Effect of drying and extrusion processing on physical and nutritional characteristics of bilberry press cake extrudates

Mild drying and extrusion processing of side streams from berry juice production can enable retention of valuable compounds in the food chain and reduce waste production. The aim of this study was to evaluate the applicability of using hot air (HA) and microwave assisted hot air (MWHA) drying combined with extrusion for conversion of bilberry press cake into value-added extruded food products. Bilberry (Vaccinium myrtillus L.) press cake was dried at 40 °C by HA and MWHA drying to a moisture content of 17% (w/w). A twin screw extruder (average feed rate 72 g/min, temperature profile 135-128-89-69 °C) was used to extrude products containing organic wholegrain rye flour and 10 % or 25 % dried bilberry press cake powder. A consumer panel (n = 15) evalutaed four extrudates on hedonic and Just-about-rigth (JAR) scales, with a mian focus on textrue properties. The results indicate that different drying tecniques implied a difference in processing time (40 % reduction with MWHA drying). However, the retention of total phenolics, physical characteristics and sensory attributes of extruded snacks containing bilberry powders were independent of drying techniques. In sum, powder of bilberry press cake can be incorporated in cereal extruded snacks with enhanced phenolic content and potential for palatable sensory properties

Microwave-dried or air-dried? Consumers' stated preferences and attitudes for organic dried strawberries. A multi-country investigation in Europe.

Non-thermal food processing technologies are becoming more important in the organic food sector because, beyond preserving the organic feature, they could offer organic products with additional benefits in terms of enhanced nutritional content and healthiness as well as better sensory properties that could satisfy the more complex demands of organic consumers. Berries have a well-known health benefits and show increasing market shares in European markets while dehydration can increase the food convenience in terms of extended shelf-life. This study investigates for the first time organic consumers' stated preferences, attitudes and individual differences for a non-thermal organic processing technology. Specifically, we investigated consumers' preferences for organic dried strawberries varying in drying technology used, such as the most conventional (i.e. thermal) air drying and the most innovative (i.e. non-thermal) microwave drying, origin, price levels, and nutrient contents in three European countries: Norway, Romania and Turkey. Data from a total of 614 consumers were collected through an online choice experiment. Results show that on average consumers prefer organic dried strawberries produced with air drying technology that have national origin, with natural nutrient content and at low price, but country and individual differences are identified. Consumers who showed least rejection for microwave dried products are young, mostly from Norway and have higher positive attitudes towards new food technologies. Consumers who showed most rejection for microwave dried products are older, mostly from Turkey and have higher positive attitudes for organic, natural and ecological products. Organic producers who adopt microwave drying might better inform consumers about the characteristics, the process and highlight the nutritional benefits of such technology. Finally, this research informs policy makers about the need to define and regulate more clearly microwave drying as an organic technology, as well as to regulate labelling to ensure that consumers are not misled and correctly informed about the new technology