Publisher Summary This chapter discusses that the knowledge of phytic acid had its beginning in the discovery by Hartig, who isolated small particles or grains (which were not starch grains) from the seeds of various plants. Phytic acid has been generally regarded as the primary storage form of both phosphate and inositol in almost all seeds. The amount of phytic acid varies from 0.50% to 1.89% in cereals (except polished rice), from 0.40% to 2.06% in legumes, from 2.00% to 5.20% in oil seeds except soybeans and peanuts (grouped under legumes), and from 0.40% to 7.50% in protein products. Many foods and seeds contain myo-inositol hexaphosphate as an important source of phosphorus, and accurate methods for its determination are needed. Phytase (meso-inositol hexaphosphate phosphohydrolase, EC 3.1.3.8) is widely distributed in plants, animals, and fungi. In mature cereal grains, legumes, and oil seeds, the major portion of the total phosphorus is present in the form of phytic acid (phytate). Experiments with animals have suggested that phytic acid in plant foods complexes with dietary essential minerals such as calcium, zinc, iron, and magnesium and makes them biologically unavailable for absorption. The correlation of phytate with the cooking quality of peas was first suggested by Mattson. Phytic acid, myo-inositol 1,2,3,4,5,6-hexakis dihydrogen phosphate serves as the main phosphorus store in mature seeds and grains. In cereals and legumes, phytic acid content ranges from 0.14% to 2.05%, which accounts for 18 to 88% of the total phosphorus.

Phytates in Legumes and Cereals

Phytic acid is present in many plant systems, constituting about 1 to 5% by weight of many cereals and legumes. Concern about its presence in food arises from evidence that it decreases the bioavailability of many essential minerals by interacting with multivalent cations and/or proteins to form complexes that may be insoluble or otherwise unavailable under physiologic conditions. The precise structure of phytic acid and its salts is still a matter of controversy and lack of a good method of analysis is also a problem. It forms fairly stable chelates with almost all multivalent cations which are insoluble above pH 6 to 7, although pH, type, and concentration of cation have a tremendous influence on their solubility characteristics. In addition, at low pH and low cation concentration, phytate‐protein complexes are formed due to direct electrostatic interaction, while at pH >6 to 7, a ternary phytic acid‐mineral‐protein complex is formed which dissociates at high Na concentrations. These complexes appear to...

Phytic acid interactions in food systems

In 1964, William Horowitz published the history of the Association of Official Agricultural Chemists (AOAC), of which he was the chief executive officer (Horwitz 1964). At that time the AOAC had existed for 80 years and had ventured very little beyond its stated purpose of validating and publishing standardized methods of analysis for substances important to agriculture and the public health through a highly structured system of interlaboratory testing and review. In the ensuing quarter of a century, however, the AOAC not only changed its name to Association of Official Analytical Chemists but also underwent a striking expansion and transformation. The highlights of that transformation are the subject of this account.

Association of official analytical chemists: 1964-1988

SUMMARY
Aspergillus flavus is an opportunistic pathogen of crops. It is important because it produces aflatoxin as a secondary metabolite in the seeds of a number of crops both before and after harvest. Aflatoxin is a potent carcinogen that is highly regulated in most countries. In the field, aflatoxin is associated with drought-stressed oilseed crops including maize, peanut, cottonseed and tree nuts. Under the right conditions, the fungus will grow and produce aflatoxin in almost any stored crop seed. In storage, aflatoxin can be controlled by maintaining available moisture at levels below that which will support growth of A. flavus. A number of field control measures are being utilized or explored, including: modification of cultural practices; development of resistant crops through molecular and proteomic techniques; competitive exclusion using strains that do not produce aflatoxin; and development of field treatments that would block aflatoxin production.

Taxonomy: Aspergillus flavus Link (teleomorph unknown) kingdom Fungi, phyllum Ascomycota, order Eurotiales, class Eurotiomycetes, family Trichocomaceae, genus Aspergillus, species flavus.

Host range: Aspergillus flavus has a broad host range as an opportunistic pathogen/saprobe. It is an extremely common soil fungus. The major concern with this fungus in agriculture is that it produces highly carcinogenic toxins called aflatoxins which are a health hazard to animals. In the field, A. flavus is predominantly a problem in the oilseed crops maize, peanuts, cottonseed and tree nuts. Under improper storage conditions, A. flavus is capable of growing and forming aflatoxin in almost any crop seed. It also is a pathogen of animals and insects. In humans it is predominantly an opportunistic pathogen of immunosuppressed patients.

Useful websites: http://www.aspergillusflavus.org, http://www.aflatoxin.info/health.asp, plantpathology.tamu.edu/aflatoxin, http://www.aspergillus.org.uk

Aspergillus flavus: the major producer of aflatoxin

When an animal eats "spoiled" or "rotten" food of any kind, it runs a largely unknown risk (except in the case of grains) of being injured by toxins or microbe-produced antibiotics, getting food wi...

Why Fruits Rot, Seeds Mold, and Meat Spoils

Determination of Aflatoxins in Agricultural Products: Use of Aqueous Acetone for Extraction

Protein-phytic acid relationship in peanuts and cottonseed

Measurement of the solid state fluorescence of aflatoxins on silica gel-coated TLC plates on a densitometer equipped for fluorescence measurements showed a linear relationship between peak areas and concentration over a range of at least 2 to 105×10−4 μg of aflatoxins per spot. Response of individual aflatoxins was in order of B2>G2>B1>G1. Aflatoxins can be measured with a precision of ±2–4%.

Objective fluorometric measurement of alfatoxins on TLC plates

Destruction of aflatoxins in peanuts during dry and oil roasting

A method for the determination of total gossypol pigments in cottonseed oils is described. The oil is dissolved in a hexane-isopropanol solvent and gossypol pigments are determined in an aliquot of the solution by means of the color developed withp-anisidine. The effect of the solvent and the oil concentration on the color developed in the method has been investigated. The stability of gossypol in the solvent employed has been demonstrated and data are presented on the recovery of gossypol added to cottonseed oils. Spectrophotometric evidence is presented indicating that a number of gossypol-like pigments are present in crude cottonseed oils and that all of these pigments react withp-anisidine to give reaction products spectrophotometrically identical with that obtained for pure gossypol with the same reagent.

Walter A Pons

Papers

Determination of Aflatoxins in Agricultural Products: Use of Aqueous Acetone for Extraction

Protein-phytic acid relationship in peanuts and cottonseed

Objective fluorometric measurement of alfatoxins on TLC plates

Destruction of aflatoxins in peanuts during dry and oil roasting

Determination of total gossypol pigments in cottonseed oils