Potravinarstvo Slovak Journal of Food Sciences
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Substantiation of regime parameters of vibrating conveyor infrared dryers
Get PDFThe analysis of constructive-technological schemes of vibrating conveyor machines for heat-exchange processing of bulk technological masses in the current mode is carried out, which allowed to substantiate the effectiveness of using a new modification of infrared dryers of vibration-wave execution with a flexible transporting body. For this scheme, a vibrating system is developed which mathematical modelling allowed to determine and substantiate the main parameters of the operating mode of the drive mechanism of the projected device. The experiments, using the developed research model, confirm and refine the results of theoretical analysis, energy efficiency and comparatively low metal consumption of the design structure. The difficulty of working with such a large number of factors led to the application of the second similarity theorem and the introduction of a mathematical model of the criteria of Stanton, Froude, Burdo, whose magnitudes are reflected through the main factors of influence and were found experimentally. After using the "dimension theory" and graph-analytic analysis of power functions, a criterial equation of the investigated process was obtained. This allows recommending the regime parameters and the design series of projected thermo-radiation dryers with vibration-wave transport of products when varying the main factors of influence
Use of ultra-high-temperature processing of raw milk to improve cheese quality
No full textThe increase in natural cheese production has brought issues related to ensuring the production of high-quality competitive products to the fore. The development of the cheese market requires constant improvement of the existing methods of production and the search for new technological solutions, which will allow us to counterbalance the low quality of raw materials, which is currently a serious problem for domestic cheese production. A promising method of realising the benefits of high-temperature (HT) and ultra-high-temperature (UHT) milk processing in cheese making is the development of new types of cheese with a high moisture content; however, there are very few publications that discuss these approaches. The development of advanced technologies for the production of low-temperature second-degree solid cheeses with the use of HT and UHT processing, related to the improvement of the technological process and the equipment and technological scheme of production of solid cheeses. The main direction of the development of cheese production at the present stage is the improvement of existing technological processes, the development of resource-saving technologies and the improvement of the natural solid rennet cheese quality. The results of our research, related to the study of the composition and safety of milk raw materials, the impact of various technological factors on the cheese production process and the quality of the products obtained, are the basis for our resource-saving technology for the production of solid rennet cheese
Development of gluten-free non-yeasted dough structure as factor of bread quality formation
Get PDFThe article is devoted to the study of the influence of hydrocolloids and animal protein concentrates on the formation of the foam-like structure of gluten-free non-yeast dough as the main factor for bread quality formation. The use of CMC in a concentration of 0.5% is found to be appropriate. The bread volume increases to 236 cm3.100g-1 in comparison with the control sample in water – 202 cm3.100g-1. It is proved that the suggested additives in the amounts of 0.5 ‒ 1.0% Helios-11 and 0.5% CMC solution cause 100% resistance of egg white foam. In this case, the foaming ability increases with the addition of Helios-11 only in amounts up to 1.0%, then decreases for higher amounts of Helios-11 or in the presence of CMC. This can be explained by the increase in density of the whipping mass and the ability of both additives to thicken solutions. In the presence of the additives, the foamy texture of the dough changes. The number of large pores (0.7 – 1.5 mm) decreases almost fourfold, and the number of small and very small pores (0.1 ‒ 0.5 mm) increases significantly. The index of form resistance of the control sample is 32, and in the presence of 0.5% CMC with 0.5 ‒ 1.0% APC is 20 ‒ 21, which indicates a decrease in the surface tension of the aqueous solutions with additives, to a large extent, in the case of joint use
Investors´ decision on the context of the effective taxation of agricultural companies
Get PDFThe analysis of the effective taxation combines two different effective tax rates which are crucial for placement and monitoring of the investment amount in the particular country. Both of these tax rates are important for investors who make a decision on the benefits, as well as the risks of corporate taxation in the country. The contribution deals with the problem of the effective taxation through effective average tax rates (EATR) and effective marginal tax rates (EMTR). Especially, it focuses on agricultural production companies. The effectivity of taxation was observed for selected intangible and tangible assets for a period of 2004 and 2018. Our analysis evaluated the influence of the change in the statutory tax rates (and the other taxes and indicators, as well) on the change in effective average tax rates on capital in the agricultural companies. Based on the results, the lowest EATR, ranging from 20.79% to 25.25%, reported agricultural lands in both reference periods and for both ways of financing. Analyzing EMTR we found out that the lowest value reported investments in intangible assets that have crucial significance for investors. Our results definitely made it clear that in the EATR ↔ EMTR relationship, a form of financing investments is decisive. This relationship is used when an investor decides between several mutually exclusive locations or types of investment in a given country. In equity financing, the most effective capital is investing in intangible assets, and when we consider financing from external sources it is investment into stocks. An increase in the statutory tax rate of 2% resulted in a 12% increase in effective average tax rates
Goat yoghurt drinks with elevated α-linolenic acid content and enriched with yacon fiber
Get PDFGoat milk and goat milk products are very valuable in human nutrition because of their favorable nutrient composition which can be further boosted by the addition of prebiotic fiber and probiotic bacteria. It has also been possible to change the fatty acid profile of goat milk through feed composition. The aim of this study was to increase the nutritional value of goat milk by producing a probiotic yoghurt drink made from milk with elevated omega-3 fatty acids and enriched with natural yacon prebiotics. Goat nutrition is one of the key factors how we can naturally increase omega-3 fatty acid content in goat milk. In our study, twenty four White Shorthair goats were divided into the control and experimental group which was supplemented with 55 mL of linseed oil per day for eight weeks to increase the monounsaturated and polyunsaturated fatty acid content in the milk. The yoghurt milk drinks were formulated from individual goat milk samples with added bifidobacteria and yacon prebiotics. Our results showed that goat feed supplementation with linseed oil indeed positively changed fatty acid profile of goat milk in which α-linolenic acid content increased while, at the same time, lauric, myristic and palmitic acid contents decreased. Also, yoghurt drinks enriched with yacon prebiotics have shown higher bifidobacteria counts compared to the control. 
Fruit as a source of antioxidants and trends in its consumption
Get PDFThe positive effects of fruit on human health are mainly attributed to their antioxidant activity. The aim of this work was to observe public awareness about antioxidants consumed in fruit, to analyze their preferences and the frequency of fruit consumption in selected population groups. Preferences were assessed by questionnaire, which was attended by 220 respondents. Information about the presence of antioxidants in fruit showed 85% of respondents. Temperate zone fruit is prefered by 48% of respondents and 52% of respondents prefer fruit of southern zone. Fresh fruit is consumed by 54% of respondents, 18% of respondents prefer fruit juices, compotes are consumed by 12% of respondents, fruit spreads by 11% of respondents, and 5% favour the dried fruit. Fruit is consumed by 31% of respondents once to three times a week, 26% of respondents consumed fruit once a day, 23% occasionally and 20% of respondents more times a day. In terms of sex, higher fruit consumption was recorded at women who consume fruit mostly once a day, while men only once to three times a week. The relationship between place of residence and the possibility to grow their own fruit as well as preference between home and the consumption of fruit by country of origin was confirmed
Diversity of microorganisms in the traditional Slovak cheese
Get PDFThe aim of the present study was to describe the microbial groups of the traditional Slovak cheese Parenica during rippening. The microbial group included the total bacterial count, coliform bacteria, enterococci, lactic acid bacteria, and microscopic filamentous fungi, which may affect the organoleptic characteristics of this product. A total of 42 cheese samples were collected from four different farms during three months. The total bacterial counts were cultivated on Plate count agar at 30 °C, lactic acid bacteria (LAB) on MRS, APT and MSE at 37 °C, coliform bacteria on VRBL at 37 °C. Gram-positive and Gram-negative isolates were identified by MALDI-TOF MS profiling. Bacillus sp. and Enterococcus faecium were the most frequently identified species of bacteria. Candida kefyr was the most distributed yeast according to microbiological methods. Lactic acid bacteria group was represented by Lactobacillus helveticus, L. jensenii, L. alimentarius, L. crispatus, L. curvatus, L. fermentum, L. suebicus, L. delbrueckii ssp. lactis, L. paracasei ssp. paracasei, Lactococcus lactis ssp. lactis, Leuconostoc lactis and Le. mesenteroides ssp. mesenteroides . This report describing the indigenous microbiota of the traditional raw milk cheeses from Slovakia. Our results provide useful information on occurrence of valuable microbial strain for the industrialization of producing of the traditional dairy products in Slovakia
Identification and antibiotic susceptibility of bacterial microbiota of freshwater fish
Get PDFThe fish meat is an essential part of human diet. However, fish may be contaminated with different microorganisms, including pathogens. Antimicrobial resistance of fish microbiota may facilitate the spread of resistant microorganisms causing serious consequences for human health. The aim of the present study was to detect bacterial contamination in fish gill, gut and skin and to determine antimicrobial susceptibility of the bacterial isolates. Rainbow trout (Oncorhynchus mykiss) and bream (Abramis bram) were obtained from the market in Jelgava city. Chub (Leuciscus cephalus), crucian carp (Carassius carassius) and tench (Tinca tinca) were collected from fishermen. Fish samples were examined for the total bacterial count (TBC), coliforms, Enterobacteriaceae, Pseudomonas spp. and Aeromonas spp. Testing was done in accordance with International Organization for Standardization (ISO) standards. Identification of all bacteria was accomplished with the Matrix Assisted Laser Desorption Ionization – Time of Flight Mass Spectrometry (MALDI-TOF MS) method. The disc diffusion method was used for the detection of antibiotic susceptibility of isolated bacterial species. TBC ranged from 2.70 to 7.00 log CFU.g-1, coliforms from 0 to 2.67 log CFU.g-1, Enterobacteriaceae from 0 to 2.85 log CFU.g-1. The highest contamination with Pseudomonas spp. and Aeromonas spp. was observed in chub gut samples with 1.60 log CFU.g-1 and 2.23 log CFU.g-1, respectively. Altogether, 16 microbial genera and 31 bacterial species were identified. The dominant bacterial species belonged to Pseudomonas spp. (54%) and Enterobacteriaceae. Pseudomonas spp. were resistant to ticarcillin, susceptibility to ciprofloxacin showed 88% of isolates. All Enterobacteriaceae isolates were susceptible to imipenem. The microbial quality of the fish was acceptable, but the presence of antibiotic resistant bacteria may further cause a negative impact on public health
Assessment of antimicrobial potential of substances isolated from some wastes of meat processing industry
Get PDFThe slaughter of farm animals generates a large number of by-products. Meat waste management includes various methods, but cost-effective technologies are still in priority. This manuscript reports the results of the study of antimicrobial activity of substances isolated from such wastes of meat processing industry as bovine and pork mucous membranes and epithelial tissues. Proteomic study included two-dimensional electrophoresis with following mass spectrometric identification. Antimicrobial activity against L. monocytogenes, P. aeruginosa and S. aureus of neutralized native extracts and after enzymatic treatment as well as its ultrafiltrates was determined by flow cytometry with EvaGreen and PI dyes. It was shown that a large number of histones were found in bovine mucous membranes as well as several tissue-specific proteins, which would be a precursor of bioactive peptides. Bovine mucous membranes of the tongue and nasal cavity possessed the greatest activity in relation to P. aeruginosa, the rate of surviving cells decreased to 22.0%. Bovine mucous membranes of the rectum and the oral cavity, submandibular lymph nodes, pig mucous membranes of the larynx, tongue, lips, and rectum increased dead cells count up to 40% of all cells. Bovine nasal mucosa and pork mucous of labial cavity possessed the greatest activity against S. aureus, the rate of surviving cells did not exceed 10.0%. Determination of antimicrobial action against L. monocytogenes of native samples and treated with trypsin showed that bovine mucous membranes of the rectum and oral cavity, pork mucosa of the lips and submandibular glands were the most active. Treatment with trypsin or ultrafiltration demonstrated different effects on activity of samples. It was shown the perspectivity of recycling of such type of by-products into effective and demanded substances which can be used, for example, in the food industry as an alternative to chemical preservatives
Effect of essential oils of Myrtaceae plants on the Penicillium commune
Get PDFThe aim of this research was to determine the inhibitory effect of vapor phase of five essential oils (EOs) on the growth of seven strains of Penicillium commune isolated from moldy milk products. Another objective was to determine the minimum inhibitory doses (in vitro and probit analyses) of EOs, which at concentration 625 μL.L-1 of air completely inhibited the growth of all strains. The antifungal activity was evaluated by the micro-atmosphere method. The essential oils used in this study were extract of plants from family Myrtaceae. Only one essential oil – clove (from Syzygium aromaticum L.; leaves) completely inhibited the growth of all strains during cultivation at 25 °C and 5 °C. Eucalyptus essential oil (from Eucaliptus globulus; leaves), tea tree essential oil (from Melaleuca alternifolia Cheel; leaves), cajeput essential oil (from Melaleuca leucadendra L.; leaves and twigs), niaouli essential oil (from Melaleuca quinquenervia (Cav.) S.T.Blake; leaves) have different effects on the growth of P. commune strains. The order of tested essential oils according to the inhibition effect on the growth of the strains of P. commune (from the strongest to the weakest effect) was: clove > tea tree > cajeput > niaouli > eucalyptus. Clove EO that completely inhibited the growth of all strains was used to determine minimum inhibitory doses (MIDs). The MIDs were 125 µL.L-1 of air for two strains of P. commune and 250 µL.L-1 of air for five strains of P. commune on the 7th and 14th day of cultivation, also. Using probit analysis, predicted MIDs90 and MIDs50 were calculated. The MIDs90 were determined from 104.93 to 301.37 µL.L-1 of air