Muscle glycogen level and meat quality in pigs of different halothane genotypes

The halothane genotype of 22 Polish landrace pigs was determined using halothane test and blood typing. Eight homozygous normal (NN), eight hetero-zygotes (Nn) and six homozygous recessive (nn) were identified. The levels of glycogen and lactate were measured in biopsy samples taken from the longissimus lumborum using a shot biopsy technique. pH (pH(1)) and IMP/ATP ratio (R) were determined at 30 min after slaughter, while pH, meat colour and water holding capacity were determined on the day after slaughter. The halothane genotype did not affect intra vitam glycogen level. The nn pigs had a higher R value and lower pH(1) than both Nn and NN animals. Heterozygous animals were intermediate between both homo-zygotes for biopsy lactate level and meat colour. The lactate content of biopsy samples was significantly correlated with pH(1) (r = -0·68; P < 0·01), R (r = 0·68; P < 0·01), meat colour (r = 0·57; P < 0·01) and water holding capacity (r = 0·45; P · 0·05).     

Muscle glycogen depletion pattern in halothane-gene-free pigs at slaughter and its relation to meat quality

Muscle fibre type composition and glycogen depletion pattern at slaughter as related to meat quality, were studied in M. longissimus dorsi of halothane-gene-free Swedish Yorkshire pigs fed a high (n=19; 10 entire males and 9 gilts) or a low (n=18; 10 entire males and 8 gilts) protein diet. The muscle consisted of, on average, 8% type I, 9% type IIA and 83% type IIB fibres. Muscle fibre areas were significantly smaller in entire male pigs than in gilts irrespective of fibre type. There were no marked differences in muscle characteristics between pigs fed the low and high protein diets. Low glycogen concentrations were found in most type I and type IIA muscle fibres, while a greater variation in glycogen content was evident in type IIB fibres. The pigs were divided into two groups according to the proportion of glycogen depleted IIB fibres (more or less than 30% depleted IIB fibres). In the group where 30% or more of the type IIB fibres were glycogen depleted, a tendency toward DFD meat (dry, firm, dark) was seen, as the meat had higher ultimate pH (5·62 vs 5·52; p=0·02), lower drip loss (2·7% vs 4·4%; p=0·007) and lower reflectance value (darker meat; 16·5 vs 20·6 EEL units; p=0·0005), compared with the group with less than 30% depleted IIB fibres. No difference in total glycogen content was found between these two groups. This indicates that the distribution of glycogen in different fibre types seems to be of importance for the ultimate meat quality.     

Muscle composition slightly affects in vitro digestion of aged and cooked meat: Identification of associated proteomic markers

Meat is an appropriate source of proteins and minerals for human nutrition. Technological treatments modify the physical–chemical properties of proteins, making them liable to decrease the nutritional potential of meat. To counteract this damage, antioxidants and chaperone proteins in muscle cells can prevent oxidation, restore the function of denatured proteins, and thus prevent aggregation. This study aimed to explore the impact of indoor vs outdoor-reared meat protein composition on digestion and to associate protein markers to in vitro digestion parameters. Indoor-reared meat tended to show less oxidation and denaturation than outdoor-reared meat and was characterised by an overexpression of contractile and chaperone proteins. Outdoor-reared meat showed amplification of antioxidant and detoxification metabolism defending against oxidised compounds. Impacts on digestion remained minor. Several protein markers of in vitro digestion parameters were found for aged and cooked meat, linked to the detoxification process and to muscle contraction.     

Determination of PAHs in various smoked meat products and different samples by enzyme immunoassay

An enzyme immunoassay was used to determine benzo[a ]pyrene (BaP) in smoked meat products and other samples of food and environmental origin. The method used has a detection limit (3 σ) of 0.1 μg kg⁻¹ and a coefficient of variation less than 10%. The main aim of the study was to compare the possible influence of different smoking processes and packaging material on the amount of BaP deposited on smoked meat product, mainly different sausages. The lowest amount of BaP was found when smoke produced by steam in the indirect method smoking‐chamber was used. A slightly protective effect of polyamide casing was noted. © 1999 Society of Chemical Industry     

生物酶制剂在肉类加工中的最新应用动态

阐述了我国肉类产品市场概况及肉类产品加工技术动态,介绍了生物酶制剂对肉制品的改善特性及其在肉制品加工中的应用。     

Comparison of various assays used for detection of beta-lactam antibiotics in poultry meat

In this study, microbiological tests for the detection of beta-lactam antibiotics in meat and meat products were evaluated. The traditional FPT (four plate test, containing Bacillus subtilis and Kocuria rhizophila), BsDA (Bacillus stearothermophilus disc assay) and a newly developed microbiological test, Premi®Test (containing Bacillus stearothermophilus) were included in the study. The limit of detection (LOD) of the Premi®Test was compared with the LOD of the traditional methods. The detection limits of the tests were determined by using beta-lactam antibiotic standards dissolved in meat juice, as well as meat tissue obtained from laying hens after experimental administration of amoxicillin. Positive samples, based on inhibition of growth of the organism in the test, were confirmed by high performance liquid chromatography (HPLC). Growth inhibition in the traditional tests is visible as a clear zone on the plate, whereas for Premi®Test, this is based on the absence of a colour change of the test. The LODs of antibiotics tested were as follows: Penicillin G (PENG) 5 µg kg^-1, amoxicillin (AMOX) 10 µg kg^-1, ampicillin (AMP) 25 µg kg^-1, oxacillin (OXA) 30 µg kg^-1, and cloxacillin (CLOX) 30 µg kg^-1 on the plate with Bacillus stearothermophilus. Beta-lactam antibiotics can be detected also on one plate seeded with Kocuria rhizophila, although the LODs are higher: PENG 10 µg kg^-1, AMOX 25 µg kg^-1, AMP 30 µg kg^-1, OXA 50 µg kg^-1, and CLOX 50 µg kg^-1. Premi®Test was performed according to the Standard Operating Procedure intended for detection of beta-lactam antibiotics in poultry tissues with following LODs: PENG 4 µg kg^-1, AMOX 5 µg kg^-1, AMP 5 µg kg^-1, OXA 40 µg kg^-1, CLOX 50 µg kg^-1. All tests are able to detect beta-lactam antibiotics such as penicillin G, ampicillin, amoxicillin, oxacillin and cloxacillin below the maximum residue level (MRL). However, the detection limits of the Premi®Test for PENG, AMOX and AMP were below the limits of BsDA and the plate containing Kocuria rhizophila.     

Evaluation of a fluid versus a powder pepsin formulation to detect Trichinella spiralis larvae in meat samples by a digestion technique

Pepsin powder constitutes a health risk, potentially causing severe allergic reactions to those handling the chemical. A fluid pepsin formulation was produced and tested, first in a preliminary study and then in a ring trial encompassing four European National Reference Laboratories (NRLs). The purpose of each trial was to ascertain and compare the action of pepsin powder with that of the pepsin fluid for digesting meat and liberating encapsulated Trichinella spiralis larvae for subsequent counting. The quality of digestion was furthermore evaluated by assessing the visibility through the digestion fluid and the amount of debris remaining after digestion. For the ring trial, at each laboratory 20 blinded replicate 100-g samples of pork meat containing a known number of encapsulated T. spiralis larvae (0 to 30) were digested by the magnetic stirrer method using either the standard pepsin powder (10 samples) or the pepsin fluid (10 samples). With an average recovery rate of 70 to 80%, all NRLs found the pepsin fluid and pepsin powder to be equally effective. The NRLs also found no difference between the two pepsin formulations with regard to debris remnants or visibility through the digestion fluid. The use of pepsin fluid may therefore constitute an improvement of the digestion procedure for the analysts involved.     

肉及肉制品碘含量检测新方法的验证

对即将实施的碘含量检测新方法进行验证分析,通过选取具有代表性的样本进行实验,研究了新方法对肉及肉制品检测结果准确性和精密度的影响.结果表明,与现有检测方法相比,新检测方法的准确性更好、精密度更高,更加适用于肉及肉制品中碘含量的测定.     

The application of additives and compounds to meat products

From the economic and perspective point of view the application of compounds and extenders in meat products represents an unavoidable world-wide development. The present study reviews additives and compounds for sausages and other comminuted meat products which have an influence on water binding and fat emulsifying. In the paper details and results of the patent publications published since 1960 are presented and discussed.     

Muscle fiber and fatty acid profiles of Mertolenga-PDO meat

The influence of phenotype and muscle type on intramuscular total lipids (ITL) neutral lipid (NL) and phospholipid (PL) compositions, cholesterol, α-tocopherol and haem iron contents were evaluated in Semitendinosus (St), Longissimus dorsi (Ld) and Supraspinatus (Ss) muscles from 39 Mertolenga young bulls. The results showed that lipid, α-tocopherol, cholesterol and haemic iron contents were not influenced by phenotype. Furthermore, the individual effect of phenotype was not a significant source of variation on ITL, NL and PL fatty acid composition. Muscle histological traits from Unicolor phenotype (n = 13) showed that Ss and Ld muscles exhibited higher proportion of type I (P < 0.001) and oxidative fibers (P < 0.001) and lower percentages of IIB fibers (P < 0.001) than St. The Ss muscle, with higher relative area occupied by oxidative fibers (P < 0.05–0.001) than Ld and St, had higher ITL (P < 0.001), NL (P < 0.001), PL (P < 0.05–0.01), α-tocopherol (P < 0.001), cholesterol (P < 0.01) and haem iron (P < 0.001) contents than its counterparts. Muscle type notably affected ITL, as a result of its influence on NL rather than in PL composition.     

Incidence of Listeria in Egyptian meat and dairy samples

A total of 180 food samples including meat (raw lean beef, frozen lean beef, and frozen chicken) and dairy products (raw milk, Zabady and Kareesh cheese) were analysed for Listeria. Isolates were differentiated using morphological, cultural, and biochemical tests and an API-Listeria kit. Zabady cheese was completely free of Listeria. The highest incidence rate (13.33%) was in frozen lean beef. Raw lean beef and milk products showed an incidence rate of 6.67%. The lowest incidence rate (3.33%) was in Kareesh cheese and frozen chicken meat samples. L. monocytogenes showed the lowest incidence rate (0.55%), isolated from one frozen lean beef sample. L. ivanovii and L. grayi showed the highest incidence rate (2.22%), isolated from 4 samples. L. innocua and L. seeligeri were positive in 3 samples (1.67%), and L. welshimeri in 2 samples (1.11%). L. monocytogenes and L. ivanovii were positive for virulence factors (hemolytic properties, and extracellular enzyme activities).     

Short communication: Gelatinization and enzymatic hydrolysis characteristics relevant to digestion and analysis of glycogen granules isolated from ruminal protozoa

Glycogen is an α-glucan produced by rumen microbes from various feed carbohydrates. It may be digested ruminally or intestinally to provide nutrients. The physicochemical and enzymatic hydrolysis characteristics of microbial glycogen have not been described in detail, but do influence its conversion to absorbable nutrients in vivo, its nutritional comparability with plant starch sources, and its accurate analysis in vitro. The objectives of this study were to determine presence or absence of a gelatinization response and to describe enzymatic digestion characteristics of glycogen granules isolated from ruminal protozoa obtained from lactating dairy cows. Protozoal glycogen granules were determined to be 98.3% α-glucan. Granules displayed gelatinization, the breaking of hydrogen bonds between molecules or branches, at 65°C compared with purified wheat and corn starches, which initiated gelatinization at 50 and 65°C, respectively. Digestion of ungelatinized samples with amyloglucosidase for 2 h at 39°C showed approximately 3-fold greater hydrolysis to glucose for protozoal glycogen (25.2% of dry matter; DM) than for wheat (9.9% of DM) or corn (8.2% of DM) starches. Based on enzymatic digestion results, protozoal glycogen may be more readily digested than intact corn or wheat starches and should be gelatinized or the hydrogen bonds otherwise disrupted to allow more complete recovery in enzymatic analysis.     

Muscle and meat quality characteristics of Holstein and Salers cull cows

Muscle characteristics and sensory rating of meat were determined in M. longissimus thoracis (LT), M. semimembranosus (SM), M. semitendinosus (ST) and M. triceps brachii (TB) from seven Holstein (HO, dairy breed) and six Salers (SA, beef breed) cull cows slaughtered at 6–7 years of age at the same fat score. Significant differences (P < 0.001) among muscle types were observed: ST was the more glycolytic and TB the more oxidative; total collagen: ST > SM = TB > LT; initial and overall tenderness: LT > TB = SM > ST, juiciness: TB > LT = SM > ST. Flavour differed only between breeds: HO > SA (P < 0.01). Three tenderness classes (high, intermediate, low) were determined from scores for sensory overall tenderness for all 52 meats: the lower total and insoluble collagen contents, the more oxidative metabolism, the more tender was the meat. Muscle type, and not breed explained most of the variability of meat quality from dairy and beef cull cows slaughtered at the same age and fat score.     

酵母精在热加工肉类香精中的应用

随着食品工业的发展和我国人民生活水平不断提高,传统的拌合型肉类香精因其香味单薄,口感较差,已逐渐被肉香味逼真,口感醇厚、鲜美的热加工香精所替代.     

老汤精粉在食品工业中的应用

综述了老汤的形成、加工方法、特点、调味机理及在食品工业中的应用、展望了其应用前景。     

浓厚味肉类提取物的开发与应用

综述了一种天然调味料一浓厚味肉类提取物的研究开发进展,主要从国内外肉类提取物的研发动态、肉类风味料的制备及产品特点、浓厚味肉类提取物的呈味特性、深厚味肉类提取物在食品中的应用等方面进行探讨,旨在让更多的国内企业了解和使用肉类提取物,提升食品的品质.     

乳化型肉产品的理论和实际应用

本文介绍了乳化型香肠的制作工艺、流程等基本情况。     

TBHQ在广式腊肉中的应用研究

以过氧化值和酸价为指标,研究了TBHQ在广式腊肉中的应用效果。结果表明,TBHQ具有较好的抗氧化性能,能有效抑制腊肉中过氧化值的升高,但对酸价的抑制作用不大。     

中式肉制品在军用食品中应用探讨

论述了中式肉制品在军用食品中应用的必要性,分析了中式肉制品在军用食品中应用的可行性,并针对其主要影响因素,探讨了中式肉制品在军用食品中应用的具体途径.     

Human IgE binding and in vitro digestion of S-OVA

S-OVA, a more thermostable form of ovalbumin (OVA), was formed from native OVA or egg white in vitro, by heating at high pH, and by storage at low temperatures. S-OVA showed a much lower reactivity against IgE than OVA, although this difference in IgE binding was minimized after simulated gastro intestinal digestion, despite S-OVA was more resistant to proteolysis, particularly to pepsin, than its native form. It is, therefore, likely that the transformation of OVA to S-OVA does not affect its ability to sensitise or trigger allergic reactions at the duodenal level. These results are discussed in the light of the described conformational changes reported to occur in the transition between OVA and S-OVA.