Food analysis niacin

Juraja, S.M., Trenerry, V.C., Millar, R.G., Scheelings, P., and Buick, D.R., 2003. Asia Pacific Food Analysis Network (APNFAN) Training Exercise The determination of niacin in cereals by alkaline extraction and high performance liquid chromatography. Journal of Food Composition and Analysis. 16 93-106. 

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. 

GW Chase, WO Landen, A-GM Soliman, RR Eitenmiller. Liquid chromatographic analysis of niacin in fortified food products. J AOAC Int 76 390-393, 1993. 

The most recent reports on niacin measurement describe the use of LC with UV detection (Hirayama 1998 LaCroix et al. 1999, 2002 Lombardi-Boccia et al. 2005 Rizzolo et al. 1991 Saccani et al. 2005 Tyler and Shrago 1980 Tyler and Genzale 1990 van Niekerk et al. 1984). There can be significant interference from food matrices due to the low specificity at the UV region of interest (Xmax = 260 nm for nicotinic acid). Successful analysis usually requires... 

The added, isotopically labelled nicotinic acid and the nicotinic acid deriving from the endogenous niacin of the food sample have virtually identical physical and chemical properties and, by virtue of the digestion step, are assumed to be in a state of equivalence in regard to their chemical and physical environment thereafter in the analysis. 

Other method performance criteria, such as precision, selectivity and sensitivity, compare very favourably with more common methods of niacin analysis in foods. 

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