Bjørg Egelandsdal

Liquid Loss as Effected by Post mortem Ultrastructural Changes in Fish Muscle: Cod (Gadus morhua L and Salmon Salmo salar

This study was performed in order to assess the effect of early post mortem structural changes in the muscle upon the liquid-holding capacity of wild cod, net-pen-fed cod (fed cod) and farmed salmon. The liquid-holding capacity was measured by a low speed centrifugation test. Transmission electron microscopy was used to discover ultrastructural changes both in the connective tissue and in the myofibrils. Differential scanning calorimetric thermograms of the muscle proteins were recorded to elucidate whether fundamental differences did exist between the proteins of the raw material tested. Multivariate statistics were used to explicate the main tendencies of variations in the thermograms. The salmon muscle possessed much better liquid-holding properties than the cod muscle, and wild cod better than fed cod regardless of the storage time. Both fed cod and farmed salmon, underwent the most severe structural alterations, probably caused by the low muscle pH values. The higher liquid-holding capacity of the salmon muscle was related to species specific structural features and better stability of the muscle proteins. The myofibrils of the salmon muscle were denser and intra- and extracellular spaces were filled by fat and a granulated material. The differences in thermograms of muscle from wild and fed cod were largely explained by the variations in pH. The severe liquid loss of fed cod is due to a low pH induced denaturation and shrinkage of the myofibrils. Post mortem degradation of the endomysial layer and the sarcolemma may have further facilitated the release of liquid.

The role of red and processed meat in colorectal cancer development: a perspective

This paper is based on a workshop held in Oslo, Norway in November 2013, in which experts discussed how to reach consensus on the healthiness of red and processed meat. Recent nutritional recommendations include reducing intake of red and processed meat to reduce cancer risk, in particular colorectal cancer (CRC). Epidemiological and mechanistic data on associations between red and processed meat intake and CRC are inconsistent and underlying mechanisms are unclear. There is a need for further studies on differences between white and red meat, between processed and whole red meat and between different types of processed meats, as potential health risks may not be the same for all products. Better biomarkers of meat intake and of cancer occurrence and updated food composition databases are required for future studies. Modifying meat composition via animal feeding and breeding, improving meat processing by alternative methods such as adding phytochemicals and improving our diets in general are strategies that need to be followed up.

Myosins from red and white bovine muscles: Part 1—Gel strength (elasticity) and water-holding capacity of heat-induced gels

Abstract Myosins were isolated from bovine M. masseter (red) and M. cutaneus trunci (white) and characterized in terms of solubility, electrophoretic pattern and susceptibility to tryptic digestion. Dynamic rheological measurements showed that white myosin is generally the superior gel former: gel strength, expressed as storage modulus, is consistently higher (a) at all temperatures above the gel-inducing minimum, (b) in both 0·2 m and 0·6 m NaCl, (c) at all concentrations investigated (≤ 20 mg/ml) and (d) at pH ≥ 5·8. In 0·6 m NaCl at pH m NaCl lost about 15% liquid on centrifugation; gels in 0·6 m NaCl displayed an inverse relationship between storage modulus and loss of liquid. The gel strength and water-holding capacity of gels made from mixtures of red and white myosin were a linear function of mixture proportions in the case of 0·2 m NaCl; 0·6 m NaCl gave gels with unpredictable properties.

Slow lowering of pH induces gel formation of myosin

Abstract It has been found that solutions of myosin (10 mg/ml) form gels at 5°C if the pH is decreased slowly, by dialysis, to a value in the region of 2.5 to 5.5. Gel strength displays strong dependence on final pH, having a maximum at about pH 4.5. Salt (KCl) concentration was found to affect gel strength positively and linearly. Differential scanning calorimetry revealed that the myosin of pH-induced gels absorbed no thermal energy when heated, implicating acid-induced denaturation as the basis of gel formation. By comparison with heat-induced gelation of myosin and from the fact that low pH is conducive to filament formation, it is suggested that filaments may also be involved in the gelation process.

Revealing Covariance Structures in Fourier Transform Infrared and Raman Microspectroscopy Spectra: A Study on Pork Muscle Fiber Tissue Subjected to Different Processing Parameters

The aim of this study was to investigate the correlation patterns between Fourier transform infrared (FT-IR) and Raman microspectroscopic data obtained from pork muscle tissue, which helped to improve the interpretation and band assignment of the observed spectral features. The pork muscle tissue was subjected to different processing factors, including aging, salting, and heat treatment, in order to induce the necessary degree of variation of the spectra. For comparing the information gained from the two spectroscopic techniques with respect to the experimental design, multiblock principal component analysis (MPCA) was utilized for data analysis. The results showed that both FT-IR and Raman spectra were mostly affected by heat treatment, followed by the variation in salt content. Furthermore, it could be observed that IR amide I, II, and III band components appear to be effected to a different degree by brine-salting and heating. FT-IR bands assigned to specific protein secondary structures could be related to different Raman C–C stretching bands. The Raman C–C skeletal stretching bands at 1031, 1061, and 1081 cm−1 are related to the IR bands indicative of aggregated β-structures, while the Raman bands at 901 cm−1 and 934 cm−1 showed a strong correlation with IR bands assigned to α-helical structures. At the same time, the IR band at 1610 cm−1, which formerly was assigned to tyrosine in spectra originating from pork muscle, did not show a correlation to the strong tyrosine doublet at 827 and 852 cm−1 found in Raman spectra, leading to the conclusion that the IR band at 1610 cm−1 found in pork muscle tissue is not originating from tyrosine.

Marinating as a technology to shift sensory thresholds in ready-to-eat entire male pork meat

This study investigated the effect of marinades in improving the eating quality in ready-to-eat boar meat. Neck chops with fat content below 18.9%, skatole ⩽1.1ppm (range 0.03-1.1) and androstenone ⩽5.6ppm (range 0.01-5.6) were used. In a screening experiment different marinades were tested for their ability to mask boar taint (defined as manure and urine odour and flavour). Liquid smoke and oregano extracts appeared to have the best potential for masking, and were studied in detail. Results from the study indicated that marinated chops with skatole content of approximately 0.4ppm appeared similar to castrates in boar taint. Chops with skatole contents above 0.7ppm remained unmasked despite the use of strongly flavoured marinades. Unmarinated chops served at 60°C were more tainted than those served at 15°C, but scored lower for boar taint when reheated, although the concentrations of androstenone and skatole remained the same. The fat content of the chops was not well correlated to the perception of boar taint. The attributes manure and urine were correlated with the level of skatole, but urine attribute was not a good indicator of the androstenone level.

Validation of the EUROP system for lamb classification in Norway; repeatability and accuracy of visual assessment and prediction of lamb carcass composition.

The EUROP classification system is based on visual assessment of carcass conformation and fatness. The first objective was to test the EUROP classification repeatability and accuracy of the national senior assessors of the system in Norway. The second objective was to test the accuracy of the trained and certified abattoir EUROP classifiers in Norway relative to EU Commissions supervising assessors. The third and final objective was to test the accuracy of the EUROP classification system, as assessed by the National senior assessors, for prediction of lean meat, fat and bone percentage and lean meat in relation to bone ratio. The results showed that the repeatability and accuracy of the national senior assessors was good, achieving high correlations both for conformation and fatness. For the abattoir assessors, there were some systematic differences compared to EU Commissions assessors, but these differences were within limits accepted by EU Commission. The relationship between abattoir and national senior assessors was good, with only small systematic differences. This may suggest that there also is a systematic difference between the national senior assessors of the system and EU Commissions assessors. The EUROP system predicted lean meat percentage poorly (R(2)=0.407), with a prediction error for 3.027% lean. For fat and bone percentage, the results showed a fairly good prediction of fat percentage, but poorer for bone percentage, R(2)=0.796 and R(2)=0.450, respectively. The prediction error for fat and bone percentage was 2.300% and 2.125%, respectively. Lean: bone ratio was predicted poorly (R(2)=0.212), with a prediction error of 0.363 lean: bone ratio.

Quality characteristics and composition of the longissimus muscle in the short-loin from male and female farmed red deer in New Zealand

Meat quality and composition characteristics are reported for the longissimus muscle from 10 red deer stags and 10 hinds aged about 20 months. All animals were pasture-finished but the stags and hinds came from different farms. The average carcass weight was 3.4 kg greater for the stag group (55.8 vs 52.4 kg; P=0.04), but measures of GR as a measure of fatness were similar and intramuscular fat content was significantly greater for the hind group (1.12% vs 0.63%; P<0.0001), as expected. The tenderness of cooked venison in terms of shear force and compression measures was significantly better for venison from the hind group, possibly due to the greater amount of intramuscular fat and slightly longer sarcomeres. The gender groups did not differ in absolute measures of colour or in the rate at which it deteriorated on display. However, the rate of colour deterioration was more rapid than other meats such as beef, as has been demonstrated elsewhere. The average ultimate pH and water-holding capacity were similar for the two groups. Venison from hinds contained more coenzyme Q(10), taurine, anserine, carnosine, and vitamin E. Group differences in fatty acid composition of intramuscular fat appeared to be mainly due to levels of fatness, which was greater for the hind group.

Determination of C22:5 and C22:6 marine fatty acids in pork fat with Fourier transform mid-infrared spectroscopy

Fatty acids in samples (n=74) of pork adipose tissue were measured with a Fourier transform mid-infrared (FT-MIR) spectrometer and by gas chromatography. The measured absorption spectra provided information to estimate partial least squares regression models for fatty acid groups, the iodine value and several fatty acids. The iodine values were predicted with correlation coefficient R=0.996 and root mean square error of cross-validation RMSECV=0.658. The sum of the two marine fatty acids of main interest, C22:5n3+C22:6n3, were predicted with R=0.982 and RMSECV=0.062. The K nearest neighbours procedure successfully classified the samples in three classes, depending on their proportions of marine fatty acids. Application of fat and absorption measurements were rapid, requiring less than 5 min of labour per sample. The results reported in this paper demonstrate that FT-MIR measurements can serve as a rapid method to determine marine fatty acids in pork fat.

Genetic Variation of an Odorant Receptor OR7D4 and Sensory Perception of Cooked Meat Containing Androstenone

Although odour perception impacts food preferences, the effect of genotypic variation of odorant receptors (ORs) on the sensory perception of food is unclear. Human OR7D4 responds to androstenone, and genotypic variation in OR7D4 predicts variation in the perception of androstenone. Since androstenone is naturally present in meat derived from male pigs, we asked whether OR7D4 genotype correlates with either the ability to detect androstenone or the evaluation of cooked pork tainted with varying levels of androstenone within the naturally-occurring range. Consistent with previous findings, subjects with two copies of the functional OR7D4 RT variant were more sensitive to androstenone than subjects carrying a non-functional OR7D4 WM variant. When pork containing varying levels of androstenone was cooked and tested by sniffing and tasting, subjects with two copies of the RT variant tended to rate the androstenone-containing meat as less favourable than subjects carrying the WM variant. Our data is consistent with the idea that OR7D4 genotype predicts the sensory perception of meat containing androstenone and that genetic variation in an odorant receptor can alter food preferences.