Suitability of quinoa fermented with Rhizopus oligosporus as an ingredient of biscuit

Abstract

To examine the possibility of using quinoa fermented with Rhizopus oligosporus (known as quinoatempeh or Q-tempeh) as an ingredient for daily-use food, soft and hard biscuits were prepared using soft flour and medium flour partially substituted with powdered quinoa and Q-tempeh, respectively. The physical properties, palatability and iron and a-tocopherol contents of the biscuits were compared with those of control biscuits prepared using 100% soft flour and medium flour. It was found that substituting 20% of the flour with powdered Q-tempeh or quinoa did not alter the thickness or volume of either type of biscuit. Substitution with quinoa powder did not affect the sensory evaluation scores of either type. Substitution with Q-tempeh powder resulted in higher sensory evaluation scores for brittleness and taste in soft biscuits, but the reddish surface color became slightly stronger. Thirty-percent substitution of flour with powder of quinoa and Q-tempeh resulted in a decrease in volume and hardness in both types of biscuit. Biscuits prepared with quinoa powder-substituted flour were given lower sensory evaluation scores in terms of the overall acceptability of hard biscuits due to their low solubility in the mouth, but substitution with Q-tempeh powder did not have the same effect. The iron and α-tocopherol contents of biscuits made with flour containing 20% Q-tempeh powder were more than 2.5 times higher than those of control biscuits. The absorption of iron from Q-tempeh powder was found to be higher than that of quinoa powder in rats for partial digestion of phosphoric compounds. These results suggest that Q-tempeh powder is more suitable than quinoa powder as an ingredient of biscuit, and may be added to flour in amounts of up to 20%. Moreover, Q-tempeh powder may be used to increase the iron and α-tocopherol contents of food products.