Shelf-life of vacuum-packaged wild boar meat in relation to that of vacuum-packaged pork: Relevance of intrinsic factors

In order to study the factors influencing the relatively poor keepability of pork compared with beef, a study with wild boar meat was carried out. Microbiological and sensory quality traits of vacuum-stored wild boar (Sus scrofa scrofa) cuts of M. longissimus dorsi (longissimus) at 0°C were determined after 1, 10, 28, 42, 56, 70, 84 and 98 days and of tenderloins after 3, 35, 49 and 63 days. The amount of glycogen, glucose and glucose-6-phosphate in the longissimus cuts was measured during storage, in order to study the processes that determine shelf-life. Tenderloins developed off-odours after 35 days, probably due to Enterobacteriaceae growth. Unacceptable discolouration of longissimus cuts and off-odour development were noticed after 84-98 days. Shelf-life comparison between wild boar meat and pork stored under similar conditions indicates that the relatively poor keepability of pork is due to intrinsic factors. Glucose depletion is probably triggering the onset of spoilage processes.     

基于电阻抗谱的猪、牛肉新鲜度快速无损评价

为了对肉品的新鲜度进行快速无损评价,研究一种基于电阻抗谱的肉品新鲜度评价方法,采用环形表面电极对4种肉品进行测定,对获得的电阻抗谱进行方差分析。结果表明：相位参数可以用于肉品新鲜度评价;对4 种肉品进行新鲜度分类实验,猪里脊肉的分类整体准确率为91.1%,猪五花肉为86.7%,牛里脊肉为88.9%,牛腩为87.8%;肉品在发生明显腐败之后,电阻抗谱的4 个参数突然变大,导致电阻抗谱与肉品新鲜度之间的线性关系消失。     

Reduction in pH and Fermentation Time of Meat Mixtures Containing Dry Acid Whey

The effect of various concentrations of dry acid whey on the pH of ground beef and pork and on fermentation activity of 11 commercial starter cultures added to a beef summer sausage formulation was determined. For every 1% (w/w) addition of dry acid (pH 4.0) whey, a reduction in meat pH of 0.11–0.13 resulted, independent of meat species, initial pH or fat content. Use of 3.5% (w/w) dry acid whey in conjunction with 1% dextrose resulted in a l–2 hr reduction in the time required for the summer sausage mixture to reach pH 5.0 compared to a mixture without whey. Dry acid whey as a direct acidulant in fermented sausages could result in a savings of time and energy in manufacturing.     

In Vitro Zinc Protoporphyrin IX Formation in Different Meat Sources Related to Potentially Important Intrinsic Parameters

For several years, researchers have studied the formation of zinc protoporphyrin IX in meat, as it is considered to be an important natural colouring agent in dry cured or fermented meat products in the absence of nitrite and/ or nitrate. Until now, however, mainly pork meat is used for these investigations. The goal of this research was to relate in vitro zinc protoporphyrin IX and protoporphyrin IX formation in eight meat sources (chicken, turkey, pork, lamb, beef, veal, horse and porcine liver) to eight intrinsic parameters using partial least squares regression (PLS) analysis. Significant differences in pH, initial metmyoglobin formation, metmyoglobin reduction ability, total heme, zinc chelatase activity, and total iron and zinc concentration between meat sources were found. Water activity, however, was not significantly different between meat sources. Liver tissue and horse meat showed the best ability to form zinc protoporphyrin IX. Formation of protoporphyrin IX was limited in all meat sources. PLS analysis revealed that mainly zinc chelatase activity, followed by total heme, total iron and zinc content, were predominant intrinsic parameters to explain variations in zinc protoporphyrin IX formation. These findings could be important for meat industry in order to establish the production of red coloured nitrite-free meat products.     

The rate of metmyoglobin formation in beef, pork, and turkey meat as influenced by pH, sodium chloride, and sodium tripolyphosphate

This study investigated the effects of pH (5·5 to 7·0), sodium chloride concentration (0·0-3·0%), and sodium tripolyphosphate concentration (0·0 and 0·5%) on the rate of metmyoglobin formation in ground beef, pork and turkey meat during refrigerated storage. Increasing the sodium chloride concentration produced a progressive increase in the rate of metmyoglobin formation in ground beef. Increasing the pH between pH 5·5 and 6·5 had no effect on the rate of metmyoglobin formation with ground beef and turkey meat, but produced a marked decrease between pH 6·5 and 7·0. In contrast pH had no consistent effect on the rate of metmyoglobin formation of ground pork and the rate of formation remained low at all pH levels. When ground beef contained 0·5% sodium tripolyphosphate, the effect of pH was reversed and the rate of metmyoglobin formation was lowest at pH 5·5, increased as the pH increased to 6·5 and then plateaued.     

Characterization and evaluation of the spoilage potential of Lactococcus piscium isolates from modified atmosphere packaged meat

A total of 222 psychrotrophic lactococci isolated from use-by day, modified atmosphere packaged (MAP) meat were identified to the species level by numerical analyses of EcoRI and ClaI ribopatterns and phylogenetic sequence analyses of 16S, rpoA and pheS genes. In addition, their meat spoilage potential was studied. The majority of the isolates (n=215) were identified as Lactococcus piscium, while seven isolates belonged to Lactococcus raffinolactis. L. piscium was shown to be adapted to growing in a variety of MAP meat products including broiler, turkey, pork, and minced meat from beef and pork, where they belonged to the predominating microbiota at the end of the storage. Numerical analyses of EcoRI and ClaI ribopatterns, and phylogenetic sequence analyses of rpoA and pheS genes were shown to be reliable tools in species level identification of meat lactococci. The spoilage potential of L. piscium was evaluated by inoculating representative isolates to MAP pork stored at 6 °C for 22 days. Development of spoilage population was monitored using a culture-independent T-RFLP approach. The sensory shelf life of pork inoculated with L. piscium was shortened compared to the uninoculated control. Alongside with the inoculated L. piscium isolates, Leuconostoc spp. present as initial contaminants in the samples thrived. This shows that even though lactococci were inoculated at higher levels compared to the natural microbiota, they did not occupy the niche and prevent the growth of other lactic acid bacteria.     

The relationship of bacterial numbers and types to diamine concentration in fresh and aerobically stored beef, pork and lamb

Bacterial numbers and putrescine and cadaverine concentrations were measured in intact beef, pork and lamb and minced beef at retail and during aerobic chill storage at 5°C. Putrescine concentrations increased consistently with 'total' aerobic viable count (TAVC) but cadaverine concentrations increased only when high numbers of presumptive Enterobacteriaceae were present. Significant changes in diamine concentration did not occur until the TAVC exceeded 4.2 × 10⁷/cm² or g when the meat was clearly spoiled. Changes prior to the onset of spoilage were not sufficient for their use as a predictive indicator of the acceptability of the meat.     

The effect of simulated transport of fresh meats on their water-holding capacity as assessed by various methods

This study was designed to establish the effects of transport vibrations on the water-holding capacity of fresh non-stimulated veal and pork and electrically- and non-stimulated beef. Furthermore, drip production was followed during storage by various methods which were compared for their suitability in industrial practice and scientific research. During storage, the amount of drip increased, whilst the rate of drip formation decreased. Filter paper wetness measured at 1 day post mortem was positively correlated with drip lost over a period of 2 weeks of refrigerated storage in poly-ethylene bags (method 1) and poly-propylene containers (method 2). This suggests that the filter paper wetness test may be useful to predict drip loss of stored meat. Simulated transport did not result in higher drip losses, although a significant increase in filter paper wetness from the fresh cut surface of veal and pork was found, suggesting that transport affects the initial rate of drip production, but not the total amount of drip. In beef, transport simulation resulted in an increase in filter paper wetness from the surface of electrically-stimulated meat, stored for 1 or 2 weeks, indicating that fluid loss was elevated due to transport vibrations. However, this effect seemed to be related to the intrinsic water-holding capacity of the sample: meat with a low intrinsic water-holding capacity seemed to be more sensitive to transport vibrations than meat with a high intrinsic water-holding capacity.     

Palatability and Appearance Traits of Beef/Pork Meat Patties

Eight beef/pork ground meat blends were made from mature (cows or sows) and youthful (steers or barrow) beef and/or pork lean. Blends were stored at — 27°C for either 14 or 150 days. Storage time decreased overall desirability scores of blends made with 20% pork fat and 80% youthful beef lean. No differences were found for flavor or overall desirability scores within the 14-day storage treatment. The consumer panel did not detect differences among treatments for source of fat or species. Results indicated beef/pork patties containing 40–80% mature lean and a minimum of 10% beef fat were equal to all-beef controls (100% beef patty) for visual and palatability traits.     

Content of heterocyclic amines and polycyclic aromatic hydrocarbons in pork,beef and chicken barbecued at home by Danish consumers

It is a well-known fact that, when meat is barbecued, several harmful components, including heterocyclic amines (HCA) and polycyclic aromatic hydrocarbons (PAH), may be formed. The aim of this study was to determine the HCA and PAH content in meat (pork, chicken and beef) when barbecued at home by Danish consumers according to their normal practice. With regard to HCA, beef contained the highest concentrations of 9H-pyrido[3,4-b]indole (norharman) and 2-methyl-β-carboline (harman), while chicken contained more 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) than pork and beef. The analysis of PAH showed a markedly higher concentration of PAH in beef compared with pork and chicken. In general, a correlation between the HCA content and the surface colour of the meat was found, the darker the colour the higher the HCA concentrations.