《食品化学与分析 Food Chemistry and Analysis》课程PPT教学课件（英文版）Vitamin

VITAMINS Vitamin A H3 C CH3 CH3 CH3 CH3 CH2 O H

VITAMINS Vitamin A H3 C CH3 CH3 CH3 CH3 CH2 O H

b - Carotene CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 H3C CH3 H3C CH3 CH3 CH3 CH3 H3C CH3 CH3 CH3 CH3 CH2OH Oxidation C H O Retainal Retinol (Vitamin A) - 2H

b - Carotene CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 H3C CH3 H3C CH3 CH3 CH3 CH3 H3C CH3 CH3 CH3 CH3 CH2OH Oxidation C H O Retainal Retinol (Vitamin A) - 2H

Food KOH (Alcoholic) Saponification 3 hrs. at room temperature Ether for Extraction Extract (vit.A and carotenoids) Total Carotenoids only at 440 nm Vitamin A + Carotenes Carr-Price Reagent Measure at 620 nm Vitamin A and b - Carotene Determination

Food KOH (Alcoholic) Saponification 3 hrs. at room temperature Ether for Extraction Extract (vit.A and carotenoids) Total Carotenoids only at 440 nm Vitamin A + Carotenes Carr-Price Reagent Measure at 620 nm Vitamin A and b - Carotene Determination

b-CAROTENE STANDARD ABSORBANCES AT 440 AND 620 nm at 440 nm at 620 nm A A

b-CAROTENE STANDARD ABSORBANCES AT 440 AND 620 nm at 440 nm at 620 nm A A

Use absorbances at 440 nm and then convert this to absorbance at 620 nm and subtract from the absorbance at 620 nm to determine the absorbance at 620 due to Vitamin A. Carotenoid Absorbance at 440nm Vitamin A Absorbance at 620 nm Carotenoid (mg/ml) Vitamin A mg/cuvette (sample) x x x x x x x x x x x

Use absorbances at 440 nm and then convert this to absorbance at 620 nm and subtract from the absorbance at 620 nm to determine the absorbance at 620 due to Vitamin A. Carotenoid Absorbance at 440nm Vitamin A Absorbance at 620 nm Carotenoid (mg/ml) Vitamin A mg/cuvette (sample) x x x x x x x x x x x

THIAMIN DETERMINATION THIOCHROME (Fluorescent) N K3 Fe(CN)6 Oxidation N S N H3C N CH2 CH3 CH2CH2OH N S N H3C N CH2 NH2 CH3 CH2CH2OH pyrimidine thiazole Excite thiochrome at 365 nm and measure the absorbance at 435 nm

THIAMIN DETERMINATION THIOCHROME (Fluorescent) N K3 Fe(CN)6 Oxidation N S N H3C N CH2 CH3 CH2CH2OH N S N H3C N CH2 NH2 CH3 CH2CH2OH pyrimidine thiazole Excite thiochrome at 365 nm and measure the absorbance at 435 nm

Thiamin Determination in Foods 5 g enriched flour 75 ml 0.1 N HCl Make volume to 100 ml Digest at 1000C for 30 min Centrifuge and filter

Thiamin Determination in Foods 5 g enriched flour 75 ml 0.1 N HCl Make volume to 100 ml Digest at 1000C for 30 min Centrifuge and filter

Oxidation of Thiamine Tube 1 Tube 2 5 ml Sample 5 ml Sample 2.5 g NaCl 2.5 g NaCl 3 ml K3FeCN6 3 ml NaOH 13 ml Isobutanol 13 ml Isobutanol Centrifuge Centrifuge Tube 3 Tube 4 5 ml Standard (thiamin) 5 ml Standard (thiamin) 2.5 g NaCl 2.5 g NaCl 3 ml K3FeCN6 3 ml NaOH 13 ml Isobutanol 13 ml Isobutanol Centrifuge Centrifuge Thiamin Standard Solution = 0.2 mg/ml Calculation of B1 (mg of B1/5 ml assay sample) = (Tube 1 – Tube) / (Tube 3 - Tube 4 )

Oxidation of Thiamine Tube 1 Tube 2 5 ml Sample 5 ml Sample 2.5 g NaCl 2.5 g NaCl 3 ml K3FeCN6 3 ml NaOH 13 ml Isobutanol 13 ml Isobutanol Centrifuge Centrifuge Tube 3 Tube 4 5 ml Standard (thiamin) 5 ml Standard (thiamin) 2.5 g NaCl 2.5 g NaCl 3 ml K3FeCN6 3 ml NaOH 13 ml Isobutanol 13 ml Isobutanol Centrifuge Centrifuge Thiamin Standard Solution = 0.2 mg/ml Calculation of B1 (mg of B1/5 ml assay sample) = (Tube 1 – Tube) / (Tube 3 - Tube 4 )

RIBOFLAVIN DETERMINATION 6,7 Dimethyl-9-D-1-Ribitylisoalloxazine N N N O O HCH HOCH HOCH HOCH CH2 OH CH3 CH3 1 2 3 5 4 6 7 8 9 1 0

RIBOFLAVIN DETERMINATION 6,7 Dimethyl-9-D-1-Ribitylisoalloxazine N N N O O HCH HOCH HOCH HOCH CH2 OH CH3 CH3 1 2 3 5 4 6 7 8 9 1 0

Fluorometric Method Autoclave in 0.1 N HCl for 30 min Adjust pH to isoelectric point to precipitate proteins Filter Determination: Test Tubes 10 ml sample, + 1 ml of riboflavin standard or 1 ml H2O + 1 ml acetic acid, + 0.5 ml KMnO4 (4%) + 0.5 ml 3% H2O2 - KMnO4 color should disappear in 10 seconds, + 20 mg powdered Na2S2O4 Calculation mg Riboflavin/ml Final Sample Solution [F(sample) - F(blank)] x 0.1 x 0.001 F(sample + standard) - F(sample) =

Fluorometric Method Autoclave in 0.1 N HCl for 30 min Adjust pH to isoelectric point to precipitate proteins Filter Determination: Test Tubes 10 ml sample, + 1 ml of riboflavin standard or 1 ml H2O + 1 ml acetic acid, + 0.5 ml KMnO4 (4%) + 0.5 ml 3% H2O2 - KMnO4 color should disappear in 10 seconds, + 20 mg powdered Na2S2O4 Calculation mg Riboflavin/ml Final Sample Solution [F(sample) - F(blank)] x 0.1 x 0.001 F(sample + standard) - F(sample) =