Nutrient composition and in-vitro starch hydrolysis of acacia colei (Maslin and thompson) seeds as affected by year of harvest

Acacia colei seed is traditional food of the Australian Aboriginal people with remarkable potential as famine food because of its ability to thrive on poor soil with low precipitation and long shelf life which was attributed to its hard seed coat. However, the impact of prolong storage on nutritional value and starch digestibility of A. colei seed flour have not been investigated. This study investigates the nutrient composition and in- vitro starch hydrolysis of Acacia colei seeds harvested and stored for a number of years. Proximate composition,minerals,starch, sugar and available lysine contents were analyzed by standard methods; fat and water soluble vitamins were analyzed using spectrophotometric method and high performance liquid chromatography (HPLC), respectively. The results revealed that crude protein and ether extract varied within 10% with harvest year. Reducing sugar did not follow any discernible trend but available lysine and vitamins decreased with year of storage. Total sugar ranged between 139.8 and 178.7 g / kg while starch was between 322.1 and 351.6 g / kg.A. colei 2006 had the highest initial rate of starch hydrolysis (t1/2 = 32.0 min) followed by A. colei 2002 (38.3 min) and A. colei 2009 (44.2 min) while A. colei 1995 recorded the least (49.7 min). The hydrolysis (HI) and glycemic (GI) index values indicated that A. colei 2002 can be ranked high, A. colei 2009 as medium while A. colei 1995 and A. colei 2006 as low. The effect of year of harvest and storage may affect nutritional parameters making their prediction difficult.