The composition of maturing Omani dates

The composition of two varieties of Omani dates, fard and khalas, was deter mined as maturity progressed. Free sugars and dietary fibre content were ex amined in detail. High-performance liquid chromatography (HPLC) of the extr acts showed that at the early green stage (Arabic kimri), dates contained s mall amounts of glucose and fructose. At the intermediate yellow (khalal) a nd red (rutab) stages, large amounts (500-565 gkg(-1) dry weight) of sucros e had accumulated, but no additional glucose or fructose was detected. At t he final mature (tamar) stage, all sucrose was converted to glucose and fru ctose (>800gkg(-1) dry weight). Dietary fibre, determined as non-starch pol ysaccharides (NSPs) by gas chromatography (GC), decreased from 250gkg(-1) ( kimri) to 50 gkg(-1) (tamar) on a dry weight basis. The principal monomers of NSPs were glucose, galactose, xylose, mannose, arabinose and rhamnose, O n a dry weight basis, pectin, protein and ash contents decreased as the dat es matured. On a fresh weight basis, changes in NSPs, pectin, protein and a sh could be attributed to loss of moisture and the accumulation of sucrose initially, or of invert sugar later as maturation progressed. (C) 1999 Soci ety of Chemical Industry.