BRAZILIAN HULL-LESS AND MALTING BARLEY GENOTYPES: II. THERMAL AND RHEOLOGICAL PROPERTIES OF STARCH

ABSTRACT Thermal and rheological properties of starch isolated from two Brazil-ian barley experimental lines, malting and hull-less, are reported. Gelatini-zation’s thermal properties were T o 53.3 and 58C, T p 59.4 and 62.7C, and DH 6 and 6.8 J/g for the malting and hull-less starch, respectively. A trendto slightly higher retrogradation rates were obtained for the malting (73.3%)compared with the hull-less (72.1%) starch, while lower hot-paste peak andfinal viscosity were observed in the former (125 and 114 RVU versus 169and 179 RVU, respectively). Changes in storage ( G′ ) and loss ( G″ ) moduliduring heating and cooling showed higher values for the starch from thehull-less line. During heating, G′ was higher than G″ and developed athigher temperatures. A trimodal distribution pattern of G″ was observed inthe starch from the hull-less barley line. Two G′ peaks at 75 and 87.5C were6.2 and 2.4 times higher, respectively, in the starch from the hull-less linethan that from the malting line.