2.2.2. Preparation of Biscuits

First step was to formulate the four flour blends (100:0, 90:10, 75:25 and 60:40 WF:RFSF, w:w). The flour blends were stored in air-tight containers until further use. The second step was premixing margarine (60% fat) with powdered sugar into a cream base and then mixing that with the flours, instant whole milk powder (26% fat and 26% protein), sodium bicarbonate, vanilla essence and water. The doughs were mixed for seven min in a mixer (KitchenAid® Precise Heat Mixing Bowl, Greenville, OH, USA), at medium speed. Mixing, resting and baking technological parameters are listed in Table 1. The control sample was prepared using the same procedure, but omitting the flaxseed. The dough was rolled out into circular shapes of 0.4 cm thickness and then the biscuits were shaped by stamping with cylindrical shapes into 5.5 cm diameter. After baking (Zanolli oven, Verona, Italy) all biscuits samples were removed from the trays for cooling, then packed in polypropylene bags and sealed until further analysis. Biscuit samples were coded as B0, B10, B25 and B40, respectively, taking into consideration the amount of RFSF (0%, 10%, 25%, 40%) as shown in Table 1. Each batch of biscuits was made the day before the sensory, texture and volatile analysis.


**Table 1.** Ingredients and technological parameters used in the preparation of biscuits.

Note: \* B0 = 0% biscuits with 100% wheat flour (control sample); B10 = biscuits with 10% RFSF; B25 = 25% biscuits with 25% RFSF; B40 = biscuits with 40% RFSF. \*\* The auxiliar materials are reported to 100% of flour blends.
