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Novel approach in food fortification by using natural deep eutectic solvent (NADES) was studied. Cocoa byproducts were chosen as sustainable source of polyphenols and extracts were prepared following the green extraction principles by using NADES. Antioxidative and biological activities of prepared extracts rich in polyphenols were determined and they were used for fortification of chocolate milk. Furthermore, electronic tongue analysis combined with SIMCA multivariate data analysis was used for the first time, to evaluate the sensory acceptability of chocolate/cocoa drinks with addition of NADES extracts, which is after safety issues, surely one of the most important features for possible application of those extracts in food industry. Based on presented results it is evident that carefully selected NADES could be used for efficient extraction of polyphenols from cocoa by-products and that obtained NADES extracts could be used for fortification in food industry, without removal of extraction solvent, since they are proven safe and estimated as sensory acceptable.

Millet is an unexploited cereal with potential in the food industry due to its nutritional value and resistance to harsh climate conditions. Nutritious millet byproducts have a potential application in the development of functional cereal products, but require processing in order to improve their physical and nutritional quality. Therefore, we investigated high intensity ultrasound as a pretreatment to increase the amount of freely available bioactives from proso millet bran. We also analysed the effect of high intensity ultrasound on enzymatic browning, water retention and protein digestibility, which are crucial for the utilization in the bakery and pasta industry. A 15 % millet bran suspension in water was treated with 400-W ultrasound probe for 5, 12.5 or 20 min, with the 60, 80 or 100 % amplitude. High intensity ultrasound treatment with 80 % amplitude for 12.5 min improved most significantly the nutritive value; the antioxidant activity measured by FRAP test increased by 15 % (p<0.05), and total phenolic content by 16 % (p<0.05). Still, the impact on the increase of water-soluble and ethanol-insoluble dietary fibre by 38 % was evident after the treatment for 20 min at 100 % amplitude. High intensity ultrasound treatment at 100 % amplitude for 5 min caused the largest improvements in water retention and limited browning of the sample. High intensity ultrasound treatment activated polyphenol oxidase, regardless of the applied heating of the sample. Due to its ambiguous impact on proso millet bran characteristics, the treatment required an optimization, which showed that the optimal pretreatment of a 15 % millet bran suspension in water is at 100 % amplitude for 9.3 min.

Summary Buckwheat hulls (BWH) are a lignocellulosic material with valuable nutrient contents, especially rutin and dietary fibre, which are worth exploring from a food industry perspective. BWH are also a voluminous material that is difficult to grind to very fine particle sizes, which can be achieved under cryogenic conditions. Therefore, we investigated the effect of fractionation by cryo‐grinding and size separation (<56, 56–180 and >180 µm) on the dietary fibre content and bioactive profile of BWH. While we hypothesised that micronisation would increase fibre solubility and release of bioactive compounds, we found that BWH must be fractionated to a size <56 µm to show a significant increase in soluble fibre content (106%), rutin (66%), total free phenolic compounds (94%) and antioxidant capacity (45–63%). Moreover, we have shown that near‐infrared spectroscopy combined with partial least squares regression can be easily used for rapid scanning of BWH to select the most suitable pre‐processing conditions for maximum nutritional value of this food industry by‐product.