The influence of time, temperature, pH and calcium carbonate on the activity of the phytase of certain cereals

Abstract

1. Tests have been carried out to investigate the hydrolysis of phytate in wheat, bran, and oats.2. Oats showed practically no phytase activity.3. Wheat phytase had an optimum pH of 5·0–5·1 and functioned at pH values down to 3·0. When hydrolysis had been arrested by acidifying to pH 2·5 for 5 min. or longer, the phytase did not recover when the pH was raised to 5·0 by the addition of sodium bicarbonate.4. There was an almost uniform increase in the rate of hydrolysis between 15 and 50° C.5. The rate of phytate hydrolysis decreased as the reaction proceeded, but the reaction continued until only a very small amount of soluble substrate remained.6. The presence of calcium, under conditions in which it could form insoluble phytate, reduced phytate hydrolysis to a considerable degree.7. These reactions are considered in relation to phytate hydrolysis in the digestive tracts of animals.

Consequences of calcium interactions with phytate and phytase for poultry and pigs

“…Calcium-phytate complexes and phytase activity Ballam et al (1985) stressed the importance of Ca and Caphytate complexes on phytate degradation and the liberation of phytate-P. In support of this, Hill and Tyler (1954a) found that Ca reduced phytate hydrolysis by wheat phytase by 22% in an in vitro system. Also, Gillis et al (1957) reported that radioactively-labeled Ca-phytate bioavailability was negligible in comparison to inorganic P (Na 2 HP 32 O 4 ) as assessed by P retention in tibia ash of broiler chicks and turkey poults.…”

“…Decades ago, Hill and Tyler (1954a) reported that Ca reduced wheat phytase efficacy, which was attributed Caphytate complex formation. Subsequently, Lei et al (1994) reported that Ca, and/or 'wide' dietary Ca:P ratios, depressed responses to exogenous phytase in weaner pigs, which was also attributed to phytate complexing Ca.…”

Comparative evaluation of the efficacy of cereal and microbial phytases in growing pigs fed diets with marginal phosphorus supply

“…The pH optimum of both phytases is about 5.5. With decreasing pH, plant phytase activities are extremely low, 25,26 whereas microbial phytase still exhibits 60% of its original activity at pH 2.0. 27,28 Thus it can be assumed that microbial phytase is still active in the fundic region of the stomach of the pig.…”

Hydrolysis of phytic acid by intrinsic plant and supplemented microbial phytase (Aspergillus niger) in the stomach and small intestine of minipigs fitted with re‐entrant cannulas

“…1997) resulting in a higher inactivation by a delayed transit of the enzyme through the stomach. Low pH values and the presence of pepsin caused significant losses of wheat phytase activity (H ILL and T YLER 1954; N AGAI and F UNAHASHI 1962; S CHEUERMANN et al. 1988).…”