In this study, we designed high fiber cookie recipe without using additives by means of extrusion-based 3D printing. We aimed to relate printing quality and cookie physical properties with dough rheology and dietary fiber content depending on the flour (oat, rye, rice, and carob flour) and fat type (olive oil or butter). The flour choice influenced all cookie quality parameters: baking loss, color, line height and width, and dietary fiber content. Results indicated that lower baking loss and better printing quality were obtained for cookie dough containing olive oil, which had higher viscosity and consistency coefficient compared with dough containing butter. Cookies with olive oil in which part of the oat flour was replaced with rye and carob flour were printed with high accuracy (≥98%), close to the ideal 3D shape. Overall, this study demonstrates the importance of selecting fat and particularly flour, as well as the extrusion rate on the quality and repeatability of 3D-printed cookies.

3D printing is an emerging technology that offers the ability to produce tailor-made foods. This work addresses the physical properties of 3D-printed snacks enriched with wheat bran as a function of flour type (oat, barley), addition of acidity regulators (citric acid, sodium bicarbonate), printing temperature (20 °C, 30 °C, 40 °C), and bran pre-processing (high-intensity ultrasound, vacuum microwave and pulsed light). Polyphenol oxidase activity, total phenolic content, antioxidant activity of bran, the viscosity profile of the flour-bran blend, the precision of 3D printing and browning kinetics of the physical properties of the dough and of baked snacks were investigated. During 1 h required to print ten pieces, the dough became very distinctly darker. Adjusting the printing temperature to 20 °C and adding sodium bicarbonate resulted in a dough, which changed colour less, but still very distinctly. Bran pre-processing inactivated polyphenol oxidase activity by 77-92%, which stopped browning of the dough within 50 min without affecting the printing precision. The use of ultrasound, vacuum microwave and pulsed light could be extended to other food components to achieve a greater inactivation of undesirable enzymes. Preprocessing techniques resulted in minor differences in the baked snack, so their future choice depends mainly on the amount of water that can be added to the recipe.

No abstract

High voltage electrical discharge (HVED) plasma processing receives more and more attention due to its potential to assure microbial safety and retain quality of treated products. The influence of combined thermal and high voltage electrical discharge plasma treatment on apple juice quality was investigated. Apple juice samples were treated under defined plasma treatment parameters of time (3, 6 and 9 min), frequency (60, 90 and 120 Hz) and temperature (30, 40 and 50 oC) in hybrid plasma reactor. Prior to treatment, juice samples were inoculated with Saccharomyces cerevisiae ATCC 204508 to investigate inactivation possibilities of plasma treatment on yeasts as common juice microorganisms. Quality parameters (pH, electrical conductivity, phenolic content and antioxidant activity) of treated and untreated apple juice were investigated and compared. Results have shown effectiveness of HVED plasma treatment in yeast inactivation up to 6.6 log10 in 9 min of treatment at 120 Hz and temperature of 40 oC. In treated samples there were no significant changes in phenolic content.

The aim of this study was to investigate the influence of high intensity pulsed electric field (HIPEF) technology on the stability of total phenols, anthocyanins, hydroxycinnamic acids, flavonols, and condensed tannins in strawberry juices (Fragaria x ananassa Duch. cv. ‘Albion’) with different ripening stages (75% and 100%) and stored at +4 °C for 7 days. The HIPEF parameters studied were: (i) electric field strength (40 and 50 kV cm−1), (ii) frequency (100 and 200 Hz), and (iii) treatment duration (3 and 6 min). Of the HIPEF parameters studied, electric field strength and frequency had a statistically significant effect on the content of all phenolic compounds. Treatment duration showed no statistically significant effects on phenolic compounds except for flavonols and condensed tannins. Storage had a positive effect on the stability of most of the phenolic compounds, with the exception of flavonols. Optimization of HIPEF processing showed that strawberry samples at both ripeness levels were suitable for HIPEF treatment to obtain functional fruit juices with a high content of polyphenols.