Food analysis thiamin

MSFIA chromatographic analysis was also applied to food analysis (Fernandez et ak, 2012), including orange juice, strawberry milkshake, and malt, for simultaneous determination of six water-soluble vitamins (thiamine, riboflavin, ascorbic acid, nicotinic... 

In terms of amino acids bacterial protein is similar to fish protein. The yeast s protein is almost identical to soya protein fungal protein is lower than yeast protein. In addition, SCP is deficient in amino acids with a sulphur bridge, such as cystine, cysteine and methionine. SCP as a food may require supplements of cysteine and methionine whereas they have high levels of lysine vitamins and other amino acids. The vitamins of microorganisms are primarily of the B type. Vitamin B12 occurs mostly hi bacteria, whereas algae are usually rich in vitamin A. The most common vitamins in SCP are thiamine, riboflavin, niacin, pyridoxine, pantothenic acid, choline, folic acid, inositol, biotin, B12 and P-aminobenzoic acid. Table 14.4 shows the essential amino acid analysis of SCP compared with several sources of protein. 

The infrared technique has been described in numerous publications and recent reviews were published by Davies and Giangiacomo (2000), Ismail et al. (1997) and Wetzel (1998). Very few applications have been described for analysis of additives in food products. One interesting application is for controlling vitamin concentrations in vitamin premixes used for fortification of food products by attenuated total reflectance (ATR) accessory with Fourier transform infrared (FTIR) (Wojciechowski et al., 1998). Four vitamins were analysed - Bi (thiamin), B2 (riboflavin), B6 (vitamin B6 compounds) and Niacin (nicotinic acid) - in about 10 minutes. The partial least squares technique was used for calibration of the equipment. The precision of measurements was in the range 4-8%, similar to those obtained for the four vitamins by the reference HPLC method. 

More recently [635], a unique extraction step in supplemented foods, by using hot water and a precipitation solution, following by HPLC-ELD/UV analysis has been performed for the simultaneous determination of pyridoxine, thiamine, riboflavin, niacin, pantothenic acid, folic acid, cyanoco-balamin, and ascorbic acid. The mobile phase consisting of phosphate buffer and methanol has been modified in order to perform ion-liquid chromatography by adding l-octanesulfonic acid sodium salt. Furthermore, triethylamine has been also added to improve peak symmetry. 

The potential of PBI LC-MS in the analysis of various vitamins was explored by Careri et al. [99-100]. The fat-soluble vitamins A, D, and E were analysed in food and multivitamin preparations [99]. Absolute detection limits in SIM mode were 0.6-25 ng after fast leversed-phase separation using a 97% aqueous methanol as mobile phase. Mass spectra in El, positive-ion and negative-ion Cl were obtained and discussed. The mass-spectral and quantitative performance of PBI LC-MS in the analysis of eleven water-soluble vitamins was also explored [100]. Detection limits were determined in SIM mode under positive-ion Cl, and were below 15 ng for ascorbic acid, nicotinamide, nicotinic acid, and pyridoxal, around 100 ng for dehydroascorbic acid, panthothenic acid, and thiamine, and above 200 ng for biotin, pyridoxamime, and pyridoxine. Riboflavine was not detected. 

Vidal-Valverde, C., and Diaz-Pollan, C., Optimization analysis by capillary electrophoresis of thiamine in meat Comparison with high perfomance liquid chromatography, Eur. Food Res. TechnoL, 209, 355,... 

Thiamine (vitamin Bj) occurs in foods in free and bound forms, the free form predominates in cereals and plants, whereas the pyrophosphate ester is the main form in animal products. Acid hydrolysis is required to release thiamine from the food matrix. Enzymatic hydrolysis is then needed to convert phosphate esters to thiamine. Prior to CE analysis it is necessary to clean up samples by using ethanol to precipitate protein and by passing through an ion-exchange resin. Thiamine has been determined in meat and milk samples using MEKC with ultraviolet (UV) detection at 254 nm, obtaining comparable sensitivity to that achieved by HPLC using an ion-pair reversed-phase column with postcolumn derivat-ization and fluorescence detection. 

We have developed a method for simultaneous analysis of thiamine hydrochloride, pyridoxine hydrochloride and cyanocobalamin in pharmaceuticals and dietary supplements (Marszall et al. 2005) and in fortified food (Lebiedzinska and MarszaH 2006) using HPLC-ED. Vitamins were determined in their free forms, so an extraction step from fortified fruit juice was performed prior to the chromatographic isolations. The extraction procedure was based on a study by Ndaw el al. (2000). The enzymatic digestion prior to the separation and quantification step made it possible to release the vitamins bound to proteins or sugars and converted vitamin esters to free forms thus we were able to obtain the total vitamin contents of the fruit juices. The supernatants were adjusted to pH 4.5 with 2.5 M sodium acetate and a single extraction procedure for all vitamins was carried out using mixture of the enzymes, papain and diastase (Lebiedzinska and MarszaH 2006). 

Figure 14.1 presents chromatograms of vitamins analysed in fruit drinks. The detection limit for thiamine hydrochloride deteetion was 9.2 ng/ml, whereas the limits for pyridoxine and cyanoeobalamin were 2.7 and 0.08 ng/ml, respectively. The proposed separation and detection procedure was applied sueeess-fully for quantitative evaluation of the studied B vitamins in pharmaeeutieal preparations and dietary supplements, and for routine control of multivitamin enriched foods. Based on those sueeessful results, we have developed also a method for analysis of vitamins Bg, B12 and Bi in seafood produets (Lebiedzinska et al. 2007). 

Tang, X., Cronin, D.A., and Brunton, N.P., 2006. A simplified approach to the determination of thiamine and riboflavin in meats using reverse phase HPLC. Journal of Food Composition and Analysis. 19 831-837. 

Velisek, J., Davidek, J., Mnukova, J., and Pistek, T., 1986. Gas chromatographic determination of thiamin in foods. Journal of Micronutrient Analysis. 2 73-80. 

There are various microbiological, chemical and animal assays available for thiamine analysis. Method selection depends on the accuracy and sensitivity required, and on the interferences due to the sample matrix. Although microbiological assays do exist for thiamine, these are rarely used. The highly fluorescent products are the basis of the thiochrome procedure for thiamine quantiflcation. Thiochrome analysis has been used to develop most of the analytical data available on the thiamine content of the food supply. 

The assays have been a powerful tool for thiamine analysis in various foods. However, the analytical process may take up to 72 h and is often plagued by poor reproducibility. It allows for the detection of thiamine amounts between 5 and 50 ng. The aseptic technique should be used throughout the microbiological assay procedure under the same conditions for successful results. 

The analysis of thiamine levels in food has traditionally been based upon the oxidation of free thiamine to give thiochrome (Gregory 1996). Variations on the basic procedure have been developed and have generally involved the measurement of thiochrome with a spectrofluorimeter. The thiochrome method depends upon the alkaline oxidation of thiamine to thiochrome (Figure 17.2). 

Ultraviolet detection at 245-254 nm is not sensitive enough for naturally occurring levels of thiamine, TMP, TPP and TTP in foods, and therefore is more used for enriched foods. Although some methods enable the determination of thiamine directly by HPLC with UV detection, the low vitamin content, very low molar absorption of thiamine and the high quantity of interfering compounds in foodstuff s means that better thiamine analysis is obtained when it is preceded by oxidation to thiochrome by either pre- or post-column reaction with or without extraction into isobutyl alcohol with precise timings and when the final analysis is carried out using HPLC with FL detection. 

Recent multivitamin analytical methods, including thiamine analysis recent development of high quality instrumental methods for thiamine analysis when a food sample is subjected to the multivitamin assay. The application of the methods to pharmaceutical materials is indicated. 

Microbiological methods for the analysis of thiamine are well-established procedures used for low-level naturally occurring vitamins in food. The use of microtitre plates coated with specific microorganisms has significantly improved thiamine analysis. 

AOAC, 1990b. Method 942.23. Thiamine (vitamin Bl) in foods—fluorometric method. Final action. In Official Methods of Analysis of the Association of Official Analytical Chemists, 15th ed. Association of Official Analytical Chemists, Arlington VA, USA, pp. 1049-1051. 

Bui, L.T.T., and Small, D.M., 2007. The contribution of Asian noodles to dietary thiamine intakes. A study of commercial dried products. Journal of Food Composition and Analysis. 20 575-583. 

Vidal-Valverde, C., and Reche, A., 1990. An improved high performance liquid chromatographic method for thiamin analysis in foods. Zeitschrift fur Lebensmittel-Untersuchung und -Forschung. 191 313-318. 

The detection limit depends on the method used. Huorometric detection is much more sensitive than its spectrophotometric counterpart. The latter method is suitable for analysis of large quantities of thiamine in pharmaceutical preparations and foods the detection limit is approximately 2 ng or 6 pmol as thiamine hydrochloride. On the other hand, the detection limit by the fluorometric method is <17 pg or 0.05 pmol as thiamine hydrocholoride. The lowest detection limit so far reported for thiamine is 5 fmol, using fluorescence (21,22). Huorescence detection is therefore more suitable for the analysis of thiamine in biological materials such as cells, blood, and urine. 

P Wimalasiri, RBH Wills. Simultaneous analysis of thiamin and riboflavin in foods by high-performance liquid chromatography. J Chromatogr 318 412-416, 1985. 

C Hassehnann, D Franck, P Grimm, PA Diop, C Soules. High-performance hquid chromatography analysis of thiamin and riboflavin in dietetic foods. J Micronutr Anal 5 269-279, 1989. 

Owing to its low molar absorptivity, the use of UV detection is mainly indicated for the analysis of fortified foods containing high concentrations of thiamin [1,7]. Low content of endogenous vitamin and high quantities of interfering substances in an extract require... 

Einglas, P. and Paulks, R., The HPLC analysis of thiamin and riboflavin in potatoes. Food... 

Kamman, J., Labuza, T., and Warthesen, J., Thiamin and riboflavin analysis by high-performance liquid chromatography, J. Food Sci., 45, 1499-1504, 1980. 

VandersUce, J. and Huang, M., Liquid chromatographic analysis of thiamin and its phosphates in food products using amproUum as an internal standard, J. Micronutr. Anal, 2, 189 199, 1986. 

---