Morphological, functional and thermal characteristics of hydroxypropylated-crosslinked barley starches

The present study investigated effects of three different levels of crosslinking using a mixture of sodium trimetaphosphate (STMP) and sodium tripolyphosphate (STPP) on hydroxypropylated barley starches. Hydroxypropylated barley starches crosslinked with 1%, 1.5% and 2% mixture of STMP and STPP were coded as HPCL(1), HPCL((1.5))and HPCL(2.0), respectively. However, the level of hydroxypropylation employed was same for all the modifications i.e. 6%. The results showed that increase in level of crosslinking increased swelling power, solubility and water holding capacity of starches. HPCL((2.0))starch demonstrated noticeably lower percent transmittance, higher percent retrogradation and elevated peak viscosity. Harder gels were produced by dual modified barley starches. A decline was observed in thermal transition temperatures after dual modification. FTIR was unable to detect much difference among different samples. However, peak at 1414 cm(-1)associated with hydroxypropylation was detected. Hydroxypropylation followed by crosslinking led to roughness and grooves formation on the surface of barley starch granules.