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Minimal processing technologies, like High Hydrostatic Pressure (HHP), heat treatments at low temperatures have an increasing role in food industry. Eggs are considered as functional foods, but for high retention of biological active compounds adequate minimal processing technologies are needed during preservation procedure. In our study, liquid egg yolk (LEY) was examined to meet consumer's expectations.Combinations of pasteurization (57–63 °C, 5–7 min) and HHP (350–400 MPa, 5 min) were used to provide microbiological stability of LEY. After these treatments samples were examined for mesophyll aerobes and Enterobacteriaceae cell counts (using Nutrient agar an incubation of 30 °C, 48 h) and viscosity attributes (Anton Paar MCR 92).Our results show that microbiological stability is significantly influenced by the different parameters of heat treatments and HHP. Heat treatment effected at least 3 orders of magnitude decrease in cell count. Viscosity attributes point out that higher pressure of HHP have a stronger effect on viscosity than the temperature of pasteurization.The results point out a great opportunity for industrial use of minimal processing technologies for LEY. Microbiological safety is strongly influenced by the order of treatments, but viscosity may be independent from the order of the treatments.

The aim of this work was to evaluate the effect of packaging perforation on quality of carrot slices during cold storage at 5 °C. Polyethylene bags with different number of perforations (3, 4, and 6) were used in this experiment. Headspace oxygen concentration, respiration, weight loss, surface color, firmness, pH, and soluble solid content were examined throughout storage. It was observed, that all the investigated packaging were effective in maintaining the quality of carrot slices compared to the control. There was no symptom of decay until 12 days. In addition, pH, soluble solid content, and firmness showed nonsignificant change. Moreover, weight loss of packed carrot slices was below 2% after 12 days of storage. Packed carrot had better appearance at the end of experiment (12 days) than that of control.

Quick frozen food are becoming increasingly popular among consumers in the last decades. During the development of a quick frozen gluten-free pie crust dough product, the aim was to develop a dough that does not suffer any harmful changes after the freeze-thaw process. The texture is one of the most important sensorial properties, and has a great influence on consumer acceptance. Texture Analyser was used to measure the hardness and the brittleness of various doughs. A quick frozen pie crust dough should be easily cut, but non-crumbling after baking. The results showed that the hardness of a dough with 10% more rice flour was bigger than the other dough’s hardness and it became harder after the freeze-thaw process, while the other dough’s hardness have not changed during the process. The first dough was less brittle than the second dough, also before and after the freeze-thaw. In conclusion, the 1st dough is harder, so it is not more easy to cut than the 2nd dough. However, the first dough being less brittle allows cutting with less crumbs. Considering the expectations, in the future the first recipe should be used to make a fast-frozen pie crust dough product.

The objective of this work was to compare the physical and thermal characteristics of two coconut oils and their blends which were observed by the results of differential scanning calorimetry (DSC) and pulsed nuclear magnetic resonance (pNMR). Fat blends composed of different ratios (fully hydrogenated coconut oil / non-hydrogenated coconut oil: 25/75, 50/50 and 75/25) were prepared and examined for solid fat content. The solid fat content of samples was determined as a function of temperature by pNMR. The DSC technique determines the solid fat index by measuring the heat of fusion successively at different temperatures. DSC calculates the actual content of solids in fat samples and how it changes throughout the duration of heating or cooling. A characteristic curve is constructed by the correlation of enthalpies. Based on our results, it is clear that both DSC and pNMR techniques provide very practical and useful information on the solid fat content of fats. DSC is dynamic and pNMR is static. A difference in the values of the solid fat indexes of samples was observed which may be due to a fundamental difference between the two techniques. These data can be used by food manufacturers to optimize processing conditions for modified coconut oil and food products fortified with coconut oil.

Emerging technologies, like High Hydrostatic Pressure, heat treatments on low temperatures, and ultra-sonication, have an increasing tendency in industrial application. Vitamin enriched foods, like eggs, are considered as functional foods, but for high retention of biologically active compounds adequate minimal processing technologies are needed. In our study vitamin C enriched liquid egg white was examined to meet consumer expectations. Several combinations of low temperature pasteurization (57 - 63°C, 5 – 7 min) and High Hydrostatic Pressure (350, 5 min) were used to provide microbiological stability of vitamin C enriched (1000 mg/L) liquid egg white. After enrichment and treatments, the samples were examined for mesophyll aerobe and Enterobacteriaceae cell counts and viscosity attributes. Our results show that microbiological stability is not significantly influenced by vitamin C enrichment, but the different parameters of heat treatments and HHP have a strong effect. Viscosity attributes (measured with Anton Paar MCR 92) analysed by Hershel-Bulkley models point out that higher pressure of HHP has a stronger influence on viscosity than the temperature of pasteurization. Our results show a great opportunity for industrial use of minimal processing technologies for liquid egg white. Keywords: High hydrostatic pressure, microbiological safety, viscosity, liquid egg white, vitamin C, functional food

In the experiments pork loin and beef sirloin were treated by pressures of 100 to 600 MPa by 100 MPa steps for 5 min. Colour changes of samples and the changes of proteins were investigated. The latter were examined with isoelectric focusing and SDS polyacrylamide gel electrophoresis. We found that myoglobin behaved completely differently in case of the two different species. Myoglobin has mostly lost its native state at 300 MPa pressure in case of pork, but the beef myoglobin could remain native even up to 500 MPa. The treatment at 300 MPa or higher pressure values caused almost complete aggregation and denaturation in case of pork and beef proteins. The results of SDS-PAGE and the colour measurement confirmed this finding.

There are numerous new technologies whose implementation in food industry is hampered by the fact that people hesitate to invest in expensive systems which they cannot be sure will work or at least are questionable in terms of a given product. Until recently, preservation by HHP, high hydrostatic pressure, was such a technology, and still is today in some branches of the food industry. Investigations were conducted to answer the question of whether the literature, the laboratory, and the industrial (or at least pilot plant) measurements and results agree with one another. We compared the literature data with two HHP systems which were significantly different in terms of treatment capacity, but their efficiency in killing microbes was studied under the same treatment parameters. Our results show that in nearly all cases only minimal differences exist between the data in the literature and the measurements taken on the two appliances.

Palm fat is one of the most commonly used fats in food industry. The main role of palm fat is to develop the desired texture of food products. Fat blends were developed to find the most appropriate mixture fitting the technological needs. In our work palm mid fraction (PMF) was mixed with anhydrous milk fat (AMF), goose fat (G), and lard (L) in a 1:1 ratio. Anhydrous milk fat represents fat consisting of a wide range of fatty acids. Goose fat is a soft, easily melting fat, and lard is characterized as animal fat with wide melting temperature interval. The measurements aimed to establish the miscibility of the fats and the effect of animal fats on the melting-solidification profile of palm mid fraction. SFC vs temperature curves, Differential Scanning Calorimetry (DSC) melting thermograms describe the melting profile of the samples. Isotherm crystallization by SFC vs time curves and DSC cooling thermograms were measured to characterize the solidification of pure fats and the blends. Since the SFC curves di...

The aim of the study was to select the most suitable freezing and thawing method for preserving the quality of pasta flata type Parenica cheese comparing different methods: slow, shock (circulated air) and cryogenic freezing and thawing at room temperature and in a refrigerator, respectively. To observe the effects of these methods on some cheese properties weight, pH, and dry-matter content were measured, stringiness was examined, and compression test were performed for texture analysis. Thermophysical properties were determined by DSC: unfreezable water content, onset point of melting, and latent heat. Sensory analyses were also carried out by profle analysis. Results of objective and subjective measurements showed similar trends: characteristics of cheese samples frozen in circulated air and thawed in refrigerator resembled the most to the control sample.

The aim of the present study was to examine the infuence of hydrolyzed, nanofltered concentrate of the ultrafltered permeate (HNF concentrate) of acid whey on the quality characteristics of milk-based ice cream. Thermophysical properties were determined by differential scanning calorimeter, consistency was measured by oscillatory rheometer, and sensorial quality was evaluated by scoring method. It was concluded that the acid whey did not increase the melting of the product, and reduced the freezing point. Cryoscopic temperature, onset point, and glass transition temperature (Tg) gradually decreased as the quantity and proportion of acid whey increased in the ice-cream. Rheological results indicated that using HNF, acid whey produced more creamy and smooth ice-cream. However, because of its characteristic taste, maximum 20% of milk could be replaced by HNF acid whey in milk-based ice-creams.

In our tests, we artificially infected liquid whole egg samples with Salmonella enteritidis, Listeria monocytogenes, and Staphylococcus aureus bacteria, and then treated the samples in “Food Lab900” high hydrostatic pressure (HHP) instrument for 3–17 min at 200–400 MPa. Subsequently, the change of the viable cell count of the specific bacteria has been tested. In addition to the samples infected with various bacteria, non-infected samples were also treated in each test and the change in viable cell count, colour and viscosity of the samples upon the effect of the treatment. In summary, it can be concluded that in each test of our investigations, the viable cell count of S. enteritidis critical for egg products is reduced significantly, while the reduction of the total viable cell count was around two magnitudes. Additionally, based on our results, microbial destruction, reduction of enthalpy (denaturation of egg white) caused by the treatment at HPP, and colour change are primarily affected by the pressur...

Dolgozatom temajakent ezert a kezműves jellegű cukraszati kremek es fagylaltok szerkezetenek stabilitasat vizsgaltam termofizikai es allomanytulajdonsagok meresere alkalmas műszerekkel. Arra kerestem a valaszt, hogy hogyan hat a kremek eseten a fagyasztas es fagyasztva tarolas, illetve a fagylaltoknal a hozzaadott savanyu savanyu savokoncetratum a termofizikai tulajdonsagokra es az allomanyra. _____ Therefore, I chose as the topic of my dissertation the research of the stability of artisanal confectionery creams and ice creams with instruments capable of thermo-physical and rheological measurements. I tried to find out how are thermo-physical and textural characteristics affected by freezing and frozen storage in creams and the addition of acid whey in ice creams.

High hydrostatic pressure (HHP) treatment of egg proteins partially limits their sensitivity to pressure. According to the literature, at the 450 MPa level, denaturation of some proteins sets in to the extent that sensory and functional characteristics are impacted. This study involved treating liquid egg (egg white, yolk, and melange) at less than the above-mentioned value, after which the microbiological effect was examined. For the study, pressure pouches were filled with 100ml of raw liquid egg per pouch. Then the samples were treated at 200, 250, 300 and 350 MPa. In each case, the level was reached by increasing pressure at a rate of 100 MPa/min. Measurements were taken at the Corvinus University of Budapest, Faculty of Food Science, Dept. of Refrigeration and Livestock Products Technology RESATO FPU 100-2000 equipment. Denaturation was determined with calorimetric (DSC) tests. From our results, it appears that even at 250 MPa pressure treatment, the viable cell count decreases. Further, it can be said that microbe count went down in the egg white samples at 300-350 MPa, below the impact level. Significant denaturation was not detected during our examinations. In summary, we state that the most HHP-sensitive liquid egg type, egg white, can be pressure treated to reduce microbe count at a level less than that which causes denaturation. Microbe reduction was smaller in yolk and melange, so higher pressure values are appropriate for these products.

Butter and anhydrous milk fat are considered valuable raw materials, therefore it is important to detect the presence of foreign fats and declare their purity. In this study, the authors compared the physical properties of pure anhydrous milk fat and its contaminated forms which were binary blends made with lard and palm fat. Tests with pulsed NMR and DSC were carried out ignoring any solvents or chemicals to observe melting and crystallization processes. Based on the results, small amounts (5-10 V/V %) of lard or palm fat can modify milk fat’s behavior in perceptible extent. Despite of this, a completely unknown fat cannot be identified by these methods only. However, with multiple replications and using statistical methods pNMR and DSC can be utilized for quality control purposes.