Jozef Nagy

Post-mortem changes in the concentration of lactic acid, phosphates and pH in the muscles of wild rabbits (Oryctolagus cuniculus) according to the perimortal situation

In this study changes in the concentrations of lactate, phosphates, and pH values of water extracts of muscles of transported and hunted rabbits during ripening were determined. Concentrations of lactate were higher in the muscles of hunted rabbits. The highest differences were obtained 24h after kill/hunt. Concentrations of lactate in the muscles of hunted rabbits were decreasing, while in the muscles of transported rabbits we observed it to increase in the 7th day and then decrease in the 14th day. Higher concentrations of phosphates were found in the muscles of transported wild rabbits. During the ripening process concentrations of phosphates were decreasing in muscles of both groups. Muscles of hunted rabbits had lower pH values during the whole ripening process. Our research showed that concentrations of lactate, phosphates and pH value post-mortem depended on the perimortal situations.

Evaluation of some parameters of post mortem changes of pheasant (Phasianus colchicus)

Post mortem changes were evaluated in muscle tissues of 99 male, uneviscerated pheasants (Phasianus colchicus) stored for up to 14 days at 0 and 4 °C. The control group (Group I) included regularly slaughtered and bled pheasants (n=33). From approximately 350 pheasants hunted on a single occasion, specimens were taken and, on the basis of X-ray examination performed from latero-lateral and dorso-ventral body projection of hunted pheasants, two groups were constituted: Group II included pheasants (n=33) with one or multiple shots in the muscle tissues but not in the body cavity, whereas Group III included pheasants (n=33) with shots in both muscle tissues and the body cavity. Each group was divided into two subgroups, in which uneviscerated pheasants were stored at 0 °C and 4 °C, respectively, for a maximum of 14 days. Randomly selected pheasants from each subgroup (n=4), were examined on days 0, 3, 7, and 14. The following post mortem changes in breast and thigh muscles were evaluated: pH value (in watery extract), lactic acid and ammonia concentration. Generally, low pH values were associated with higher concentrations of lactic acid, most pronounced in breast muscle. Significant differences (P<0.05) in pH – both at 0 and 4 °C storage temperature – were found for breast muscles between Groups I and II, albeit average differences were merely in the range of merely 0.1 to 0.2 units. Thigh muscles of Group I had significantly lower pH (0.2 to 0.4 units) than Groups II and III, for all study days. A statistically significant difference (P<0.05) was found between the lactic acid concentrations in breast muscles (4 °C) between groups II and III. The highest average concentrations of ammonia in the breast muscle (day 14) were determined in the Group III (4 °C), and the lowest in the group of slaughtered pheasants (4 °C). The highest average concentrations of ammonia in the thigh muscles were in Group III (0 °C), and the lowest in the group of slaughtered pheasants (0 °C). This difference was statistically significant (P<0.05). In summary, muscles from pheasants being slaughtered instead of hunted were characterised by lower pH, higher lactic acid and lower ammonia concentration at the end of the storage period.

The efficacy of air spray chilling and its impact on microbial quality of broiler carcasses

This study was focused on the evaluation of the period necessary for chilling of poultry carcasses through recording of temperature in the breast muscles and microbial associations on the surface in relation to body weight (BW). The temperature was measured in sixty broiler carcasses divided into six equal weight categories (1.3, 1.4, 1.5, 1.6, 1.7 and 1.8 kg). For the temperature measurements the module ELPRO was used. The module was placed in the body cavity and the probe was inserted into breast muscle. The mean temperature of breast muscles immediately after slaughter ranged from +38.8 to 40.30°C. The mean temperatures after chilling of carcasses with average BW<1.5 kg were lower than +4°C (1.30±1.127; 3.20±0.658; 3.30±0.524), but higher in carcasses with BW>1.5 kg (5.10±1.231; 7.90±2.356; 9.30±2.966). Average total viable count (TVC) on the surfaces before chilling was 3.99±0.19 log CFU/100 cm2 (1.2 to 1.5 kg), and 3.93±0.14 log CFU/100 cm2 (1.6 to 1.8 kg). A statistically significant increase (P<0.05) in TVC after chilling in both weight categories (n=6) was found. Average TVC after chilling was 4.28±0.11 CFU/100 cm2 (1.2 to 1.5 kg), and 4.33±0.08 (1.6 to 1.8 kg). Average Enterobacteriaceae count was reduced in the lower weight group (1.3 to 1.5 kg) from 3.11±0.35 to 2.97±2.97 during chilling, but it significantly (P<0.05) increased (3.07±0.28 to 3.13±0.14) in the higher weight group (1.6 to 1.8). Salmonella was not detected in either of the samples.

MECHANICALLY RECOVERED MEAT

Mechanically recovered meat (MRM) comprises meat shaved or pressed off from bones or carcasses as well as meat removed from sinews or fatty trimmings. Texture and composition of the product depend on the body part and species (pork, poultry, and fish being most common) as well as on the rendering technology, but proximate composition is similar to that of cut up meat. Microbiological contamination and, more specifically, prions in central nervous tissue from cattle are food safety issues. The addition of MRM is restricted in various countries, and/or may require special labeling of foods.

Effect of quantum therapy on pork quality.

In this study the impact of quantum therapy on meat quality of slaughtered pigs was investigated. For this purpose the pigs were treated with different doses of magnet-infrared-laser (MIL) radiation. Animals were divided into four groups according to radiation doses (4096, 512, and 64 Hz, and control without application), which were applied in the lumbar area of musculus longissimus dorsi (loin) at various time intervals prior to the slaughter (14 d, 24 h, and 1 h). Animals were slaughtered and the meat quality was evaluated by determining of pH value (1, 3, and 24 h post slaughter), drip loss, colour, and lactic acid and phosphoric acid amounts. MIL therapy can be used in various fields of veterinary medicine as are surgery and orthopaedics, internal medicine, dentistry, pulmonology, gastroenterology, gynaecology, urology, nephrology, and dermatology. The results achieved showed that MIL radiation used in a short period before slaughter (1 h) can cause a change in the meat quality, as reflected by the non-standard development of pH values, increases in drip loss, and changes of meat colour.