The paper deals with the investigation of the ascorbic acid influence on the analytical results of polyphenol content in the samples of the spearmint, fennel, and thyme homogenates. The homogenates without and with addition of ascorbic acid and water were prepared and stabilized by high-pressure treatment. Their analysis was accomplished by high-performance liquid chromatography (HPLC) with DAD detection and by combination of liquid chromatography with mass spectrometry (LC-MS). Volatile terpenes were analyzed in all homogenates by combination of gas chromatography with mass spectrometry technique (GC-MS). The content of polyphenols of acidic nature, e.g., rosmarinic acid, revealed the highest difference between analytical results of the samples with and without ascorbic acid. Finally, prepared herb homogenates are suitable food supplements, which will find increasing application in various food preparations.

High-pressure processing (HPP) represents a promising alternative to conventional Holder pasteurisation (HoP) used by human milk banks worldwide. The objective of this study was to identify whether the HPP would achieve the same or better retention of the content of selected analytes than the HoP. Samples collected from 15 breast milk donors were processed in four ways: i) no treatment; ii) HoP; iii) HPP in cycles (350 MPa, 4 cycles); iv) continuous HPP (350 MPa, 20 min). The content of secretory immunoglobulin A (sIgA), lactoferrin and lysozyme was determined using commercially available ELISA kits, and the lipase activity was assessed using an A-lipase activity assay kit. Data were compared statistically using paired t-tests. HoP significantly reduced the content of lysozyme and lactoferrin as well as lipase activity (P < 0.001). Cycled HPP significantly decreased lipase activity (P = 0.002), while continuous HPP led to a significant decrease in lysozyme content (P = 0.001) and lipase activity (P = 0.014). Cycled HPP showed high retention of pretreatment levels of lysozyme-median 99 (88; 99%), lactoferrin-84 (66; 105%), and sIgA content-83 (28; 117%). Among the studied treatment regimens, the best preservation of initial levels of bioactive components was achieved using HPP at 350 MPa in cycles.

Human milk is a vital source of nutrition for infants providing essential nutrients for optimal growth and development. However, the processing methods applied to ensure its safety may affect its nutritional composition. The aim of this study was to compare the nutritional profile of alpha-tocopherol and retinol content in human milk, both raw and processed by Holder pasteurization or high-pressure processing. Our study followed a design that included milk samples obtained from 12 female donors (age ranged from 30 to 38) in the lactation period up to 6 months after delivery. Every milk sample was divided into four groups: (i) no treatment, (ii) subjected to Holder pasteurization (HP), (iii) and (iv) subjected to high-pressure processing (HPP), which differed in the way the pressure was applied. The results showed that both HP and HPP significantly affected the nutritional profile of the milk. Retinol level was approximately 20 % lower after both treatments than in untreated milk. The main difference was in tocopherol levels, which decreased by 46 % after HP, whereas these concentrations decreased by only 26 % in the cumulative pressure HPP-treated samples. These results suggest that the use of HPP should be considered as a prospective approach to human milk processing. Since HPP has advantages in preserving heatsensitive compounds and the levels of vitamin E decrease less.

The physical properties and structure of collagen treated with high-pressure technologies have not yet been investigated in detail. The main goal of this work was to determine whether this modern gentle technology significantly changes the properties of collagen. High pressure in the range of 0–400 MPa was used, and the rheological, mechanical, thermal, and structural properties of collagen were measured. The rheological properties measured in the area of linear viscoelasticity do not statistically significantly change due to the influence of pressure or the duration of pressure exposure. In addition, the mechanical properties measured by compression between two plates are not statistically significantly influenced by pressure value or pressure hold time. The thermal properties Ton and ∆H measured by differential calorimetry depend on pressure value and pressure hold time. Results from amino acids and FTIR analyses show that exposure of collagenous gels to high pressure (400 MPa), regardless of applied time (5 and 10 min), caused only minor changes in the primary and secondary structure and preserved collagenous polymeric integrity. SEM analysis did not show changes in collagen fibril ordering orientation over longer distances after applying 400 MPa of pressure for 10 min.

Although Holder pasteurization is the recommended method for processing breast milk, it does affect some of its nutritional and biological properties and is ineffective at inactivating spores. The aim of this study was to find and validate an alternative methodology for processing breast milk to increase its availability for newborn babies and reduce the financial loss associated with discarding milk that has become microbiologically positive. We prepared two series of breast milk samples inoculated with the Bacillus cereus (B. cereus) strain to verify the effectiveness of two high-pressure treatments: (1) 350 MPa/5 min/38 °C in four cycles and (2) cumulative pressure of 350 MPa/20 min/38 °C. We found that the use of pressure in cycles was statistically more effective than cumulative pressure. It reduced the number of spores by three to four orders of magnitude. We verified that the method was reproducible. The routine use of this method could lead to an increased availability of milk for newborn babies, and at the same time, reduce the amount of wasted milk. In addition, high-pressure treatment preserves the nutritional quality of milk.

The aim of this work was to compare selected physicochemical properties of air dried ‘Golden Delicious’ apples, pretreated either by high-pressure processing (HPP), ultrasound (US) or pulsed electric field (PEF). Following parameters of pretreatment were used: HPP–400 MPa for 15 min, US–21 kHz, 180 W for 45 min, PEF–1 kV/cm, 3.5 kJ/kg. The quality of materials was evaluated by their rehydration properties, hygroscopicity, color and total phenolic content. To compare the effectiveness of the utilized methods, determined properties were expressed as relative comparison values against the reference sample obtained without any pretreatment in the same conditions. The performed research demonstrated that properties can be shaped by the application of proper pretreatment methods. For instance, PEF was shown to be the best method for improving water uptake during rehydration, whereas HPP was the most effective in decreasing hygroscopic properties in comparison with untreated dried apples. Among the investigated methods, HPP resulted in the deepest browning and thus total color difference, while the effects of US and PEF were comparable. For all pretreated dried apples, the total phenolic content was lower when compared with reference material, though the smallest drop was found in sonicated samples.

The need to reduce the content of questionable health preservatives leads to the search for new methods to extend the shelf-life of meat products. The spectrum of possible approaches includes physical methods and the use of additives from natural sources. In this study, we examined the influence of the combination of high-pressure processing (HPP) and the addition of natural antimicrobials on the shelf-life of cooked ham. The samples of cooked ham were produced in a professional meat processing plant. One half of the samples were produced according to a traditional recipe, and the other was enriched with potassium lactate in the form of a commercial product PURASAL® Hirer P Plus. This product is produced via sugar fermentation and contains high levels of potassium lactate, a compound with high antimicrobial activity. Cooked hams were inoculated by bacteria Serratia liquefaction, vacuum packaged and treated by HPP. Packaged ham samples were stored at 3°C for 40 days and the total microbial count was examined during this storage period in defined intervals. The combination of HPP and potassium lactate from natural sources significantly reduced the total microbial counts in cooked hams and, thus, could be a suitable solution for the meat industry.

Red and white grape musts were enriched with 7-hydroxymatairesinol (HMR), which is the main lignan contained in spruce knots. Lignan enrichment was achieved by adding a spruce knot ethanol extract. Enriched musts were stored for 12 months and during storage must samples were periodically analyzed for HMR and alpha-conidendrin content, antioxidant activity, total polyphenols, and anti-mutagenicity. The data were statistically evaluated in order to determine the influence of grape type, quantity of added lignan extracts, addition of sugar, method of preservation and storage time on the quantity of lignans added, antioxidant activity, total polyphenols, and anti-mutagenicity. Lignan content was significantly influenced by the addition of lignan extracts. After storage, lignan content had changed only moderately and the added lignans were stable in the stored musts. Total polyphenol content and antioxidant activity of grape musts were significantly increased by the type of must grape and by thermomaceration. Thermomacerated red musts exhibited higher anti-mutagenicity compared to thermomacerated white musts, independent of lignan addition.

Hydroxymatairesinol (HMR) is the main lignan found in spruce knots. This lignan has been used for enrichment of musts and wines. Quality parameters of these products have been studied for several years and for storage times up to one year. Parameters included HMR concentration, antioxidant activities expressed as ferric reducing antioxidant power and 2,2-difenyl-1-picrylhydrazyl, total polyphenols, and sensory parameters, i.e. consumer acceptability. The main goal of this work was to study and provide relationships between the above mentioned quality parameters. We analysed cross-correlations of all these parameters and found statistically significant correlations between lignan concentration and consumer acceptability, which can be phrased as a warning against high lignan concentrations. The strongest correlations were found between antioxidant parameters and total polyphenol content that supports the antioxidative behaviour.

Grape juice quality can be substantially influenced by different processing methods and their parameters. This study deals with the influence of thermomaceration temperature and its holding time on important juice quality parameters such as the content of trans -resveratrol, trans -piceid, trans -ε-viniferin, and 2,4,6-trihydroxyphenantrene-2- O -glucoside. All the aforementioned compounds together with antioxidative capacity, total polyphenols, and antimutagenic activity were measured. This study used the following grapes: Blaufränkisch, Blaufränkisch bio, Saint Laurent, Grüner Veltliner, Grüner Veltliner bio, and Müller-Thurgau. For all tested grape varieties, the most important processing parameters were temperature and thermomaceration holding time. There were no significant differences in the content of the studied compounds. Three preservation technologies, freezing, bottle pasteurization, and high-pressure treatment, were also studied regarding the content of abovementioned biologically active compounds. Results of this study can be immediately applied to grape juice production.

Red and white musts were enriched with the lignan hydroxymatairesinol, which is the main lignan contained in spruce knots. Chips from the milled spruce knots were then used to enrich grape musts. After enrichment, the musts were stored and samples were taken in 1, 5, 9, and 12 months. The samples were subjected to a variety of analyses and sensory evaluations. Analyses included hydroxymatairesinol and alpha-conidendrin content, antioxidant activity (determined by the FRAP method), content of total polyphenols, sensory evaluation (intensity of woody aroma, intensity of bitterness and astringent taste, and consumer acceptability), and must antimutagenicity. The analysis of variance allowed predicting which factors such as grape type, quantity of added wood chips, sugar addition, method of preservation, and storage time had the most significant influence on the analytical parameters (lignan content, antioxidant activity, and total polyphenol content). In all cases lignan content in the musts was significantly influenced by the addition of spruce wood chips. Total polyphenol content in the musts was significantly affected by the type of musts and by heat treatment (time of thermomaceration). Evaluation of must antimutagenicity showed that all samples, except the sample of white musts after thermomaceration without holding at temperature and without adding chips (10 g/20 kg mash), inhibited mutagenicity.

Red and white wines [Gruer Veltliner white wine and Blue Limberger (Blaufrakisch) red wine (vintage 2013)] were enriched with lignan hydroxymatairesinol originated from spruce knots. These spruce knots with removed resin were extracted with ethyl alcohol of agricultural origin. Ethanol extracts of lignans were then used to enrich wine sorts. Enriched wines were stored for 13 months. At 2, 6, and 13 months, samples were taken and subjected to a variety of analyses and sensory evaluations. Analyses included 7-hydroxymatairesinol and alpha-conidendrin lignan content, antioxidant activity (as determined by FRAP), total polyphenols, and sensory evaluation. The obtained data were evaluated using the analysis of variance to determine which factors e.g. wine type, quantity of added lignan extracts, additional sugar, method of preservation, and storage time had the most significant influence on lignan content, antioxidant activity and polyphenol content. In all cases the lignan content in the wines was significantly influenced by the addition of lignan extracts. After one year of storage, lignan contents changed only moderately and added lignans were stable in stored wines. Total polyphenol content in wines and the antioxidant activity of wines were significantly influenced by the type of wine (i.e., red or white). The presented method of wine enrichment with lignans opens the door for the production of extra quality wines.

The goal of this work was to provide evidence for the inhibitory effects of fresh hops on the growth of Helicobacter pylori. Fresh hops were homogenised after harvest and the homogenate was treated using pascalisation (treatment with high pressure). This homogenate was used for testing the growth inhibitory effects on strains of H. pylori, a pathogenic microorganism, isolated from patients suffering from gastritis or gastric ulcers. The tests demonstrated reliable inhibitory effects and open the possibility of hops being used as a supplement to the treatment of H. pylori infections.

Grapes from two varieties - Franc (red) and Green Veltliner (white) were processed using UV radiation at selected powers and times. Irradiated grapes were stored for 24, 48, and 72 h at room temperature. A second set of grapes was dipped into ozonised water. We tested the influence of ozone concentration, dipping time, and storage time. All experiments were performed using grapes harvested in 2009, 2010, and 2011. The two treatments were compared relative to trans-resveratrol content in grape skins and juices (prepared from treated grapes).

We used the germinated soybeans to prepare and evaluate soya yoghurts, with substantially reduced alpha-galactosides (AG) contents. The lower AG content allows the production of final products that do not cause flatulence. To enable us to control the final consistency and other sensory parameters of soya yoghurts, it was necessary to study the influence of the dry matter content on these quality parameters, i.e. the yield stress, appearance, flavour, taste, soya off-flavour, consistency, and overall impression. Establishing the relationships between the dry matter content and qualitative parameters allowed for an easy prediction of the optimal amount of dry matter to maximise soya yogurt quality from the sensory perspective. The optimum amount of dry matter was found to be 6.5%.

The goal of this work was to design mixed vegetable (vegetable-fruit) juices which are preserved by high pressure, have an increased content of bioactive substances, are made from locally available produce, and offer excellent nutrition and appealing taste. The new products were prepared on laboratory scale units and underwent nutritional, microbiological, and sensory evaluations. The basic composition, total polyphenol content, ascorbic acid content, and total antioxidant activity were determined.

The aim of this work was to find sensory suitable combinations of not commonly used vegetables, that is, cabbage, celeriac and parsnip, into mixed fruit-vegetable juices, two-species vegetable juices and vegetable juices with whey. These juices might have the potential to offer consumers new, interesting, tasty and nutritional products. Another interesting variation could be preparation of vegetable juices in combination with sweet whey. Nutritional and sensory evaluations were carried out using juices prepared in the laboratory. The total phenolic content, in addition to ascorbic acid and antioxidant activity, was determined. The developed juices with high nutritional value should increase very low fruit and vegetable consumption in the Czech population. The prepared juices were high pressure pasteurized (410 MPa). This technique retains the desired levels of important nutritional substances, while being destructive to live microbial cell structure. The germination of spores is suppressed by low pH value.

TOTUSEK J., TRISKA J., LEFNEROVA D., STROHALM J., VRCHOTOVA N., ZENDULKA O., PRUCHOVA J., CHALOUPKOVA J., NOVOTNA P., HOUSKA M. (2011): Contents of sulforaphane and total isothiocyanates, antimutagenic activity, and inhibition of clastogenicity in pulp juices from cruciferous plants. Czech J. Food Sci., 29: 548-556.The consumption of Cruciferous vegetables is important for the prevention of cancerous diseases, particularly colorectal cancer. The effects of technological treatments (freezing, pasteurisation, high-pressure treatment) on the content of isothiocyanates, considered to be the active substance, were observed in single-species vegetable juices prepared from cruciferous vegetables (broccoli, cauliflower, Brussels sprouts, white and red cabbage). The contents of sulforaphane and total isothiocyanates were studied relative to the temperature, action period, and time delay after juice pressing. Sulforaphane and total isothiocyanates were determined by HPLC. Sulforaphane content in various parts of fresh broccoli was also assessed. Antimutagenic activity of the juices (frozen, pasteurised, and high-pressure treated) was evaluated using the Ames test and the following mutagens: AFTB1 (aflatoxin B1), IQ (2-amino-3-methyl-3H-imidazo-[4,5-f]quinoline), and MNU (2-nitroso-2-methylurea). Clastogenicity inhibition of the mutagens, in response to broccoli juice, as well as of pure sulforaphane, was observed using an in vivo experiment (the micronucleus test). It was shown that in terms of sulforaphane content, it is best to let broccoli juice stand for 60 min after pressing and pH adjustment. Sulforaphane content does not change under heating to 60 degrees C. Its content decreases considerably (compared to fresh juice) with heating to higher temperatures than 60 degrees C. High-pressure treatment preserves mutagenic inhibition to the same degree as juices freezing.

An experimental protocol to harmonize the pressure and temperature-histories of model samples treated in different individual high pressure pilot units was developed. This protocol was based on the endpoint strategy. Step zero of this protocol consisted of an exploratory measurement of the pressure, temperature-history of the pressure transmitting medium in the different chambers without the use of a container. In steps one and two of the protocol, the temperature of a sample was measured, which was placed in a container. Two types of samples were considered, a pure water sample allowing free convection (step 1) and a viscous water-based system (using a water soluble thickener) preventing free convection in the sample container (step 2).The high pressure units differed primarily in pressure build-up and pressure release times. The suggested endpoint strategy enabled the minimization of differences in temperature-histories during the pressure holding phase. Pressure, temperature-histories measured in the different high pressure units and information on the inactivation kinetics of α-amylase based systems were used to compare the process impact of different pressure, temperature-histories on the enzyme inactivation. The differences in temperature-histories significantly influenced the degree of enzyme inactivation; in particular the temperature-histories during the pressure build-up phase substantially contributed to differences in residual enzyme activity.Industrial relevanceBoth in laboratory scale studies (e.g. microorganism and enzyme inactivation) as well as in the industrial implementation, different high pressure units are being used. Different layouts (e.g. vessel volume, sensor locations etc.) are observed leading to a.o. differences in pressure build-up and release and consequently in dynamic temperature pressure time conditions in different vessels and at different locations of one single vessel. Specific attention should be given to this issue, both in conducting kinetic studies as well as in scale-up from lab-scale processes to industrial scale processes. This manuscript shows that if the same process is implemented in different units, differences in pressure temperature time conditions are observed resulting in differences in impact (shown by enzyme inactivation). These differences can be minimized using an end point strategy, i.e. when implementing protocols based on a specified endpoint condition at the start of the holding phase.

The quasi-adiabatic temperature increase due to compression heating, during high-pressure (HP) processing (HPP), was studied using specially designed equipment. The temperature increase was evaluated as the difference in temperature, during compression, between atmospheric pressure and nominal pressure. The temperature was measured using a thermocouple in the center of a polyoxymethylene cup, which contained the sample. Fresh meat balls, pork meat pate, and tomato puree temperature increases were measured at three initial temperature levels between 40 and 80 degrees C. Nominal pressure was either 400 or 500MPa. Results showed that the fat content had a positive effect on temperature increases. Empirical equations were developed to calculate the temperature increase during HPP at different initial temperatures for pressures of 400 and 500MPa. This thermal effect data can be used for numerical modeling of temperature histories of foods during HP-assisted pasteurization or sterilization processes.