The microencapsulation of tea and herbal extracts is gaining considerable attention in the food industry, particularly in the production of instant powders. This review examines the application of spray-drying and freeze-drying technologies for the encapsulation of bioactive compounds, focusing on the role of wall materials. Over the past two decades, carbohydrate-based (e.g., maltodextrin), gum-based (e.g., gum Arabic), and protein-based (e.g., whey protein isolate) materials have been widely used due to their impact on sensory properties, stability, protection of bioactive compounds, and other critical attributes of encapsulated products. Despite their widespread use, these materials have distinct advantages and limitations, such as cost, availability, and compatibility with different extracts. This review provides a comprehensive analysis of their physical and chemical properties, examines alternative and emerging wall materials (e.g., beta-cyclodextrin, sodium alginate, and inulin), and highlights the potential of combining different materials to optimise encapsulation outcomes. It also identifies current research gaps and future directions to improve the efficacy and quality of encapsulated tea and herbal powders.

In this investigation, the antioxidant capacity of stirred-type hypoallergenic and lactose-free yogurt was improved using cylindra-type beetroot peel extract. Milk proteins were hydrolyzed with papain at different concentrations (0.008 g·L⁻¹ and 0.012 g·L⁻¹) and, subsequently, milk with papain-hydrolyzed proteins were fermented with yogurt starter culture with or without lactase. Antioxidants and betalains were extracted from beetroot peel using microwave heating-assisted water extraction. Extraction was performed considering different amounts of beetroot peel (10 g·L⁻¹, 30 g·L⁻¹ and 50 g·L⁻¹) and temperature-exposed times (1 min, 3 min, and 5 min) at 450 W power. The extract with highest antioxidant capacity was incorporated into papain-treated and starter culture-fermented yogurt at different amounts (10-, 20-, 30-, and 40-volume%). Papain hydrolysis of milk proteins followed by starter culture fermentation of milk significantly reduced the allergenicity of yogurt (>90% with 0.012 g·L⁻¹ of papain and lactase) than control. Addition of 30% beetroot peel extract after post-fermentation stage significantly enhanced the red colour intensity of yogurt. The antioxidant capacity of yogurts produced by hydrolysed milk proteins by 0.012 g·L⁻¹ of papain and starter culture fermentation with lactase was improved approx. 3.5-fold than control due to the addition of 40% beetroot peel extract after fermentation.

This study explores the use of microwave-assisted extraction of bioactive compounds from peppermint (Mentha piperita L.) using aqueous ethanolic and β-cyclodextrin solvents. The experiments were performed according to Response Surface Methodology, and the central composite design was employed, with the independent variables being treatment time, microwave power and solvent concentration. During the research, the total polyphenol content (TPC, expressed as gallic acid equivalents, GAE), total flavonoid content (TFC, expressed as quercetin equivalents, QUE), antioxidant capacity (AC) using the FRAP (Ferric Reducing Antioxidant Power, expressed as ascorbic acid equivalents, ASE) and DPPH (2,2-diphenyl-1-picrylhydrazyl) methods, and total menthol content (TMC, expressed as menthol equivalents, MEE) were examined. For the ethanolic extraction, the optimum conditions were 571 W, 7.3 min, and 10% v/v. The following results were obtained for these parameters: TPC, 1025 µg GAE/mL; TFC, 66.69 µg QUE/mL; FRAP, 3786.24 µg ASE/mL; DPPH, 80.24%; and TMC, 62.63 µg MEE/mL. In the case of β-cyclodextrin, the optimum conditions are 800 W, 11.81 min, and 1.70 mM. In this case, the results are as follows: TPC, 949.29 µg GAE/mL; TFC, 90.75 µg QUE/mL; FRAP, 4275.54 µg ASE/mL; DPPH, 89.81%; and TMC, 84.99 µg MEE/mL. β-cyclodextrin increased the flavonoid, antioxidant and menthol content, although there were no significant differences between the concentrations. The use of ethanol had a greater effect on the polyphenol content. β-cyclodextrin proved to be an effective green alternative solvent for peppermint.