Beef protein composition

EFFECT OF POSTMORTEM AGING ON BEEF PROTEIN COMPOSITION ... 

The flavor enhancer monosodium glutamate (MSG) is currently used in virtually every type of savory prepared-food. Unfortunately, MSG has several deleterious side effects on a large proportion of the population. Fortunately, a naturally occurring peptide isolated from a muscle food (beef) can serve not only as a potential replacement for MSG but also as a nutritional adjuvant. The peptide, called BMP or beefy meaty peptide, acts as a flavor enhancer and is found to occur naturally in beef Chapter 6). Research on BMP suggest that it is not only non-allergenic but, by virtue of its protein composition, is a nutritionally sound replacement for MSG. 

The changes in the protein composition and flavor of "cooked" and "cooked- -stored" beef seemed to be related to degradation by free radical species induced during lipid oxidation 1-10, 16, 22, 23), Based on the information presented in the aforementioned publication, it seemed reasonable to suggest that the appearance of "bitter" and "sour" tastes and the disappearance of "meaty" and "beefy" flavors were a result of the activity of the free radicals derived from lipid oxidation on flavor proteins (2, 24-28),... 

Food-derived anticarcinogens, conjugated dienoic derivatives of linoleic acid, 262-270 Food quality health concerns, 5-6 maintenance by natural and synthetic compounds, 56-76 molecular s proaches to study, 1-6 related to antimicrobial peptides, 303-318 Foodbome pathogens, ionizing radiation, 296-298 Free radical(s) beef flavor peptides, 89-91 oxidation generating system, 88-89,91/ protein composition, 88-89,91/... 

In a number of methods, isolation of the nucleoprotein complex (stage 2) is avoided. In the isolation of ribonucleic acid from beef pancreas,1241 nuclear material and cell debris are removed from a normal-saline extract of the minced tissue, which is then brought to half-saturation with sodium chloride (to dissociate the protein from the nucleic acid). After removal of the protein, the nucleic acid is precipitated with alcohol. However, the suggestion has been made126 that it is more satisfactory to isolate the nucleoprotein first, and this has been carried out, for instance, in the extraction of the ribonucleic acid from fowl sarcoma GRCH 15.126 Nucleoprotein complexes have also been isolated from baker s yeast127 and have been separated into various fractions, the nucleic acids from which differ slightly in composition. In addition, nucleoproteins have been isolated by complex formation with cetyltrimethylammonium bromide.128... 

Table V shows the composition of the liquid meals for this study. As in the previous study, two levels each of cottage cheese and beef were fed to the subjects. In addition, 45 g of protein from soy isolate was also fed. The phytic acid content of this meal was 126 mg. A basal diet containing all nutrients except protein was also included in this study. It was necessary to reduce the fat content of the basal diet for palatability the total energy for this meal only was 250 kcal. In this study, the calcium and phosphorus levels of each meal were equalized across all levels and sources of protein. Levels of other meal components were maintained as constant as possible and are shown at the bottom of Table V.

An evaluation of the composition of the cooking juices, as presented in Table IV, demonstrates, by difference, that fat is retained to a greater extent by the soy concentrate meat product than by the soy flour meat product or the ground beef. The meat product containing soy flour lost more fat during cooking than did the all-beef (Table IV). Similar results were reported by Anderson and Lind ( ). When soy protein concentrates are used in canned meat products like chili, the fat islands within the chopped meat products and the fat cap are eliminated (10). When 4% soy concentrate was added to a minced pork product, cook out of fat and moisture was reduced 31% for pasteurized product and 34% for sterilized product. 

Figure 9. The effect of storage on protein and peptide composition in cooked ground beef stored in a refrigerator of 4 days (adapted from 7). Upper graph represents the size exclusion chromatography of acidic extracts of fresh, cooked, and cooked-stored beef. Lx)wer graph represents the reverse phase HPLC of peak II from the size exclusion chromatography.

Apart from differences between muscle tissues from various parts of an animal, there are qualitative and quantitative differences in composition between animal species. Therefore, analytical methods will always have lo be tested on material from each individual species, since differences in fat composition, in the presence of species-specific proteins, and in colored components such as in the case of myoglobin in poultry and beef may influence both the extraction and the separation of the analytes. As an example, a recovery higher than 70% was obtained for furazolidone after spiking chicken and veal calf muscle tissue but only 10% after spiking pork tissue (16). In this study, the recovery from pork meat could markedly be improved by addition to the aqueous exfraction solvent of about 25% acetonitrile, an observation indicating binding of furazolidone to pork-specific proteins. 

The general composition of the complex in all systems studied so far is also universal they always contain two h-type cytochromes, one cytochrome of c type and a high potential Fe-S protein (the Rieske protein, so called after its discoverer in Complex III of the respiratory chain of beef heart mitochondria). In addition to these functions in electron transfer, the h/cj complexes also play a role in energy transduction, since they represent an essential part of the proton translocating apparatus of photosynthetic electron transfer chains. 

Approximately 95% of total lipids of LD from bovine heart are constituted by TAG. The amount of protein present in these LD is about 5% of total mass, and the amount of phospholipids varies from 3 to 7% of total lipid. The major phospholipids forming the monolayer of these LD are phosphatidylcholine (ca. 50%) and phosphatidylethanolamine (30-40%). The NEFA content is very low. The chemical composition of LD in beef heart with their high TAG content and the rather small amount of phospholipids resembles the composition of chylomicrons. A striking difference, however, is the lack of cholesterol and cholesteryles-ters in LD from beef heart whereas these lipid species occur at approximately 1-2% of total lipid in chylomicrons. Furthermore, the protein content of LD is two to three times higher than of chylomicrons. In contrast to bovine heart LD, those of stellate cells from the rat liver consist of retinylesters, TAG, free cholesterol and a small amount of phospholipids [142]. A general characteristic of LD regardless of the cell type appears to be the content of approximately 5% phospholipids of the total mass (reviewed in Ref. [143]). 

DiCorleto and Zilversmit (1977) reported that the phospholipid exchange proteins from either beef heart or beef liver were not able to catalyze the exchange of phosphatidylcholine between phosphatidylcholine multi-lamellar vesicles and small unilamellar vesicles. However, by adding acidic phospholipids to the multilamellar vesicles, protein-enhanced exchange was observed. This assay is versatile and can be easily performed. Both substrates are well-defined particles in which the composition can be readily manipulated. The separation of acceptor and donor membranes by centrifugation is rapid and nearly complete with 98—99% of the multilamellar vesicles being sedimented and with 90% of the small unilamellar vesicles remaining in the supernatant. 

That the radiolysis of meats containing similar proteins and comparable fatty acids involves similar primary and secondary processes leading to a common set of radicals stable at -40°C is shown by the ESR spectra in Figure 12 for irradiated, enzyme-inactivated chicken, beef, ham, and pork [3, 62], These spectra reflect the commonality in radicals derived from the muscle proteins, myosin and actin, and fi-om the constituent triglycerides, which have slightly different fatty acid compositions. The minor consequences of this compositional... 

In recent years several attempts have been made to isolate some of the translocator proteins. Major progress has been achieved with the purification of the adenine nucleotide translocator. This protein has been isolated in its native form and its molecular weight and immunological properties have been characterised [57,104]. The carrier protein from beef heart and rat liver is a dimer. The of each of the subunits is 30000. In heart, the carrier protein makes up 10% of the total mitochondrial protein. The amino acid composition of the yeast protein has been determined recently [105]. 

Mills, E.W., Comerford, J.W., Hollender, C., Harpster, H.W., House, B. and Henning, W.R. (1992). Meat composition and palatability of Holstein and beef steers as influenced by forage type and protein source. Journal of Animal Science, 70, 2446-2451. 

The composition of beef tallow is modified by diet. Dietary fat can be encapsulated in protein hardened with formaldehyde in order to protect the fat from the microflora in the rumen (see milk). Unsaturated fats fed in this way produce more unsaturated depot fats and milk fat (Garrett et aL, 1976). 

Whenever the calculated biological value was compared to experimental determinations of the biological value, the two values were found to be extremely close. Such mathematical formulas are limited by the fact that the proteins are not all digested at equal rates. This difficulty has been overcome by estimating the amino acid composition not directly after total hydrolysis of the protein, but on the product of peptic and tryptic digestion of the protein. Such experiments have revealed that whereas the amino acids of the proteins contained in roast beef or wheat or peanut flour are readily available, the amino acids of cotton seed flour are not [27]. 

---