Jan Kuchtík

Meat quality characteristics of lambs of three organically raised breeds

Carcass and meat (muscullus quadriceps femoris [MQF]) quality characteristics were evaluated in ten lambs per each of Zwartbles (ZW), Suffolk (SF) and Oxford Down (OD) breeds, raised organically and slaughtered at a mean live weight of 38 kg. Meat of ZW lambs had lower (P<0.05) collagen, myoglobin and intramuscular fat content than OD lambs, and lower (P<0.05) tenderness and juiciness scores in comparison with OD and SF lambs. Despite a low polyunsaturated/saturated fatty acid ratio (0.13 in all three breeds; P>0.05), meat of the pasture-fattened lambs can be considered a dietetically superior food with very favourable (0.85-0.88; P>0.05) polyunsaturated fatty acid n - 6/n - 3 ratio, and containing per 100g of muscle on average 62 mg of EPA+DHA (differences between breeds not significant, P>0.05) and no more than 20mg of dietetically unfavourable arachidonic acid.

Chemical and physical characteristics of lamb meat related to crossbreeding of Romanov ewes with Suffolk and Charollais sires

The aim was to evaluate the effects of crossbreeding Romanov (RO) ewes with Suffolk (SF) and Charollais (CH) sires on the chemicophysical characteristics and FA profile of the Quadriceps femoris muscle (QFM) in lambs fattened under organic conditions. The experimental animals were male lamb twins of two different crossbreds; CH 50 RO 50 and SF 50 RO 50. Lambs were slaughtered at an average live weight of 31kg. CH 50 RO 50 displayed higher contents of dry matter and intramuscular fat of the QFM. A lower pH value of CH 50 RO 50 was reflected in an increase of WHC. Meat of SF 50 RO 50 lambs had more lightness (L*) and yellowness (b*). The CH 50 RO 50 genotype showed a significantly higher proportion of C18:3n-3cis and n-3 PUFA than the SF 50 RO 50 genotype. The genotype also affected the Δ(9)-desaturase (16) index.

Utilization of FT-NIR Spectroscopy to Check Acidity of Various Types of Cheeses.

Background: Monitoring the acidity of cheese is an important control mechanism in various stages of manufacture, including aging. Acid development in cheesemaking is essential to cheese flavor, texture, and safety. Objective: The aim of the work was to develop and validate calibration models by using NIR spectroscopy, which allows for the monitoring of changes in cheese acidity (pH and titration acidity) during cheese ripening. Methods: Cheeses were analyzed by an FT-NIR spectrometer. Each of the samples was analyzed three times, and for calibration, an average spectrum was used. A partial least-squares regression was used to develop calibration models. The constructed calibration models were validating by full cross-validation. Results: Calibration models were created with a high correlation coefficient for the following cheese pH levels: blue cheese (0.966), Olomouc curd read smear cheese (0.984), and fresh goat cheese (0.980). Results of the calibration of titratable acidity are functional for fresh goat cheese (0.953) and mozzarella (0.999). Conclusions: The results of these new calibration methods showed the possibility of NIR technology for the fast determination of pH and titratable acidity. Highlights: Detection of cheese acidity using FT-NIR spectrometry enables rapid evaluation of the process of lactic acidification in particular cheese technological operations, including the maturing of cheeses.

Interspecies and seasonal differences of retinol in dairy ruminant´s milk

Milk is an essential source of macronutrients and among lipophilic vitamins is significant source of retinol. The contribution of milk to the reference daily intake for retinol varies from 11% to 16%, worldwide. The most consumed dairy products are fresh, dehydrated and condensed milk in which the amonuts of retinol are not modified to those of in whole milk. Retinol is essential to ensure a good functionality of the immune system and plays a critical role in vision, reproduction, cell differentiation as well as growth and development and is found only in animal tissues. The aim of our study was to evaluate the interspecies differences in the retinol concentration of whole raw bovine, caprine and ovine milk and to observe seasonal variation of retinol in bulk tank milk samples. Samples of raw milk were colleceted on different farms in the Czech Republic between 2013 and 2014. Retinol was measured by ultra high performance liquid chromatography with UV detection (325 nm) in isocratic mode after alkaline saponification with methanolic potassium hydroxide solution and liquid-liquid extraction into non polar organic solvent of whole raw milk. To avoid vitamin losses or degradation during the procedure, antioxidants were added to the sample extraction media. Our results indicate significant interspecies differences between bovine and ovine milk and caprine and ovine milk. Concentration of retinol is very similar in bovine and caprine milk 0.96 ±0.11 mg/L, 0.94 ±0.25 mg/L, respectively. The mean concentration in sheep´s milk is 1.75 ±0.24 mg/L. The seasonal variation of retinol in raw bovine milk was detected as high significant, with the highest concentration during winter. These results contribute to the nutrition evaluation of milk in the Czech Republic and indicate, that the sheep´s milk is the best source of retinol among the milks of ruminants kept in the Czech Republic, however it is not used in its fluid form for human consumption.