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.

Galacto-oligosaccharides (GOS) are prebiotics manufactured enzymatically from lactose as substrate. The growing GOS market facilitates the valorization of dairy by-products which represent cheap and abundant sources of lactose. Large-scale GOS production typically employs soluble enzymes in batch reactors that are commonly associated with low enzyme usability and, therefore, high operational expenditures. In this study, we investigate the possibility of recovering enzymes by ultrafiltration (UF) and reusing them in repeated reaction steps. The proposed process scheme included 24 h batch reaction steps with Biolacta N5, a commercial enzyme preparation of Bacillus circulans origin. The reaction steps were followed by UF steps to separate the carbohydrate products from the enzymes by applying a volume concentration factor of 8.6. Then, the collected biocatalysts were reused for repeated cycles by adding fresh lactose. Enzyme losses were quantified with a direct method by analyzing the underlying relationship between reaction rates and enzyme dosage obtained from additional experiments conducted with known enzyme loads. Within five cycles, the enzyme activity declined gradually from 923 to 8307 U·kg⁻¹, and the half-life was estimated as ca. 15.3 h. The outcomes of this study may serve as a basis for further optimization of the reported process scheme with enhanced enzyme usability.

Grape pomace is a phenolic-rich by-product of grape processing with notable antioxidant properties, yet the valorization potential of pomace derived from unripe grapes (UG) used for verjuice production remains poorly characterized. Unlike ripe grape (RG) pomace, which has been extensively studied, there is a lack of fraction-specific data comparing the phenolic content and antioxidant capacity of UG and RG pomace. This study compared the phenolic content and antioxidant capacity of pomace fractions (seeds, skins, and stems) obtained from UG and RG of the white cultivar Bianca, processed under identical conditions. Ethanolic extracts were analyzed for total phenolic content (TPC), total flavones and flavonols content (TFFC), ferric reducing antioxidant power (FRAP), and DPPH radical scavenging activity. Pomace fractions were analyzed in triplicate, and differences between maturity stages were evaluated statistically. Seed fractions showed the highest values, with UG seeds reaching 104 ± 1.5 mg GAE/g DW (TPC) and 1720 ± 198 µmol AAE/g DW (FRAP), exceeding RG seeds by 38% and 78%, respectively. Overall, UG fractions consistently exhibited higher phenolic content and antioxidant activity than RG fractions across most measurements. In contrast, TFFC trends differed among fractions, reflecting the selectivity of the AlCl₃ method toward flavones and flavonols. These findings demonstrate that pomace generated during verjuice production possesses substantially higher antioxidant potential than corresponding pomace from ripe grapes. The results highlight verjuice-derived pomace as a promising source of natural antioxidant ingredients for food and nutraceutical applications, supporting its valorization within circular economy frameworks.