Microencapsulation of bioactive compounds from peanut residues: stability study and application in yogurt

Peanut skin, a byproduct of peanut processing, is a rich source of phenolic compounds (520.65 mgGAE (100 g)^-1 d.b.) with strong antioxidant capacity, but which remains underutilized. The direct incorporation of phenolic extracts into dairy products is challenging, due to their instability during processing and storage and possible interactions that may affect product quality. Encapsulation techniques can improve the stability and functionality of these bioactive compounds. This study evaluated peanut skin as a sustainable source of phenolics and compared two encapsulation methods - spray drying and ionic gelation - to stabilize its extract prior to incorporation into yogurt, with quality monitored over 42 days of storage.

Spray drying with maltodextrin and ionic gelation using pectin-starch microparticles crosslinked with calcium chloride were applied as stabilization strategies. Both methods achieved high encapsulation efficiency (90-95%) and similar phenolic concentrations, although wet ionic gelation microparticles presented a more intense reddish color. During storage, the microparticles effectively preserved phenolic compounds, antioxidant activity, and color stability. When incorporated into yogurt, phenolic content reached 18.87 mgGAE g^-1 d.b. for spray-dried particles and 18.20 mgGAE g^-1 d.b. for wet particles. Antioxidant activity remained around 75%, while color variation was minimal (ΔE < 3.56). No significant changes were observed in acidity, proximate composition, or microbiological quality.

Peanut skin can be converted into a stable, value-added functional ingredient for yogurt. Both encapsulation techniques preserved the phenolic compounds and product quality during storage, representing a scalable and sustainable strategy to enhance the nutritional value of dairy products while reducing agro-industrial waste. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.