SUBJECTS meat extract

Two thousand parts by volume of an aqueous culture medium (pH 7.2) comprising 0.5% of glycerol, 0.5% of polypeptone, 0.5% of yeast extract and 0.3% of meat extract is inoculated with Escherichia coli Rll (IFO-13560). The medium is incubated at 37°C under aeration for 18 h. The culture broth is subjected to centrifuge to recover 4.4 parts of wet cells. The cells are suspended into 17.6 parts by volume of 0.05 M phosphate buffer (pH 7.0). The suspension is subjected to ultrasonic oscillation (Kaijo Denki Co., Ltd. T-A-4201, 4280-type, 2A) to disintegrate the cells, followed by removing the debris (insoluble materials) by centrifugation, whereby 17 parts by volume of crude enzyme solution is obtained. 

Mattila et al. (205) described a two-dimensional HPLC procedure for determining vitamin D3 and 25-hydroxyvitamin D3 in meat and milk products. Samples were saponified in the presence of vitamin D2 and 25-hydroxyvitamin D2 as internal standards, and the extracted un-saponifiable matter was subjected to normal-phase semipreparative HPLC to obtain a fraction containing 25-hydroxyvitamin D2 + 25-hydroxyvitamin D3 and a fraction containing vitamin D2 + vitamin D3. The collected fractions were evaporated and purified by reversed-phase HPLC. Fractions were again collected, after which vitamin D3 was quantified by tandem-column reversed-phase HPLC and 25-hydroxyvitamin D3 by tandem-column normal-phase HPLC. Analytical chromatograms of a purified extract of chicken are shown in Fig. 12. 

In a method proposed by Booth et al. (141) for the determination of phylloquinone in various food types, extracted samples are subjected to silica solid-phase extraction followed, in the case of meat or milk samples, by further purification using reversed-phase solid-phase extraction or liquid-phase reduction extraction, respectively. The final test solution is analyzed by NARP-HPLC, and the fluorescent hydroquinone reduction products of phylloquinone and the internal standard are produced online using a postcolumn chemical reactor packed with zinc metal. 2, 3 -Dihydrophylloquinone, a synthetic analog of phylloquinone, is a suitable internal standard for the analysis of vegetable juice, whole milk, and spinach. Another synthetic analog, Ku23), is used for the analysis of bread and beef, because a contaminant in the test solution coelutes with dihydro-phylloquinone. 

Daft (1988) employed a photoionization detector and an electrolytic conductivity detector connected in series to a capillary GC to detect 1,1-dichloroethane at ng /g levels in fumigants and industrial chemical residues of various foods (e.g., diary products, meat, vegetables, and soda). Typically, foods were extracted with isooctane and injected in GC column for analysis. However, foods containing lipid and fat were subjected to further clean-up on micro-florisil column prior to GC analysis. 

Solid or semi-solid samples may require extraction with an aqueous solution to isolate the ionic components in a form suitable for IC. The actual procedures vary widely, depending on the type of sample. For example, meat and sausage products to be analyzed for nitrate and nitrite are first homogenized mechanically, extracted wth a 5 % borax buffer solution in a hot water bath, and then subjected to a precipitation with strong solutions of potassium hexacyano ferrate and zinc sulfate. The aqueous extracts are diluted further with de-ionized water and filtered through a membrane prior to injection. 

Rababah T, Hettiarachchy NS, Horax R, Cho MJ, Davis B, Dickson J (2006) Thiobarbituric acid reactive substances and volatile compounds in chicken breast meat infused with plant extracts and subjected to electron beam irradiation. Poult Sci 85 1107-1113... 

Meat was homogenized in 0.1 M HCl, heated at 100°C for 1 h, cooled, and adjusted to a pH of 4.5 to 5. The mixture was then subjected to enzymatic hydrolysis with mylase 100 and papain for 4 h at 45 to 50°C. To cleave thiamine to 4-methyl-5-(2-hydroxyethyl)thiazole, NaHSOs or Na2S03 was added, the pH was readjusted to 4 to 5, and the mixture was again heated at 100°C for 2 h. After the addition of trichloroacetic acid (TCA), the mixture was chilled and filtered. The filtrate was adjusted to a pH of 11 to 12 and then extracted with chloroform, which was evaporated to dryness. The residue was taken up in 1 mL internal standard solution and the latter was concentrated to 0.5 mL. The resulting sample was stored for analysis. 

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