Hydrothermal processing of barley (cv. Blenheim):: Optimisation of phytate degradation and increase of free myo-inositol

Optimal conditions were developed for hydrothermal processing of whole barley kernels (cv. Blenheim) to degrade phytate (myo-inositol hexaphosphate) and to increase the content of free myo-inositol. The hydrothermal treatment comprised of two wet steeps, where lactic acid solution of different concentrations was used, and two dry steeps followed by successive drying. Experiments were performed as a central composite design and evaluated by multiple linear regression. The variables in the experiments were temperature in the first wet and dry steep (T-1), temperature in the second wet and dry steep (T-2) and lactic acid solution concentration in both wet steeps (C) and mathematical models were developed in these variables. Optimal conditions for maximal phytate degradation and for maximal increase of free myo-inositol were T-1 = 48 degrees C, T-2 = 48-50 degrees C and C = 0.8%, at these conditions the amount of phytate was reduced by 95-96% and the free myo-inositol concentration was increased from 0.56 to 2.45 mu mol/g d.m. We conclude that this hydrothermal process can be used to produce a barley product (cv. Blenheim) with a low phytate content and a high level of free myo-inositol. (C) 1999 Academic Press.