Our goal was to explore the interactions between the acoustic phenomena taking place in the ultrasound field, the concentration of the biological particles of the ultrasound field, and the cell biology effects of these interactions. Using output power of 9 W cm-2 and frequency of 1.117 MHz, the concentration was determined, expressed in g l-1, of lyophilized Saccharomyces cerevisiae baker's yeast needed for stopping cavitation in the sound field. Then by using multiples of the aforementioned concentration, we monitored the acoustic phenomena occurred in the sound field and, simultaneously, we examined the survival dynamics of the cells. Examined acoustic phenomena were the following: acoustic streaming, standing wave, and cavitation. Physical parameters (suspension density, dissolved oxygen, temperature) of the sound field had essential effect on the acoustic phenomena formed in the ultrasound field and on the threshold levels of their formation. The phenomena affected the composition of the material in the sound field, so an acoustical phenomenon - cell biological effect chain reaction took place during the radiation.
The total concentrations of the Ʃ16 polycyclic aromatic hydrocarbons (PAHs) were examined in some samples of baked ready-to-eat foods (cake, sausage roll, meat pie, burger, and bread) with a view to provide information on the hazards associated with the consumption of these hawked street foods. The measurements were performed by using a gas chromatograph-mass spectrometer (GC-MS) after hexane/dichloromethane extraction and clean-up. The total concentrations of the PAHs in these samples of ready-to-eat baked foods ranged from 427.4 to 1224 μg kg–1, 289.9 to 853.7 μg kg–1, 574.4 to 2333 μg kg–1, 364.6 to 2906 μg kg–1, and 15.7 to 213.1 μg kg–1 for cake, sausage roll, meat pie, burger, and bread, respectively. The results indicated that these baked ready-to-eat foods were mainly contaminated with 2-, 3-, and 4-ring PAHs. The concentrations of benzo(a)pyrene were less than 0.1 μg kg–1 in nineteen out of the twenty samples examined.
Authors:M. Szalai, J. Szigeti, L. Farkas, L. Varga, A. Réti, and E. Zukál
The shelf-lives of major commercial cooked meat products (i.e., Bologna sausage, Italian-type cooked sausage, and cooked ham) packaged under vacuum or modified atmospheres were tested in this study. Samples were taken from commercial meat processing lines, sliced to 1.2 mm thickness and placed overlapped into polypropylene trays sealed with plastic films. The headspace of modified atmosphere packaged formulations consisted of 30% CO2 and 70% N2 or 60% CO2 and 40% N2. The samples thus produced were stored under refrigerated conditions. The values of microbiological, chemical, physical or sensory properties were plotted against storage time, and Gompertz curves were fitted to all time series that changed from an initial to a final value during any period of storage. The influence of headspace CO2 concentration on the properties of sliced cooked meat products varied considerably and, therefore, it was not possible to specify general rules. However, the presence of CO2 in the packaging atmosphere slowed down the rate of microbial growth, thereby delaying the spoilage of meat products. A CO2 level of 60% had beneficial effects on both the microbiological and sensory properties of sliced sausages and cooked ham. It was concluded that cooked meat products packaged under modified atmospheres had a shelf-life of 20 days.
Lactic acid fermentation of carrot as a method of preservation using different lactic acid bacteria, viz.
Lactobacillus plantarum, Pediococcus cerevisiae
as such and in sequence at different temperatures and with varying salt content (2, 2.5 and 3%) were employed in the fermentation of carrot. The differences in fermentation behaviour of different microorganisms were quite contrasting at 26 °C, but the sequential culture started deviating from the very first day and acidity increased up to 6 days. A temperature of 26 °C and salt concentration of 2.5% were the best for lactic acid bacteria (LAB) fermentation of Asiatic carrot as highest acidity (1.40% lactic acid), low pH and low reducing sugars were achieved in sequential fermentation. The LAB count of 7.8×10
was also higher at these concentrations coupled with higher sensory scores of the products. Among the fermentation types tried, sequential culture fermentation of the vegetables produced the product with higher acidity, low pH and reducing sugars. The sequential culture fermentation imparted the fermented products better flavour, texture and taste than other products fermented naturally or with lactic cultures of
Pediococcus cerevisiae, Lactobacillus plantarum
in single separate fermentation. Based on the overall and sensory quality evaluation, the fermented carrot product prepared with sequential culture was the best followed by the product prepared using natural microflora.
The study was conducted to examine the effect of penicillin (0.003 IJ ml -1 of milk) in concentration below the sensitivity level of biological methods (Delvo SP and Resasurine test) on yoghurt cultures. According to the results obtained, the stated penicillin concentration prolonged the period of final incubation in the bulk starter (3 h and 20 min) and in yoghurt (3 h and 40 min). The total count of S. thermophilus colonies in the bulk starter and yoghurt is also reduced with a loss of one (log 7.32), that is, two logarithmic numbers (log 6.53) compared with the control samples (without penicillin). The total count of L. bulgaricus colonies was higher in the control samples compared with the experimental samples. Upon the final incubation period and storage for 18 h at 5 °C, there was a drop in the titratable acidity and an increase in pH values of the control samples. Microscopic examination of the control samples showed a gradual disappearance of streptococci with a complete prevalence of lactobacilli in yoghurt. Additionally, morphological changes occurred in streptococci (long chains) and lactobacilli (long and irregular rods).
Authors:A. Păucean, D.C. Vodnar, V. Mureșan, F. Fetea, F. Ranga, S.M. Man, S. Muste, and C. Socaciu
The lactic acid bacteria are key microorganisms for the production and preservation of fermented dairy products, cheeses, sourdough bread, and lacto-fermented vegetables. This study was developed to monitor lactic acid produced by Lactobacillus plantarum ATCC 8014 and Lactobacillus casei ATCC 393, as single strains and combined, in fermenting media by Fourier Transform Infrared Spectroscopy coupled to multivariate statistical analysis. Media containing different mixtures of carbohydrates were chosen as model fermenting media for monitoring lactic acid concentration by infrared spectroscopy, due to the fact that vegetable and animal food matrices could contain different carbohydrates as carbon sources. Three different types of media were obtained by adding different carbohydrates to a basic MRS medium. HPLC was used as reference method for lactic acid quantification. The calibration set (n=36) was used for building model, while a validation set (n=13) for testing the robustness of the developed model. The coefficients of determination between predicted and reference values were 0.986 and 0.965, while root mean square error for calibration and validation sets recorded values of 0.127 and 0.263 g·l−1, respectively. Results confirmed the efficiency of FTIR spectroscopy combined with multivariate statistics, as a rapid, reliable, and cost-effective tool for routine monitoring of lactic acid.
Authors:B. Nagy, J. Soós, B. Horvath, M. Kállay, B. Nyúl-Pühra, and D. Nyitrai-Sárdy
, V. , Pons , A. & Duboudieu , D. ( 2007 ): Assay of glutathione in must and wines using capillary electrophoresis and laser-induced fluorescence detection. Changes in concentration in dry white wines during alcoholic
In a 120 min osmotic dehydration procedure followed by an air drying process, the effect of carboxy-methyl cellulose (CMC) on some qualitative characteristics of apple slabs including browning index (BI) and rehydration capacity were studied. Moreover, the relation between textural and sensory properties, such as hardness, cohesiveness, springiness, adhesiveness and chewiness, was investigated. Samples containing higher coating concentrations (1–1.5%) showed higher rehydration capacity and lower browning index compared to those with lower coating concentrations (0.25–0.5%). Weibull distribution model was used to investigate the effect of coating concentration on drying kinetics. The results of sensory tests showed that the overall acceptance of samples is increased with decreasing coating concentration, and an appropriate correlation was found between sensory properties and textural parameters.
Authors:Tamás Magyar, Felipe Werle Vogel, Florence Tóth, Attila Nagy, János Tamás, and Péter Tamás Nagy
products formed during hydrolysis. The metabolism of these compounds results in the formation of alcohols, ketones, CO 2 , H 2 S and, mainly volatile organic acids, with acetic, propionic and butyric acids found in higher concentrations [ 10, 14 ]. The