347 Czech Journal of Food Sciences, 38, 2020 (6): 347–358 Review https://doi.org/10.17221/223/2020-CJFS Phenolic compounds are an internal physiological regulator in plants. Tey also afect the growth hor- mone auxin indole-3-acetic acid (IAA). Additionally, phenolic compounds are responsible for the protec- tion of plants from sunlight by absorbing short high- energy wavelengths. Tey can also protect the plants from insects and serve as an attractant for pollinators. Phenolic compounds can be released from the food matrix in the gastrointestinal tract by enzymes and pH conditions. Te released free phenolics are absorbed in the small intestine, followed by conjugation with other compounds, leading to their introduction into the blood circulation system. In recent years, a variety of bioactivities of phenolic acids have been reported such as anti-cancer activity, inhibitory activity against hepatitis C virus, anti-bacterial and anti-viral proper- ties, mitigation of angina pectoris and hypertension, efectivity against diabetes, cardiovascular disease, and neurodegenerative disease (Shahidi & Yeo 2016). An extrusion process modifes the functional prop- erties of ingredients and texturises them. Short-time processing gives a potential advantage for retaining phenolics compared to other heat treatments (Xu et al. 2017) but some authors found a great loss (> 50%) of phe- nolics during extrusion (e.g. Repo-Carrasco-Valencia 2009; Altan et al. 2009). Tus, researchers have investi- gated the improving of the nutritional profle of extrud- ed products by functional ingredients such as fruits, vegetables, or edible by-products (Shevkani et al. 2019; Zeng et al. 2019). Extrusion has also been reported to increase the total amount of bound phenolics while decreasing the free ones (Sarawong et al. 2014). In ad- dition, because sensory properties of extrudates are important, it is necessary to seek suitable composition of the input mixture and optimal parameters of the ex- trusion process. Common reasons for the use of extrusion to process bioactive mixtures are: • high content of nutritional substances such as vitamins or phenolics • re-use of by-products (wastes) from food tech- nology • decrease of the calorie content of the extruded food and inhibition of starch digestion • change in the colour of the product • gluten-free products. New food compositions to increase the content of phenolic compounds in extrudates Evžen Šárka*, Marcela Sluková, Petra Smrčková Department of Carbohydrates and Cereals, University of Chemistry and Technology Prague, Prague, Czech Republic *Corresponding author: evzen.sarka@vscht.cz Citation: Šárka E., Sluková M., Smrčková P. (2020): New food compositions to increase the content of phenolic compounds in extrudates. Czech J. Food. Sci., 38: 347–358. Abstract: Phenolic compounds are linked to a number of health benefts, including antioxidant, antibacterial, antigly- caemic, antiviral, anticarcinogenic, anti-infammatory and vasodilatory properties. To improve a great loss of phenolics during extrusion, researchers have investigated incorporating functional ingredients into the extrusion input mixture. Other reasons for the addition of active ingredients are the re-use of by-products from food technology, decreasing the calorie content of extruded food, inhibition of starch digestion, and the colour change of the gluten-free products. Te paper presents 28 examples of new designs for extrusion based on rice, corn, cassava, sorghum, and lentil fours and on other crops, together with the analyses of phenolics. Te present results show the highest total phenolic content in sorghum among cereals, and lentil four and orange peel powder among mixtures for extrusion to prepare extrudates. Te highest content of total favonols was found in the mixture containing corn and freeze-dried red and purple potatoes. Keywords: thermal processing; rice; sorghum; extrusion; phenolic acids; favonols