Levels of nitrate, nitrite and nitrosamines in model sausages during heat treatment and in vitro digestion - The impact of adding nitrite and spinach (Spinacia oleracea L.).

Nitrite derivatives react with endogenous precursors forming N-nitrosamines associated with development of colorectal cancer. The present study aims to investigate the formation of N-nitrosamines in sausage during processing and in vitro gastrointestinal digestion after adding sodium nitrite and/or spinach emulsion. The INFOGEST digestion protocol was used to simulate the oral, gastric, and small intestinal phases of digestion, and sodium nitrite was added in the oral phase to mimic the input of nitrite from saliva as it has shown to affect the endogenous formation of N-nitrosamines. The results show that the addition of spinach emulsion, in spite of it being a source of nitrate, did not affect the nitrite content in either batter, sausage, or roasted sausage. The levels of N-nitrosamines increased with the added amount of sodium nitrite, and further formation of some volatile N-nitrosamines was observed during roasting and in vitro digestion. In general, N-nitrosamine levels in the intestinal phase followed the same trend as in the undigested products. The results further indicate that nitrite present in saliva may cause a significant increase in N-nitrosamine levels in the gastrointestinal tract and that bioactive components in spinach may protect against the formation of volatile N-nitrosamines both during roasting and digestion.

Meat consumption and consumer attitudes - A Norwegian perspective.

Norway has lower meat consumption than other North European countries. Meat is acknowledged as important for food security in Norway, as Norway's agricultural possibilities are best suited for free-ranging and self-foraging animals. Meat has a strong position in the Norwegian diet, particularly as a centrepiece for special occasions. Good taste, product variety, and affordable price make meat a convenient choice. Norwegian consumers are not worried about animal welfare in local production, nor highly driven by environmental motives for reducing their consumption. Meat analogues have a very small market share, and taste and processing level do not make it a primary replacement for meat reducers. Still, Norwegian consumers' attitudes towards meat have become more diverse in later years. More consumer segments display meat-reducing behaviours citing both health and sustainability reasons. Females are particularly interested in reducing meat consumption, young age and urban lifestyle are other characteristics of meat reducing segments.

In-Line Estimation of Fat Marbling in Whole Beef Striploins (Longissimus lumborum) by NIR Hyperspectral Imaging. A Closer Look at the Role of Myoglobin.

Fat marbling, the amount, and distribution of intramuscular fat, is an important quality trait for beef loin (Longissimus lumborum) and is closely connected to sensory properties such as tenderness, juiciness, and flavor. For meat producers, it would be of value to grade and sort whole loins according to marbling on the production line. The main goal of this study was to evaluate high-speed NIR hyperspectral imaging in interaction mode (760-1047 nm) for in-line measurement of sensory assessed marbling in both intact loins and loin slices. The NIR system was calibrated based on 28 whole striploins and 412 slices. Marbling scores were assessed for all slices on a scale from 1 to 9 by a trained sensory panel. The calibrated NIR system was tested for in-line measurements on 30 loins and 60 slices at a commercial meat producer. Satisfactory accuracy for prediction of marbling was obtained by partial least squares regression for both slices and whole loins (R2 = 0.81 & 0.82, RMSEP = 0.95 & 0.88, respectively). The concentration of myoglobin in the meat and its state of oxygenation has a strong impact on the NIR spectra and can give deviations in the estimated marbling scores. This must be carefully considered in industrial implementation.

Vitamin K2 improves proliferation and migration of bovine skeletal muscle cells in vitro.

Skeletal muscle function is highly dependent on the ability to regenerate, however, during ageing or disease, the proliferative capacity is reduced, leading to loss of muscle function. We have previously demonstrated the presence of vitamin K2 in bovine skeletal muscles, but whether vitamin K has a role in muscle regulation and function is unknown. In this study, we used primary bovine skeletal muscle cells, cultured in monolayers in vitro, to assess a potential effect of vitamin K2 (MK-4) during myogenesis of muscle cells. Cell viability experiments demonstrate that the amount of ATP produced by the cells was unchanged when MK-4 was added, indicating viable cells. Cytotoxicity analysis show that MK-4 reduced the lactate dehydrogenase (LDH) released into the media, suggesting that MK-4 was beneficial to the muscle cells. Cell migration, proliferation and differentiation was characterised after MK-4 incubation using wound scratch analysis, immunocytochemistry and real-time PCR analysis. Adding MK-4 to the cells led to an increased muscle proliferation, increased gene expression of the myogenic transcription factor myod as well as increased cell migration. In addition, we observed a reduction in the fusion index and relative gene expression of muscle differentiation markers, with fewer complex myotubes formed in MK-4 stimulated cells compared to control cells, indicating that the MK-4 plays a significant role during the early phases of muscle proliferation. Likewise, we see the same pattern for the relative gene expression of collagen 1A, showing increased gene expression in proliferating cells, and reduced expression in differentiating cells. Our results also suggest that MK-4 incubation affect low density lipoprotein receptor-related protein 1 (LRP1) and the low-density lipoprotein receptor (LDLR) with a peak in gene expression after 45 min of MK-4 incubation. Altogether, our experiments show that MK-4 has a positive effect on muscle cell migration and proliferation, which are two important steps during early myogenesis.

Can postmortem proteolysis explain tenderness differences in various bovine muscles?

This study investigated the relationship between postmortem proteolysis, muscle pH decline, sarcomere length (SL), intramuscular fat (IMF) and Warner-Bratzler shear force (WBSF) in four bovine muscles (biceps femoris (BF), infraspinatus (IS), longissimus lumborum (LL), psoas major (PM). The WBSF was low in BF, IS and PM, while LL had a higher value (P<0.001), but still considered as tender. The PM had fastest pH decline (P<0.001), ultimate pH was lowest in LL and PM and highest for IS (P<0.001), sarcomeres were longest for PM and shortest for BF and LL (P<0.001), while IS and PM had more IMF than BF and LL (P=0.038). Troponin T degradation was similar in all muscles after 2d postmortem, however after 13d LL had more degradation than IS (P=0.003). The MMP-2 activity increased during storage (P=0.001), while IS had less activity than the other muscles (P=0.022). Although the variation in proteolytic activity could not explain the variation in WBSF, the study provides useful knowledge for the meat industry for optimising processing and storage procedures for different beef muscles.

Formation of Malondialdehyde, 4-Hydroxynonenal, and 4-Hydroxyhexenal during in Vitro Digestion of Cooked Beef, Pork, Chicken, and Salmon.

Red meat high in heme iron may promote the formation of potentially genotoxic aldehydes during lipid peroxidation in the gastrointestinal tract. In this study, the formation of malondialdehyde (MDA) equivalents measured by the thiobarbituric acid reactive substances (TBARS) method was determined during in vitro digestion of cooked red meat (beef and pork), as well as white meat (chicken) and fish (salmon), whereas analysis of 4-hydroxyhexenal (HHE) and 4-hydroxynonenal (HNE) was performed during in vitro digestion of cooked beef and salmon. Comparing products with similar fat contents indicated that the amount of unsaturated fat and not total iron content was the dominating factor influencing the formation of aldehydes. It was also shown that increasing fat content in beef products caused increasing concentrations of MDA equivalents. The highest levels, however, were found in minced beef with added fish oil high in unsaturated fat. This study indicates that when ingested alone, red meat products low in unsaturated fat and low in total fat content contribute to relatively low levels of potentially genotoxic aldehydes in the gastrointestinal tract.

Vitamin K2 in different bovine muscles and breeds.

Meat is a natural source of vitamin K, a vitamin associated with reduced bone loss and prevention of osteoporosis. Whether vitamin K content varies between breeds and muscles in cattle is not known. In the present study, contents of vitamin K1 (phylloquinone) and K2 (menaquinone, MK) were analysed in three different muscles from steers of two different breeds, Norwegian Red and Jersey, respectively. Results showed that MK4 was the most dominant of the vitamin K2 analogues, while only traces were found of MK6 and MK7. Both breeds had higher levels of MK4 in M. biceps femoris (BF) and M. longissimus dorsi (LD) compared to M. psoas major (PM). The results also showed significantly higher MK4 levels in muscles from Jersey compared to Norwegian Red. Furthermore, MK4 was not associated with intramuscular fat, suggesting a physiological role for MK4 in skeletal muscle cells. There were no association between vitamin K content and tenderness.

Modelling of beef sensory quality for a better prediction of palatability.

Despite efforts by the industry to control the eating quality of beef, there remains a high level of variability in palatability, which is one reason for consumer dissatisfaction. In Europe, there is still no reliable on-line tool to predict beef quality and deliver consistent quality beef to consumers. Beef quality traits depend in part on the physical and chemical properties of the muscles. The determination of these properties (known as muscle profiling) will allow for more informed decisions to be made in the selection of individual muscles for the production of value-added products. Therefore, scientists and professional partners of the ProSafeBeef project have brought together all the data they have accumulated over 20 years. The resulting BIF-Beef (Integrated and Functional Biology of Beef) data warehouse contains available data of animal growth, carcass composition, muscle tissue characteristics and beef quality traits. This database is useful to determine the most important muscle characteristics associated with a high tenderness, a high flavour or generally a high quality. Another more consumer driven modelling tool was developed in Australia: the Meat Standards Australia (MSA) grading scheme that predicts beef quality for each individual muscle×specific cooking method combination using various information on the corresponding animals and post-slaughter processing factors. This system has also the potential to detect variability in quality within muscles. The MSA system proved to be effective in predicting beef palatability not only in Australia but also in many other countries. The results of the work conducted in Europe within the ProSafeBeef project indicate that it would be possible to manage a grading system in Europe similar to the MSA system. The combination of the different modelling approaches (namely muscle biochemistry and a MSA-like meat grading system adapted to the European market) is a promising area of research to improve the prediction of beef quality. In both approaches, the volume of data available not only provides statistically sound correlations between various factors and beef quality traits but also a better understanding of the variability of beef quality according to various criteria (breed, age, sex, pH, marbling etc.).

Chicken meat nutritional value when feeding red palm oil, palm oil or rendered animal fat in combinations with linseed oil, rapeseed oil and two levels of selenium.

Chicken meat nutritional value with regard to fatty acid composition and selenium content depends on the choice of dietary oil and selenium level used in the chickens' feed. The objective of this study was to investigate the effect of replacing commonly used rendered animal fat as a dietary source of saturated fatty acids and soybean oil as a source of unsaturated fatty acids, with palm oil and red palm oil in combinations with rapeseed oil, linseed oil and two levels of selenium enriched yeast on chicken breast meat nutritional value. The study also wished to see whether red palm oil had a cholesterol lowering effect on chicken plasma.204 male, newly hatched broiler chickens were randomly divided into twelve dietary treatment groups, and individually fed one out of six dietary fat combinations combined with either low (0.1 mg Se /kg feed) or high (1 mg Se/kg feed) dietary selenium levels. Linseed oil, independent of accompanying dietary fat source, lead to increased levels of the n-3 EPA, DPA and DHA and reduced levels of the n-6 arachidonic acid (AA). The ratio between AA/EPA was reduced from 19/1 in the soybean oil dietary groups to 1.7/1 in the linseed oil dietary groups. Dietary red palm oil reduced total chicken plasma cholesterol levels. There were no differences between the dietary groups with regard to measured meat antioxidant capacity or sensory evaluation. Chicken meat selenium levels were clearly influenced by dietary selenium levels, but were not influenced by feed fatty acid composition. High dietary selenium level lead to marginally increased n-3 EPA and higher meat fat % in breast muscle but did not influence the other LC PUFA levels. Chicken breast meat nutritional value from the soybean oil and low selenium dietary groups may be regarded as less beneficial compared to the breast meat from the linseed oil and high selenium dietary groups. Replacing rendered animal fat with palm oil and red palm oil had no negative effects on chicken muscle nutritional value with regard to fatty acid composition. Red palm oil decreased total chicken plasma cholesterol, confirming the cholesterol reducing effect of this dietary oil.

The effect of technology information on consumer expectations and liking of beef.

European consumers increasingly attach value to process characteristics of food. Although beef technologies are hardly communicated to consumers, providing consumer-oriented information about technology application might increase perceived transparency and consumer acceptance. This study investigates how information about beef technologies influences consumer expectations and liking of beef. Beef consumers in Belgium (n = 108) and Norway (n = 110) participated in an information experiment combined with sensory testing in which each consumer tasted three beef muscles treated with different technologies: unprocessed tenderloin M. Psoas major, muscle profiled M. Infraspinatus, and marinated (by injection) M. Semitendinosus. The findings indicate that detailed information about beef technologies can enhance consumers' expectations and liking of beef. However, this effect differs between countries and beef technologies. Information becomes either less relevant when the product is actually tasted, as indicated by the findings in Norway, or more relevant when information is confirmed by own experience during tasting, as indicated by the findings in Belgium.

Classification of different bovine muscles according to sensory characteristics and Warner Bratzler shear force.

The aim was to examine how well different beef muscles from Norwegian Red bulls respond to the consumer needs. Ten carcasses were slaughtered at a commercial abbatoir, chilled at 4°C for 48h, and 10 muscles excised. After ageing for 9days at 4°C, the muscles were subjected to sensory and chemical analyses and classified according to these analyses in 4 quality groups. The results regarding the comparative quality of the muscles were similar to results from other studies on predominantly steers. M. infraspinatus showed superior tenderness, juiciness and colour properties and was the only muscle to be consistent in tenderness with 80% of the samples in the highest sensory quality class. Also M. triceps brachii and M. semimembranosus adductor were reasonably tender and consistent in tenderness. As compared with the studies on steers, the M. biceps femoris and M. vastus lateralis seemed to be less tender in bulls. Results regarding sensory colour intensity, juiciness and taste showed similar findings. The pattern of association between the muscles in this study was highly irregular as the relative muscle quality varied widely, which means that using M. longissimus dorsi as a quality indicator of all muscles in the carcass is questionable.