Guidelines on reporting treatment conditions for emerging technologies in food processing.

In the last decades, different non-thermal and thermal technologies have been developed for food processing. However, in many cases, it is not clear which experimental parameters must be reported to guarantee the experiments' reproducibility and provide the food industry a straightforward way to scale-up these technologies. Since reproducibility is one of the most important science features, the current work aims to improve the reproducibility of studies on emerging technologies for food processing by providing guidelines on reporting treatment conditions of thermal and non-thermal technologies. Infrared heating, microwave heating, ohmic heating and radiofrequency heating are addressed as advanced thermal technologies and isostatic high pressure, ultra-high-pressure homogenization sterilization, high-pressure homogenization, microfluidization, irradiation, plasma technologies, power ultrasound, pressure change technology, pulsed electric fields, pulsed light and supercritical CO2 are approached as non-thermal technologies. Finally, growing points and perspectives are highlighted.

Factors Affecting Bacterial Inactivation during High Hydrostatic Pressure Processing of Foods: A Review.

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.

Ultra-high-pressure homogenization (UHPH) system for producing high-quality vegetable-based beverages: physicochemical, microbiological, nutritional and toxicological characteristics.

BACKGROUND: A relatively new technology based on a continuous system of ultra-high-pressure homogenization (UHPH) was used for producing high-quality soy and almond beverages as an alternative to conventional heat treatments (pasteurization and UHT). The aim of this study was to compare those treatments by analyzing the most relevant quality parameters with a broad vision from the production to the potential toxicological changes, passing through the main nutritional characteristics. RESULTS: UHPH treatment at 200 MPa, 55 °C T(in) produced a higher reduction of microorganisms than pasteurization. UHPH treatment at 300 MPa, 75 °C T(in) led to complete inactivation of microorganisms, similar to UHT treatment. A much better colloidal stability was observed in both UHPH-treated almond and soy beverages compared with those processed by conventional heat treatments. UHPH treatments led to the same increase in digestibility as heat treatments and did not produce a reduction in the availability of lysine. In addition, UHPH samples of soy beverage seem to be less allergenic based on their lower gut immune response in comparison with heat-treated samples. CONCLUSION: UHPH treatments could be used to produce high-quality commercial vegetable beverages with different quality standards (fresh or long-life storage) according to consumer preference.

Effect of tiger nut-derived products in gluten-free batter and bread.

Tiger nut is a tuber used to produce tiger nut milk that yields a high quantity of solid waste, which can be dried and used as fiber source. The objective of this paper was to evaluate the quality of gluten-free bread formulated with different tiger nut-derived products in order to substitute soya flour (which is an allergen ingredient) and, at the same time, increase the use of tiger nut-derived products. Four gluten-free formulations based on corn starch and containing tiger nut milk, tiger nut milk by-product, tiger nut flour, or soya flour (as reference formulation) were studied. Tiger nut milk increased G' of gluten-free batter and rendered breads with the softest crumb (502.46 g ± 102.05), the highest loaf-specific volume (3.35 cm(3)/g ± 0.25), and it was mostly preferred by consumers (61.02%). Breads elaborated with tiger nut flour had similar characteristics than soya flour breads (except in color and crumb structure). The addition of tiger nut milk by-product resulted in a hard (1047.64 g ± 145.74) and dark (L(*) = 70.02 ± 3.38) crumb bread, which was the least preferred by consumers. Results showed that tiger nut is a promising ingredient to formulate gluten-free baked products.

Effect of Ultra-High Pressure Homogenization (UHPH) and Conventional Thermal Pasteurization on the Volatile Composition of Tiger Nut Beverage.

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 fresh 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.

Effect of HHP and UHPH High-Pressure Techniques on the Extraction and Stability of Grape and Other Fruit Anthocyanins.

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.

Ultra-high pressure homogenisation of milk: technological aspects of cheese-making and microbial shelf life of a starter-free fresh cheese.

Fresh cheeses from pasteurised (80 °C for 15 s), homogenised-pasteurised (15 + 3 MPa at 60 °C; 80 °C for 15 s) or ultra-high pressure homogenised milks (300 MPa and inlet temperature of 30 °C) were produced in order to evaluate different technological aspects during cheese-making and to study their microbial shelf life. Although the coagulation properties of milk were enhanced by ultra-high pressure homogenisation (UHPH), the cheese-making properties were somewhat altered; both conventional homogenisation and UHPH of milk provoked some difficulties at cutting the curd due to crumbling and improper curd matting due to poor cohesion of the grains. Cheese-milk obtained by UHPH showed a higher microbiological quality than milk obtained by conventional treatments. Starter-free fresh cheeses made from UHPH-treated milk showed less syneresis during storage and longer microbiological shelf-life than those from conventionally treated milk samples.

Effect of Ultra-High-Pressure Homogenization Processing on the Microbiological, Physicochemical, and Sensory Characteristics of Fish Broth.

The effect of ultra-high-pressure homogenization (UHPH) treatments at 300 MPa at inlet temperatures (Ti) between 45 and 75 °C on the microbiological, physical, and sensorial characteristics of fish broth was evaluated. Before the application of UHPH treatments, different fish broth formulations were tested, selecting the formula with the best organoleptic and nutritional characteristics and the lowest cost, containing 45% monkfish heads and rock fish in the same proportion. The microbiological shelf-life of fish broth during cold storage at 4 and 8 °C was extended by a minimum of 20 days by applying UHPH treatments at inlet temperatures (Ti) between 45 and 65 °C. Fish broth UHPH-treated at Ti = 75 °C was microbiologically sterile during storage at 4 °C, 8 °C, and room temperature. Fish broth UHPH-treated was physically stable, significantly reducing the particle size. Color showed higher luminosity and lower yellowness as the inlet temperature increased. In fish broth UHPH-treated at Ti = 75 °C, selected for its microbiological stability, no differences were observed in the nutritional composition, antioxidant activity, and sensorial perception compared to untreated fish broth. Hence, UHPH treatments showed to be an alternative to preserving fish broth with an improved microbiological shelf-life and good sensorial characteristics.

Use of UHPH to Obtain Juices With Better Nutritional Quality and Healthier Wines With Low Levels of SO2.

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.

White wine processing by UHPH without SO2. Elimination of microbial populations and effect in oxidative enzymes, colloidal stability and sensory quality.

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.

Changes in the volatile composition of a semihard ewe milk cheese induced by high-pressure treatment of 300 MPa.

The effect of high-pressure (HP) treatment (300 MPa, 10 min) on the volatile profile of semihard ewe milk cheeses was investigated. The HP treatment was applied at two different stages of ripening (1 and 15 days; 3P1 and 3P15) and microbiota, proteolysis indexes (soluble nitrogen and total free amino acid content), and volatile compounds were assayed at 15, 60, 90, and 150 days of ripening. The intensity of odor and aroma of cheeses was also assayed. 3P1 cheeses presented the highest content of free amino acids and were characterized by the lowest amounts of aldehydes, ketones, short-chain free fatty acids, and terpenes and higher levels of ethanol and ethyl esters. 3P15 cheeses were characterized by the highest content of short-chain free fatty acids and pyruvaldehyde and the lowest abundance of secondary alcohols and were more similar to control cheeses than those HP-treated on the first day. Intensities of odor and aroma were not significantly influenced by the HP treatment. However, the panellists found some differences in 3P1 as compared with control and 3P15 cheeses in what they perceived as lower odor and aroma quality.

Fate of Escherichia coli strains inoculated in model cheese elaborated with or without starter and treated by high hydrostatic pressure.

The aim of this research was to study high hydrostatic pressure inactivation of two strains of Escherichia coli (E. coli O59:H21 [CECT 405] and E. coli O157:H7 [CECT 5947]) inoculated in washed-curd model cheese elaborated with and without starter and the ability of these strains for survival, recovery, and growth. Samples were treated at 300, 400, and 500 MPa for 10 min at 20 degrees C and analyzed after the treatment and after 1, 7, and 15 days of storage at 8 degrees C to study the behavior of Escherichia populations. Cheeses elaborated with starter showed the maximum lethality at 400 and 500 MPa, and no significant differences in the baroresistant behavior of either strains were detected, except for E. coli O157:H7 at 400 MPa in cell counts obtained with thin agar layer method medium, where the decrease value was significantly lower. In cheese elaborated without starter, the highest decrease value was observed at 500 MPa, except for E. coli O59:H21 in cell counts obtained with selective culture medium, where the highest decrease value was also found at 400 MPa. The ability to repair and grow was not observed in model cheese elaborated with starter, as cell counts of treated samples decreased after 15 days of storage at 8 degrees C. By contrast, in cheese elaborated without starter, all pressurized samples showed the trend to repair and grow during the storage period in both strains. These results suggest that the presence of starter and low pH values are the main factors that control the ability of Escherichia strains inoculated in this type of cheese and treated by high hydrostatic pressure to recover and grow.

Ultra high pressure homogenization of almond milk: Physico-chemical and physiological effects.

Ultra high pressure homogenization (UHPH) of food is a processing technology to improve food safety and shelf life. However, despite very short treatment duration UHPH may lead to changes in chemical and physico-chemical properties including formation of submicro-/nano-particles. This may affect the physiological or toxicological properties of the treated food. Here, we treated raw almond milk (AMr) with UHPH at 350 MPa and 85 °C (AMuhph), known able to inactivate food relevant microorganisms. UHPH-treatment led to about a threefold increase of the mean particle size. There was a nearly complete loss of antigenicity investigated by ELISA for determination of traces of almond proteins. The content of vitamins B1 and B2 remained unchanged, while free exposed sulfhydryl groups decreased. Despite of observed modifications, UHPH-treatment of almond milk did not cause any changes in cyto- or genotoxic effects and antigenotoxic capability of protecting intestinal cells against iron induced DNA damage in vitro.

Survival and growth of Yersinia enterocolitica strains inoculated in skimmed milk treated with high hydrostatic pressure.

Four human pathogenic strains of Yersinia enterocolitica (serotypes O:1, O:3, O:8, and O:9) were inoculated (7-8 log CFU/ml) in UHT skimmed milk and treated at 300, 400, and 500 MPa for 10 min at 20 degrees C, and then kept at 8 degrees C to assess their evolution for 15 days. Treatments at 400 and 500 MPa caused the highest lethality, generally reaching counts below detection level (1 CFU/ml) in the culture media. At 300 MPa, the most baroresistant serotypes were O:3 and O:8. After 15 days of storage at 8 degrees C, Y. enterocolitica showed growth over 8 log (CFU/ml) in all treatments. Kinetic study of microbial inactivation in skimmed milk was performed with serotype O:8 at 300 MPa, showing a tailing after 35 min of pressure treatment.

Behavior of Yersinia enterocolitica strains inoculated in model cheese treated with high hydrostatic pressure.

The effects of high hydrostatic pressure treatment and the ability for survival, repair, and growth of three human pathogenic serotypes (O:1, O:3, O:8) of Yersinia enterocolitica were investigated in washed-curd model cheese made with pasteurized bovine milk. Samples were treated at 300, 400, and 500 MPa for 10 min at 20 degrees C and analyzed at 0, 1, 7, and 15 days to assess the viability of the Yersinia population. A long-term study (up to 60 days of ripening after high hydrostatic pressure treatment) was also undertaken. Treatments at 400 and 500 MPa caused maximum lethality, and only the treatment at 300 MPa showed significant differences (P < 0.05) between serotypes; the most baroresistant was O:3. Ability to repair and grow was not observed after 15 days of storage at 8 degrees C. Yersinia counts in untreated cheese samples also decreased below the detection limit at day 45 in the long-term study. These results suggest that the cheese environment did not allow recovery of injured cells or growth. A primary contributing factor to this effect seemed to be the low pH resulting from the production of lactic acid during cheese ripening.

Comparing the effects of ultra-high-pressure homogenization and conventional thermal treatments on the microbiological, physical, and chemical quality of almond beverages.

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

Characterisation of volatile profile in soymilk treated by ultra high pressure homogenisation.

The effect of ultra high pressure homogenisation (UHPH) on the volatile profile of soymilk was studied and compared with conventional treatments. Soymilk was treated at 200 MPa combined with two inlet temperatures (55 or 75 °C) and treated at 300 MPa at 80 °C inlet temperature. UHPH-treated soymilks were compared with base product (untreated sample), pasteurised soymilk (90 °C, 30s) and ultra high temperature (UHT; 142 °C, 6s) treated samples. Volatile compounds were extracted by solid-phase microextraction and were identified by gas chromatography coupled with mass spectrometry. Pasteurisation and UHPH treatments at 200 MPa produced few changes in the volatile composition, reaching similar values to untreated soymilk. UHT treatment produced the most important effects on volatile profile compared to UHPH at 300MPa and 80 °C. Hexanal was the most abundant compound detected in all treatments. The effect of UHPH technology on volatile profile induced modifications depending on the combinations of processing parameters.

Influence of ultra-high pressure homogenisation on antioxidant capacity, polyphenol and vitamin content of clear apple juice.

Ultra-high pressure homogenisation (UHPH) is a recently developed technology and is still under study to evaluate its effect on different aspects of its application to food products. The aim of this research work was to evaluate the effect of UHPH treatments on quality characteristics of apple juice such as antioxidant capacity, polyphenol composition, vitamin C and provitamin A contents, in comparison with raw (R) and pasteurised (PA) apple juice. Several UHPH treatments that include combinations of pressure (100, 200 and 300MPa) and inlet temperatures (4 and 20°C) were assayed. Apple juice was pasteurised at 90°C for 4min. Antioxidant capacity was analysed using the oxygen radical antioxidant capacity (ORAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP) assay while total phenolic content was determined by the Folin-Ciocalteau assay. According to the FRAP and DPPH assays, UHPH processing did not change apple juice antioxidant capacity. However, significant differences were detected between samples analysed by TEAC and ORAC assays. In spite of these differences, high correlation values were found between the four antioxidant capacity assays, and also with total polyphenol content. The analysis and quantification of individual phenols by HPLC/DAD analytical technique reflects that UHPH-treatment prevented degradation of these compounds. Vitamin C concentrations did not change in UHPH treated samples, retaining the same value as in raw juice. However, significant losses were observed for provitamin A content, but lower than in PA samples. UHPH-treatments at 300MPa can be an alternative to thermal treatment in order to preserve apple juice quality.

Effects of ultra-high-pressure homogenization treatment on the lipolysis and lipid oxidation of milk during refrigerated storage.

Free fatty acid (FFA) release and quantification and lipid oxidation extent of ultra-high-pressure homogenized (UHPH) milk samples were evaluated to assess the effect of UHPH on the susceptibility of milk lipids to lipolysis and oxidation. Milk was UHPH-treated at 200 and 300 MPa with inlet temperatures of 30 and 40 degrees C. UHPH-treated samples were compared to high-pasteurized milk (PA; 90 degrees C, 15 s). Results showed that all FFA increased significantly during storage only in 200 MPa samples. Lipid oxidation was measured as an accumulation of lipid hydroperoxides as the primary oxidation product and malondialdehyde and hexanal as the secondary oxidation products. Samples treated at 300 MPa presented higher malondialdehyde and hexanal content compared to 200 MPa treated-samples and to PA milk.

Ultra-high pressure homogenization-induced changes in skim milk: impact on acid coagulation properties.

The effects of ultra-high pressure homogenization (UHPH) on skim milk yogurt making properties were investigated. UHPH-treated milk was compared with conventionally homogenised (15 MPa) heat-treated skim milk (90 degrees C for 90 s), and to skim milk treated under the same thermal conditions but fortified with 3% skim milk powder. Results of the present study showed that UHPH is capable of reducing skim milk particle size which leads to the formation of finer dispersions than those obtained by conventional homogenisation combined with heat treatment. In addition, results involving coagulation properties and yogurt characteristics reflected that, when increasing UHPH pressure conditions some parameters such as density of the gel, aggregation rate and water retention are improved.