Essential amino acids ratio

Table II. Essential Amino Acid Profiles (g/16g N) and Protein Efficiency Ratios of Various Protein Food Ingredients...

Walter et al. (38) measured the protein efficiency ratio (PER) of flour prepared from sweet potatoes which were cooked in a drying oven. Because the PER is determined on the basis of a diet containing 10% protein, the Jewel and Centennial sweet potatoes used in this study were stored until sufficient starch had metabolized to increase crude protein content to 11.25% (dry basis). When the flour was fed to Sprague-Dawley strain rats, the corrected PER values were 2.22 and 2.00 for Centennial and Jewel cultivars, respectively, compared to 2.50 for casein. Centennial had the highest PER value of the two cultivars because its NPN content was lower. The net effect of increased NPN content is to lower the amount of essential amino acids as a percentage of the total nitrogen and thus decrease the PER value. 

From amino acid compositions, evaluations o7" the nutritional potentials of cucurbit meals and globulins can be calculated according to FA0/WH0 (54). The A E ratios, which are the amounts of each essential amino acid relative to the total amount of essential amino acids, are shown in Table II. These data indicate that, like most other oilseeds, cucurbit seeds are deficient in lysine and sulfur-containing amino acids. However, sulfur-containing amino acids are considerably high in CitrullI us colocynthis (egusi, ancestral watermelon) seed protein and exceed the suggested level in FA0/WH0 reference protein (55). 

A protein that is unduT7 rich in the ten essential amino acids would not provide sufficient nitrogen for other metabolic processes without obligatory catabolism of the essential amino acids. Thus, the proportion of the total nitrogen intake that essential amino acids form indicate how a given protein fulfills nutritional requirements for proteins. This proportion, the E/T ratio (54), indicative of the amount of protein nitrogen supplied by essential amino acids, is (in g of essential amino acids per g of nitrogen)... 

The ratio of essential to non-essential amino acids is high in kwashiorkor but normal in marasmus. The cause of this may be low activities of the enzymes for metabolising the essential amino acids. These are required for any protein synthesis that must take place even in kwashiorkor. 

Protein hydrolysis in 6N HCl and subsequent analysis to determine amino acids (except tryptophan, which is acid labile) chemically present is a first step in protein quality evaluation. The chemical score and the EAA index represent attempts to use this information to chemically estimate nutritional quality of protein their obvious limitation is their disregard for amino acid availability. The chemical score is obtained by evaluating the percent of the limiting amino acid in comparison to that amino acid in whole egg protein ). The EAA index is the geometric mean of the ratios of each of the essential amino acids to those amino acids occurring in whole egg (4). 

Several essential amino acids have been shown to be the limiting factor of nutrition in plant proteins. In advanced countries, the ratio of vegetable proteins to animal proteins in foods is 1.4 1. In underdeveloped nations, the ratio is 3.5 1. which means that people in underdeveloped areas depend upon vegetable proteins. Among vegetable staple foods, wheat easily can be fortified. It is used as flour all over the world. L-Lysine hydrochloride (0,2% ) is added to the flour. Wheat bread fortified with lysine is used in several areas of the woilcl in Japan it is supplied as a school ration. 

TADLE 1. REPRESENTATIVE ESSENTIAL AMINO ACID PATTERNS A/E RATIO (MILLIGRAMS PER GRAM OF TOTAL ESSENTIAL AMINO ACIDS)... 

AIE Ratio equals ten times percentage of single essential amino acid to the total essential amino acids contained. 

A distribution of amino acids in dietary proteins can be obtained accordingly by taking both animal and plant proteins at a ratio of 1 3-4. Although plant proteins are lower cost, they are markedly deficient in some essential amino acids. Their protein efficiency is low without addition of deficient ammo acids. Enrichment of human and animal diets with free amino acids, such as lysine, methionine, threonine, and tryptophan, as a substitute for animal proteins, has proved successful. 

The limiting amino acid can be determined by taking the ratio of the amino acid present in the test protein and dividing it by the amount in the reference protein. The amino acid with the lowest ratio (test protein/reference) is the limiting amino acid. In this example, the single limiting amino acid is histidine (a dietary essential amino acid for young children). The lowest ratio is for the sum of phenylalanine and tyrosine. 

Proteins are either complete or incomplete. Complete protein simply means that it contains at least the minimal amounts of amino acids to sustain life. Which of course under lines the fact that a high protein "content" does not necessarily mean a high quality protein. It is the essential amino acid pattern and ratio that counts most. The essential amino acids are L-Leucine, L-Isoleucine, L-Valine, (These three are branch chain amino... 

The protein efficiency ratio (PER) of sesame seed protein is 1.86 (35). The PER value can be raised to 2.9 when sesame seed protein is supplemented with lysine (36). El-Adawy (37) added sesame products including sesame meal, sesame protein isolate, and protein concentrate to red wheat flour to produce flour blends. It was found that water absorption, development time, and dough weakening were increased as the protein level increased in all blends however, dough stability decreased. Sesame products could be added to wheat flour up to 16% protein without any detrimental effect on bread sensory properties. The addition of sesame products to red wheat flour increased the contents of protein, minerals, and total essential amino acids the in vitro protein digestibility also increased significantly. 

Although many vitamins may be administered as a single dose at various time intervals, many of the patient s requirements will be found in what is basically an emulsion formulation, prepared aseptically and thus with no terminal sterilization. The product usually contains both essential and non-essential amino acids rather than fully formed protein and energy is provided at a ratio of 0.6-1.1 MJ per gram of protein nitrogen. A mixture of carbohydrate (glucose) and fat (as an emulsion) provides the energy. Electrolytes, trace elements and vitamins are included as required. Thus the TPN fluid is... 

One of the substances commonly treated as a vitamin is niacin, which is synthesized from the essential amino acid tryptophan. The ratio is approximately 60 mg of tryptophan being required to produce 1 mg of niacin (1). This has led to niacin requirements being expressed as niacin equivalents (NE), based on the amount of tryptophan in the diet. It must be kept in mind that tryptophan is essential and is the precursor to the neurotransmitter serotonin in addition to being part of protein structure. Therefore, niacin can be thought of as tryptophan sparing. 

Kwashiorkor Decrease in essential amino acids and tyrosine more than nonessential Ratio of essential to unessential amino acids helpful in diagnosis even with subclinical levels of protein deficiency abnormal phenylalanine tolerance test... 

Uremic patients are often catabolic and exhibit a negative nitrogen balance that takes a greater protein intake to correct (K9), Moreover, amino acid losses during hemodialysis (K10) and albumin losses from peritoneal dialysis are not insignificant. There is a decrease in the body pool of albumin and other proteins (Z2). Several essential amino acids in the plasma are decreased, while some non-essential ones are increased. Tyrosineiphenylalanine and valine glycine ratios are decreased. A most common abnormality is an increase in hydroxyproline, citrul-line, and 1,3-methylhistidine. These abnormalities are corrected by hemodialysis (F14). 

The biological value of food proteins is greatly influenced by the ratio of their essential amino acids. Most food proteins, first of all plant proteins, are deficient in some essential amino acids. The limiting essential amino acid in legume and milk proteins is methionine, and in cereal proteins it is lysine. Beside the knowledge of the requirements of quality and composition of amino acids, it is equally important to know whether these amino acids can be best utilized as free amino acids, in the form of peptides or proteins. The following possibilities exist for improving the balance of essential amino acids in the proteins ... 

Choosing proteins with different amino acid contents for complementation by mixing in an appropriate ratio is a very difficult and not always available method. One of the main problems is, for instance, that methionine usually is one of the limiting essential amino acids in all proteins of nonanimal origin. 

The /trotein rfficiency ratio (PER) describes how weU a protein supplies essential amino acids. This parameter is useful for deciding how much of a food you need to eat. Most coUege-age, nonpregnant females require 46 g (or about 1.6 oz) of complete protein, and males require 58 g (or about 2 oz) of complete protein per day. If one chooses only a single source of protein for the... 

The protein efficiency ratio is an arbitrary measurement of the essential amino acid content of a given type of protein. 

Few foods supply proteins that contain all of the essential amino acids in the ratios that conform to the body s requirements. This is true regardless of how they are grown. The result is an inefficient use of the protein unless supplementary limiting amino acids are supplied, as is now being done. All of the essential amino acids must be supplied at the same time in order to realize maximum efficiency with respect to both growth and... 

The nutritional value of lupin is similar to that of soybean (Yanez et al., 1979). It contains essential amino acids (lysin, leucin, threonin) (Kanny et al., 2000), although the content of methionine is low and supplementation can increase the protein efficiency ratio (Yanez et al., 1983 Catricheo et al., 1989) (Table 22.2). 

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