Publisher Summary This chapter discusses the analysis of total phenols and other oxidation substrates and antioxidants by means of Folin-Ciocalteu reagent. Analyses of the Folin-Ciocalteu (FC) type are convenient, simple, and require only common equipment and have produced a large body of comparable data. Under proper conditions, the assay is inclusive of monophenols and gives predictable reactions with the types of phenols found in nature. Because different phenols react to different degrees, expression of the results as a single number—such as milligrams per liter gallic acid equivalence—is necessarily arbitrary. Because the reaction is independent, quantitative, and predictable, analysis of a mixture of phenols can be recalculated in terms of any other standard. The assay measures all compounds readily oxidizable under the reaction conditions and its very inclusiveness allows certain substances to also react that are either not phenols or seldom thought of as phenols (e.g., proteins). Judicious use of the assay—with consideration of potential interferences in particular samples and prior study if necessary—can lead to very informative results. Aggregate analysis of this type is an important supplement to and often more informative than reems of data difficult to summarize from various techniques, such as high-performance liquid chromatography (HPLC) that separate a large number of individual compounds .The predictable reaction of components in a mixture makes it possible to determine a single reactant by other means and to calculate its contribution to the total FC phenol content. Relative insensitivity of the FC analysis to many adsorbents and precipitants makes differential assay—before and after several different treatments—informative.

Analysis of total phenols and other oxidation substrates and antioxidants by means of folin-ciocalteu reagent

Conjugated linoleic acid (CLA) is a naturally occurring anticarcinogen found in milk fat and body fat of ruminants. Although CLA is an intermediate in ruminal biohydrogenation of linoleic acid, we hypothesized that its primary source was from endogenous synthesis. This would involve Delta(9)-desaturase and synthesis from trans-11 18:1, another intermediate in ruminal biohydrogenation. Our first experiment supplied lactating cows (n = 3) with trans-11 18:1 by abomasal infusion and examined the potential for endogenous synthesis by measuring changes in milk fat CLA. By d 3, infusion of trans-11 18:1 resulted in a 31% increase in concentration of cis-9, trans-11 CLA in milk fat, demonstrating that an active pathway for endogenous synthesis of CLA exists. Our second experiment examined the quantitative importance of endogenous synthesis of CLA in lactating cows (n = 3) by abomasally infusing a putative stimulator (retinol palmitate) or an inhibitor (sterculic oil) of Delta(9)-desaturase. Infusion of retinol palmitate had no influence on milk fatty acid desaturation, and yield of CLA in milk fat was not altered. However, sterculic oil infusion decreased the concentration of CLA in milk fat by 45%. Consistent with Delta(9)-desaturase inhibition, the sterculic oil treatment also altered the milk fat concentration of other Delta(9)-desaturase products as indicated by the two- to threefold increase in the ratios of 14:0 to 14:1(,) 16:0 to 16:1 and 18:0 to cis-18:1. Using changes in the ratio of 14:0 to 14:1 as an indication of the extent of Delta(9)-desaturase inhibition with the sterculic oil treatment, an estimated 64% of the CLA in milk fat was of endogenous origin. Overall, results demonstrate that endogenous synthesis of CLA from trans-11 18:1 represented the primary source of CLA in milk fat of lactating cows.

Conjugated linoleic acid is synthesized endogenously in lactating dairy cows by Delta(9)-desaturase.

Histamine fish poisoning revisited.

Regulations relating to mycotoxins have been established in many countries to protect the consumer from the harmful effects of these compounds. Different factors play a role in the decision-making process of setting limits for mycotoxins. These include scientific factors, for example the availability of toxicological data and occurrence data, detailed knowledge about possibilities for sampling and analysis, and socio-economic issues. By the end of 2003, approximately 100 countries (covering approximately 85% of the world’s inhabitants) had specific regulations or detailed guidelines for mycotoxins in food. The regulations were related to aflatoxins (B1, B2, G1 and G2), aflatoxin M1, trichothecenes (deoxynivalenol, diacetoxyscirpenol, T-2 toxin and HT-2 toxin), fumonisins (B1, B2, and B3), agaric acid, ergot alkaloids, ochratoxin A, patulin, phomopsins, sterigmatocystin, and zearalenone. In Europe, and in particular in the EU, regulatory and scientific interest in mycotoxins has undergone a development in the last decade from autonomous national activity towards more EU-driven activity with a structural and network character. Harmonized EU limits now exist for 40 mycotoxin–food combinations. It is expected this number will grow in 2007 to approximately 50. The direct or indirect influence of European organizations and programs on the EU mycotoxin regulatory developments is significant. They include the European Food Safety Authority, the Scientific Cooperation on Questions relating to Food, the Rapid Alert System for Food and Feed, the creation of an EU Community Reference Laboratory for Mycotoxins and a mandate of the EC to the European Standardization Committee in methods for analysis for mycotoxins in food. Large pan-European research and networking projects as “BioCop” and “MoniQA” are also important.

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Regulations relating to mycotoxins in food

http://department.utcc.ac.th/science/images/stories/2549/7.pdf

Assessment of phenolic content and free radical-scavenging capacity of some Thai indigenous plants

Official methods of analysis of AOAC International , Official methods of analysis of AOAC International , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

William Horwitz

Papers

Official Methods of Analysis of AOAC International