Some quality characteristics of cookies made of buckwheat, corn and rice flour and determination of their shelf-life

In this study, cookie dough prepared in laboratory conditions with 4 different flour combinations (buckwheat (100%), buckwheat-corn (50-50%), buckwheat-rice (50-50%), buckwheat-corn-rice (50-25-25%)) and with and without transglutaminase (TG) addition were baked in a traditional oven. After being packaged in modified atmosphere (70% N2 and 30% CO2), baked cookies were kept in an incubator in 25°C for 6 months. Proximate analyses were carried out on the buckwheat, corn and rice flours which were used separately or in combination in the dough recipe. Physical, chemical, structural and sensory analyses were carried out in the first day and once in every 30 days throughout storage on the cookies that were prepared. Following the analyses, changes in the quality features of the cookies wereinvestigated and their shelf-life determined. A marked difference was observed in the spread ratio value of the cookies that were produced using different types of flours or their combinations and TG addition. While it was observed that cookies prepared with buckwheat-rice flour (1:1) had the highest spread ratio, lowest spreadingratio was observed in cookies prepared with buckwheat flour (100%). The spread ratio value of the cookies containing TG was higher than the cookies which did not containing TG. Use of different flours or their combination affected the L* and b* values of the cookies during the storage but did not affect the a* value. Storage timeon the other hand affected all three values whereas TG addition did not have any effects either. While flour type or combination had a significant effect on the total starch content of the cookies. Cookies obtained with formulations containing tranglutaminase had a significantly lower resistant starch content. Flour type, tranglutaminase addition and storage timewere observed to have significant effects on TBA value of the cookies and values from oxidation to peroxide and p-anisidine of the oils extracted from the cookies throughout the 6-month storage period. The free fatty acidity value on the other hand was affected only by TG addition and storage duration. The shelf-life of the cookies were calculated using a mathematical-statistical approach with the SigmaPlot v12.0 program based on the results of the free fatty acidity. As a result of the sensory analysis performed, it was observed that the cookies that did not contain TG and are prepared with buckwheat-rice flour (1:1) have were generally preferred more by the panelists. The sensory values of the cookies decreased throughout the storage period. In consequence of the study, it was observed that the type of the flour used, TG addition and storage duration result in changes in physical, chemical, structural and sensory characteristics of the cookies.