Compounds in meat

A Posyniak, S Semeniuk, J Niedzielska, J Zmudzki. Solid-phase extraction and liquid-chromatography analysis of nitrofuran compounds in meat. Chem Anal (Warsaw) 39 289-294, 1994. 

It thus seemed that the origin of the various components in meat volatiles could best be established by analyzing irradiation-induced compounds in meat protein and meat fat separately. Accordingly, a 500-gram sample of meat, the same size of sample normally used in irradiation studies of whole meat, was separated into a protein, a lipid, and a lipoprotein fraction by means of a methanol-chloroform extraction of the fat. The dry, air-free, fractions were then irradiated separately with 6 megarads of gamma radiation in the manner used for whole meat. The analytical results (Table V) show clearly that mainly sulfur compounds and aromatic hydrocarbons are formed in the protein fraction, whereas mainly aliphatic hydrocarbons are formed from the lipid. The lipoprotein fraction produced, as expected, both aliphatic hydrocarbons and sulfur compounds. Only the lipoprotein fraction had a characteristic irradiation odor. 

Probably the most important reactant in the formation of volatile meat flavor compounds is hydrogen sulfide. It can be formed by several pathways during meat cookery, but one mechanism is Strecker degradation of cysteine in the presence of a diketone as established by Kobayashi and Fujimaki (29). The cysteine condenses with the diketone and the product in turn decarboxylates to amino carbonyl compounds that can be degraded to hydrogen sulfide, ammonia and acetaldehyde. These become very reactive volatiles for the formation of many flavor compounds in meat and other foods. 

The identification of these types of compounds in meat flavor remains a major challenge to the flavor chemist with sophisticated modern analytical tools. 

Recently, a heat-labile compound in meat extract which decreases the heat stability of soybean trypsin inhibitors was reported (53). It is tempting to speculate that this is some type of protein-disulfide reductase, but further work is needed on this point... 

Development of immunoassays for residue analysis of small molecules has been well documented in the literature (8-9. 141 and by the articles in this volume. Recently, Dreher and Podratzki (101 reported the development of an immunoassay for endosulfan and its metabolites using a rabbit polyclonal antiserum. This assay however, did not readily detect other related cyclodiene insecticides. We report here the development of a monoclonal antibody that detectes all nine of the cyclodiene insecticides tested plus toxaphene, and the incorporation of this antibody to an immunoassay for detecting these compounds in meat, fish, and dairy products at, or below, the tolerance levels. 

Meat is traditionally regarded as a good source of protein and B vitamins. Apart from the phospholipids lecithin, cephalin and sphingomyelin, which make a major contribution to the total lipid content, the remaining P compounds in meat are individually present in quantities of less than 0.1%. These compounds include creatine phosphate (CP), inosinic acid, B group vitamins. 

Juszkiewicz, T. Posyniak, A. Semenjuk, S. Niedzielska, J. Determination of 5-nitrofuran compounds in meat by high-performance thin layer and liquid chromatography. Residues Vet Drugs Food Proc. EuroResidues Conf. 1993, 2, 401 03. 

Sulfur-containing flavor compounds in meat can be categorized into aliphatic, thiamines, thiazoles, and all others. Model studies have shown that cysteine reacts to produce thiazoles that have some meaty odors (15). However,... 

The development of new chemicals for the protection of fats from oxidative changes has progressed at a very rapid rate during the past decade. Hilditch (1944) has reviewed some of the British work on stabilization of dried foods, including meats, with antioxidants. Lundberg (1947) made a survey of the antioxidants proposed for use in foods at that time and Riemenschneider (1947) reviewed briefly the activity of antioxidants of interest to cereal chemists. Unfortunately, there does not seem to be a recent comprehensive review of the subject. Space limitations will not permit more than a brief r6sum4 here, directed particularly at the possible usefulness of these compounds in meat. 

Flores M, Olivares A, Dryahina K, et al. Real time detection of aroma compounds in meat and meat products by SIFT-MS and comparison to conventional techniques (SPME-GC-... 

Budin, J.T., C. Milo, G.A. Reineccius, Perceivable odorants in fresh and heated sweet cream butters, m Food Flavors and Chemistry, Spanier, H., F. Shahidi, T.H. Parliment, C. Mussinan, C.-T. Ho, E. Contis, Eds., Royal Society of Chem., Lxtndon, 2001, p. 85. Meynier, A., D.S. Mottram, Volatile compounds in meat-related model systems Investigation on the effect of lipid compounds on the MaiUard reaction between cysteine and ribose, in Progress in Flavour Precursor Studies, P. Schreier, P. n-terhalter, Eds., Allured Publ., Carol Stream, 1993, p. 383. 

Figure 3 Comparison of inosine 5 -monophosphate (IMP) and related compounds in meat from two beef breeds fed on grass.

Whereas there is much information on the volatile composition of cooked meat and the relative importance of different compounds in meat aroma, very Httle is known about the relationship between these compounds and their flavor precursors. Trace amounts of sugars, sugar phosphate, and ribonucleotides are important for the formation of meaty aroma. These precursors appear to be variable in concentration in meat, and this could lead to variation in the sensory quahty of meat. A major challenge for future research in meat flavor is to relate such changes in precursors to sensory quality and the formation of aroma volatiles. 

Table 6 Character Impact Flavor Compounds in Meats and Fish...

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