Milk is a food of high nutritional value processed by heat treatment. Heat treatment of milk is a technological process designed to inhibit the growth of microorganisms and extend the shelf life of products. The heating process directly affects the molecular structure of whey proteins by the process of denaturation. It leads to the formation of a whey protein–casein polymer complex. Based on these facts, milk heat-treatment conditions should be controlled during milk processing. This work focuses on describing the whey protein denaturation process and formation of the complex of whey protein with casein. The effect of heat treatment on individual milk protein fractions alpha-casein (α-cas), beta-casein (β-cas), kappa-casein (κ-cas), beta-lactoglobulin (β-lg) and alpha-lactalbumin (α-la) was studied by SDS-PAGE. Formation of the whey protein–casein polymer complex increased significantly (p < 0.05) on increasing the temperature and duration of the heat treatment.
The review summarizes the latest scientific findings and recommendations for the prevention of three very common wine faults of non-microbial origin. The first group, presented by the reductive aromas, is caused mainly by excessive H2S and other volatile sulfur compounds with a negative impact on wine quality. The most efficient prevention of undesirable reductive aromas in wine lies in creating optimal conditions for yeast and controlling the chemistry of sulfur compounds, and the pros and cons of correction methods are discussed. The second is browning which is associated especially with the enzymatic and non-enzymatic reaction of polyphenols and the prevention of this fault is connected with decreasing the polyphenol content in must, lowering oxygen access during handling, the use of antioxidants, and correction stands for the use of fining agents. The third fault, atypical aging, mostly occurs in the agrotechnics of the entire green land cover in the vineyard and the associated stress from lack of nutrients and moisture. Typical fox tones, naphthalene, or wet towel off-odors, especially in white wines are possible to prevent by proper moisture and grassland cover and alternating greenery combined with harmonious nutrition, while the correction is possible only partially with an application of fresh yeast. With the current knowledge, the mistakes in wines of non-microbial origin can be reliably prevented. Prevention is essential because corrective solutions for the faults are difficult and never perfect.
1 January 2021 in International Journal of Food Properties
“Slovak bryndza” is a traditional Slovak cheese manufactured by milling a lump of matured ewe’s cheese or by milling a mixture of lump ewe’s cheese and lump cow’s cheese. The percentage of lump ewe’s cheese is greater than 50% w/w dry matter. Differences in the purchase prices of ewe’s and cow’s milk create the potential for adulteration. The detection of cow’s milk compounds by isoelectric focusing of γ-caseins after plasmolysis is a suitable method for the determination of adulteration of this traditional cheese. The analysis and final results may be affected by factors affecting laboratory activity and biological factors. Biological factors are manifested primarily as variations in the casein content of ewe’s and cow’s milk. Despite this variation, this method may also be used for quantification purposes. We were able to establish a reliable calibration line from the internal reference materials prepared in our laboratory. The mean composition of Slovak bryndza cheese determined in our research was protein 18.7 ± 1.9 g 100 g−1, fat 24.0 ± 1.8 g 100 g−1, lactose 1.5 ± 1.9 g 100 g−1, ash 4.5 ± 0.3 g 100 g−1, fat in dry matter 49.3 ± 2.6 g 100 g−1, casein 18.4 ± 1.9 g 100 g−1, gamma casein 0.60 ± 0.19 g 100 g−1, and bovine-to-ovine gamma casein ratio 0.65 ± 0.12 g 100 g−1.
In this work, we investigated the effect of UV-C radiation (254 nm) on turbidity, microbial count and sensoric properties of the grape juices treated or not treated with sulphur dioxide. The UV-C radiation is considered to be germicidal against microorganisms. This technology is routinely used to treat drinking water. Application of this method for the purpose of treating the wine was tested in few studies. These studies have shown a positive effect on the inactivation of microorganisms, but they not dealt in detail with the sensory properties of grape juice after the treatment. The main idea of using this method appears to eliminate the sulphur dioxide from wine making technology. There are people who have a genuine allergy to sulfites, and these allergies are often linked with asthma. These people have an rapid onset of symptoms when drinking liquids like wine treated with sulphur dioxide. In our work we have found that the application of this method of treating the grape juice is problematic. Intensity of UV-C radiation increases the turbidity of grape juices. This effect was observed in all grape juices with or without addition of sulphur dioxide and also in clarified or not clarified grape juices. We found that UV-C radiation negatively affect the sensory properties of grape juices. This effect was more pronounced in grape juices treated with SO2. The smell and taste were significantly negatively changed. Exposure of grape juice treated with sulphur dioxide to UV-C radiation can probably lead to arising the sulphur compounds, which affects the smell and taste of grape juices. Also, it is very likely that the negative change in taste and smell may affect the quality of produced wines. For this purpose, we do not recommend to use UV-C treatment for the grape juice treatment. It will be interesting to conduct a detailed analysis of the grape juices composition before and after UV-C radiation treatment.
28 June 2020 in Potravinarstvo Slovak Journal of Food Sciences
Food fraud is one of the long-standing causes of scandals attracting particular attention for a long time. This study aimed to monitor food fraud in the European Union and to identify the relationships among the countries where the cases were reported, adulterated commodities (seafood, eggs, milk, meat, fish, and their products) and types of fraud. The secondary data were covered by the survey focused on consumer knowledge about fraudulent activities, ingredient substitution, masking of origin, mislabeling, placing on the market of foods not fit for human consumption within Slovak inhabitants. Primary and secondary data were used to achieve this aim. Primary data were obtained from the Food Fraud and Quality Knowledge Center (KCFFQ) and secondary data from the questionnaire survey from 354 respondents. During the period from 2017 to 2019, 163 cases of food fraud were reported, most of which originated from Italy and mainly concerned fish and fish products. Based on primary data and one-way ANOVA statistical tests, we confirmed five hypotheses. There was found no statistical impact of the country on the type of food fraud (p = 0.0067), but the significant effect was determined on which food was adulterated (p = 0.000001). There was no statistical correlation among years and countries where the cases were reported (p = 0.110), but the statistically significant correlation was confirmed among years and commodities (p = 0.0043) and types of fraud reported (p = 0.009). Based on the processed secondary data from the questionnaire, we can conclude some information or public interest in food fraud problems.