Impact of protein composition for predictable food quality (Betydning av proteinsammensetning for forutsigbar råvarekvalitet)

The main objective of the program was to achieve a more predictable quality of meat and wheat. Protein composition and functionality have great impact on their raw material quality, and are greately determined by genetic and environmental factors. However, the underlying molecular mechanisms are largely unknown. Our first objective was to improve our molecular understanding of tenderness and muscle growth in cattle. Through analysis of proteins, muscle structure and gene expression, we have found that animal gender (beef, steers, heifer), feeding (pasture, concentrates) and genetics (breeding) have an impact on meat quality, both in terms of intramuscular fat, tenderness and protein composition. We have established a new method for proteome analysis (LC-MS/MS) that can identify and quantify around 1,000 different proteins in muscle, which we have used to examine protein changes in meat resulting from different genetics, feeding and storage, and samples from in vitro muscle cell experiments. We have also tried, but not succeeded, to verify protein markers for tenderness in new animal material. This is likely due to the fact that tenderness is a complex quality parameter, in which genetics, environment and processing can have major impacts. The connective tissue can affect eating quality of meat, and we have now shown that it can also be important for muscle growth. Blocking the function of a connective tissue component in mice resulted in smaller muscle fibers and thus decreased muscle mass and body weight. In addition, we have found that vitamin K2 also has a positive effect on muscle growth. We have expanded our in vitro cell model system for bovine muscle cells to produce differentiated cells that can grow in 3D, providing a small step towards working with a muscle tissue in culture. Our second objective was to produce knowledge that can be used to improve eating quality of different beef muscles. We have detected variation between different muscles in structure, protein degradation and stability of connective tissue components, which may explain why some muscles are tender while others remain tough. Proteome analysis have shown that proteins involved in anchoring the muscle and connective tissue together is different in varying muscles. These proteins are important for the development of normal muscle fiber size and can affect tenderness. In addition, the level of proteases that break down connective tissue and muscle fibers differ among muscles, and we found differences in connective tissue proteins and glycoproteins previously shown to affect meat eating quality. We have shown that enzymes from kiwi fruit can be used to tenderize tough muscles. The enzymes are very effective, and we have examined how to optimize and control the tenderization process using these enzymes, which is necessary before recommendations can be given to industry. In addition, we have found that beef can be an important source of vitamin K2 in the Norwegian diet, which may reduce consumers' health concerns about eating beef. Our third objective was to obtain a better molecular understanding of baking quality of wheat, and in particular how gluten quality is affected by factors related to growth environments. Variation in quality due to environmental factors has been prominent in Norwegian wheat, and are challenging for the industry. A high degree of polymerization of gluten proteins will normally provide strong gluten and good baking quality. Results from field trials have shown that gluten quality can be weaker in cool seasons in Norway, while our experiments in climate chambers showed that low temperature alone did not result in poor quality. Our new hypothesis points towards an interaction between temperature, precipitation and pathogenic fungi. Frequent rain after yellow ripening can affect polymerization and cause impaired gluten quality. Fungi that infect the grains can produce gluten-degrading proteases. We have performed extensive characterization of gluten protein samples infected with F. graminearum. The results have shown that the build-up of gluten polymers is inhibited in Fusarium-infected samples, and they contain proteases that can degrade gluten. This can result in significantly weakened baking quality, and can be a major contributing factor to variation in gluten quality of Norwegian wheat. We have developed methods to identify proteases using proteome analysis, and some specific proteases from F. graminearum have been identified. Extensive studies of how various gluten proteins are synthesized and built up to large polymeric proteins during grain development have also been done. Through this program, we have identified several factors that may affect gluten quality and cause undesirable variations in baking quality. After some more testing, this will provide grounds to suggest new measures in the supply chain to achieve good and stable baking quality of Norwegian wheat.

The objective of this program is to obtain a more predictable quality of meat and wheat. This will be achieved through expanded knowledge of the molecular mechanisms underlying the accumulation and composition of proteins. Although being very different f oods, proteins are the major component determining meat and wheat quality. Common for both of these raw materials is that quality and functionality of the protein component is determined to a large extent by genetics and environmental factors. Combining t hese raw materials in the same research program thus make efficient use of methodologies and advanced instrumentation that is beneficial for both food groups. Understanding the molecular mechanisms for muscle growth and physiology are necessary to obtain an optimal meat production. Multiple factors, such as animal background (e.g. genetics, gender, feeding), muscle composition and post mortem storage are known to influence meat quality, however the molecular mechanisms are not fully understood. In this p rogram we will focus on several aspects of tenderisation and meat quality. First we will study markers of tenderness at the protein level. Second, we will use cell model systems to study muscle growth related to feeding and nutrition and last we will stud y the impact of connective tissue and extracellular matrix for eating quality of beef. Good and stable gluten quality of Norwegian wheat is of overall importance for the milling and baking industry. Wheat sorted as food, based on Falling Number, has show n large variation in gluten protein quality. More research is required to reveal the biological mechanisms and to identify the weather conditions causing the gluten protein degradation and loss of gluten protein polymerisation. The present project will fo cus on phenomena linked to gluten protein synthesis and their polymerisation in the desiccation phase and degradation of gluten proteins, and how these are affected by variable weather conditions.