Determination of Sialic Acid in Milk and Products Using High Performance Anion-Exchange Chromatography Coupled with Pulsed Amperometric Detection

Abstract

Abstract:A resolved succinct environmental-friendly chromatography method was developed for determination of N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc) in bovine milk and products using high performance anion-exchange chromatography coupled with pulsed amperometric detection. The conditions affecting separation, detection, and sialic acid release from milk were optimized. The separation was finished on CarboPac PA20 anion-exchange column using 100 mM NaOH and 20-300 mM NaAc elution in 20 min at a flow rate of 0.5 ml min -1 . The separation and detection temperatures were both at 30°C. The detection was carried out on gold working electrode. The detection limits (25 l injection, three times of the baseline noise)were 3.0 and 1.8 g l -1 , and the linear range of 5-500 g l -1 was obtained. The spiked recovery of Neu5Ac and Neu5Gc in real samples was 88%-115%.

Porcine Milk Oligosaccharides and Sialic Acid Concentrations Vary Throughout Lactation

“…This dynamic in the form of SA throughout lactation suggests that porcine milk more closely matches human than bovine milk, which typically contain roughly 5% of the total SA acid as the free form. Notably, our results were lower than those described for human colostrum (35 and 1500 mg/L for free and total, respectively) (36, 37) and bovine milk (15–500 mg/L of total SA) (35, 38). Additionally, the ratio of free-to-bound SA appeared to continually decrease throughout lactation, suggesting that more SA was being incorporated into other compounds.…”

“…Only 5% of the total SA typically exists in the free or unbound form (29). Following a similar trend to overall OSs, the total and free SA concentrations of porcine milk were lower than what has been described for human milk, yet similar to that found in bovine milk (15 mg/L) (35). However, it is important to note that there are relatively few studies that have evaluated SA concentrations of bovine milk, and variability exists in factors, including maternal breed (wide range of concentrations ranging from 15 to 500 mg/L) and methodologies employed for quantification (e.g., colorimetric vs. HPLC).…”

“…In quantitative terms, this developmental insufficiency may increase the dietary SA requirement to maintain biological processes and ensure optimal development. As infant enzyme systems supporting SA production mature throughout the lactation period, their dietary requirements for free SA decrease, hence the biological basis for milk SA to decrease throughout lactation (35–37). The values for free SA reported in our study are in agreement with the literature, where a decrease was observed throughout lactation.…”

Sialic acid (N-acetyl and N-glycolylneuraminic acid) and ganglioside in whey protein concentrates and infant formulae

“…Although these formulae do not reach the ratio found in HM, they come closer to it than the other formulae. These ratios are intimately linked to the origin of the milk (species), since Tang et al (2008) in bovine and powdered milk obtained a Neu5Ac/Neu5Gc ratio of between 1.3 and 91.3. Recently, Spichtig et al (2010) obtained ratios of 36.5, 0.1 and 0.8 for cow, ewe and goat milk, respectively.…”

“…Total SA ranges from 1546.4 mg L À1 (colostrum) to 91.0 mg L À1 (mature milk) (Carlson, 1985;Martín-Sosa, Martín, García-Pardo, & Hueso, 2004;Neeser, Golliard, & Del Vedovo, 1991;Wang, Brand-Miller, McVeagh, & Petocz, 2001). No data on specific forms of SA (Neu5Ac and Neu5Gc) in human milk (HM) have been found in the literature, and only a few studies have been made in the milk of other mammalian species (Puente & Hueso,1993;Spichtig, Michaud, & Austin, 2010;Tang, Liang, Cai, & Mou, 2008). In this context, gangliosides also decrease their content and change their profile: from 7.3 mg L À1 distributed as GD 3 (Neu5Aca2,8Neu5Aca2,3Galb1,4Glc-Cer) 70% and GM 3 (Neu5-Aca2,3Galb1,4Glc-Cer) 9% (colostrum) to 4.0 mg L À1 distributed as GD 3 9% and GM 3 85% (mature milk of 390 days of lactation) (Iwamori, Takamizawa, Momoeda, Iwamori, & Taketani, 2008;Martín-Sosa et al, 2004;Takamizawa, Iwamori, Mutai, & Nagai, 1986).…”