Controlling of Auto Oxidation Process of Soft Dough Biscuits Using Flavonoids Extracted from Green Tea (Camellia sinensis)

"Since consumer attitude towards the artificial anti oxidant used in controlling of auto oxidation of fat in food products is gradually waning, finding out of alternative plant base anti oxidant sources for food products are important. Hence, aim of this study is to explore the possibility of using flavonoids, extracted from green tea in controlling of auto oxidation process in biscuits. 300g of green tea at 3.0% moisture content was taken and ground to get 150 micron particles. 25g of ground tea was subjected to decoction process to extract flavonoids. Since preliminary test results revealed that flavonoids concentration beyond 500ppm causes to disturb the taste profile of biscuits, three treatments of biscuits were prepared using 200ppm, 300ppm and 400ppm flavonoids to a standard biscuits recipe along with a control treatment without incorporating anti oxidant. Biscuits obtained from four treatments were stored under normal atmospheric condition in triple laminate pouches for a period of 6 months. Samples were drawn from each treatment monthly including just after preparation too to determine changes occurrence on peroxide value, free fatty acid level and organoleptic properties pertaining to five sensory stimuli such namely, aroma, crunchiness, texture and over all acceptability. All treatments were replicated thrice and results obtained from 4 treatments were finally compared with a commercial sample too. Results revealed that peroxide value of commercial biscuits, 200ppm, 300ppm and 400ppm flavonoids incorporated biscuits and biscuits in control treatment were increased from the initial value of 1.5 to 2.1, 2.9, 3.0, 3.5 and 10.5meq respectively during the period of 6 months. However, peroxide value of all treatments was remained below the standard value of SLSI (Sri Lanka Standards Institution) 10meq except the control treatment. In the case of free fatty acid level, which was also increased from the initial value of 0.25% to 0.4%, 0.6%, 0.65%, 0.8% and 1.6% in the same treatment order of above during 6 months. Free fatty acid level of all treatments was also remained below the standard value of SLSI (1.0%) except the control treatment. Sensory evaluation revealed that there was no significant difference between 300ppm and 400ppm flavonoids incorporated biscuits samples and the commercial product. Therefore, incorporation of 400ppm of flavonoids extracted from green tea is a viable option in controlling of auto oxidation process of soft dough biscuits. "