A Comparison of the Growth of the ‘Purpurea’ Silver Birch Cultivar ( Betula pendula Roth) Propagated by Grafting and with the in Vitro Culture Method

摘要

Background. Cooling and freezing are the most popular methods of meat and fat preservation. During cooling low temperatures do not destroy the structure of meat and fatty tissue or cause big changes in their quality. The freezing of meat and fat causes changes in their quality, which are directly connected with the freezing process followed by frozen storage. The aim of the study was to analyse changes in selected physicochemical properties of horse meat and fat during cold and frozen storage. Material and methods. Samples of the longest dorsal muscle and neck fat collected from 16 horse semi-carcasses were used as the research material. One batch of the meat samples was subjected to laboratory analyses after 48 and 120 h of cold storage. The other three batches were frozen and stored for 1, 3 and 6 months at a temperature of –22°C. Results. The extension of frozen storage of horse meat to 3 months (directly after defrosting) caused colour brightening and reduced thermal dripping, in comparison with the cold-stored raw material. Further extension of storage to 6 months decreased the meat quality by darkening its colour and caused greater thawing dripping (no statistically significant differences) with simultan­eous improvement of thermal dripping. There were statistically significant differences both in peroxide and acid values for cold-stored and frozen neck fat. The values increased during freezing and frozen storage. Conclusions. The study showed that the time of cold and frozen storage determined physicochemical properties of horse meat and fat. Therefore, it seems appropriate to conduct further research on changes in physicochemical properties of horse meat and fat stored under cooling conditions in modified atmosphere.