Department of Functional Food and Commodities Faculty of Human Nutrition and Consumer Sciences, Warsaw University of Life Sciences, 159 c Nowoursynowska, 02-0776 Warsaw, Poland.
Meat Sci. 2012 Aug;91(4):408-13. doi: 10.1016/j.meatsci.2012.02.023. Epub 2012 Feb 24.
Vitamin B12 is an animal origin nutrient of a substantial importance in human diet. Its concentration in foodstuffs is low and its chemical forms are diverse, which significantly hampers its precise determination. The determination method of choice is HPLC (high performance liquid chromatography) coupled with inductively-coupled-plasma mass spectrometry (ICP-MS). The main disadvantage of this method is high instrumentation cost and complexity of handling. The aim of this work was to develop a novel approach for determination of vitamin B12 bio-active forms in beef and beef liver. The proposed method comprises the following steps: (i) vitamin B12 is cleaved off from peptides using thermal denaturation in a weakly acidic environment; (ii) sample is cleaned-up using liquid-liquid extraction and reversed phase solid phase extraction; and finally (iii) vitamin B12 is determined using HPLC and single-quadrupole mass spectrometer with ESI source. Vitamin B12 concentrations in various beef meats were in the 2.84-3.95 μg 100g(-1) range. Average B12 concentration in beef liver was 153,60 μg 100g(-1) (n = 15). Major forms of B12 present in beef meat include adenosine cobalamin (AdoCbl) and in smaller quantities hydroxycobalamin (OHCbl). Major forms of vitamin B12 present in beef liver include OHCbl (48.2%), AdoCbl (33.8%), methylocobalamin (MeCbl, 16.3%), and cyanocobalamin (CNCbl, 1.7%). Thermal treatment noticeably decreases B12 the content in meat. Depending on conditions of treatment, B12 concentrations in the 1.04-2.20 μg 100g(-1) range were found in processed meats.
维生素 B12 是一种动物源性营养素，在人类饮食中具有重要意义。它在食物中的浓度较低，且化学形式多样，这极大地阻碍了其精确测定。首选的测定方法是高效液相色谱（HPLC）与电感耦合等离子体质谱（ICP-MS）联用。该方法的主要缺点是仪器成本高且操作复杂。本工作旨在开发一种用于测定牛肉和牛肝中维生素 B12 生物活性形式的新方法。该方法包括以下步骤：（i）在弱酸性环境中通过热变性从肽中裂解维生素 B12；（ii）使用液液萃取和反相固相萃取对样品进行净化；最后（iii）使用 HPLC 和带有 ESI 源的单四极杆质谱仪测定维生素 B12。不同牛肉中的维生素 B12 浓度在 2.84-3.95 μg 100g(-1)范围内。牛肝中平均 B12 浓度为 153.60 μg 100g(-1)（n = 15）。牛肉中存在的主要维生素 B12 形式包括腺苷钴胺素（AdoCbl），其次是羟钴胺素（OHCbl）。牛肝中存在的主要维生素 B12 形式包括 OHCbl（48.2%）、AdoCbl（33.8%）、甲基钴胺素（MeCbl，16.3%）和氰钴胺素（CNCbl，1.7%）。热处理会明显降低肉中的 B12 含量。根据处理条件的不同，加工肉中的 B12 浓度在 1.04-2.20 μg 100g(-1)范围内。
