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Natural bioactive compounds (BCs) are types of chemicals found in plants and certain foods that promote good health, however they are sensitive to processing and environmental conditions. Microencapsulation by spray drying is a widely used and cost-effective approach to create a coating layer to surround and protect BCs and control their release, enabling the production of high functional products/ingredients with extended shelf life. In this process, wall materials determine protection efficiency, and physical properties, bioavailability, and storage stability of microencapsulated products. Therefore, an understanding of physicochemical properties of wall materials is essential for the successful and effective spray-dried microencapsulation process. Typically, polysaccharide-based wall materials are generated from more sustainable sources and have a wider range of physicochemical properties and applications compared to their protein-based counterparts. In this review, we highlight the essential physicochemical properties of polysaccharide-based wall materials for spray-dried microencapsulation of BCs including solubility, thermal stability, and emulsifying properties, rheological and film forming properties. We provide further insight into possibilities for the chemical structure modification of native wall materials and their controlled release behaviors. Finally, we summarize the most recent studies involving polysaccharide biopolymers as wall materials and/or emulsifiers in spray-dried microencapsulation of BCs. [ABSTRACT FROM AUTHOR]

Polyphenols are commonly retrieved from plant material with solid-liquid extraction, the optimization of which requires fundamental laboratory-scale investigation, to clearly identify variables and variable levels crucial to the process. When performing scaling-up, the process result should be the anticipated one, irrespective of the scale adopted. However, the use of different equipment (extractor) might affect key parameters pertaining to extraction performance, providing diversified outcome for the same plant matrix extracted with a given solvent. To test this hypothesis, potato peels were chosen as a model plant matrix and extraction optimization was carried out using water/ethanol mixtures. All process variables (ethanol concentration, liquid-to-solid ratio, stirring speed) were maintained unchanged, except for extractor volume, which varied from 25 to 250 mL, and stirring bar length, which varied from 19 to 40 mm. The set of optimized values in each case was different, illustrating the effect of extractor dimensions on the extraction optimization. However, extraction yield in total polyphenols was essentially the same in cases examined. Kinetics also revealed that depending on the extractor volume and stirring bar length, extraction rate constant and diffusivity may be significantly impacted. Notable differences were also found in the major potato peel polyphenols, chlorogenic and caffeic acids, but these differences were not reflected on the antioxidant characteristics of the extracts, which were virtually unaffected. This study demonstrated for the first time that extractor dimensions affect significantly the settings of optimization of stirred-tank polyphenol extraction on a laboratory scale, leading to diversified conclusions. [ABSTRACT FROM AUTHOR]