Vitamin B12

Vitamin B12 is a water-soluble vitamin and a family of compounds called cobalamins which includes cyanocobalamin, hydroxocobalamin, and the two coenzyme forms 5'-deoxyadenosyl-cobalamin (adenosylcobalamin) and methylcobalamin. Cyanocobalamin and hydroxocobalamin are used in most dietary supplements, and are converted into adenosylcobalamin and methylco-balamin in the body. Vitamin B12 found in nature appears to be from microbial synthesis. Meats and meat products, especially liver and kidney,...

Enumeration and Confirmation of Staphylococcus aureus

Figure 34.7 shows the conventional enumeration method of Staphylococcus spp. (based on Ref. 82). The method has a detection limit > 100 cfu g. If staphylococci lesser than 100 cfu g are expected, then the procedure followed for L. monocytogenes enumeration may be applied. Low numbers of St. aureus are of little significance because extensive growth is needed to produce sufficient amounts of enterotoxin to cause illness therefore, an enrichment step is not required for the isolation of the...

Mass Spectrometry

An alternative technique to separate and identify peptides is high-performance liquid chromato-graphy (HPLC) coupled with MS. A schematic workflow of a typical LC-MS experiment is shown in Figure 5.3. HPLC includes ion-exchange (IEX), size-exclusion (SEC), hydrophobic hydrophilic-interaction (HIC HILIC), and reversed-phase chromatography (RPC). Several comprehensive systems combining two, three, or more chromatography steps coupled with MS for protein identification have been developed. For a...

References

Bredahl, L., Cue utilization and quality perception with regard to branded beef, Food Qual. Prefer., 15, 65, 2003. 2. Bernu s, A., Olaizola, A. and Corcoran, K., Extrinsic attributes of red meat as indicators of quality in Europe an application for market segmentation, Food Qual. Prefer., 14, 265, 2003. 3. Grunert, K.G., What's in a steak A cross-cultural study on the quality perception of beef, Food Qual. Prefer, 8(3), 157, 1997. 4. Oude Ophuis, P.A.M. and Van Trijp, H.C.M., Perceived quality...

Vip Fitness Food

1 toluidine blue, 1 lugol, 1 red oil, Figure 19.4 Diagram of a confocal laser scanning microscope (CLSM). single point (or an array of points), which is scanned to produce a complete image (Figure 19.4). Another major advantage of CLSM is the exclusion of out-of-focus blur, since the fluorescence emissions from the illuminated regions of the sample above and below the focal plane are not allowed to reach the photomultiplier and form an image. The development of electron microscopy (EM) has...

The Calpain System 621 Introduction

Calpains are calcium-activated proteinases with an optimum activity at neutral pH. In mammalian skeletal muscle, the calpain system consists of at least three proteinases -calpain, m-calpain, and calpain 3, also referred to as skeletal muscle-specific calpain, or p94, and an inhibitor of and m-calpain, calpastatin. Both and m-calpain are composed of two subunits with molecular weights of 28 and 80 kDa.19-22 An important characteristic of and m-calpain is that they undergo autolysis in the...

Composition of Meat 2021 Carcass

The accurate, objective prediction of carcass composition is an issue of great interest to livestock producers and retailers (Table 20.1). Because of the pricing system for marketing swine, fat and lean composition is determined on the live animal. Ultrasonic techniques have been applied to both live pigs and carcasses and provide the basis for a uniform grading system for swine before and after slaughter. Ultrasound instruments are commercially available. However, predicted lean meat yield can...

Dumas Method

Laboratory Painting

Another method for determining nitrogen content of organic materials was developed by Jean-Baptiste Dumas, a French chemist. He found that nitrogen could be analyzed by first combusting the material at high heat in the presence of oxygen and subsequently measuring the volume of gaseous nitrogen released. Although his method was originally described in 1833, the results were somewhat variable and the Kjeldahl method proved to be much more reliable. In recent years, the Dumas combustion method...

Triacylglycerol Structure

Relative to the other lipid classes, the structure of triacylycerols is relatively simple. Triacylglycerols consist of a glycerol (i.e., three-carbon alcohol) backbone containing three fatty acids in ester linkage. The glycerol, primarily, is derived from glycerol-3-phosphate, which in turn is produced by the metabolism of glucose or, in liver, by the phosphorylation of free glycerol catalyzed by glycerokinase. In adipose tissue and intestinal mucosal cells, 2-monoacylglycerol (produced by the...

Factors Affecting the Sensory Quality of Meat

Several factors can affect the sensory properties of meat, such as type of meat, genetic factors, production and rearing conditions, effect of postmortem practices, product preparation, and ingredients and warmed-over flavor (WOF). Some of them are detailed in the following sections. There has been a strong trend in the last decades for most industries to expand their horizons and compete at a global level. Therefore, research must be conducted with a global perspective, which means that the...

Influence of Postmortem Processing on Meat Microstructure

Different microscopy techniques have been used to characterize meats and to analyze the changes in muscle tissue that take place under different postmortem storage or cooking conditions. Some authors 7,8 have observed the microstructure of rabbit semimembranosus muscles by LM. They found that the muscle tissue of the dead animal presented a type of structure in which the myo-fibrils were perfectly packed and the intercellular connections of the connective tissue remained unchanged as the...

Binaglia Palm

Igene, J.O., Role of triglycerides and phospholipids on development of rancidity in model meat systems during frozen storage, Food Chem., 5, 263, 1980. 2. Pikul, J., Leszczynski, D.E. and Kummerow, F.A., Relative role of phospholipids, triacylglycerols and cholesterol esters on malonaldehyde formation in fat extracted from chicken meat, J. Food Sci., 49, 704, 1984. 3. Erickson, M.C., Lipid oxidation of muscle foods, in Food Lipids. Chemistry, Nutrition, and Biotechnology, Akoh, C.C. and Min,...

Sample Preparations and Treatments of Muscle Foods

One of the most important steps for successful microbiological analysis of any material is sample preparation. Without proper sampling procedures the data obtained will have limited meaning and usefulness. With the advancement of microbiological techniques and miniaturization of kits and test systems to even smaller sizes, proper sample preparation becomes critical. Statistic sampling plans for various foods for microbiological analysis is beyond the scope of this review. Sample preparation...

Sharp and Blunt Blades

Bourne7 suggested that using a flat-edge blade would simplify interpretation of time-force curves from WBS determinations. Several researchers70-74 have investigated the possibility of using a flat-edge blade instead of the traditional V-notched Warner-Bratzler blade. Overall, it was determined that the V-shaped blade cutout resulted in lower shear values74 compared to the flat blade for beef longissimus and semitendinosus muscles. Sharp and blunt blades and needles have been evaluated73,75 for...

Direct Detection Methods

Trichinella Muscle

In official meat inspection, only direct methods of detecting Trichinella larvae are used. Samples are taken as described in legislation Commission regulation EC No. 2075 2005 5 , in EU countries . Sample sites are set according to the vulnerability of muscles of each animal species. If the predilection muscles of the animal are not known, diaphragm or tongue should be used. Sample size also varies depending on the animal species. Samples are taken at the slaughter line with a knife or with...

Instrumentation and Biomass Measurements of Microbes

As the field of rapid methods and automation develops, the boundaries between instrumentation and diagnostic tests will merge. As mentioned in the miniaturization and diagnostic kit section, instrumentation is now playing an important function in diagnostic kit systems and the trend will continue. The following discussions are mainly on instrumentation related to signal measurements of microbial growth in muscle foods and other materials. Instruments can be used to monitor changes in a...

Riboflavin Vitamin B2

Riboflavin, known as vitamin B2, is a water-soluble vitamin naturally found in foods. Riboflavin acts as an integral component of two coenzymes flavin adenine dinucleotide FAD and flavin mononucleotide FMN . Riboflavin occurs naturally in foods as free riboflavin and as the protein-bound coenzymes, FAD and FMN. Organ meats liver, kidney, and heart are considered rich sources of riboflavin. Riboflavin is stable to heat, acidic conditions, and oxidation if light is excluded. Riboflavin is...

Other Texture Measurement Systems

Over the years, a number of devices have been developed for objectively measuring meat texture, and many have been reviewed6,8,23,36-42 extensively. Szczesniak and Torgeson6 reviewed about 20 texture devices covering shearing, penetration, biting, compression, and grinding. Many texture devices never gained the popularity of WBS or were deemed not acceptable due to low correlation to WBS measurements. Among these are the Christel Texturometer,43,44 KT device,45 Dassow's shear-jaw device,41 the...

Confirmation of Listeria monocytogenes

L. monocytogenes presence can be confirmed by various biochemical tests. The tests are performed on purified cultures. From the PALCAM or Oxford agars, five suspected and randomly selected colonies are isolated and streaked on tryptone soya agar, containing 0.6 yeast extract TSYEA . Listeria species are easily identified by Gram staining, motility, catalase, and oxidase reaction. Listeria spp. is gram-positive, small rod-shaped, motile, catalase-positive, and oxidase-negative. Motility test...

Vitamin C

Vitamin C is a water-soluble vitamin and occurs in two forms, the reduced ascorbic acid and the oxidized dehydro ascorbic acid. Ascorbic acid is reversibly oxidized to dehydro ascorbic acid. Further oxidations convert dehydroascorbic acid into the inactive and irreversible compound dike-toglutamic acid. There are two enantiomeric pairs, L- and D-ascorbic acid and L- and D-isoascorbic acid. L-Ascorbic acid and D-isoascorbic acid known as D-araboascorbic acid and erythobic acid have the...

Changes in Fish Postmortem

The pH fall postmortem in fish is usually small and ends at 6.3-6.5, a full pH unit higher than in meat.16 Owing to this higher ultimate pH value, spoilage starts early and a number of degradation products, especially of proteins and fat, appear in higher concentrations than in meat. Another compound in fish involved in the regulation of osmotic pressure is trimethylamine oxide TMAO, 40-120 mg kg sea fish16 . Postmortem it is decomposed by bacteria to trimethylamine, which is the typical fishy...

Methods of Cholesterol Determination in Food

Various methods have been developed for cholesterol determination in foods due to the necessity of precise and accurate results. The majority of the methods used in food are gravimetric, colori-metric, enzymatic, and chromatographic. The first method used to determine cholesterol in foods was the gravimetric method, in which the cholesterol is separated by precipitation with digitonin or tomatin.5 This analytical method is time consuming and has low sensitivity. Although colori-metric methods...

Assessment of the Oxidative Modification of Proteins 133211 Determination of Protein Thiol Oxidation

Myosin contains approximately 42 thiol SH groups,101 which have been reported to be highly reactive in the presence of ROS. In oxidized systems, cysteine is degraded into cysteine disulfide and sulfenic acid, whereas methionine is readily oxidized to methionine sulfoxide.90 The loss of free SH groups in muscle proteins is commonly used as an indicator of protein oxidation. Ellman's reagent or 5,5'-dithiobis 2-nitrobenzoate DTNB rapidly forms a disulfide bond with the thiol and releases a...

Niacin Vitamin B3

Niacin is one of the water-soluble B-vitamins known as vitamin B3. The term niacin is the generic descriptor for nicotinic acid and nicotinamide, which are essential for formation of the coenzymes, nicotinamide adenine dinucleotide NAD , and nicotinamide adenine dinucleotide phosphate NADP , in the body. Niacin can be biosynthesized from the amino acid tryptophan. Meats including organ meats contain large amounts of niacin and tryptophan. Nicotinic acid is found mainly in plant foods, but...

Simultaneous Distillation Extraction

Likens And Nickerson Apparatus

Steam distillation finds application in the analyses of volatiles from beverages and high-water-content foods, although it is less applicable to fats and oils. It has the disadvantage that large quantities of aqueous distillate require further extraction with a solvent, to separate the volatiles from the water. Concentration of the extract is then necessary. The formation of artifacts may also be a problem. One of the most widely used techniques in aroma analysis combines steam distillation...

Fat Soluble Vitamins 2411 Vitamin A and Carotenoids

Vitamin A is a fat-soluble vitamin that is essential for humans and other vertebrates. Vitamin A as retinoids, primarily retinyl esters, is abundant in some animal-derived foods, whereas carotenoids are abundant in plant foods as pigments. Animals cannot synthesize carotenoids. They obtain carotenoids from plant sources in their diets such as corn, green feedstuffs, vegetables, and fruits. Provitamin A carotenoids a-carotene, yS-carotene, and yS-cryptoxanthin are converted into vitamin A in the...

Fleisch Fur Jensen

Der kleine SFK, Lebensmitteltabelle f r die Praxis, 3rd edition, Wiss. Verlagsgesellschaft, Stuttgart, Germany, 2004. 2. McCance, R.A. and E.M. Widdowsen. The Composition of Foods, 5th revised edition. Royal Society of Chemistry, Cambridge, UK. 3. Honikel, K.O. and R. Wellh user. Zusammensetzung verbrauchergerecht zugeschnittener Schweinefleischteilst cke. Fleischwirts 73 863-866, 1993. 4. Bauer, F. Personal communication, 2007. 5. EU Council Directive 90 496 EEC...

Detection and Confirmation of Yersinia enterocolitica

Figure 34.8 shows the conventional method for detecting Y. enterocolitica based on Ref. 103 . If specific serotypes are considered e.g., O 3 , then two isolation procedures are proposed to run in parallel.17 The procedure involving enrichment with irgasan ticarcillin chlorate ITC broth is selective for serotype O 3 and possibly O 9, although some workers found poor recovery of the serotype O 9 from ground pork, using ITC.104 After enrichment with ITC, plating of the samples should be done on...

Determination of Cholesterol Oxides

The cholesterol oxide content in foods found in the literature varies widely, due mainly to different analytical methodologies used. The analysis of COP is strongly influenced by their chemical structures, as these compounds have different functional groups that provide different polarity and chemical properties to the molecules. However, some COP are isomers and thus have similar chemical, spectrophotometric, and fragmentation characteristics.114 As COP occurs at low levels micrograms gram ,...

Quantification of Total Phospholipids and Phospholipid Classes

The quantification of either total PL or isolated PL classes either scraped from the TLC plate or eluted from the SPE cartridge or from the HPLC column has been extensively performed by determination of the amount of phosphorus after digestion of PL, following the method described by Barlett.69 The released inorganic phosphorus is thereafter analyzed by reaction with ammonium molybdate to form phosphomolybdic acid, which is subsequently reduced, forming a blue compound that is determined...

Determination of CLA Isomers

The determination of CLA isomers is of particular interest in products of ruminants due to their formation, along with trans C18 1 isomers, during the biohydrogenation processes in the rumen. The most important trans fatty acid, t11 C18 1, is further converted into c9, t11 CLA, the quantitatively most important CLA, by delta-9 desaturase activity in the intermediary metabolism. The CLA concentrations reported for ruminant meat vary between 4.3 and 19 mg g lipid for lamb meat and between 1.2 and...

Muscle Protein Analysis

An early paper that systematically examined the composition of muscle tissue was conducted by von Furth.5 He used a variety of salt solutions to prepare protein-containing extracts. Nitrogen was determined by the Kjeldahl method. The nitrogen composition of various food items, including meat, was reported as early as 1906.6 Grossfeld7 studied the water and nitrogen content of minced meat and sausage products, and he concluded the nitrogen X 6.25 factor, originally proposed by Kjeldahl, was...