Jiří Mlček

Antioxidant and radical oxygen species scavenging activities of 12 cultivars of blue honeysuckle fruit.

Abstract Rop O., Řeznicek V., Mlcek J., Jurikova T., Balik J., Sochor J., Kramařova D., 2011. Antioxidant and radical oxygen species scavenging activities of 12 cultivars of blue honeysuckle fruit . Hort. Sci. (Prague), 38 : 63–70.The fruit of blue honeysuckle ( Lonicera caerulea L. var. kamtchatica (Sevast.) Pojark.) belongs to the fruit of great value because of itsunique chemical composition. The aim of our measurement of this fruit species was to select the cultivars which could be the most suitable food supplement in relation to strengthening human immunity system. The comparison of the fruit of 12 cultivars was made. The highest contents of polyphenolic substances were recorded in the cultivar Zolushka with the value of 9.03 g of gallic acid/kg fresh mass. In particular cultivars the DPPH (2,2-diphenyl-1-picrylhydrazyl) test was performed to determine antioxidant activity which ranged from 6.59–10.17 g of ascorbic acid equivalent/kg fresh mass. For comparison, scavenging activity of reactive oxygen species (superoxide anion, hydroxyl radical, and nitric oxide) was determined by using a 25% methanolic extract of fruit of particular cultivars. Antioxidant potential was also assessed using the rat liver slice model. The highest values of scavenging activity were found in the cultivars Zolushka, Goluboe vreteno, and Gerda. The cultivars Zolushka, Goluboe vreteno, and Gerda had also high values of flavonoids. The presented results may be used when popularizing this fruit species and also when studying the properties of new food and genetic resources.

Evaluation of Polyphenolic Profile and Nutritional Value of Non-Traditional Fruit Species in the Czech Republic — A Comparative Study

Dry matter, organic acids, ascorbic acid, minerals (nitrogen, phosphorus, potassium, calcium, magnesium, sodium) and polyphenolic profile of a number of non-traditional fruit species and their genotypes, namely blue honeysuckle (Lonicera spp.), Saskatoon berry (Amelanchier alnifolia), black mulberry (Morus nigra), Tomentosa cherry (Prunus tomentosa Thunb.) and jostaberry (Ribes nigrum x Grossularia uva-crispa) were investigated. The results showed that Lonicera genotypes displayed high levels of ascorbic acid and they were rich in minerals, with the cultivar ‘Amfora’ achieving the leading position in nitrogen, phosphorus and potassium content among all lesser known fruit species. Amelanchier cultivars represented a valuable source of ascorbic acid and calcium, ‘Tišňovský’ and ‘Smoky’ together with Morus nigra ‘Jugoslavska’ accumulated the highest level of examined polyphenolic compounds. Regular consumption of studied less common fruit species can bring health benefits so they can represent a high potential value for fruit growers and in addition they can be utilised as functional foods.

Polyphenolic extracts of edible flowers incorporated onto atelocollagen matrices and their effect on cell viability.

The phenolic extract of chives flowers (Allium schoenoprasum, Liliaceae), introduced Sage (Salvia pratensis, Lamiaceae), European elderberry (Sambucus nigra, Caprifoliaceae) and common dandelion (Taraxacum officinale, Asteraceae) were characterised by High Performance Liquid Chromatography and incorporated in different concentrations onto atelocollagen thin films. In order to assess the biological impact of these phenolic compounds on cell viability, human immortalised non-tumorigenic keratinocyte cell line was seeded on the thin films and cell proliferation was determined by using an MTT assay. In addition, their antimicrobial activity was estimated by using an agar diffusion test. Data indicated the concomitance between cell viability and concentration of polyphenols. These findings suggest that these phenolic-endowed atelocollagen films might be suitable for tissue engineering applications, on account of the combined activity of polyphenols and collagen.

Nutritional Potential of Selected Insect Species Reared on the Island of Sumatra

Inhabitants of the Indonesian island of Sumatra are faced with the problem of insufficient food supplies and the consequent risk of undernourishment and health issues. Edible insects as a traditional and readily available food source could be part of the solution. The nutritional value of insects depends on many factors, e.g., species, developmental stage, sex, diet, and climatic conditions. However, edible insects bred in Sumatra for human consumption have never before been assessed with regard to their nutritional value. Our study involved analyses of crude protein, chitin, fat and selected fatty acid contents of giant mealworm larvae (Zophobas morio), larvae of the common mealworm (Tenebrio molitor) and nymphs of the field cricket (Gryllus assimilis). Crude protein content in the samples ranged from 46% to 56%. Highest (35%) and lowest (31%) amounts of fat were recorded in giant mealworm larvae and larvae of the common mealworm, respectively. Chitin amounts ranged from 6% to 13%. Based on these values, which are comparable to those known from other food insects reared in different regions of the world, the edible species bred in Sumatra could become food sources with a potential to help stave off hunger and undernourishment.

Influence of garlic extract on antioxidant status of chicken.

In 2006 the European Union banned the feeding of antibiotic growth promoters because of possible risk of drug resistance in human pathogens bacteria. This is the reason for the study of various phytogenic additives and their extracts as a natural source of biologically important compounds. Antimicrobial substances are a commonly included in chicken feed rations. They are used mainly as prevention against various diseases, and also to stimulate growth. The beneficial effects of garlic on animal organism resulting from their antimicrobial, antioxidative and antihypertensive properities. Studies focused on growth, conversion and meat quality of different types of animals indicate its positive effects. In our experiment we studied the influence of garlic extract in a dose of 0, 10 g and 15 g per 1 kg of chicken feed mixture. We focused on weight gains and antioxidant status of an organism. The experiment took 39 days. 54 seven-day-old chickens were included in the experiment. The chickens were weighed once a week, when aged 11, 17, 24, 31 and 38 days, at the same time of the day. The chickens had ad libitum access to feed ration and water. The chickens were taken blood sample at the end of the experiment when 39 days old. Their antioxidant status were measured using ABTS, FRAP and DPPH methods. Our results show that owing to higher concentration of garlic extract in feed ration the antioxidant status of observed chickens was increased. DPPH method showed an increase in antioxidant status of both experimental groups by 38% (a group with a dose of 10 g/kg of mixture) and by 46% (a group with a dose of 15 g/kg of mixture) compared to the control group. When using FRAP method, antioxidant status of both G10 and G15 groups increased by 24%, resp. 16%. No evidential differences in antioxidant activity between the experimental groups and control group were found using ABTS method. The supplement of garlic extract into a feed ration did not have any influence on weight gains of chickens.

Polyphenols and their Mechanism of Action in Allergic Immune Response

Mini review article deals with the most studied group of chemical compounds – polyphenols – predominantly flavonoids in relation to their allergic immune response. There is clarified and discussed their mechanism of action as well. We emphasized on the strongest inhibitors of allergic reactions - luteolin, fisetin and apigenin, but in the second part the currently studied flavonoids have been summarized as well.

Interaction of polyphenols and wine antioxidants with its sulfur dioxide preservative

Wine is considered to be a significant alcoholic beverage, which is the result of fermentation of grape must or mash. Wine is a must when the substances contained in it play a major role, which are essential inhibiting water, carbohydrates, acids, minerals, nitrates, polyphenols and aromatics. These biochemical components are an important tracking element in wine evaluation in terms of chemical analyzes. An important parameter of monitoring is polyphenolic substances. Polyphenol substances are identified in plant materials as several thousand pieces with a very diverse structure. However, they have a common feature up to one or more aromatic rings substituted with hydroxyl groups. These substances may be present in plant material in a small or large amount. The total daily intake of polyphenols is estimated at 1 g. This is a higher intake than antioxidant vitamin intakes and it is confirmed that their antioxidant activity is higher than that of antioxidant vitamins. When monitoring the content of all polyphenols (TPC) in selected samples using a spectrophotometric method, a higher TPC content of red wines against white white wines can be observed. Total antioxidant activity is introduced to compare antioxidant effects of different mixtures and is based on the ability to eliminate radicals. Antioxidant activity and effects of polyphenols can be inhibited by the addition of preservatives to wine. The preservative is sulfur dioxide (SO2), which has antimicrobial and antioxidant effects. This compound is not harmless because it is a strong allergen, blocks bacteria in the digestive tract and prevents the conversion of sugars and alcohol derivatives in the liver by blocking vitamin B. In the normal life, SO2 is consumed under the E 220 mark. The aim of this work is to monitor the change in the total polyphenols content related to free and bound sulfur dioxide (SO2) content using accredited OIV-MA-AS323-O4B: R, 2009 samples in wine samples. Comparison of organic wines and wines produced by classical, it was found that organic wine have a higher content of biologically active substances and have a strong correlation factor TAA total SO2 (r = 0.77 to 0.91), depending on the wine variety.

The influence of guar gum on textural and sensory properties of rolls made from semi-finished frozen products.

Textural and sensory properties of rolls produced from semi-finished frozen products with additions of guar gum were assessed. A commercial wheat flour T 512, ingredients such as yeast Saccharomyces cerevisiae, rapeseed oil, sodium chloride were used for preparing dough and final products. Guar gum and commercial additive Trial RC2 were used as additives for production. The textural properties of rolls were measured by a TA-XT Plus Texture Analyzer. All samples were evaluated by selected assessors. A five-point hedonic scale was used for evaluation characteristics such as taste, pliancy, texture, porosity, stickiness, gumminess, crispness and quality. The obtained data showed nonsignificant difference in moisture of rolls after baking and 3 days after baking. Control sample of rolls had higher firmness in comparison to other samples with guar gum after baking. Samples of rolls with higher addition of guar gum (10 g.kg -1 and 15 g.kg -1 ) had less firmness in comparison to control sample and sample with 5 g.kg -1 of guar gum. Sensory analysis showed negligible differences among all samples in monitored characteristics. Sensory assessors evaluated all samples as identical. Increased addition of guar gum in rolls led to the extension of shelf life (lower firmness) at unchanged sensory properties of the rolls.

Comparison of Chemical, Textural and Organoleptic Properties of Pastry Sheets with Two Different Additives

Abstract The effect of additions of Arabic gum and commercially used additive Frosty, commonly used for the bread production which is intended for freezing, on the quality of pastry sheets was determined. Frosty decreased active acidity and conversely increased titration acidity in the wheat flour dough and in final products. Higher addition of Arabic gum prolonged the freshness (= moisture) more than Frosty. Arabic gum had insignificant effect on the titration acidity or pH of the dough or the titration acidity of the final products. Both additions of Arabic gum (15 g kg−1 and 30 g kg−1) and higher addition of Frosty (30 g kg−1) decreased the firmness of the pastry sheets. Fresh samples of pastry sheets with lower addition of the Frosty were better in taste, crispness, porosity and quality than the samples with higher addition of the Arabic gum. However, pastry sheets with Frosty lost moisture faster and therefore became less fresh quicker, in comparison with samples with Arabic gum added.

Effect of different storage conditions on the microbiological characteristics of insect

When introducing a novelty food, its safety needs to be monitored. One of the safety aspects of human health is microbial contamination. In this work, microbiological parameters of long-term stored edible insect material - mealworm ( Tenebrio molitor ), lesser mealworm ( Alphitobius diaperinus ), field cricket ( Gryllus assimilis ), and migratory locust ( Locusta migratoria ) were evaluated. The monitored indicators (colony forming units, enterobacteria, lactic acid bacteria, yeasts and moulds) were evaluated using common microbiological methods. All samples of stored insect were determined as safe for human consumption, except for the lesser mealworm sample from 2016, in which case the limit was exceeded. Sample of adult field cricket seems to be suitable for long-term storage, as it contained the lowest amount of microorganism. Sample of dried Gryllus assimilis from 2014 had the lowest microbial contamination. Further results suggest that, for long-term storage, the most suitable way of preparation is killing with boiling water, drying at 103 °C for 12 hours and subsequent hermetic packaging.