Development of hops-based ingredients with enhanced techno-functionalities

Currently, the food industry has started to decrease, eliminate or replace the use of synthetic additives with natural counterparts extracted from plants. Hop (Humulus Lupulus L.) represents a rich source of diverse secondary metabolites (e.g. bitter acids and polyphenols) of interest for both sensory and techno-functional properties. However, the instability of these compounds during storage and food processing has stimulated the use of different encapsulation techniques for their protection. Aim of this study was the development of new hop-based ingredients with enhanced techno functional properties and stability suitable for application in food products with improved functional and sensory properties. Hop extract was obtained from hop pellets using ultrasounds (100 Watt, 50 KHz) for 30 minutes. After solvent removal, the hop extract was formulated with maltodextrin (MD), gum Arabic (GA), a mixture of maltodextrin and β cyclodextrin (βCD), and GA and βCD in the proportion 1:1 (w/w). Spray-drying (SD) was used as encapsulation technology at two different inlet temperatures (Tinlet) (120 °C and 150 °C). After SD the powdered hop extracts were characterized for their moisture content (Mc), water activity (aw), solubility, hygroscopicity, water sorption isotherms, color, microstructure, bitter acids (BA), polyphenol content (TPC) and yield (TPC Y%), polyphenol encapsulation efficiency (TPC EE%), and antioxidant activity (AOA) by FRAP and ABTS assay. Results showed that the highest Tinlet enables the production of powders with lower Mc, aw, TPC, TPC Y%, AOA, and higher lightness, hygroscopicity, and TPC EE%. Samples encapsulated with MD compared to those encapsulated with GA showed a brighter and green-yellow colour and lower TPC EE%. Furthermore, GA and MD affected to different extent the other physical and chemical properties of the microencapsulated powders depending on the spray-drying Tinlet. The use of βCD as carrier in the formulation positively affected TPC, TPC Y%, bitter acids, and AOA but decreased the TPC EE%.