Journal of Cereal Science 25 (1997) 83–91 Phytate Reduction in Whole Grains of Wheat, Rye, Barley and Oats after Hydrothermal Treatment K. Fredlund*, N.-G. Asp*, M. Larsson², I. Marklinder‡ and A.-S. Sandberg² *University of Lund, Chemical Center, Department of Applied Nutrition and Food Chemistry, P.O. Box 124, S-221 00 Lund, Sweden, ²Chalmers University of Technology, Department of Food Science, P.O. Box 5401, S-402 29 Go ¨ teborg, Sweden, and ‡University of Uppsala, Department of Domestic Sciences, Dag Hammarskjo ¨ ldsv. 21, S-752 37 Uppsala, Sweden Received 18 August, 1995 ABSTRACT Whole grains of different cereals have traditionally been prepared with water and heat prior to dehulling, but knowledge of the effect on nutritional properties is limited. The aim of the present study was to investigate if phytate reduction occurred during hydrothermal treatment of whole grains. Wheat, rye, hulled and dehulled barley, hulled oats and naked oats were incubated with either water or acetate buffer (pH 4·8) at 55 °C for 24 h with the exception of oats, which were incubated at 37 °C. Phytate in wheat, rye and barley was reduced by 46–77% when water was used and by 84–99% when acetate buffer was used. The phytate reduction in oats was considerably less, 8–26%, but, after grinding and soaking, phytate was reduced by 72–77% in dehulled oats and by 88–94% in naked oats. Citric acid and citrate buffer was used for pH adjustment in some experiments, and their use resulted in less phytate reduction than when acetate and lactic acid were used. Wet-steeping of naked oats and naked barley in water at 53–57 °C for 20–30 min reduced the bacterial counts by 99·97%, and the addition of acid prevented bacterial growth during the incubations. It was concluded that cereals with reduced phytate content and good hygienic quality can be developed and produced using hydrothermal treatment of whole grains.  1997 Academic Press Limited Keywords: whole grains, phytate reduction, hydrothermal treatment. over many hours and became warm through the INTRODUCTION procedure. Hulled oats were steeped in hot water, Cereals have been a basic food for the past 10 000 kept in a warm place over night and dried in an years. Until the industrial period, cereals, such as oven. After processing, oats were easily dehulled barley and oats, were treated by hydrothermal in a grain pound. The hulls were separated from techniques prior to dehulling 1–3 . The grains of the kernels by the winnowing, or were sifted out cereals, such as barley, rice, millet and dinkel, after milling. Hydrothermal techniques are still were dehulled by pounding in a mortar after practised in some countries. sufficient water had been added to prevent dis- Phytate is present in all cereals and contains integration of the grains. The grains were pounded 50–85% of the total content of phosphorus 4,5 . Phytate negatively affects the bioavailability of many essential elements, such as calcium, iron and  : IP 3 –IP 6 =Inositol tri-, tetra-, pen- zinc 6–12 . ta- and hexaphosphate; c.v.=cultivar; cfu=colony Phytase, a naturally occurring enzyme in cer- forming units; pHd=pH measured directly; pHh=pH eals, hydrolyses phytate (myo-inositol hexaphos- measured after homogenising; d.m.=dry matter. phate) to myo-inositol and inorganic phosphates Corresponding author: K. Fredlund, College of Kalmar, Department of Natural Sciences, P.O. Box 905, S-391 29 Kalmar, Sweden. via intermediate myo-inositol phosphates (penta- 0733–5210/97/010083+09 $25.00/0/jc960070  1997 Academic Press Limited