Tremlová (2017) Application of principal component analysis method for characterization chemical, technological, and textural parameters of farmed and pastured red deer,

The objective of this work was to study the changes in chlorophyll contents in green teas stored under different conditions and to suggest the most suitable way and length of green tea storage. A secondary aim was to evaluate the possibility of using the chlorophyll content as an indicator of tea freshness. Samples for analysis were obtained from a range of tea-growing regions. Chlorophyll contents were measured using UV-vis spectrophotometry. Chlorophyll absorbance was measured at 642.5 and 660 nm. Prior to storage, chlorophyll concentration in teas ranged from 1.12 to 1.89 mg per 1 g of tea, which corresponded to data given by other authors. Storage was found to lead to a decline in chlorophyll concentration. From the 6 th month of storage onwards, a significant decrease (P < 0.05) was observed in all samples, irrespective of storage conditions. Based on the findings of this study, original and metal packaging can be considered the most chlorophyll-friendly. On the other hand, glass and paper packaging stored in direct daylight were found to have the strongest impact on chlorophyll concentration. Overall, it can be concluded that the storage time can have a strong influence on oolong green tea colour as an important qualitative variable. Thus, the shelf-life of tea should be shorter than the 12 months claimed by most manufacturers. Once the relationship between changes in chlorophyll concentration and length of the storage period had been established, the chlorophyll content was suggested as an indicator of the storage time (freshness) of a tea substance.

Background. Differences in the types and percentages of essential amino acids (EAAs) in food could infl uence the value of protein consumed and proteins with a high content of EAAs are the most important components of poultry meat. The use of probiotics for meat and carcass quality improvement has been questioned, while feed supplementation with thyme essential oil (TEO) could be considered as useful natural supplement to be applied in the poultry industry to improve meat quality. Material and methods. Day-old broilers Ross 308 (n = 400) were randomly divided into four groups based on the feed supplement as follows: control, probiotics 0.05%, TEO 0.05% and combination of probiotics and TEO, while the fattening period was 42 days. Six birds of both sexes from each group were selected as a sample, slaughtered and then stored (-18°C) for 6 months till the analysis. The muscular homogeneous sample (50 g) from the breast and thigh of each sample bird was analysed by the Fourier Transform Infrared Spectroscopy method using the device Nicolet 6700. The essential amino acids content was determined and the quality indicators include chemical score, amino acid score, EAA index and biological value were calculated. Results. The obtained results show that for all the tested EAAs of the breast and thigh muscles, the content numerically increased gradually and progressively within the groups as the control scored the minimum followed by the probiotics group, then the combination group and fi nally the TEO group which scored the highest results. Conclusion. It can be concluded that the TEO promoted the increase of all the EAAs and consequently the quality indicators with signifi cant different compared with the control group and signifi cantly different for some EAAs and quality indicators compared with the probiotics group and the combination group.

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