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Thiamin extraction method

The meat was homogenized; a 10 g sample was weighed and suspended in 10 ml of de-mineralized water.

After the addition of 1 ml of saturated trichloroacetic acid (TCA) the sample was stirred using a magnetic

stirrer for 20 min.

3 ml of 4 % TCA was added and the sample was stirred for another 20 min. The samples were transferred to

centrifuge tubes, and rinsed twice with 2 ml of 4 % TCA. The samples were centrifuged for 20 minutes at

3000 rpm. The upper phase was decanted and transferred to a graduated cylinder and the volume adjusted to

10 ml with 4 % TCA. The extracts were then filtered through an 8.0 µm filter and immediately injected into

the HPLC.

HPLC identification of thiamin

HPLC analysis was performed on a Waters 600 E high-performance liquid chromatograph (Waters, Milford,

MA, USA) equipped with an analytical Symmetry C18 column (3.9 mm x 150 mm; 5 µm) fitted with Nova-

Pack c18 precolumn insert and the Waters 991 photodiode array detector.

For separation and identification of thiamin the following elution method was used:

Methanol-(0.05 M sodium phosphate + 0.005M hexanesulfonic acid) buffer (ph=3.0), in the gradient:

isocratic at the methanol-buffer (3:97, v/v) within 1 min, linear gradient to 45:55 (v/v) to 22 min, and isocratic

at 3:97 (v/v) to 8 min, at the flow rate 1 ml/min. A Waters 991 photodiode array detector was used at the

wavelength of 254 nm. Using these conditions recovery of thiamine was 89.3 %.

Results and discussion

Sensory characteristic

Average marks given by the panelists for particular features were as follows:

• carrots and green peas mixture

The most preferable thermal treatment method was heating in the Thermomix (3.6 points). The experts gave

slightly fewer points to the traditional style (3.2 points). Carrots and green peas cooked in the Pressure-cooker

took third place ex aequo with the Slo-Cooker method (2.5 points). Steamed carrots and green peas were the

least desired by panelists (2.3 points).

• pork loin

The group preferred cooked meat prepared in the Slo-Cooker (4.3 points). The traditional method was

slightly less popular among the experts (3.8 points). Meat cooked in the Thermomix was also less desired by

the group (3.4 points). The meat prepared in the Pressure-cooker was judged as the least desired (2.3 points).

• potatoes

The panelists preferred potatoes cooked in the customary style (using cold water – 3.7 points). Potatoes

prepared in the Pressure-cooker were a little less desired (3 points). The steamed potatoes turned out to be the

least preferred (Poki-steamer 2.2 points). The quality of potatoes cooked in the Slo-Cooker was at a slightly

higher level (2.4 points).

Identification and quantification of thiamin

Thiamin level in the meat was reduced by all thermal treatments (0.07-0.25 mg/100g) as compared to the

uncooked value (0.41mg/100g.)

Similar results were found with the various thermal treatments of the carrots and green peas mixture with

the lowest content being in the Slo-cooker (0.01mg/100g) and the highest level in the Pressure-cooker (0.08

mg/100g). The unprocessed thiamin level was 0.11 mg/100g.

FORUM WARE 32 (2004) NR. 1 - 4


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