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Rapid population growth requires more intense production of food industry, with two major consequences: significant amount of food processing residues and more sewage sludge originating from biological wastewater treatment plant. Sludge is a big concern for the disposal for wastewater treatment plant. The European Union makes an effort regarding the reduction of organic fractions disposed at a landfill. Composting is a cost-effective and ecological-friendly alternative for managing biodegradable organic fractions. Experiments of co-composting of sewage sludge, green waste and food waste, at carbon/nitrogen ratios 8.75, 18.00 and 24.90, were performed during three months by monitoring of temperature, pH, moisture, carbon and nitrogen proportion, carbon/nitrogen ratio, and germination index. The results showed that co-composting of sewage sludge, green waste and food waste is effective and results in the production of quality compost

In this work, the influence of high-power ultrasound (HPU) followed by pulsed electric field (PEF) in the hurdle concept (HPU + PEF) on the content of biologically active compounds (BACs) and antioxidant activity in strawberry juices stored at 4 °C/7 days was investigated. The HPU was performed with an amplitude of 25% and pulse of 50% during 2.5, 5.0 and 7.5 min, while the PEF was performed with an electric field strength of 30 kV cm−1 and frequency of 100 Hz during 1.5, 3 and 4.5 min. The results obtained indicate that the synergy of the mechanisms of action for technologies in the hurdle concept plays a critical role in the stability of BACs and antioxidant activity. Juices treated with HPU + PEF hurdle technology and kept at 4 °C for 7 days showed a statistically significant decrease in all BACs, antioxidant capacity and pH. Shorter HPU + PEF treatment times favored the preservation of BACs in juices. Regarding total phenolic compounds, flavonols, condensed tannins and antioxidant capacity, optimization of hurdle parameters showed that a shorter HPU treatment time of 2.5 min provided the best yield of these compounds. In summary, by optimizing and adjusting the parameters of the HPU/PEF technology, it is possible to produce functional strawberry juice.

This work investigated the influence of pulsed electric field (PEF) and high-power ultrasound (HPU) combined with hurdle technology to preserve the bioactive compounds (BACs) content and antioxidant activity in stored strawberry juices. PEF was performed at 30 kV cm−1, 100 Hz during 1.5, 3, and 4.5 min, while HPU was performed at 25% amplitude and 50% pulse during 2.5, 5.0, and 7.5 min. Total phenols and hydroxycinnamic acids were the most stable BACs during the hurdle treatment without influence of the duration of both treatments, while flavonols and condensed tannins showed a significant stability dependence with respect to the duration of both treatments. Total phenols were also stable during storage, in contrast to the individual groups of BACs studied. A chemometric approach was used to optimize the parameters of the hurdle treatments with respect to the highest level of BACs and the antioxidant activity of the treated juices. In general, shorter treatment times in the hurdle approach resulted in better stability of BACs and antioxidant activity. The hurdle technology investigated in this study has the strong potential to be an excellent concept for optimizing the operating parameters of PEF and HPU technologies in the preservation of functional foods.

Research background. Two methods of milk treatment were used, ultrasound (innovative method) and bactofugation, after which the physicochemical and sensory properties of the milk were examined, with the primary aim of achieving the quality and consistency of the pasteurized milk. Experimental approach. Ultrasound power of 200 and 400 W and frequency of 24 kHz with constant wave cycle were used. Milk was treated for 2.5, 5, 7.5 and 10 min with sonification at 20 °C (room temperature) and thermosonification (ultrasound at temperature higher than room temperature) at 55 °C. The purpose of this study is to investigate the effect of high-power ultrasound combined with a slightly increased temperature on whole, skimmed and skimmed cow’s milk pretreated with bactofugation. Results and conclusions. The best sensory quality was achieved when milk was treated with ultrasound power of 200 W at 20 °C for max. 7.5 min. This research shows the potential of the applications of high-power ultrasound in dairy industry combined with bactofugation as a pre-treatment of milk at a slightly increased temperature (up to 55 °C). Novelty and scientific contribution. The application of these two treatments requires milder processing conditions than pasteurization, it is economical and more environmentally friendly technological process that preserves better nutritional values of milk, which is preferred by consumers.

Research background. The application of high power ultrasound combined with a slightly increased temperature on raw cow’s milk, skimmed cow’s milk and skimmed cow’s milk that passed the bactofugation process was analysed. We combined ultrasound with bactofugation of milk to achieve the microbiological accuracy that is equivalent to pasteurization. Experimental approach. The milk samples (200 mL) were treated for 2.5, 5, 7.5 and 10 min with high-power ultrasound (200 and 400 W) with a frequency of 24 kHz. The treatments were conducted with a constant duty cycle of 100%. Temperatures during the treatments were 20 and 55 °C. The somatic cell count of the aerobic mesophilic bacteria, as well the number of Enterobacteriaceae, Escherichia coli and Staphylococcus aureus cells were analysed. Results and conclusions. From the perspective of the reduction of the total count of bacteria, the best result was achieved by high-power ultrasound at 400 W treated for 10 min. High reduction of Enterobacteriaceae, E. coli and S. aureus cells was achieved with ultrasound treatment of raw, skimmed and skimmed cow’s milk that passed the bactofugation with a power of 200 and 400 W regardless of the treatment time. Novelty and scientific contribution. This work combines bactofugation and high-power ultrasound for the inactivation of microoganisms. This combination was used at a slightly increased temperature (up to 55 °C), which is much more economical than pasteurization, while it preserves the sensory and physicochemical properties of milk.

The aim of this study was to investigate the influence of high intensity pulsed electric field (HIPEF) technology on the stability of total phenols, anthocyanins, hydroxycinnamic acids, flavonols, and condensed tannins in strawberry juices (Fragaria x ananassa Duch. cv. ‘Albion’) with different ripening stages (75% and 100%) and stored at +4 °C for 7 days. The HIPEF parameters studied were: (i) electric field strength (40 and 50 kV cm−1), (ii) frequency (100 and 200 Hz), and (iii) treatment duration (3 and 6 min). Of the HIPEF parameters studied, electric field strength and frequency had a statistically significant effect on the content of all phenolic compounds. Treatment duration showed no statistically significant effects on phenolic compounds except for flavonols and condensed tannins. Storage had a positive effect on the stability of most of the phenolic compounds, with the exception of flavonols. Optimization of HIPEF processing showed that strawberry samples at both ripeness levels were suitable for HIPEF treatment to obtain functional fruit juices with a high content of polyphenols.

In this study, we designed high fiber cookie recipe without using additives by means of extrusion-based 3D printing. We aimed to relate printing quality and cookie physical properties with dough rheology and dietary fiber content depending on the flour (oat, rye, rice, and carob flour) and fat type (olive oil or butter). The flour choice influenced all cookie quality parameters: baking loss, color, line height and width, and dietary fiber content. Results indicated that lower baking loss and better printing quality were obtained for cookie dough containing olive oil, which had higher viscosity and consistency coefficient compared with dough containing butter. Cookies with olive oil in which part of the oat flour was replaced with rye and carob flour were printed with high accuracy (≥98%), close to the ideal 3D shape. Overall, this study demonstrates the importance of selecting fat and particularly flour, as well as the extrusion rate on the quality and repeatability of 3D-printed cookies.

The aim of this study is to determine the effect of high intensity ultrasound (amplitude, temperature and treatment time) on the inactivation of food spoilage bacteria Escherichia coli 3014, Staphylococcus aureus 3048, Salmonella sp. 3064, Listeria monocytogenes ATCC 23074 and Bacillus cereus 30. The model suspensions of bacteria were treated with 12.7-mm ultrasonic probe operated at 600 W nominal power (ultrasonic treatment implemented at 20 kHz) and at amplitudes of 60, 90 and 120 µm. Also, treatment time of 3, 6 and 9 min and temperature of 20, 40 and 60 °C were used. The results were statistically processed with STATGRAPHICS Centurion computer program and response surface methodology. All three parameters studied seem to substantially affect the inactivation of bacteria in pure culture. The results also indicate increased inactivation of microorganisms under longer period of treatments, particularly in combination with higher temperature and/or amplitude. After ultrasonic treatment at 60 °C, 9 min and 120 μm, the viability of cells was not confirmed for Escherichia coli 3014, Staphylococcus aureus 3048, Salmonella sp. 3064 and Listeria monocytogenes ATCC 23074. Under the mentioned conditions the highest inactivation (3.48 log CFU/mL) of Bacillus cereus 30 was obtained.

The aim of this study is to determine various textural properties of heat-induced gels prepared from wheat and potato starch suspensions (10 %) treated with tribomechanical micronisation and activation (TMA). Particle size measurements showed that the TMA treatment caused a significant decrease in particle size and change in particle size distribution of powdered starches. Scanning electron microphotographs showed an obvious impact on the structure and size of starch granules. The effect of TMA treatment on the texture profile of wheat and potato starch gels was assessed by measuring their textural properties, such as hardness, adhesiveness, cohesiveness, springiness and gumminess. The texture profile analyses of the TMA-treated wheat and potato starch gels showed lower hardness and gumminess; however, adhesiveness, cohesiveness and springiness were higher when compared with untreated suspensions. TMA treatment caused no significant lowering of the initial gelatinization temperatures. Results of differential scanning calorimetry measurements showed a decrease in the enthalpy of gelatinization. This can be explained by the disruption of starch granules by mechanical forces during the TMA treatment, which made the granules more permeable to water during the heating step of differential scanning calorimetry analysis.

Ultrasonication is a nonthermal food processing method that is used in several applications (extraction, treatment before drying, freezing, inactivation of microorganisms, etc.) in ultrasound processing. The objective of this study is to investigate the effect of high power ultrasound and pasteurisation on the aroma profile and sensory properties of apple juice and nectar. Samples were treated according to the experimental design, with high power sonicator at ultrasound frequency of 20 kHz under various conditions (treatment time: 3, 6 and 9 min, sample temperature: 20, 40 and 60 °C, and amplitude: 60, 90 and 120 μm). The aromatic profiles of juices showed that, compared to the untreated samples of juices and nectars, ultrasonic treatment led to the formation of new compounds (which were not present in the untreated samples) or to the disappearance of compounds that were found in the untreated samples. Samples treated at the highest amplitude (120 μm) were used for evaluation and comparison with untreated and pasteurised samples using electronic tongue study. Principal component analysis confirmed the results of electronic tongue study, which showed that the ultrasound-treated and pasteurised juices had different scores compared to the untreated samples.

High-intensity ultrasound was used to investigate the inactivation of microorganisms in raw bovine milk. Raw bovine milk with 4% of milk fat was treated with ultrasonic probe that was 12 mm in diameter and with 20 kHz frequency immerged in milk directly. In the ultrasound treatment, three parameters were varied according to the statistical experimental design. The centre composite design was used to design and optimise the experimental parameters: temperature (20, 40, and 60°C), amplitude (120, 90, and 60 µm), and time (6, 9, and 12 min). All analyses were performed immediately after sonication and after 3 days and 5 days of storage under refrigeration at 4°C. The factors that seem to affect substantially the inactivation of microorganisms in using ultrasound are the amplitude of the ultrasonic waves, the exposure/contact time with the microorganisms, and the temperature of the treatment. The results achieved indicate a significant inactivation of microorganisms under longer periods of the treatment with ultrasonic probe, particularly in combination of higher temperature and amplitude. The output optimal value of total bacteria count was defined by Statgraphics where the lowest bacteria count was 3.688 log CFU/ml for the following specific ultrasound parameters: amplitude 120 μm, treatment time 9.84 min, and temperature 45.34°C.

Inactivation of Staphylococcus aureus and Escherichia coli in milk containing 4 % milk fat was carried out using a 20 kHz power ultrasound. The experiments were planned and performed according to the statistical experimental design. Specifically, central composite design was used to optimize and design three experimental parameters: temperature (20, 40 and 60 °C), amplitude (60, 90 and 120 μm) and treatment time (6, 9 and 12 min). It was found that Gram-negative bacteria (Escherichia coli; D120 mm=2.78 min at 60 °C) are more susceptible to the ultrasonic treatment than Gram-positive bacteria (Staphylococcus aureus; D120 μm=4.80 at 60 °C). Nevertheless, all three parameters studied seem to substantially affect the inactivation of both Staphylococcus aureus and Escherichia coli in milk using ultrasonic treatment. The results also indicate increased inactivation of microorganisms under longer period of treatments, particularly in combination with higher temperature and/or amplitude.

Ultrasonication is a non-thermal method of food preservation that has the advantage of inactivating microbes in food without causing the common side-effects associated with conventional heat treatments, such as nutrient and flavour loss. In this work high intensity ultrasound was used to investigate inactivation Enterobacteriae count in raw milk. Raw milk with 4% of milk fat was treated with ultrasonic probe that was 12 mm in diameter and with 20 kHz frequency immerged in milk directly. For ultrasounds treatment, three parameters varied according to the statistical experimental design. Centre composite design was used to optimize and design experimental parameters: temperature (20, 40 and 60 °C), amplitude (120, 90 and 60 μm) and time (6, 9 and 12 minutes). All analyses were performed immediately after sonication and after 3 and 5 days of storage in refrigeration at 4 °C. The facts that substantially affect the inactivation of microorganisms using ultrasound are the amplitude of the ultrasonic waves, the exposure/contact time with the microorganisms, and the temperatureof treatment. The achieved results indicate significant inactivation of microorganisms under longer period of treatments with ultrasonic probe particularly in combination with higher temperature andamplitude. Output optimal value of Enterobacteriae count has been defined by Statgraphics where lowest Enterobacteriae count (1.06151 log CFU mL-1) was as follows for specific ultrasound parameters: amplitude of 120 μm, treatment time for 12 min and temperature of 60 °C.

The aim of this study was to examine the effect of high-power ultrasound (US) and highpressure processing (HP) on model systems composed of whey protein concentrate (WPC) and whey protein isolate (WPI) with or without guar gum addition. This kind of systems can be found in food production industry so the aim was to use novel food processing technologies to be utilized as a method for products development. Aqueous suspensions (10 g kg-1) of powdered whey proteins were treated with either ultrasound or high pressure. The treatment conditions were as follows: US: frequency of 30 kHz, for 5 and 10 min; HP: pressure intensity 300-600 MPa, for 5 and 10 min. Rheological and thermophysical properties were analyzed after guar gum addition (0.5 g kg-1). Ultrasound treatment showed a significant influence on all examined properties through protein denaturation caused by cavitation and microstreaming effects. High pressure caused significant increase in viscosity and consistency coefficients of model systems with and without guar addition. Significant decrease of initial freezing and initial thawing temperature was observed in all samples. With this research the direct influence of ultrasound and high-pressure treatment on the rheological and thermophysical properties of whey protein isolate and concentrate model systems with or without guar gum was demonstrated.

Ultrasound represents a non-thermal food processing technique and has great potential to be used in the food industry. The objective of this research was to observe ultrasound impact on physical properties of model systems prepared with whey protein isolates (WPI) or whey protein concentrates (WPC) with or without sucrose or milk powder addition. This kind of systems is often used in milk beverages and milk based products. Model systems with protein and milk powder or sucrose addition were treated with high power ultrasound (HPU) probe of 30 kHz frequency for 5 and 10 minutes. After sonication several properties were determined and examined: solubility, emulsifying and foaming properties, rheological and thermophysical properties. Ultrasound treatment showed severe influence on all examined properties, caused by protein denaturation as a consequence of cavitation and microstreaming effects. Ultrasound treatment caused decrease in protein solubility for whey protein isolate and whey protein concentrates model systems, compared to untreated sample. There was statistically significant increase in foam volume of model systems, prepared with sucrose or milk powder and WPI after ultrasound treatment. Statistically significant decrease in emulsion activity and emulsion stability indices was observed for model systems prepared solely with isolates and concentrates. After treatment of whey protein model systems (with or without milk powder or sucrose) with 30 kHz ultrasound, the changes in consistency coefficients (k) were observed, but there were no significant changes in flow behaviour indices (n). After addition of milk powder or sucrose, statistically significant decrease in initial freezing and melting temperatures was observed due to the ultrasound treatment.

Particulate β-glucans were isolated from brewer’s yeast using three different procedures – alkaline (A), alkaline-acidic (AA) and alkaline-acidic with mannoprotein removal (AAM) and dried using three different methods – air drying (AD), lyophilization (L) and spray drying (SD). In this work, the obtained β-glucan preparations were tested for their microstructure, rheological properties, swelling, water-holding and oil-binding capacities. According to their rheological properties, suspensions containing 1 and 2 % (by mass) of spray-dried samples belong to the category of dilatant fluids. Among the spray-dried samples, rheological behaviour and water-holding capacity of the preparation AA-SD differed from those obtained by other two procedures (A-SD and AAM-SD). Concerning different drying methods applied, swelling was the lowest in the lyophilized samples and the most pronounced in the air-dried ones. Oil-binding capacity was the highest in the lyophilized preparations and increased proportionally to the number of processing steps applied in the isolation procedure.

The purpose of this investigation is to study the influence of high intensity ultrasound and pasteurization on the stability of anthocyanins and their content in strawberry juice. Different ultrasound process parameters for the treatment of juices are compared to the classical thermal treatments. For ultrasound treatments, three parameters were varied according to the statistical experimental design. Central composite design was used to optimize and design experimental parameters: temperature (25, 40 and 55 °C), amplitude (60, 90 and 120 μm) and time (3, 6, and 9 min). It was found that the anthocyanin content after pasteurization (85 °C for 2 min) was reduced by 5.3 to 5.8 % compared to untreated juices. After treatment with ultrasound (20 °C for 3, 6 or 9 min) or thermosonication (40 °C for 3, 6 or 9 min and 60 °C for 3 or 6 min), the degradation of anthocyanins was generally less intensive and was 0.7–4.4 % compared to the untreated juices. Only in the case of ultrasonic treatment at a temperature of 55 °C and treatment time of 9 min the total content of anthocyanins, compared to untreated juice, was reduced by 5.8 to 7.1 %, and their degradation was greater than that of pasteurized juices. From the results it can be concluded that total anthocyanin content was greater in more than 85 % of the selected ultrasound treatments compared to pasteurized juices. Ultrasound treatment can replace pasteurization in terms of preserving total anthocyanin content. The modelling approaches using response surface methodology (RSM) developed in this study exploit data in order to identify the optimal processing parameters for lowering degradation of anthocyanins in strawberry juice during ultrasound processing.

The effects of high power ultrasound of 24 kHz and ultrasound bath of 24 kHz frequency on the textural and pasting properties of corn starch suspensions was examined. Suspensions were treated with different intensities and treatment times (15 min and 30 min) using an ultrasound probe set and bath. The treatments with high power ultrasound probes caused a significant lowering of the starting gelatinisation temperatures of corn starch. The ultrasound treatment caused disruption of starch granules by cavitational forces and made the granules more permeable to water. The highest viscosity was observed for the treatment with 300 W probe. Also, a statistically significant increase in solubility in water (20°C) was observed, being caused by the disruption of starch granules and molecules by ultrasound treatment. When applying more powerful ultrasound, starch granules, specifically in the amorphous region, are much more mechanically damaged. The texture profile analyses of the starch gel prepared from the suspensions that had been treated with ultrasound probe presented higher hardness and higher values of adhesiveness and cohesiveness when compared with untreated suspensions or those treated with ultrasound bath. Micrography showed an obvious impact of ultrasound on the structure of starch granules. Ultrasound treatment ruptures and mechanically damages the starch granules causing collapse of cavitation bubbles which induces high pressure gradients and high local velocities of the liquid layers in their vicinity.

Since food choice is always a unique and personal experience, consumer behaviour is important for food manufacturers and marketers in term of product success. Due to the beneficial healthprotective effects of dairy beverages, this market segment is very innovative and fast-growing. The aim of this pilot-study was to examine the consumption patterns, purchasing behaviour and motivesfor selection of dairy beverages. The sample of this study included 114 participants (44 males and 70 females) which were interviewed face-to-face at the entrance of 5 shopping centres. The surveyinstrument consisted of closed questions regarding habits of consumption, purchasing habits and motives for selection of dairy beverages. Gender specific differences were tested. The results obtained have shown that females consumed more milk and milk drinks (p

Moisture sorption isotherms describe the relation between the moisture content of the dry material (food) and relative humidity of the surrounding environment. The data obtained are important in modelling of drying process conditions, packaging and shelf-life stability of food that will provide maximum retaining of aroma, colour and texture as well as nutritive and biological value. The objective of this research was to establish the equilibrium moisture content and water activity, as well as monolayer value of two commercial powdered whey protein isolates before and after tribomechanical micronisation and enzymatic hydrolysis, respectively. At the same time it was necessary to evaluate the best moisture sorption isotherm equation to fit the experimental data. The equilibrium moisture contents in investigated samples were determined using standard gravimetric method at 20 °C. The range of water activities was 0.11 to 0.75. The monolayer moisture content was estimated from sorption data using Brunauer-Emmett-Teller (BET) and Guggenheim-Anderson-de Boer (GAB) models. The results have shown that tribomechanically treated whey protein isolates as well as protein hydrolizates had lower monolayer moisture content values as well as higher corresponding water activity. Therefore, in spite of the fact that they have lower moisture content, they can be storage at higher relative humidity compared to untreated samples. BET model gave better fit to experimental sorption data for a water activity range from 0.11-0.54, while GAB model gave the closest fit for a water activity to 0.75.

This paper presents research of the high power ultrasound effect on rheological and foaming properties of ice cream model mixtures. Ice cream model mixtures are prepared according to specific recipes, and afterward undergone through different homogenization techniques: mechanical mixing, ultrasound treatment and combination of mechanical and ultrasound treatment. Specific diameter (12.7 mm) of ultrasound probe tip has been used for ultrasound treatment that lasted 5 minutes at 100 percent amplitude. Rheological parameters have been determined using rotational rheometer and expressed as flow index, consistency coefficient and apparent viscosity. From the results it can be concluded that all model mixtures have non-newtonian, dilatant type behavior. The highest viscosities have been observed for model mixtures that were homogenizes with mechanical mixing, and significantly lower values of viscosity have been observed for ultrasound treated ones. Foaming properties are expressed as percentage of increase in foam volume, foam stability index and minimal viscosity. It has been determined that ice cream model mixtures treated only with ultrasound had minimal increase in foam volume, while the highest increase in foam volume has been observed for ice cream mixture that has been treated in combination with mechanical and ultrasound treatment. Also, ice cream mixtures having higher amount of proteins in composition had shown higher foam stability. It has been determined that optimal treatment time is 10 minutes.

Preservation of food with thermal sterilisation is usually the most common way nowadays. Besides the positive aim of preservation regarding microorganisms’ reduction, elevated temperature in processing simultaneously causes serious changes in nutritive and organoleptical properties of food. Loss of food quality is related to structure and texture deformations, modification of macromolecules and creation of new compounds coming from reactions that are catalised with temperature. One of the new non-thermal processes that can in large scale improve different processes in food industry is ultrasound. In the last five years, new applications of high power ultrasound (HPU) include inactivation of enzymes and microorganisms, assistance in membrane processes, improvement of dairy product texture, improvement of functional properties of proteins etc. High power ultrasound application is used in emulsification and milk homogenization, but in these processes the most important thing is to monitor possible negative effect like oxidation of fats, inactivation of valuable enzymes and denaturation of proteins. Controled and optimized application of ultrasound demands application of specific ultrasound frequency and optimal treatment time. Treatments should be performed at lower temperatures to avoid negative side effects on treated materials.

Recently, a lot of investigations have been focused on development of the novel food processing techniques with the aim to obtain the high quality food products. High intensive ultrasound applied to the milk can destroy some microorganisms and save energy and process time significantly, using milder thermal treatment and obtaining product with higher nutritive value. Therefore, ultrasound treatment has proved to be potentially very successful technique of milk sterilization, particularly in combination with increased temperature.

Whey proteins constitute 18-20% of total milk protein content. Their nutritive value, accompanied by diverse physico-chemical and functional properties, make whey proteins widely applicable in food industry. Highly risen demands of consumers for tastier, healthier, suitable and more natural food products have given dairy industry the opportunity for development and enrichment of food products with whey protein supplements in order to increase their functional and nutritive properties. Development of these supplements mainly depended on recognition of the importance in understanding molecular basis of whey protein functionality from food scientists. Thereby, the aim of this paper is to expose the basis of whey protein functionality at one place, as the important supplement for food products.

Whey protein fractions represent 18 - 20 % of total milk nitrogen content. Nutritional value in addition to diverse physico - chemical and functional properties make whey proteins highly suitable for application in foodstuffs. In the most cases, whey proteins are used because of their functional properties. Whey proteins possess favourable functional characteristics such as gelling, water binding, emulsification and foaming ability. Due to application of new process techniques (membrane fractionation techniques), it is possible to produce various whey - protein based products. The most important products based on the whey proteins are whey protein concentrates (WPC) and whey protein isolates (WPI). The aim of this paper was to give comprehensive review of nutritional and functional properties of the most common used whey proteins (whey protein concentrate - WPC and whey protein isolate - WPI) in the food industry.

The aim of this paper is to examine the influence of high hydrostatic pressure treatment on the rheological and thermophisical properties of β-lactoglobulin and carragenan model systems. Suspensions of β-lactoglobulin were treated with a high hydrostatic pressure in a range of 300 to 600 MPa. Holding period was 5 and 10 minutes.Measurements were performed using rotational viscosimeter Rheometric Scientific RM-180 at 20 oC. The rheological parameters were determined by the Ostwald de Waele law. The results of the investigation have shown that all investigated systems are non-Newtonian – pseudoplastic. All samples treated with high hydrostatic pressure have changed rheological characteristics. The extent of protein denaturation was proportional to the intensity of applied pressure and holding time. The phase transition temperatures were determined by differential thermal analysis (DTA). High pressure treatment caused depression of freezing point and melting point, respectively. Carragenan acts as a crioprotectant.

The aim of this study was to determine functional properties: solubility, dispersibility, viscosity, emulsifiying, foaming and rheological properties of hydrolyzed whey protein (HWP) and whey protein isolate (WPI). Particle size analysis and specific area of HWP and WPI were performed by «Mie – theory» of «light scatering» using «Malvern Mastersizer X». The results of this analysis have shown that HWP had higher particle size and specific area than WPI.By examing functional properties, it has been established that HWP has higher solubility, dispersibility, emulsifiying properties as well as foam stability (FSI and MFS) compared to WPI. Rheological properties of protein suspensions were determined in 10, 15, and 18 % suspension of proteins (HWP and WPI) by rotational viscosimeter, Brookfiel DV-III at 25°C. Apparent viscosity at 200 s-1 was calculated, using Newtonian law. On the basis of measured shear rate and shear stress, using least squere method, rheological parameters, flow behavior indeks (n) and consistency coefficient (k) were determined according to the Ostwald de Waele model. The highest viscosity was observed in 18% HWP model system while the least viscosity was found in a model system prepared with 10% WPI.

Nutritional value in addition to diverse physico-chemical and functional properties make whey proteins highly suitable for food purpose. One of important functional demand of whey proteins is their capability to induce and stabilize aerated food products.The aim of this work was to obtain whey protein isolate and β-lactoglobulin with improved foaming properties, what will in addition to its high nutritional value, make them more acceptable for use in whipped dairy products. For these purpose, whey protein isolate and β-lactoglobulin were treated with high hydrostatic pressure of 400, 500 and 600 MPa, for holding period of 10 minutes. Solubility changes were expressed as nitrogen solubility. Turbidity measurements of diluted protein solutions were used to obtain information about protein aggregation in addition to scanning electron microscopicpictures. Assessment of foaming properties has been based on the foam volume and foam stability. All analysis were carried out on whey protein isolate and β-lactoglobulin before and after high pressure treatment. The results obtained showed pressure-induced structural changes together with partial denaturation in both samples proportional to the intensity of applied pressure. The observed effects of pressure treatments on foaming properties clearly indicate that the extent of pressure-induced changes in the physicochemical properties of whey protein isolate and β-lactoglobulin positively affected foamability and foam stability, respectively.

Whey proteins are commonly used in the food industry due to their nutritive value and functional properties. The most important functional properties of whey proteins are solubility, viscosity, water holding capacity, emulsification and foaming. The aim of this study was to determine functional properties of main whey protein fractions (α-lactalbumin and β-lactoglobulin) which have the biggest influence on the functional properties of whey proteins. Particle size analysis and specific area of α-lactalbumin and β-lactoglobulin were performed by «Mie – theory» of «light scatering» using «Malvern Mastersizer X». The results of this analysis have shown that β-lactoglobulin had higher particle size and specific area than α-lactalbumin.By examining functional properties (solubility, dispersibility, emulsifiying properties – emulsion activity index (EAI) and emulsion stability index (ESI) and foaming properties) of α-lactalbumin and β-lactoglobulin, it has been established that β-lactoglobulin has higher solubility, dispersibility, emulsifiying properties as well as foaming properties than α-lactalbumin. Rheological properties of protein suspensions were determined by rotational viscosimeter, Brookfiel DV-III at temperature 25°C. Rheological parameters, flow behavior indeks (n) and consistency coefficient (k) were determined by the power-law model. The results of investigation have shown that 10% suspenzion of α-lactalbumin and β-lactoglobulin are non-Newtonian fluids and they exhibited pseudoplastic properties.

Investigations with powdered whey protein concentrates containing 60 % (WPC-60) or 80 % (WPC-80) of proteins were carried out. In this work proteins were treated using the laboratory equipment for tribomechanical micronisation with three different rotor speeds. Before and after the tribomechanical treatment, the analyses of the particle size and particle distribution as well as the specific area and scanning microscopy were carried out. The influence of tribomechanical treatment as well as hydrocolloid addition on the rheological properties of model systems of whey protein concentrate (10 % of total solid) was studied. Rheological parameters, flow behavior index (n) and consistency coefficient (k) were determined by the power-law model. The results obtained showed that the tribomechanical treatment involves a significant decrease in particle size, a change in particle distribution and an increase in specific area of powdered whey proteins. Systems without hydrocolloid addition were Newtonian, but those with hydrocolloid addition exhibited pseudoplastic properties. The viscosity of model systems containingn tribomechanically treated whey protein concentrates (TWPC) was greater in comparison with the same systems prepared with untreated WPC. Systems with greater amount of proteins (WPC-80) had higher viscosity than the same systems containing lower amount of proteins. Hydrocolloid addition affected an increase of viscosity of model systems prepared with untreated WPC. The most significant increase of consistency coefficient (k) was observed in systems with carboxymethylcellulose (CMC) and addition of a special type of carboxymethylcellulose (CMC E466) known as DIKO, icecream binder 0911-E. In systems containing tribomechanically treated TWPC hydrocolloids had various effects. In systems with guar gum, carragenan, inulin, pectin or amid pectin, viscosity increased in comparison with those prepared with untreated WPC. CMC and DIKO affected a significant viscosity decrease of TWPC model systems, which is the consequence of the interaction between proteins and (CMC) hydrocolloids. The found effects were pronounced more strongly as the rotor speed of TMA equipment was greater.

Knowledge of thermophysical properties, especially the phase transitions temperature, specific heat and enthalpy, are essential in defining the freezing process parameters as well as storage conditions of frozen food. In this work thermophysical properties of 10% model solutions prepared with 60% whey protein concentrate (WPC) with various hydrocolloids addition (HVEP, YO-EH, YO-L i YO-M) were investigated. Powdered whey protein concentrate was treated in equipment for tribomechanical micronization and activation at 40000 rpm (Patent: PCT/1B99/00757) just before model solutions preparation. Particle size analysis was performed using Frich –laser particle sizer “analysette 22”. The phase transition temperatures were determined by differential thermal analysis (DTA), while specific heat and enthalpy were calculated according to several mathematical equations. The results have shown that, due to tribomechanical treatment, certain changes in thermophysical and energetic properties of materials occurred. Tribomechanical treatment affects changes in granulometrical composition of WPC which result in higher abilities of reactions with hydrocolloids in model solutions and significant changes in thermophysical properties of the mentioned models.

Hydrocolloids are long-chain polymers, used in food production at small quantities (from 0,05 to 5 %) to achieve appropriate rheological properties, prevent syneresis, increase the viscosity and stability of foodstuffs and for crystallization process control. The aim of this work was to investigate the influence of tribomechanical micronization of powdered whey protein concentrate on the rheological properties of whey proteins model systems as well as the influence of severalcarboxymethylcellulose hydrocolloids addition in such systems.Measurements were done using rotational viscosimeter, Brookfield DV-III at temperature 20 oC. The rheological parameters were determined by powerlaw model. The results of investigation have shown that all investigated systems are non-Newtonian. Depending on the pretreatment of whey proteins and the mass fractions of hydrocolloids they exhibited pseudoplastic or dilatant properties.Particle size analysis was performed using Fritsch – laser particle sizer “analysette 22”. The operation of tribomechanical micronization caused the decreasing of particle size and incrasing specific area of whey proteins. Tribomechanical treatment of whey proteins had significant influence on the rheological parameters and the type of flowing.