The effect of minerals and mineral chelators on the formation of phytase-resistant and phytase-susceptible forms of phytic acid in solution and in a slurry of canola meal

• Published in: Animal feed science and technology Vol. 81; no. 3; pp. 177 - 192
• Main Authors: Maenz, David D, Engele-Schaan, Carmen M, Newkirk, Rex W, Classen, Henry L
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.1999; Elsevier
• Subjects: ACIDE PHYTIQUE; ACIDO FITICO; Animal productions; Biological and medical sciences; Canola; CHELATEUR; CHELATING AGENTS; CHELATION; Feed and pet food industries; FITATOS; Food industries; Fundamental and applied biological sciences. Psychology; HARINA DE COLZA; Microbial phytase; MINERAL NUTRIENTS; Minerals; NUTRIENTES MINERALES; PHYTATE; PHYTATES; PHYTIC ACID; QUELACION; QUELATOS; RAPESEED MEAL; SUBSTANCE NUTRITIVE MINERALE; Terrestrial animal productions; TOURTEAU DE COLZA; Vertebrates; Chelation; Minerals; Canola; Phytic acid; Phytate; Microbial phytase; Phthalic acid; Chemical resistance; Enzyme; 6-Phytase; Phosphoric monoester hydrolases; Esterases; EDTA; Inorganic element; Citric acid; Property formulation relationship; Microbial origin; FEED ADDITIVES; Antinutrient factor; Chelating agent; Hydrolases; Rapeseed meal; Feed; Digestibility
• ISSN: 0377-8401; 1873-2216
• DOI: 10.1016/S0377-8401(99)00085-1

Minerals can readily bind to phytic acid and thus have the potential to form mineral–phytate complexes that may be resistant to hydrolysis by phytase activity of animal, plant and microbial origin. In simple solution, at pH 7.0, mineral concentrations from 0.053 mM for Zn 2+ up to 4.87 mM for Mg 2+ caused a 50% inhibition of phytate-P hydrolysis by microbial phytase. The rank order of mineral potency as inhibitors of phytate hydrolysis was Zn 2+ ⪢ Fe 2+ > Mn 2+ > Fe 3+ > Ca 2+ > Mg 2+ at neutral pH. Acidification of the media to pH 4.0 decreased the inhibitory potency of all of the divalent cations tested. The inhibitory potency of Fe 3+ showed a moderate increase with declining pH. Inclusion of 25 mM ethylenediamine-tetraacetic acid (EDTA) completely blocked Ca 2+ inhibition of phytate hydrolysis at pH 7. Inorganic P comprised 0.20–0.25 of the total P in a slurry of canola meal. Incubation with microbial phytase increased inorganic P up to 0.50 of total P levels. Supplementation with chelators such as EDTA, citrate and phthalate increased the efficacy of microbial phytase in hydrolyzing phytic acid. Incubation of canola meal with 100 mM phthalic acid plus microbial phytase resulted in complete hydrolysis of phytate-P. Competitive chelation by compounds such as EDTA, citric acid or phthalic acid has the potential to decrease enzyme-resistant forms of phytic acid and thereby improve the efficacy of microbial phytase in hydrolyzing phytic acid.