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The influence of flour type and dough pH on 3D printing precision and colour of wholemeal snack

Cereal snack foods of tailored nutritional value and structure can be made by 3D printing. Still, 3D printing brings many challenges that need to be resolved, such as the precision of printing and the appearance of printed dough. Usual ways for increasing cereal foods nutritional value is through usage of wholemeal flours and bran, which can impair the quality of traditional snack products. Thus, this study aimed to investigate the influence of wholemeal flour type (oat or barley) and dough pH (5.4, 6.2 and 7.0) on the precision of 3D printing and the colour of 3D printed dough. The recipe consisted of oat or barley flour, wheat bran, pea proteins, sunflower oil, salt, and water, without or with baking soda or citric acid (to obtain pH=7.0 and pH=5.4, respectively). Snack dough was 3D extruded using Createbot S3 printer. The precision of 3D printing was determined by digital image analysis as the proportion of white pixels, using ImageJ software, and calculating the deviation of printed samples from the desired shape. Dough colour was determined by measuring lightness (L*), red index (a*) and yellow index (b*) using spectrophotometer (Konica Minolta CM-700d, Japan). The precision of 3D printing was significantly affected only by dough pH (p=0.02) ; it was higher as the dough pH was lower. Overall, oat dough at pH 5.4 was printed with the highest precision (95%). The opposite, dough lightness was significantly (p<0.05) greater at higher pH. The intensity of red colour of 3D printed dough was significantly (p=0.04) affected by the interaction of flour and pH ; it was the greatest for barley dough at pH 5.4 and 6.2 (3.40 ± 0.26 and 3.34 ± 0.15, respectively). Yellowness was also influenced by the flour choice and pH (p<0.01), being the most intensive (16.86) for barley dough at pH 5.4. We can conclude that dough from wholemeal oat and barley flour can be 3D printed with high precision, but its pH value should be carefully adjusted. Future studies should investigate the processing parameters of 3D printing which might affect the 3D printing precision of wholemeal dough.

Snack 3D printing precision, wholemeal oat flour, barley flour, dough colour, pH value

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