Minimisation of vitamin losses in fortified cookies by response surface methodology and validation of the determination methods

Food fortification is one of the global strategies to decrease micronutrient deficiency in the society. Flour, cereal products including cookies, are significant vehicles for food fortification. In this study, flour was fortified with thiamine, riboflavin and niacin at a level to meet 25–35% of recommended dietary allowance for each vitamin. Cookies were produced using the fortified flour with some variation in baking temperatures (190, 205, and 220 °C) and baking times (9, 12, and 15 min). Effects of baking temperatures and baking times on quality characteristics, colour values, and vitamin contents of fortified cookies were investigated. The processing conditions were optimised by response surface methodology (RSM) to minimise the vitamin losses in cookies. The vitamin losses in the cookies produced at different baking temperatures and baking times were in the range of 1.8–50.0%, 1.6–24.4% and 0.6–11.9% for thiamine, riboflavin and niacin, respectively. Validation studies were also carried out and the results indicated that the equipment and the method were suitable for vitamin B analyses in cookies. Overall, the optimum conditions for minimum vitamin losses were determined as 190 °C baking temperature and 15-min baking time according to RSM.