Miroslav Jůzl

Effect of foliar application of selenium on the content of se-lected amino acids in potato tubers (Solanum tuberosum L.).

Selenium (Se) is an important element associated with the enhancement of antioxidant activity in organisms. Po- tato is very suitable for fertilisation with Se (biofortification). The experiment was performed to examine the effect of foliar application of Se as sodium selenite (200 or 400 g Se/ha) at the tuberisation stage on a spectrum of amino acids in tubers of varieties. The trends of amino acids were consistent in both years of the study. Application of Se increased the relative content of total essential (EAA) and non-essential (NEAA) amino acids relative to the con- trols (Karin: EAA 16.81-21.73% and NEAA 14.18-18.63%; Ditta: EAA 4.71-13.00% and NEAA 5.78-6.49%). The increase in the content of phenylalanine (Phe) was particularly significant (up to 48.9%) when also the contents of aspartic acid (Asp), glutamic acid (Glu), threonine (Thr), and tyrosine (Tyr) increased significantly compared with the controls. The results of changes in the content of isoleucine (Ile), leucine (Leu), lysine (Lys), methionine (Met), valine (Val), alanine (Ala), arginine (Arg), proline (Pro), cysteine (Cys), glycine (Gly), histidine (His), and serine (Ser) were also discussed. The highest dose of selenium is shown as a stress factor. Its toxic effects resulted in a change of amino acid contents.

The effect of feeding milk thistle seed cakes on quality indicators of broiler chickens meat

This study was conducted to evaluate the effect of feeding milk thistle (Silybum marianum L.) seed cakes at dose 5% and 15% in feed mixture on quality indicators of broiler chickens meat. The used milk thistle seed cakes contained 3.73% of flavonolignans and 129.83 mg.kg-1 of cyanidin-3-glucoside. A 150 cockerels of Ross 308 were divided into three equal groups. The chickens were fattened on conventional deep litter system. The experimental groups received feed mixtures containing 5% of milk thistle seed cakes (MT5), 15% of milk thistle seed cakes (MT15) and third group was control - without milk thistle seed cakes (C). The trial lasted 37 days. At the end of trial was observed significant higher average weight of chickens (2,320.31 g) in control group. Compare to that the experimental group MT5 achieved significant lower mean bodyweight 2,166.69 g. From the perspective of fattening was decreased growth of chickens where a higher percentage of milk thistle seed cakes (MT15). The group MT15 was up to 420 g lower slaughter weight compared to the control group. This was probably due to the higher content of fiber in the feed. At the end of experiment 15 birds were selected randomly from each group, weighed and slaughtered. Feathers were removed and chickens were eviscerated. Carcass yield was calculated for each group like as percentage of live weight. The MT5 and MT15 group had significantly higher breast meat tenderness that the control group. Initial pH1 was highest in group with its middle addition of milk thistle seed cakes (MT5). Significant differences were not observed between control and group MT15. Breast meat was rated as the best in parameter flavour in control and MT15 group. The thigh meat was evaluated significantly best for colour parameter in MT15 group. Fibreness was rated as the finest in MT15 group. The addition of milk thistle seed cakes do not worsened sensory characteristic of breast or thigh meat of broilers and reflects optimal sensory quality traits.

Evaluation of selected quality parameters of reduced salt frankfurters

Higher 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.

The effect of feeding wheat varieties with different grain pigmentation on growth performance, texture, colour and meat sensory traits of broiler chickens

The feeding effect of of three spring wheat genotypes (Vanek, Konini and UC66049) with different grain colour on growth performance, body composition and meat quality parameters of broiler chickens was tested. Ninety chickens were divided into three groups (control, Konini and UC) with 30 chickens in each. The tested genotypes were compares with standard variety Vanek (control) with common (red) grain colour. The two experimental groups received feed mixtures containing 38.2% of wheats with different grain colour: groups Konini (n = 30) and UC (n = 30) with. The third group (n = 30) had 38.2% of common wheat Vanek cultivar (Control group). The live weight of chickens between the experimental groups and control group was not significant different, as well as body composition and chemical analysis of breast and thigh meat of chickens. The feeding of wheat with different grain colour had no effect on performance parameters of broiler chickens. Breast meat tenderness according to the Razor Blade Shear Force was higher in control group against experimental groups. The colour change was not significantly different in all coordinates. pH values (measured after 1-hour post mortem) were found significantly higher in the group fattening with Konini wheat than control and UC groups. Chickens meat from the experimental group was characterised by steady overall quality. The effect of various feeding had no effect on meat quality in terms of relevance to consumers.

THE EFFECT OF STORAGE TEMPERATURE ON THE QUALITY AND FORMATION OF BLOOMING DEFECTS IN CHOCOLATE CONFECTIONERY

The study aimed at assessing changes in the quality of certain types of chocolate products over the storage period with particular focus on the formation and development of fat and sugar bloom in chocolate products. Seven products were selected in collaboration with a chocolate factory to undergo monitoring and analysis and stored at four temperature regimens (6 °C, 12 °C, 20 °C and 30 °C). Five samplings were carried out over the storing period (18 weeks) for evaluation of the dynamics of changes in their quality. Each sampling was accompanied by sensory evaluation; selected physical attributes were also analysed: changes in colour (∆E*ab) within the CIE (L*a*b) system and changes in hardness using the TIRAtest 27025. The results showed a significant effect of storing temperature on the intensity of changes in the quality of products. The results of sensory evaluation of selected products showed that the highest quality for the majority of descriptors was achieved by products stored at temperatures of 6 °C and 12 °C. As regards samples stored under the temperature regimen of 20 °C, the products started to show visible differences, caused primarily by the formation of fat bloom while storing at 30 °C proved to be extremely unsuitable for all the tested products. Since storing temperatures of 6, 12 and 20 °C did not considerably affect hardness and colour of each product, no distinct changes occurred under such temperature regimens. From the aspect of analytical measurements of colour and hardness of each product, storing at temperatures of 20 °C can be termed appropriate. In all the analyses, the effect of the temperature regimen of 30 °C was significantly negative due to defects caused by blooms on the chocolate, meaning that such temperatures are not advisable for storing chocolate products, even over a short term.