Stability of vitamins in food

Thermal degradation kinetics of ascorbic acid, thiamine and riboflavin in rosehip (Rosa canina L) nectar

“…Processing and storage of food through chemical reactions cause loss of vitamins. Because of the relative unstability and their critical role in nutrition, qualitative and quantitative analysis of vitamins are important issues for food manufacturers (Dttoway, 1993;Moreno & Salvado, 2000). Because of high selectivity thanks to solid phase extraction (removing interfering components), HPLC is the preferred method for the separation of vitamins (Cho et al, 2000;Kadakal et al, 2007).…”

Effect of retorting and oven cooking on the nutritional properties of beef frankfurters blended with palm oils

“…This observation suggests that vitamin E is highly stable to sterilization (high temperature and short time) compared with oven cooking (low temperature and long time cooking). Another reason may possibly be due to the storage conditions, where the retorted beef frankfurters were stored at room temperature while the oven-cooked beef frankfurters were stored at -18 C. According to Ottaway (1993), vitamin E is unusual in that it exhibits reduced stability at temperatures below freezing. At high temperatures, oxygen has lower solubility in fats/oils so that autoxidative peroxide formation proceeds at lower rates and becomes gradually substituted by polymerization reactions (Marinova and Yanishlieva 1992).…”

Analysis of Folate by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

“…The FA derivatives differ with respect to the state of oxidation of the pteridine ring, the number of glutamate residues conjugated to the para-amino-benzoic acid moiety, and the type of substitution at the 5-and/or 10-carbon position. 1,2 Only reduced folates are found naturally in plants and animals. In humans, the predominant form of folate in the blood is 5-methyltetrahydrofolic acid (MTHF, II), whereas tetrahydrofolic acid (THF, III) is the major circulating form in the porcine species.…”

“…THF forms the prosthetic group of many enzymes that are involved in the transfer of 'one carbon' moieties in amino acid and nucleotide metabolism, conversion of homocysteine to methionine, methylation of transfer RNA, and de novo purine nucleotide synthesis. 2 Prokaryotic cells can produce FA from other metabolites, while eukaryotes cannot and thus eukaryotes require FA in their diet. 4 Polyglutamates based on MTHF predominate in fresh food, but on storage these break down slowly to monoglutamates and are oxidized to less available folates.…”

“…Yeast extract, wheat bran and wheat germ, egg yolk, some cheeses and green leafy vegetables are rich sources of folates in addition to liver. 2,6 Bioavailability of the different forms and conjugates of FA are still poorly understood. Therefore, there is a need to separately determine the amount of different folates in foods and biological samples.…”