Microencapsulation of hop bioactive compounds by spray drying: Role of inlet temperature and wall material

This study explores the effect of spray-drying (SD) inlet temperatures (T_inlet 120 and 150 °C) and wall material on the chemical and physico-chemical properties of microencapsulated hop extracts (MHE). Hop extract was formulated with maltodextrin (MD) and gum Arabic (GA) used in single or in combination with β-cyclodextrin (βCD). MHE were evaluated for physical properties, bitter acids (BA), total polyphenol content (TPC) and encapsulation efficiency (TPC EE), and antioxidant capacity (AOC). Powders produced at T_inlet 150 °C exhibited the highest flowability and generally higher TPC yield. Besides T_inlet, MD enabled the obtaining of MHE with the highest encapsulation efficiency.

Highlights

• Spray-drying can be used to encapsulate hop extract successfully.
• Inlet temperature significantly affected the physico-chemical properties of powders.
• Wall materials affected powders’ physico-chemical properties based on the T_inlet.
• Beta-Cyclodextrin positively affected bitter acids when T_inlet 120 °C was used.

Other physico-chemical and antioxidant properties differently varied depending on the T_inlet. Overall, the βCD addition positively affected α-acids, and β-acids of MHE obtained at T_inlet 120 °C. ATR-FTIR analysis showed hydrogen bond formation between hop compounds and βCD. Multifactorial ANOVA highlighted that T_inlet, W, and their interaction influenced almost all the chemical and physico-chemical properties of MHE.

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Materials

Hop pellets T90 (batch E287/21/10595) of cv. Hallertau Herkules grown in Germany and harvested in 2021 were purchased from P.A.B. S.r.l. Mr. Malt (Pasian di Prato, Udine, Italy) and used in all experiments. The hop pellets were packed under vacuum in high-barrier plastic bags and stored at ‒40 °C until use.

The cv. Hallertau Herkules variety was chosen following preliminary tests characterizing seven varieties (Cascade, Opal, Hallertau Tradition, Perle, Magnum, Mandarina Bavaria, and Herkules) for their alpha and beta acid content, antioxidant capacity, total phenolic content, chlorophylls and carotenoids content, flavonoids and flavans content, and aromatic profile (data not shown). Since our work aims to preserve both the content of alpha and beta acids and the antioxidant properties, the Herkules variety was selected due to its favourable levels of alpha and beta acids and high antioxidant capacity compared to the other varieties examined.

For all the experiments food-grade wall materials were used i.e. maltodextrin DE12 (Glucidex®IT-12 Mw= 18.6 x 103 Da) was purchased from Roquette Freres (Lestre, France); gum Arabic was purchased from Kerry Ingredients & Flavours Ltd. Global Technology & Innovation Centre (Millennium Park Naas, Co. Kildare, IRELAND) and β-cyclodextrin (CAVAMAX® W7 FOOD, lot.no. 701651, purity > 98%) from Wacker Chemie AG (Hanns-Seidel-Platz München, Germany). All the reagents used for analysis were purchased from Sigma-Aldrich, (Steinheim, Germany).

Simona Tatasciore, Veronica Santarelli, Lilia Neri, Carla Daniela Di Mattia, Alessandro Di Michele, Dino Mastrocola, Paola Pittia, Microencapsulation of hop bioactive compounds by spray drying: Role of inlet temperature and wall material, Current Research in Food Science, Volume 8, 2024, 100769, ISSN 2665-9271, https://doi.org/10.1016/j.crfs.2024.100769.

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