Organic amino acid content

Oily fishmeal is allowed in organic rations and it has an even higher essential amino acid content than full-fat soya. However, its use in poultry rations is limited partly by cost, restrictions on the source of the fishmeal imposed by organic standards, the fact that some customers demand birds that are fed on a vegetable-based diet and concerns about fishy taints to the product (Walker and Gordon, 2001). 

FAO, "Amino Acid Content of Foods and Biol. Data on Protein, "U.N. Food and Agriculture Organization, Rome, 1970. 

Food and Agriculture Organization of the United Nations. Food Policy and Food Science Service Nutrition Division. 1970. Amino acid content of foods and biological data on proteins. FAO Nutritional Studies No. 24, Rome. 

All tissues contain free amino acids and a much larger fraction of bound (i.e. protein) amino acids. In cestodes, the free amino acid pool ranges from 100-400 mg/100 g fresh weight. Table 6.4 illustrates the qualitative differences that have been reported for the amino acids of some hymenolepidid cestodes (79). In general, however, there is no major departure in the amino acid content of cestodes from that of other organisms. 

Proteins are large polypeptides with molecular weights ranging from a few thousand into the millions. They contain 16% N on the average. Because some 20 amino acids are present in most proteins and there is no limitation to the size and amount of each amino acid a protein may contain, the number and types of proteins found in nature are almost limitless. Each protein has certain physical and chemical properties that are uniquely suited to its role in the living organism. The properties a protein may exhibit are ultimately a result of its amino acid content. Amino acid side chains determine whether the protein is water soluble, whether it is acidic or basic, and the shape it assumes. It is thus extremely important to study the amino acid content and sequences in proteins, as well as to ascertain their shapes and sizes. To exhibit a specific biologic property, a protein must not only contain the correct amino acid sequence but it must also have the appropriate size and shape. 

Portal circulation carries amino acids to the liver, and the general circulation then distributes them throughout the organism. The amino acid content of plasma depends on the dietary state of the individual. After a meal, the free amino acid concentration in plasma increases by about 200-250% compared with that seen... 

In vitro protein digestibility of seaweed proteins is influenced by the species, seasonal period, and content of antinutritional factors such as phenolic and polysaccharides (Fleurence, 1999a Mabeau and Heurence, 1993). Activity of proteolytic enzymes may be reduced due to the reaction of amino acids with oxidized phenolic compound (Wong and Cheimg, 2001). Differences between the prediction of protein quality (based on amino acid content/amino acid requirement ratios) and the actual protein quality (based on the performance in living organisms) seem to be a reason of variations in the utilization of the amino acids comprised in different proteins. 

The nutritive value of a protein depends on its capacity to provide nitrogen and amino acids in adequate amounts to meet the requirements of an organism. Thus, in theory the most logical approach for evaluating protein quality is to compare amino acid content (taking bioavailability into account) of a food with human amino acid requirements. A number of comparisons have been made using reference patterns such as those derived from egg and milk protein. The first major change in procedure was substitution of a provisional pattern of amino acid requirements for the egg protein standard. 

The factors regulating the production of acids are unknown. Different yeast strains produce different amounts, and vitamin deficiencies increase the excretion of some organic acids e.g. thiamine deficiency leads to increased pyruvate levels. Many oxo-acids are produced as the result of amino acid metabolism (see below) therefore, the wort amino acid content is important. 

The presence of organic acid substituents in exopolysaccharides increases the lipophilidty of the molecule. In addition, for some exopolysaccharides with relatively high organic acid contents, their interaction with cations and with other polysaccharides may be influenced. Several amino adds have also been found in bacterial exopolysaccharides, including serine and L-glutamic add (Figure 7.1). 

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