Potravinarstvo Slovak Journal of Food Sciences
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Effect of essential oils of Lamiaceae plants on the Rhizopus spp.
Get PDFThe aim of this study was to evaluate the fungicidal effect of eleven essential oils against six isolates of the genus Rhizopus. Isolates were obtained from various moldy foods (chestnut, bread, strawberry, nectarine, blackberry and cherry tomatoes). The essential oils used in this study were extracts of basil (Oscimum basilicum L.), hyssop (Hyssopus officinalis L.), lavender (Lavandula angustifolia MILLER.), marjoram (Origanum majorana L.), mint (Mentha piperita L.), oregano (Origanum vulgare L.), rosemary (Rosmarinus officinalis L.), sage (Salvia officinalis L.), summer savory (Satureja hortensis L.), thyme (Thymus vulgaris L.) and wild thyme (Thymus serpyllum L.). Semi-quantitative composition of the essential oil samples was determined by gas chromatography coupled with mass spectrometry (GC-MS). The GC-MS analyses of the essential oils led to identification of 139 compounds, of which 49 were presented in ≥1% amount in at least one essential oil. The antifungal activity of essential oils against the Rhizopus spp. was determined, using micro-atmosphere method (0.625 μL.ml-1 of air), during 7 days. Seven essential oils: thyme, mint, summer savory, lavender, marjoram, oregano and wild thyme completely inhibited the growth of all isolates. Other essential oils have different effects on the growth of isolates. Basil essential oil stimulated growth of two isolates on the second day of cultivation. The growth of other isolates was, by contrast, inhibited by this essential oil in the same time of cultivation. Hyssop essential oil completely inhibited growth of two isolates, other 4 isolates were inhibited to fourth day of cultivation. In conclusion, certain essential oils are highly effective in vapour phase and can be used in another test of their antifungal activity and could be used in control of Rhizopus spp. or other fungal pathogens
Eggs and their consumption affected by the different Factors of purchase
Get PDFConsumers' buying behavior and preferences are affected by many factors such as the product quality, price, labeling and country of origin. The objective of this paper was to examine the opinions of the Slovak consumers about the purchase and consumption of eggs and identify their preferences at egg purchase. The input data were obtained using a questionnaire survey. The method of descriptive statistics and selected methods of measuring dependence or associations were used. The existence of statistically significant relationships was verified by the Pearson chi-square test or by the Fisher's exact test. The statistical proof of relationships was evaluated based on the significance of the test characteristic (p-value). The existence of dependence between the most important factor affecting purchasing of eggs - a price of eggs, and the age of the respondent - was confirmed. Further, the relationship between the preferred place of buying eggs and the classification criterion was also proved, i.e. whether a respondent is a breeder of the egg type of hens or not. The relationship between the preferred place of buying eggs and the gender of a respondent was confirmed as well. There was determined the dependence on the gender of a respondent in the question related to eggs consumption
The effect of the regular consumption of lard from fats of crossbreed Mangalitsa and breed of meat type pig on the lipid profile of consumers
Get PDFThe aim of this study was to evaluate the influence of consumption of lard processed from crossbreed of the original mangalitsa genotype and the breed of meat type pigs on selected biochemical parameters: total cholesterol (T-C), LDL cholesterol, HDL cholesterol and triacylglycerols (TAG). Twenty-nine probands participated in the study, of which 14 women and 15 men (aged 21 - 59) who consumed regularly lard four times a week during 5 weeks. By evaluating the lipid profile of probands, we observed elevated hypercholesterolemia at the beginning of the study in 43% women and 27% men. Statistically significant differences were recorded in this group of probands, where we recorded a decrease in TC of 0.55 mmol.L-1 in the whole sample of probands with p <0.05 probability in the 2nd sample of study after 5 weeks of consumption of lard. Borderline high (up to 3.35 mmol.L-1) was found in 21% of women and 33% of men, and above LDL cholesterol was found in 79% of women and 60% of men. This high level of LDL cholesterol is considered a risk factor for the development of atherosclerosis. We can conclude from the results that regular consumption of lard has significantly reduced the total cholesterol levels, especially in women, this effect has been associated with lowering LDL cholesterol (p <0.01) and lowering HDL cholesterol. 
Evaluation of the functional state of peach varieties (Prunus persica Mill.) when exposed hydrothermal stress to plants
Get PDFThe article presents data on the change in the ratio of pigments and fluorescence of chlorophyll in peach leaves in the optimal period of vegetation and under hydrothermal stress. When determining the resistance of a peach to unfavorable environmental factors, methods based on laboratory, fixed changes in the physiological and biochemical processes occurring in plants are used. In the period of inadequate water availability, the water deficit in peach leaves increased to an average of 15%, while less stable - an increase in the parameter to 18% was observed. It is shown that the xeromorphic character of the leaf apparatus is associated with a slight change in the anatomical characteristics of the leaf (the thickness of the leaf blade before and after the drought), which determines the permanence of the turgor. In this case, in the leaves of resistant varieties, the loss of turgor is insignificant (LSD (p ≤0.05) = 7.24); the thickness of the leaf fluctuates within 0.20 mm. On the background of stress impact, a clear varietal difference was shown, which allowed us to develop a scale for a comparative assessment of the resistance of peach varieties and clones. During the active growth of the assimilation surface, an increase in the amount of green pigments in the leaves of experimental plants was noted. Perspective varieties of peach contain significantly higher amounts of chlorophylls compared to other varieties (LSD (p ≤0.05) = 0.30). Under unfavorable conditions, in these varieties the ratio of the sum of chlorophylls to carotenoids is higher, which is confirmed by their more developed adaptive potential. Reorganization of the pigmentary apparatus during the period of hydrothermal stress is accompanied by an increase in the coefficient of photosynthetic activity (Kf_n) and a decrease in the fluorescence level (F_T) of chlorophyll. Thus, the water deficit, pigment composition and fluorescence of chlorophyll make it possible to identify the resistance of peach varieties and clones to the action of hydrothermal stressors. Based on the results of the studies, the most resistant varieties and clones of peaches have been identified for the humid subtropics of Russia (Larisa, Early bloy, Medin red, Slavutich, Donetskij zheltij, Vanity and Form 1)
Effect of sorbitol on dough rheology and quality of sugar replaced cookies
Get PDFA high amount of sugar is used in bakery products, which may cause diabetes, high blood glucose levels and obesity. Due to these reasons, sugar is being replaced with substitutes. There is different carbohydrate-based sugar substitutes (polyols) that can efficiently replace sugar. Among polyols, sorbitol is an efficient replacer that can mimic sugar with minimal effects on cookie quality. Effects of different sorbitol levels (0 to 12.5%) were seen on the dough rheology. Mixographic studies showed that peak height and mixing time reduced with the addition of sorbitol. Farinographic studies showed that water absorption and the mixing tolerance index of dough reduced with the supplementation of sorbitol, whereas dough development time, arrival time, dough stability time and softening of dough increased. Extensographic studies revealed that sorbitol substitution produced hard, cohesive, adhesive and elastic dough. Sugar in cookies formulations was reduced from 100 to 50% by replacing with sorbitol 0 to 50%. Physical analysis of sorbitol containing cookies showed that the diameter and spread factor of cookies decreased with higher levels of sorbitol, whereas thickness, color, hardness and water activity of cookies increased. The calorific value of cookies decreased with the increasing levels of sorbitol. At upto 20% replacement of sugar, other parameters of cookies were not affected. Sensory evaluation of the cookies showed that hedonic points for sensory evaluation parameters reduced with the increasing levels of sorbitol, T2 (20% replacement) showed maximum overall acceptability
Heating and dehydration of grain and cereals at a combined energy supply
Get PDFThe paper dwells on the development of experimental dependencies of heating and dehydration of grain and cereals when varying the irradiance, ambient temperature in the heat treatment zone and the initial moisture content of product, and the development of the mathematical models for heating and dehydration of some grains and cereals. The grain was heated on the laboratory equipment with quartz halogen linear infrared emitters. The irradiance on the working surface in the treatment zone was determined by calculation using a specially developed program. The ambient temperature was determined by a thermocouple thermometer placed in a ceramic tube. The grain temperature was estimated as average by weight by a thermocouple thermometer after its transfer into a thermally insulated container. The following dependencies have been obtained: 1 - Temperature dependence of the heating time for different heating modes and initial moisture content. 2 - Dependence of moisture content on the heating time under different conditions and initial moisture content. 3 - Dependence of moisture content on a temperature under different conditions and constant initial humidity. The models of the heat-moisture exchange and dehydration processes have been created, and the model parameters K0 and KT of the temperature dependence of some grains have been identified, as well as their dependence on moisture content and treatment modes has been evaluated. It has been established that this model describes adequately the process of dehydration to an extent limited by the upper temperature value of grain not much more than 100 ºÐ¡. Within not limited to the upper temperature value of grain not much more than 100 ºÐ¡. From the presented graphs and earlier obtained results for barley and millet, it can be assumed that the model describes adequately experimental data on the small-sized (3 - 5 mm) objects
Inhibitory effect of aqueous extracts of raw and roasted Sesamum indicum L. seeds on key enzymes linked to type-2 diabetes (α-amylase and α-glucosidase) and Alzheimer's disease (acetylcholinesterase and butyrylcholinesterase)
Get PDFSesame (Sesamum indicum L.) seeds are nutritional food, but researches have limited knowledge about the antioxidant, antidiabetic and anticholinesterase activities of the seed. This study was conducted to determine the antioxidant activity, enzyme inhibitory potential (α-amylase and α-glucosidase) and acetylcholinesterase inhibitory property of aqueous extracts of raw and roasted sesame seeds. Antioxidant activities were analyzed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging property, 2,2-azino-bis-(3-ethylbenthiazoline-6- sulphonic acid (ABTS) scavenging ability, iron chelating ability and ferric reducing antioxidant power (FRAP). Anti-Alzheimer's potential was determined using acetylcholinesterase and butyrylcholinesterase enzyme inhibition assay. The results showed that the total phenolic and flavonoid contents were higher in the roasted S. indicum sample with the values of 19.81mg/100g and 17.19 mg/100g respectively. The raw S. indicum sample showed higher antioxidant activity in DPPH, and iron chelation assays; while roasted S. indicum sample showed higher in the reducing power and ABTS scavenging activity. However, anticholinesterase activity was higher in the roasted S. indicum sample than in the raw S. indicum sample. The extracts inhibited α-amylase activity in a concentration-dependent manner (20 - 100 µg.mL-1). The raw sample (16.55 ±0.89%) had higher inhibitory α-amylase activity compared to the roasted sample (15.78 ±0.48%) at 100 µg.mL-1. Inhibition of α-glucosidase was higher in the roasted sample at 100 µg.mL-1 (19.40 ±0.26%) compared to the raw sample at the same concentration (3.65 ±0.52%). These findings suggest that S. indicum L. is not only nutritious but also showed potential pharmacological properties
Addition of rutin/quercetin mixture to spreadable processed cheese: antioxidant and textural characteristics
Get PDFSpreadable processed cheese is a traditional product made from a mixture of cheese, fat, water and emulsifying salts.The aim of this research was prepared spreadable processed cheese with new functional properties. Spreadable processed cheese enriched with the mixture (1:1) of rutin and quercetin (1.0 g.100g-1) was prepared at two melting temperature (80°C and 90°C) for three holding times (1, 5 and 10 min). The effect of melting temperature and holding time on the quercetin and rutin content was assessed using liquid chromatography with UV detection after ultrasonic-assissted extraction to methanol. The corresponding antioxidant characteristics were determined using spectrophotometric assays for total phenolics (TPC) and radical scavenging activities DPPH and ABTS. The extraction yield for quercetin varied from 45.8 to 66.4% and from 12.8 to 40.8% for rutin. The level of quercetin significantly descrased with the increase of holding time, while rutin content has increased with the increase of melting temperature. TPC values ranged from 10.8. to 14.8 mg GAE·g-1 in SPC sample enriched with rutin/quercetin mixture, and the increase of melting temperature resulted in the decrease of TPC values. DPPH and ABTS assays did not reveal any statistically significant pattern using Kruskal-Wallis ANOVA. The addition of the mixture of flavonoids into the processed cheese significantly reduced the complex modulus in comparison with the control sample (without flavonoids). This indicate that the structure of enriched SPC sample was more flexible than those in control processed cheese samples. Both melting temperature and holding time increased the complex modulus. Spreadable processed cheese are scarcely used as a carrier of flavonoids in scientific researches probably due to very complex matrices. Our research proved that spreadable processed cheese containing rutin/quercetin mixture can be used as a functional food.  
Characterization of Escherichia coli strains isolated from raw vegetables
Get PDFVegetables are an important part of the human diet. Sometimes, contamination by pathogenic Escherichia coli can be underestimated; moreover there is a risk of antibiotic resistance spreading via the food chain. The purpose of this study was to examine the prevalence of Escherichia coli in fresh vegetables sold in retail market in the Czech Republic and to evaluate the risk to human health. Antibiotic resistance against 12 antibiotics, the presence of 12 virulence and 15 resistance genes were determined among 15 isolated strains. Most of tested strains belonged to B1 phylogenetic group, less frequently represented was B2 and D phylogroup. These results indicate that most strains are probably of human origin. All E. coli strains were resistant to at least one of twelve tested antibiotics. A multidrug resistance was observed in four strains. In this study, the presence of virulence factors Einv and papC and also genes encoding toxins (CNF1, CNF2) was detected. Nevertheless, none strain can be considered as STEC or EHEC. The widespread appearance of a growing trend associated with the prevalence of antibiotic resistance among enterobacterial isolates is undeniable and the possibility of transfer to humans cannot be ignored. Nevertheless, these results indicate that raw vegetables sold in the retail market can constitute a potential health risk for consumers
Evaluation of selected quality parameters of reduced salt frankfurters
Get PDFHigher salt content in foods brings health risks associated with hypertension and leads to an increased risk of strokes and fatal vascular diseases. For this study, a frankfurter was chosen as a frequently consumed meat product. In repetitions, four groups of products were produced with different salt contents (2.0% and 1.4%) and the kind of meat used (CPF - Control Pork Frankfurters, RPF - Reduced salt Pork Frankfurters, CBF - Control Beef Frankfurters, RBF - Reduced salt Beef Frankfurters). Basic chemical parameters (dry matter, fat and salt content), colour parameters (CIE L*, a* and b*) and basic sensory analysis were performed before (UT - untreated) and after heat treatment (HT - heat treated). The lower salt content and the type of meat used have a significant effect (p ˂0.05) on the colour of the products. In almost all parameters frankfurters with pork meat scored better than frankfurters with beef meat. The lower salt content and the type of meat used proved to have affected the colour of the products. After heat treatment there were found statistical significant differences in saltiness between control and salt reduced group (UT, p = 0.0098; HT p = 0.0001). Sensory results were better with pork and higher salt. A more key role than salt content in frankfurters is played by the type of meat. Debrecener´s frankfurter was selected for this study, and its formula can serve as a good example for the manufacturers that there is no need to worry about one third salt mixture reduction in the recipe on frankfurters sensory analysis