Fig. 1

DNA extraction methods. A CTAB [6], B Wizard^® Magnetic DNA Purification System for Food (PROMEGA, REF: FF3751), C DNeasy mericon food (QIAGEN, Cat 69514). Lanes 1 and 17: 1 Kb Ladder (PROMEGA, REF: G571A), lanes 2–4 (flour): DNA extracted from banana and soy flour, pre-cooked maize flour. Lanes 5–7 (cereal): DNA extracted from oats, soy, and flakes. Lanes 8–10 (grain): DNA extracted from soy grain, microwave popcorn, and sweet corn. Lanes 11–13 (snack): DNA extracted from corn chips, cheese, and corn snacks. Lanes 14–16 (sausage): DNA extracted from pig, res, species sausages. The lanes were loaded with 5 µl of DNA samples. D A260/280 ratio from DNA extracted with CTAB method [6], Wizard^® Magnetic DNA Purification System for Food (PROMEGA, REF: FF3751), and DNeasy mericon food (QIAGEN, Cat. 69514), measured with NanoDrop™ 2000 (Thermo Scientific). Variance analysis using ANOVA in combination with Tukey test show significant differences within the DNA extraction methods in the snack and sausage group food. Values with the same letter are not statistically different (p > 0.05). Tukey test was made independently for each group food. The bars represent the standard error from the average (flour n = 10; cereal n = 4; grain n = 3; snack n = 4; sausage n = 14). The red line at 1.8 indicate the value optimum for 260/280 ratio