Characterizing the diversity of grain phytic acid content in Indian rice landraces by multivariate genetic analyses

Phytic acid (PA) acts as chelator of cationic mineral elements iron (Fe) and zinc (Zn) and obstructs their absorption in the human gut. We have evaluated a set of 162 traditional rice landraces for phytic acid phosphorus (PA-P), inorganic phosphorus (Pi) and total phosphorus (TP). Wide variability was observed for PA-P, Pi and TP ranging from 1.12 to 3 mg/g, 0.004 to 0.16 mg/g and 1.17 to 3.04 mg/g respectively. The mineral micronutrients, Fe and Zn were not in correlation with PA-P, Pi and TP implicating the possibility of their independent improvement while PAP showed a significant positive correlation with TP and significant negative correlation with Pi. Principal component analysis (PCA) identified two principal components PC1 and PC2, explaining 50.6 % and 32.1 % of the total variation, respectively. Cluster analysis grouped the accessions into four clusters. The study has also led to the identification of promising donors such as P1490 and Gowri with low PA content to be utilized in rice biofortification programmes.

The use of phytase in finishing pig diets

Phosphorus (P) is an essential mineral for pigs and deficiency can cause rickets, osteomalacia or osteoporosis and has been associated with poor fertility and production performance. Traditionally P has been supplied in the inorganic form as the organic form found in cereal grain (phytic acid) is unavailable to pigs as they lack endogenous phytase. Dietary phytases have been shown to play a major role in pig diets, releasing P from phytic acid thus decreasing the need for supplementary P and reducing P excretion (Harper et al 1997). Phytase supplementation has also been reported to improve digestibility of nitrogen, calcium, magnesium, zinc and copper (Jongbloed et al 1993). Some researchers (e.g. Jongbloed and Kemme 1990) suggest that diet processing may reduce enzyme activity and therefore liquid enzyme products have been developed which can be applied after processing. The aims of this study were to examine the effectiveness of several phytase products (including dry vs. liquid) in improving overall digestibility and reducing excretion of P and other nutrients.

Structure of "phytic acids"

Evidence is presented to show that cereal grain phytic acid has the myoinositol hexaorthophosphate structure suggested by Anderson and not the hydrated myoinositol tripyrophosphate structure proposed by Neuberg. DL-Myoinositol 1,6:2,3:4,5-tripyrophosphate which is structurally related to the Neuberg formulation has been prepared. The "phytic acid" fraction from chicken blood has been shown to be predominantly 1,3,4,5,6-myoinositol pentaphosphate. The structures assigned to these compounds have been confirmed by 31P nuclear magnetic resonance.