This review provides detailed information on the main features of these novel techniques, their current status in anthocyanin extraction, and their effects on stability and process sustainability.
Staphylococcus aureus
ATCC6538 was inoculated in skimmed milk, orange juice, and Tris buffer samples. Inoculated samples were subjected to high hydrostatic pressure (HHP) treatments at 700 MPa for ...5 min at 4 °C starting temperature with fast, medium, and slow rates of compression and decompression. The objective of this study was to determine the effects of changing rates of compression and decompression on inactivation of
S
.
aureus
during HHP processing. Immediate effect of different HHP treatments was not significantly different. However, during subsequent storage in refrigeration, highest microbial inactivation was the result of treatments with fast compression and slow decompression rates in all matrices.
Tiger nut beverages are non-alcoholic products that are characterized by their pale color and soft flavor. Conventional heat treatments are widely used in the food industry, although heated products ...are often damaging to their overall quality. Ultra-high pressure homogenization UHPH) is an emerging technology that extends the shelf-life of foods while maintaining most of their
characteristics. The present work deals with the comparison of the effect of conventional thermal homogenization-pasteurization (H-P, 18 + 4 MPa at 65 °C, 80 °C for 15 s.) and UHPH (at 200 and 300 MPa, and inlet temperature of 40 °C), on the volatile composition of tiger nut beverage. Headspace-solid phase microextraction (HS-SPME) was used for detecting volatile compounds of beverages, which were then identified by gas chromatography-mass spectrometry (GC-MS). A total of 37 different volatile substances were identified in tiger nut beverages, which were primarily grouped into the aromatic hydrocarbons, alcohols, aldehydes and terpenes chemical families. Stabilizing treatments increased the total amount of volatile compounds (H-P > UHPH > R-P). H-P was the treatment that produced the most changes in the volatile composition of RP, while treatment at 200 MPa had a minor impact. At the end of their storage, these products were also characterized by the same chemical families. This study evidenced the UHPH technology as an alternative processing of tiger nut beverages production that minimally modifies their volatile composition.
Ultra High Pressure Homogenization (UHPH) consists of continuous pumping of must at pressures above 200 MPa, usually 300 MPa, and its subsequent instantaneous depressurization to atmospheric pressure ...after passing through a special valve. In the valve, the intense impact forces and shear stresses, together with the temperature, lead to the death of microbial cells and also to the inactivation of oxidative enzymes. Intense mechanical stresses also result in nanofragmentation of colloidal particles increasing the release of nutritional factors such as YAN and others, thus improving colloidal stability. Molecules with sensory impact such as terpenes are not affected by the UHPH process, thus preserving the varietal character, nor can thermal markers such as furfural be detected. UHPH-processed musts show and maintain higher antioxidant activity than control musts and show less browning effects during processing and even later throughout and after fermentation. This technique also affects the extraction and stability of anthocyanins and other phenolic compounds by increasing their release from cell structures and protecting them from oxidation. The antimicrobial effect and the inactivation of oxidative enzymes allow the production of wines without or with a very low level of sulfur dioxide. The ability to inactivate enzymes by affecting their tridimensional structure may also have some effect on colloidal proteins by preventing protein haze or facilitating the use of protease enzymes.
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