Marián Tokár

The antioxidant and antimicrobial activity of essential oils against Pseudomonas spp. isolated from fish

Natural products of plant origin, which include essential oils (EO) could be used as a growth inhibitor of pathogenic and spoilage microflora in food. The objective of this study was to determine the antibacterial and antioxidant activity of 21 EO against 10 Pseudomonas species isolated from freshwater fish. The chemical composition of EO was determined by gas chromatography/mass spectrometry. The disc diffusion method and detection of minimum inhibitory concentration (MIC) were used for the determination of the antimicrobial activity. All the EO tested exhibited antimicrobial activity, however, Cinnamomum zeylanicum EO was the most effective against Pseudomonas spp. both according to the disc diffusion and MIC methods. The EOs of Cymbopogon nardus, Origanum vulgare, Foeniculum vulgare and Thymus serpyllum showed the highest antioxidant activity of 93.86 μg, 83.47 μg, 76.74 μg and 74.28 μg TEAC/mL. Application of EO could be an effective tool for inhibition of growth of Pseudomonas spp. on fish.

Changes of the dough rheological properties influenced by addition of potato fibre.

Fibre is an important component of diet and nutrition and is one of the groups of biologically important substances consumed in insufficient quantity. One possibility to increase its intake is to enrich with fibre the food consumed in significant quantities, such as bread and pastries. The aim of this experimental work was to verify the influence of the addition of commercially produced potato fibre Potex to wheat flour and to evaluate the changes in physical properties of subsequently prepared doughs. The addition of 1%, 3%, 5% and 7% of Potex has been chosen and rheological properties were evaluated by the means of E-Farinograph (consistency, water absorption, dough development time, stability and degree of softening), Extensograph-E (resistance to extension, maximal resistance to extension, extensibility, extensibility maximum and energy dough), and Amylograph-E (beginning of gelatinization, viscosity, maximum of gelatinization). The addition of Potex depending on the amount changed the physical dough properties: above 3% of addition significantly increased the beginning of gelatinization and with increasing addition the maximum of gelatinization has increased. Based on the evaluation of farinograph curves it can be concluded that the addition of Potex increased water absorption of composite flours, prolonged dough development time and dough stability. Extensograph measurements showed, with increasing addition of Potex the decrease in dough extension. All doughs were easy to process and with the suitable amount of addition their satisfactory parameters could be maintained. From a technological point of view, the addition of fibre (Potex) up to 3% was fully acceptable and did not significantly alter the rheological properties of processed doughs.

Composition of fatty acids in selected vegetable oils

Plant oils and fats are important and necessary components of the human nutrition. They are energy source and also contain fatty acids - compounds essential for human health. The aim of this study was to evaluate nutritional quality of selected plant oil - olive, rapeseed, pumpkin, flax and sesame; based on fatty acid composition in these oils. Fatty acids (MUFA, PUFA, SFA) were analyzed chromatography using system Agilent 6890 GC, injector multimode, detector FID. The highest content of saturated fatty acids was observed in pumpkinseed oil (19.07%), the lowest content was found in rapeseed oil (7.03%), with low level of palmitic and stearic acids and high level of behenic acid (0.32%) among the evaluated oils. The highest content of linoleic acid was determined in pumpkinseed (46.40%) and sesame oil (40.49%); in these samples was also found lowest content of α-linolenic acid. These oils have important antioxidant properties and are not subject to oxidation. The richest source of linolenic acid was flaxseed oil which, which is therefore more difficult to preserve and process in food industry. In olive oil was confirmed that belongs to the group of oils with a predominantly monosaturated oleic acid (more than 70%) and a small amount of polysaturated fatty acid. The most commonly used rapeseed oil belongs to the group of oils with the medium content of linolenic acid (8.76%); this oil also showed a high content of linoleic acid (20.24%). The group of these essentially fatty acids showed a suitable ratio ∑n3/n6 in the rapessed oil (0.44).

MOLECULAR PROPERTIES OF SELECTED POLYSACCHARIDES DETERMINED BY SEC CHROMATOGRAPHY AND THEIR IMPACT ON WATER ABSORPTION OF WHEAT FLOUR

Chemical composition and solubility in water of selected polysaccharides as β-glucan, arabinoxylan and inulin preparation were determined. All these preparation were of good purity, they consist of at least 71% of polysaccharide of intrest. Solubility in water was the highest in the case of inulin and the lowest in the case of β-glucan. Molecular properties of examined preparations were determined by SEC chromatography. β-glucan and arabinoxylan were of much higher molecular mass than inulin. Molecular mass of examined polysacharides was corelated with increase of water absorption of the flour caused by 2% addition of each polysaccharide. doi:10.5219/173

Process of obtaining of sugar from sugar beet and influence on its quality

Cooking of massecuites has been study in the connection with different particle size distribution of white sugar. During the crystallization is possible to operate with parameters which have influence on particle size of white sugar. Dry matter of juice in crystallizer, volume of the standard syrup in crystallizer and heating curve of crystallization process are constant parameters in this process. Quantity of slurry (seed magma crystallizate) and volume of slurry massecuite are parameters which can be changed for control the particle size distribution of white sugar. Five variants of viable parameters have been trying for obtain ideal particle size distribution of white sugar. As a best has been evaluated variant with 1100 cm 3 of slurry and 20 % of volume of slurry massecuite in crystallizer. This variant has had the crystals proportions captured by the sieves between 1.00 and 0.40 mm with minimal differences in weight. More results have been related to reduction of losses of sugar in molasses with the right setting for the line of cooling crystallization process. The looses of sugar can be reduced by adding two coolers in the end of cooling crystalization process what will decrease a temperature to 40 ° C. This temperature will lead to more efficient crystallization in the cooling crystallization process. doi:10.5219/122

THE EVALUATION OF ANTIOXIDANT ACTIVITY OF MILLING FRACTIONS OF SELECTED CEREALS GROWN IN THE YEAR 2010

Cereals are good source of biologically active compounds that contribute to reducing the risk of coronary heart disease and also inhibit oxidation in human plasma. The aim of this study was to evaluate of antioxidant potential of four milling fractions of selected cereals grown in the year 2010. Methanol was used to extract the antioxidant compounds from cereals. Free radical scavenging activity of samples was measured using DPPH assay and reducing power was determined using FRAP assay. Secondary was evaluated of total phenolic and flavonoid content of cereal extracts. We found that flour fractions (break flour and reduction flour) showed the lower proportion of the total antioxidant potential than bran fractions (fine bran and coarse bran). Extract from barley had the highest values of antioxidant activity and phenolic content. doi:10.5219/163

Determination of Biological and Sensory Profiles of Biscuits Enriched with Tea (Camellia sinensis L.) Powder

Abstract The aim of this work was to characterise the biological and sensory profile of biscuits enriched with green (1 and 3%) and black tea (1 and 3%) powders. Biscuits without the addition of tea were used as a control. Phenolic concentration, flavonoid concentration, and antioxidant activity were determined spectrophotometrically. Amino acid composition was determined using automatic amino acid analyser AAA 400 and crude fibre content using an Ancom analyser. Sensory profiles were evaluated by comparison of enriched and control biscuit samples. The enriched biscuits showed higher phenolic and flavonoid concentration and antioxidant activity estimated by DPPH and phospholybdenum method in comparison with levels in the control group. The best results for antioxidant activity estimated by DPPH and phosphomolybdenum methods were achieved in biscuits enriched with black tea powder (3%): 2.25 and of 32.64 mg TEAC·g−1, respectively. Total phenolic concentration was 1.16 mg GAE·g−1, and total flavonoid concentration was 0.13 mg QE·g−1. These biscuits had higher concentration of crude fibre in comparison with the control group and the highest concentration (0.64%) was found in biscuits with addition of 3% green tea powder. The amino acid composition in samples, including in the control sample was balanced, with slightly higher concentration of threonine, serine, and methionine in enriched samples, but this parameter was not statistically significant. Biscuits enriched with green and black tea had higher sensory scores for taste, smell and aftertaste.

Green Barley as an Ingredient in Pasta: Antioxidant Activity and Sensory Characteristics Evaluation

Summary The aims of the present study was to determine antioxidant activity, sensory properties as well as total polyphenol, flavonoid and chlorophyll content of raw and cooked pasta enriched by 1%, 3% and 5% addition of green barley powder. Results of antioxidant activity showed that increase of green barley addition increase antioxidant activity of pasta. The values in raw pasta obtained by DPPH ranged from 1.17 (control) to 1.81 (5% addition) mg TEAC/g DM, after cooking values ranged from 0.82 (control) to 1.59 (5% addition) mg TEAC/g DM. Similar tendency was signed by molybdenum reducing antioxidant power method. In enriched pasta was also found higher content of total polyphenol (0.19 in control raw sample and 1.81 mg GAE/g DM in pasta with 5 % of green barley addition; values of cooked pasta ranged from 0.10 in control sample to 0.73 mg GAE/g DM in pasta with 5 % of green barley addition) as well as total flavonoid content (results of raw pasta were from 0.00 in control sample to 0.41 mg QE/g DM in pasta with 5% of green barley addition; values of cooked pasta were from 0.00 in control sample to 0.29 mg QE/g DM in variant with 5% green barley). Green barley also enriched pasta for chlorophyll with the best results in 5% addition. From prepared variants of enriched pasta the best overall acceptability was sign in 3% of green barley addition. Pastas enriched with plant-derived bioactive compounds such as green barley may confer health benefits to consumers.

Antimicrobial Effect of Sage (Salvia officinalis L.) and Rosemary (Rosmarinus officinalis L.) Essential Oils on Microbiota of Chicken Breast

Abstract The aim of the study was to evaluate the antimicrobial effect of sage and rosemary essential oils (EO) on microbiota of fresh chicken breast. Sample treatments were stored without packaging, vacuum-packaged, vacuum-packaged with EDTA 1.5% v/w, sage and rosemary EO treatment 0.2% v/w. Assessment of food quality was done by anaerobic plate count (APC), and Enterobacteriaceae, lactic acid bacteria (LAB) and Pseudomonas spp. counts a period of 16 days of storage at 4 ± 0.5 °C. Bacterial species were identified with a MALDI TOF MS Biotyper. Antimicrobial activity of isolates against both EO were tested. The APC varied from 2.97 log CFU/g to 6.81 log CFU/g, LAB from 2.35 log CFU/g to 3.36 log CFU/g and Enterobacteriaceae from 0.00 log CFU/g on day 0 to 4.77 log CFU/g with the highest counts on day 16 and in control unpackaged samples. Pseudomonas spp. was found only on days 0, 4, 8, and 12, with counts from 0.00 log CFU/g on day 16 to 2.89 log CFU/g on day 4 in control unpackaged samples. APC were represented by Staphylococcus and Kocuria, LAB with Lactobacillus and Enterobacteriaceae with Buttiauxella, Escherichia, Hafnia, Serratia and Yersinia. The Pseudomonas genus was represented by ten species. The best antimicrobial effect on APC, Enterobacteriaceae, LAB and Pseudomonas was achieved by application of EO. The results suggest the potential use of Salvia officinalis L. and Rosmarinus officinalis L. EOs as natural food preservatives and potential sources of antimicrobial ingredients in the food industry.

Characteristics of starch breads enriched with red potatoes

Starch breads may often be low in nutritional value, in comparison to traditional products, as they contain less dietary fibre, protein and micro and macro elements. As an effect a risk of mineral deficiencies and digestive problems caused by lack of dietary fibre could be expected in persons adhering to gluten free diet. To eliminate such problems, a continuous research on gluten-free bread nutritional enrichment, has been done in recent years. Raw material used to enrich gluten free products should include: inulin, lupine, radish, soy, lucerne sprouts, oilseeds, different type of dried fruits. Among the most commonly used raw materials, there are flours from gluten free cereals and pseudocereals such as buckwheat, amaranth and maize are very popular. It seem that valuable alternative could be considered a red, purple or pink potatoes as starch breads additives. The aim of this work was to investigate the effect addition of freeze-dried color potatoes on crude fiber, polyphenols, anthocyanins and flavonoids and nutritional value of gluten free breads. It could be concluded, that freeze-dried color (red, purple, pink) potatoes enriched the gluten free breads (starch breads) with health promoting bioactive components, like polyphenols, and highly valuable protein. The most promising additive was Magenta Love red potato variety lyophilisates, because gluten free breads enriched with this component were characterized by high protein content and the highest content of free and bound polyphenols, flavonoids, anthocyanins. The presence of all these components increased the nutritional and pro-health value of gluten free product as starch bread.