Potravinarstvo Slovak Journal of Food Sciences
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Study of the influence of brewing water on selected analytes in beer
Get PDFBrewing water is one of the basic raw materials for beer production and knowledge of its composition and pH is essential for the proper conduct of the entire brewing process. In this study, it was observed how the composition of water influences OG values, content of B vitamins, organic acids and iso-α-acids. For brewing, synthetic water was prepared by adding chemicals to deionized water. Models of hard (pH 8.47 ±0.08) and soft (pH 7.68 ±0.23) synthetic water were used for brewing pale bottom-fermented lager beers. Samples of wort, hopped wort, young beer and beer were collected during beer production. HPLC-DAD was used for B vitamins and iso-α-bitter acids quantification. Determination of organic acids was done by ion chromatography with conductivity detector. Obtained data were statistically processed with ANOVA (Analysis of Variance) and interval of confidence was set to 95%. According to the statistical analysis, water composition affects analytes content during beer production and in the final product. Hard water seemed to be a better extraction buffer and its composition (pH) positively affected some processes during brewing technology. One of them was obtaining higher OG values compared to soft water. The beer made from hard water also contained more B vitamins. Composition of brewing water had no influence neither on concentration of organic acids nor on iso-α-acids in conditions of homebrewing
The effect of coffee beans roasting on its chemical composition
Get PDFDrinking coffee has become part of our everyday culture. Coffee cultivation is devoted to over 50 countries in the world, located between latitudes 25 degrees North and 30 degrees South. Almost all of the world's coffee production is provided by two varieties, called ‘Arabica’ and ‘Robusta’ whereas the share of Arabica is 70% of the world's coffee harvest. Green (raw) coffee can not be used to prepare coffee beverages, coffee beans must first be roasted. Roasting coffee and reaching a certain degree of coffee roasting determine its flavor and aroma characteristics. In the present study the fate of sucrose, chlorogenic acid, acetic acid, formic acid, lactic acid, caffeic acid, total phenolic compounds and 5-hydroxymethylfurfural was studied in coffee (Brazil Cerrado Dulce, 100% Arabica) roasted in two ways (Medium roast and Full city roast). It has been found that almost all sucrose has been degraded (96 – 98%) in both roasting ways. During Medium roast 65% of chlorogenic acid contained in green coffee was degraded while during Full city roast it was 85%. During both Medium and Full city roasting, the formation of acetic acid but especially formic and lactic acid was recorded. The highest concentration of organic acids was recorded at Full City roasting at medium roasting times (3.3 mg.g-1 d.w. acetic acid, 1.79 mg.g-1 d.w. formic acid, 0.65 mg.g-1d.w. lactic acid). The amount of phenolic substances also increased during roasting up to 16.7 mg.g-1 d.w. of gallic acid equivalent. Highest concentrations of 5-hydroxymethylfurfural were measured at medium roasting times at both Medium (0.357 mg.g-1 d.w.) and French city (0.597 mg.g-1 d.w.) roasting temperatures. At the end of roasting, the 5-hydroxymethylfurfural concentration in coffee were 0.237 mg.g-1 d.w. (Medium roast) and 0.095 mg.g-1 d.w. (Full city roast)
Effect of somatic cell counts occurred in milk on quality of Slovak traditional cheese - Parenica
Get PDFThe aim of this work was to compare somatic cell count in milk used for making steamed cheese Parenica in Slovak industrial dairies and small farm dairies and to find out whether somatic cell counts in milk affect the dry matter content of Parenica cheese. The samples of raw milk were taken from 3 industrial dairies (A, B, C) and from 3 farm dairies (E, F, G), produced traditional Slovak cheese Parenica in period from January untill December 2018. The somatic cell count in milk was determined by FossomaticTM 5000 (Foss, Denmark) and dry matter of cheese by oven drying method to constant weight. There were no statistically significant differences (p >0.05) for somatic cell counts in milk processed in industrial and farm dairies. Lower somatic cell counts were determined in milk amples from industrial dairies (mean value 326.55 thousand in 1 mL) in comparison to milk samples from farm dairies (mean value 507.67 thousand in 1 mL). Statistically lower dry matter content (p <0.01) in the samples of Parenica cheese was found out in farm dairy E in comparison to other dairies. The relationship between somatic cell count in milk and dry matter in cheese was confirmed by the relatively low correlation coefficients in dairies, A = 0.22; C = 0.15 and F = -0.12 and higher correlation coefficients in dairies, B = -0.32; D = 0.45 and E = -0.48. Obtaining a more accurate effect of somatic cell count on cheese quality requires the continuation of the research on a larger number of samples and consideration of other factors
Evaluation of selected parameters of edam type cheese packed under foil with natural antimicrobial agents
Get PDFThe aim of this study was to evaluate the properties of essential oils packed in foils derived from different plant sources used in Edam type cheese on selected parameters (total viable count of microorganism, coliform bacteria, micromycetes, sensory parameters and instrumental colour). Essential oils have antibacterial and antifungal activities against microorganisms. However, the concentration of these substances applied in cheeses should be considered carefully because of their possible negative influences on sensory parameters. Mixture of the essential oils (clove/cinnamon/thymol in a 1:2:1 ratio), three concentrations (3.9 %, 6.6 %, 9.0 %), respectively mixture of the essential oils (eugenol/thymol/cinnamon in a 1:1:1 ratio), three concentrations (0.10 %, 0.19 %, 0.24 % as a 5% solution in limonene in a dry coating) were used. Samples wrapped in polystyrene dishes were stored in the refrigerator at 3 - 6 °C. Analyses were made after 48 h, 168 h (144 h), 216 h (240 h) respectively. Taste is the most affected by presence of essential oils. The effectiveness of the film with the mixture A seems to be more effective in eliminating microorganisms. Negative sensory changes were observed at higher concentration. Based on the results, the tested foils seem to be promising materials suitable for packaging of cheese
Effect of plant growth regulators on biochemical compounds of tangerine (Citrus unshiu Marc.)
Get PDFWe investigated the effect on tangerine of new generation plant growth regulators. The use of drugs in the period of fruit ripening has led to increased 2.0 - 3.7 times abscisic acid (AA) and 1.9 - 4.7% of Indole-acetic acid (IAA) acid in the leaves. Studies have shown that Indole-acetic acid and abscisic acid beginning of a sharp accumulation of their hormones coincides with action of stress factors and growth dormancy period. The use of the regulators had an impact not only on their content in leaves but also on fruit quality. For example, treatment Indole-acetic acid and Obstaktin led to an increase in the fruit of vitamin C. After treatments with plant growth regulators has been a significant decline in the total number of organic acids (up to 2.35% at the option of Melaphen and to 2.50% at Obstaktin, LSD (p ≤0.05) = 0.06). By reducing the content in the fruits of organic acids to all variants increased the sugar-acid index. After each spraying tangerine on the treatment options plant growth regulators has been a significant increase the dry matter. Thus, the positive effect of plant growth regulators on all the quality characteristics of tangerine was shown. In the summer period, the treatment by regulators may have a protective effect, increases the content in plants the content of Indole-acetic acid. The plant growth regulators of new generation have a positive effect on quality of dwarf tangerine. Given that the plants of tangerine in the subtropical zone of Russia each summer have to drought and are losing not only in yield, fruit quality too, new regulators may exert a protective effect, because increases the content in plants is Indole-acetic acid, which activates gene expression of drought resistance
The study correlation between physicochemical properties, botanical origin and microbial contamination of honey from the south of Ukraine
Get PDFThe honey production is one of the most important agriculture branches of Ukraine. Since the beginning of 2000 year, honey becomes one of the first products of agriculture production that was allowed to export from Ukraine to the EU countries. The present study aims to evaluate microbial composition of honey of higher and first grades from south of Ukraine, which differ in water, sugar content and acidity. The correlation beetween physicochemical properties, botanical origin and microbial composition of honey were investigated. Total aerobic count (TAC), total count of fungi (TFC) and yeast (TYC), number of sporeforming anaerobes (SFA), Bacillus cereus and Clostridium botulinus were determined. Plate dilution method with specific cultural mediums and incubation conditions was used for indication and identification of microorganisms as well for quantitative CFU count determination in 1g of honey. The results indicated that the value of TAC was from 1.4 ±0.1 x 102 to 3.7 ±0.5 x 102 CFU.g-1 in higher grade honey and from 2.1 ±0.3 x 102 to 4.6 ±0.4 x 102 CFU.g-1 in first grade honey. Average amounts of fungi and yest in the first grade honey were more than in higher grade honey and amounted 15.±0.9 CFU.g-1, 6.48 ±0.7 CFU.g-1 and 17.98 ±1.2 CFU.g-1, 8.04 ±0.8 CFU.g-1 respectively. Also it was found that, 25.8% and 37.1% of higher and first grade honey samples had sporeforming anaerobes. The more of samples with Bacillus cereus and Clostridium botulinum were among samples of first-grade honey samples. In addition, we have determined that, samples of buckwheat honey and honey from fodder crops of both grades were more contaminated with all microorganisms than samples of sunflower honey and honey from fruit and non-fruit trees.Results of this work has revealed the relationship between the number of different groups and species of microorganisms in higher and first grade honey from south of Ukraine and its physicochemical properties and botanical origin. Our research could help to substantiate the sources of contamination of honey and confirm the existing findings of scientists about the direct proportional dependence of the content of microorganisms in honey, depending on its moisture content, acidity and sugars
Authentication and preference mapping of ham
Get PDFEffective connection between the food industry and consumer demands are specific needs of consumers whitch were monitored in this study by using a preferential mapping method. Preference mapping is based on Principal Component Analysis (PCA), which is performed on preferences ratings given for each product and preferences of each consumer through an online questionnaire. Key features for the consumer choice were colour, odour, consistency, total flavour and overall appearance. We verified the composition and mapped the preferences of 10 hams purchased in Slovakia. In view of the persistence of identified cases of food counterfeiting and meat fraud, intensive monitoring and scrutiny is required through effective and accurate analytical methods, which are crucial for maintaining consumer confidence and ensuring compliance with local legislation and labeling. The reference approach for identifying animal species in food is the PCR method, which is however limited to several animal species, meat types. The use of microarray technology enables the identification of a wider range of animal species and greater user comfort, especially the speed of obtaining the results. It allows 24 animal species to be identified in one analysis in 8 samples at a time. Detection was performed using Chipron LCD Aarray Kit Meat 5.0. In all analyzed samples, components of animal origin were identified in accordance on the packaging of the products. The Meat 5.0 LCD chip, which was used for analysis, has detected the presence of other animal species
Consumer behaviour of young generation in slovakia towards cocoa-enriched honey
Get PDFThe new trend of healthy lifestyle increases consumers´ attention towards superfoods or functional food. Due to this fact, honey enriched with various healthy foods such as cocoa, cinnamon, ginger or dried fruits has started to appear on the European market. The aim of this research paper was to investigate consumer´s perception and preferences for cocoa-enriched honey. Consumer research was based on questionnaire survey extended by product testing. This survey was conducted in 2018 (February and March) and in total 257 young Slovak consumers between 18 - 30 years participated. Each respondent tested and evaluated sensory attributes of the product (taste, aroma, colour and texture) using a 5-point scale. Statistical analyses included Friedman test, Mann-Whitney U test, Fisher's Exact Test, Pearson Chi-square test and Cramer'V coefficient. Results showed that the cocoa-enriched honey was evaluated as tasty, aromatic, gently, delicious, special, with ideal sweetness and amount of cocoa. All sensory attributes were evaluated positively (2 - good). Females were more interested in the purchase of this product. Moreover, the product would be purchased mostly by respondents who consider it a healthier alternative to commercial chocolate spreads or by those who consider their eating habits healthy. Laboratory tests revealed that the antioxidant activity of the product was higher in comparison to normal honey. In conclusion, the obtained information could be used in product positioning, promotion and designing appropriate marketing strategy
Bioinformatics analysis of aflatoxins produced by Aspregillus sp. in basic consumer grain (corn and rice) in Saudi Arabia
Get PDFThe food contaminants by aflatoxins are inevitable even when all precautions and good agricultural practices are applied. Samples of white rice and corn (yellow, red) grains were collected from different local markets and houses. Three Aspergillus flavus strain isolated were identified using molecular characterization of AFLR (aflR) toxin gene. DNA genome of the three A. flavus isolates (namely A. flavus _ YC; A. flavus _ RC; A. flavus _ Rice) which corresponds to isolates from, yellow corn, red corn and white rice respectively were used as a template for PCR to amplify Aspergillus flavus AFLR (aflR) toxin gene. Partially sequenced was amplified using a specific primer set to confirm its identity, phylogenetic relationships between the three isolates as well as determination of the corresponding antigenic determinants. The epitope prediction analysis demonstrated that there were 1, 2, 3 and 4 epitopes whose score were equal 1 in A. flavus _ YC; A. flavus _ RC; A. flavus _ Rice, respectively. Interestingly, there were great dissimilarity in the epitope sequences among the three isolates except in RLQEGGDDAAGIPA, SPPPPVETQGLGGD, RPSESLPSARSEQG and PAHNTYSTPHAHTQ were found to be similar between all isolates. This work articulates that the molecular identification and characterization of three A. flavus using Aspergillus flavus AFLR (aflR) toxin gene and the unique antigenic determinants that could be used for design of a broad-spectrum antibody for rapid detection of A. flavus in foods and support quality system of food safety
Characteristics of flour and dough from purple and blue wheat grain
Get PDFThe characteristics of flours and doughs prepared from wheat grains containing purple pericarp (variety PS Karkulka and Jumiko) and wheat grain containing blue aleurone (variety Skorpion) were tested and compared with commercial wheat to evaluate the applicability of colored wheat in bread making. The fine flours prepared from colored wheat grains significantly differed in the activity of the amylase enzyme, expressed as Hagberg falling number. Zeleny sedimentation volume of flour prepared from grains of the PS Karkulka variety (36 mL) was significantly higher than the values of AF Jumiko and Skropion (34 mL) varieties. The results of uniaxial deformation test indicated that doughs prepared from wheat varieties PS Karkulka and Skropion can be elongated; the dough is, however, weak and can be expected to rupture more easily than dough prepared from variety AF Jumiko, as well as commercial flour. Even if some variations in the values of farinographic dough development time and stability were also observed, clear differences in the behavior of doughs prepared from colored and commercial flours were not found. The differences in dough behavior during heating test were also negligible. It can be concluded that none of the tested colored wheat grains exhibited characteristics completely different from the others or the commercial one. The results may indicate the applicability of all tested colored wheat grains in yeast-leavened bread production