Effect of phytase supplementation on micronutrients dialyzability in wheat bran
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Date
2021-09
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CCSHAU, Hisar
Abstract
Bread wheat, a staple cereal, have considerably low amount of iron (Fe) and zinc (Zn) bioavailability mainly due to the presence of phytic acid (PA; myo-inositol-1,2,3,4,5,6-hexakisphosphate), a phosphorus storage form in seeds, as a potent chelator of divalent cations. Wheat bran (WB) is a residue of the rolled milled wheat grain and it is rich source of dietary fibres, minerals, inorganic phosphates, vitamins, and tannins. The major portion of PA is accumulated in aleurone layer and globoid crystals of wheat. The PA chelates of Fe and Zn is a major source of concern for monogastric animals as lack of suitable digestible enzyme make this complex insoluble and decreases bioavailability of these micronutrients. Supplementation of exogenous phytase for dephytinization and value addition of cereals based foods is considered as a promising approach. In present study, experimental five wheat varieties were taken and their bran samples were collected for determining their chemical and biochemical properties (including content of PA, tannin, total dietary fibre, protein, inorganic phosphate, Fe and Zn) affecting the micronutrient bioavailability by either way. Significant variation was noticed in dietary fibre, crude protein and micronutrient content. Exogenous phytases from two different sources (fungal phytase from Aspergillus orizae strain SBS50 and wheat phytase from Sigma-Aldrich) were used to treat the wheat bran samples and determine their effects on above parameters. Phytase untreated samples were taken for comparative analysis of results obtained. For phytase treatments, 0.2 U/g phytase enzyme was used for both enzyme and results revealed that the PA content and tannin content was reduced by phytase treatment in the range of 37.2-39.5 % with wheat phytase and 7.90-33.33 % with Aspergillus phytase, respectively. Wheat phytase treatment was found more effective for PA, whereas, the Aspergillus phytase was found more effective in increasing the inorganic P content in treated bran samples. The inorganic P content in phytase treated bran sample was increased in the range of 16.30-29.62 % over untreated with maximum content was obtained in bran of WH 711 &WH 1021. Protein content after phytase treatment was increased for crude protein, whereas, soluble protein content was reduced to different extent. It was revealed that under given experimental conditions, phytase treatment resulted in decreased micronutrient dialyzability to different extent, with 7.11-45% reduction with wheat phytase treatment. Overall, wheat phytase treatment was found as comparatively better over Aspergillus phytase under given experimental conditions and bran of WH 1021 was found superior in studied quality attributes under given treatments. It is proposed to conduct the similar study with higher dose of phytase enzyme and in vitro digestion similar to gastric conditions before dialysis could give a greater and better insight into this area. The decreased dialyzability might be associated to experimental conditions and lower phytase dose. However, the results of the study showed that adding phytase to wheat bran improved its nutritional value for food applications.