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Abstract
The effect of three types of emulsifiers (polyglycerol monostearate ester – E475, sucrose stearate ester – E473 and modified inulin palmitate ester – HP-25) on the starch retrogradation in sponge cake (SC) during storage was investigated. The method of differential scanning calorimetry (DSC) was applied to determine the changes in the starch retrogradation during the staling process. The retrogradation temperature and the enthalpy of the endothermic transition decreased when emulsifiers were added. The lowest values of the enthalpy for the whole storage period were found for SC with 1% HP-25. The methods of differential thermal analysis (DTA) and thermogravimetry analysis (TGA) showed significantly bigger (1.43 times) amount of strongly bound water in the crumb of the SC with E475 and HP-25 in comparison to the control sample on the sixth day of storage. Based on our results, emulsifiers possessed retarding effect on the starch retrogradation and extend the shelf-life of the SC.
Abstract
One of the biggest challenges of raspberry production in Hungary nowadays is reducing the unfavorable effects of climate change. The maturation phase of main varieties within this region falls in a period of extremely high temperature and atmospheric drought detaining desirable fruit growth. Dedicated plant breeding alone is not enough. An immediate action is required. There has been a need for physical protection against excessive direct radiation. In order to restore, or even save the domestic raspberry production and market, introducing of greenhouse or polytunnel solutions are needed. Experimental plantations of three different raspberry varieties were set in two repetitions: covered and uncovered versions. Each cover has characteristic interaction with light which can generate different environmental conditions and also differences in plant growth and fruit quality. Besides the monitoring of elementary biological indicators, a wide range of sensors (temperature, humidity, solar irradiation) was used to identify differences and to find the optimal tunnel material for maximal plant productivity. Within the framework of the project we also tested a portable spectroradiometer and a snapshot imaging camera to study the practical value of proximal sensing in water- and photosynthetic light use efficiency and vitality mapping.
Abstract
Excessive consumption of salt causes many diseases, including high blood pressure and cardiovascular system disease. In most countries, salt intake is above the WHO guideline daily intake. In Hungary, the average salt intake is more than double the recommended value. Based on these, significant changes are needed in food technology and recipes. To avoid excessive salt intake Hungary has joined the European Union's community program for salt reduction.
The aim of this study was to compare the salt content in different areas of Mangalitsa ham during the dry salting, and compare the average salt content with the regulations of the Codex Alimentarius Hungaricus. The ham was dry salted with 10% by weight of the meat and placed in a controlled atmosphere storage room. The curing took 21 days. The NaCl uptake was measured with Mohr method. The ham was cut at 3 points Cushion (C), Fore Cushion (FC) and Butt End (BE). The salt content of BE was generally higher than the other two areas (C, FC). The differences can be explained by the difference in the thickness of the pieces of meat and fat. The average salt content of the different areas did not exceed the threshold limit in the Codex Alimentarius Hungaricus. At the beginning of the experiment, the salt content of each meat layer was very different, the absorbed salt was concentrated in the surface layer. Over time, as the ham lost a lot of water and due to the lack of outer salt, a significant increase in salt content began in the meat centrum. By day 80, the salt content of the meat centrum exceeded the salt content of both the fat and the surface layer.
Abstract
Micro-organisms can attach to food surfaces and develop biofilms which present a concern in food and environmental safety. The main goal of the current study was to investigate the biofilm formation of six non-pathogenic Listeria strains under different stress conditions using a microplate assay. The effect of the weak biofilm-forming non-pathogenic Listeria strains on the biofilm formation of a strong biofilm-forming pathogenic Listeria strain (Listeria monocytogenes #8) was also examined. Listeria innocua CCM4030, Listeria innocua 2885 and Listeria seeligeri/welshimeri 292 showed the same patterns of biofilm formation with increasing NaCl concentrations from 0.05 to 15%, but all the other strains showed a continuously decreasing trend of OD595 in the same conditions. This study showed that in the case of non-pathogenic Listeria strains, higher concentrations of NaCl do not present a stress condition that enhances biofilm formation. Decrease in pH inhibited biofilm formation for all the non-pathogenic Listeria strains. The weak biofilm forming non-pathogenic Listeria strains (Listeria innocua 2885 and Listeria innocua CCM4030) overgrew the strong biofilm-forming Listeria strain (Listeria monocytogenes #8) during biofilm formation. This phenomenon could be beneficial and potentially be used as a novel control strategy to prevent the colonization of the pathogenic Listeria at food processing facilities such as in meat industry.
ABSTRACT
Lablab purpureus (L.) Sweet is a common bean in Asia. High protein content and similar amino acid composition with soybean makes good substitutes against dependency on imported products in Asian countries. One example of a bean product is vegetable milk. Fortification is executed to create a product, which compels our diet. Many people experience low protein and mineral intake from food. Fortification of plant origin products utilizing food waste by-products, namely eggshell waste by-product, may give an opportunity on this field. Milk created using beans is processed immediately. However, physiological process (germination) is capable of increasing its nutrition quality. This research focuses on variation of germination time: 0, 12, 24, 36, and 48 h. Protein digestibility is selected as the main parameter to consider the time. Protein, and mineral content, pH, and total soluble solid content of the milk are analyzed. Germination time of 36 h establishes sprout with digestible protein of 13.36 ± 0.59 g/100 g, milk protein content of 7.21 ± 0.06 g/100 g, pH of 6.74 ± 0.17, and total soluble solid content of 19.0 brix. The addition of eggshell extracted calcium as calcium fortification is 2% w/v, which resulted in mineral content of 276 ± 0.13 mg/100 g.
Abstract
Eggs are commonly used in the food industry because of their excellent nutrient value and also for their coagulating, foaming, emulsifying, colouring and flavouring properties. Manufacturers substitute shell eggs with processed egg products, such as liquid whole egg, liquid egg yolk or albumin. They have a shelf life of a few weeks, but freezing can increase it to 1 year. However, freezing causes gelation in case of egg yolk. This process is highly dependent on the conditions of freezing and thawing.
In our study, raw liquid egg yolk was frozen and stored for 14 days at −18 °C. On days 1, 7 and 14 samples were thawed by two different methods. Denaturation temperature and enthalpy were investigated by differential scanning calorimetry. Besides, rheological properties were examined at 20 °C, Herschel–Bulkley model was fitted to flow curves of the examined samples. The dry matter content was also recorded during the experiment. Two-way ANOVA was used to analyse data.
The results of the study showed that method of thawing had no significant effect on calorimetric and rheological properties and dry matter content. In contrast, freezing and frozen storage had a significant effect on denaturation enthalpy and rheological properties.
Abstract
The statement of overheating of honey during the processing is important in quality characterization of honey products. Four Hungarian acacia honeys were heated up to 35, 40, 50, 60, and 80 °C and held in water bath for 0.5, 4 and 24 h. The electrical impedance spectrum of honeys before and after heating at room temperature (22 °C) were measured with precision LCR meters in frequency range from 30 Hz up to 30 MHz at 1 V voltage with Ag/AgCl electrodes. The spectra after open-short correction were approached with a circuit model consisting of a serial connection of two distributed elements and a resistance. The model parameters were determined. One of the resistance parameters can be used for detecting the previous heating of honey after detailed investigation of the recrystallization process following the heating. The complex electrical permittivity also was determined in the frequency range from 1 MHz up to 3 GHz.
Abstract
Excessive consumption of added sugar is associated with many health problems, for example obesity, type 2 diabetes, etc. Hence there is an urgent need for the product reformulation by total replacement or partial reduction of sugar in food industry. The aim of this research was to study the effect of sugar substitution (by stevia and xylitol) on model confectionary systems. We investigated differences in the texture properties, the viscosity and thermal properties of the blends. Based on our results, the sugar substitution affects the physical properties of the measured samples. The apparent viscosity and the texture properties were changed due to the different dry matter content in the samples. In the differential scanning calorimeter (DSC) curves the different melting of the samples were expressed according to the changes in sugar content. Further work is needed in this field to follow up the discovered changes in thermal behaviour of these mixtures.
Abstract
Blood coagulation is a process, which is initiated by certain physico-chemical effects. This process results in a change in the blood from the sol state, that is well suited for further processing, to gel state. 13 blood clotting factors take part in the cascade system of blood coagulation. Trisodium-citrate affects factor IV, the calcium, and prevents the change in blood texture. The effect of different concentrations of trisodium-citrate (0, 0.48, 2.4, 4.8, 9.6, 14.4, 19.2, 24 w/w%) on the texture of blood is investigated. Porcine blood was collected in 20 cm3 test tubes in a slaughterhouse directly before trisodium-citrate addition and was stored for one day under refrigerated conditions. The samples without trisodium-citrate coagulated and the samples with high trisodium-citrate (4–5 g) became solid as well because of the protein salting-out. The viscosity of successfully treated samples and the shear stress were measured with a rotational viscometer (Physica MCR 51, Anton-Paar) with concentric cylinders and Couette type method. The flow behavior of all samples could be described by the Herschel-Bulkley model. The yield point, the consistency index and the power of law index, which are determined by the equation of the model, showed that the samples with lower trisodium-citrate content coagulated “better” and the sample with high trisodium-citrate were most similar to Newtonian fluid. The results are trend-likes, but significant differences may be expected in the case of higher sample amount. The yield point of the sample, which contained 14.4 w/w% trisodium-citrate, was by 37.3% less than the sample containing 0.48% trisodium-citrate, and the consistency index of the sample with 3 g trisodium-citrate was by 20.5% higher than that of the sample with 0.48% trisodium-citrate. Thanks to these results a cheaper concentration and drying of porcine blood and blood fractions are available because no surplus water is added to the blood.
Abstract
Spray drying is a widely used process to turn slurries into dry powders and is especially important for thermally-sensitive materials, that are often found in the food or pharmaceutical industry. However, detailed insight into the drying kinetics during spray drying is difficult to investigate due to the boundary conditions in a spray drying tower. As a result, there is a lack of important information on the drying process and subsequent solidification of individual droplets. In this context, an experimental setup for a droplet positioned in a stationary ultrasonic field of an acoustic levitator is designed to enable a non-contacting measurement of the drying kinetics and the subsequent solidification process. To generate a comparable situation like in a real spray drying process, the droplet is positioned in an airflow, where air temperature, humidity, and velocity can be adjusted over wide range. Using an infrared camera to measure the surface temperature and a Complementary Metal Oxide Semiconductor (CMOS) camera for object recognition, the droplet can be observed continuously and drying kinetics of the droplet can be determined from the measured surface temperature and decreasing droplet size. Result of a 10 wt.% aqueous micro particle TiO2 suspension are reported and show that the investigated method is a very valuable and fast tool to safely scale-up spray drying systems very close to real process conditions. Especially when only small sample amounts are available in an early development stage.
