Microencapsulation of niger seed oil: Impact of protein types, maltodextrin ratios, and drying methods on stability and functional properties

Authors: SUNDAR, SHYAM - Guru Nanak Dev University; SINGH, BALWINDER - Khalsa College; KAUR, AMRITPAL - Guru Nanak Dev University; Yadav, Madhav

Submitted to: Food Hydrocolloids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/2025
Publication Date: 5/19/2025
Citation: Sundar, S., Singh, B., Kaur, A., Yadav, M.P. 2025. Microencapsulation of niger seed oil: Impact of protein types, maltodextrin ratios, and drying methods on stability and functional properties. Food Hydrocolloids. https://doi.org/10.1016/j.foodhyd.2025.111553.
DOI: https://doi.org/10.1016/j.foodhyd.2025.111553

Interpretive Summary: Niger seed oil (NSO) is a bioactive-rich oil known for its antioxidant, anti-inflammatory, antimicrobial, antifungal, and anticancer properties. However, its high unsaturated fatty acid (UFA) content, particularly linoleic acid, make it prone to oxidative degradation. This prompted scientists to explore the microencapsulation of NSO to make it stable and enhance its functional attributes. Maltodextrin (MLD) in combination with protein is commonly used as a wall material to emulsify and trap essential oil for its stabilization, and microencapsulation. In this study, we have used three easily available protein isolates—whey protein isolate (WPI), soy protein isolate (SPI), and pea protein isolate (PPI). These protein isolates were mixed with maltodextrin in four different ratios (1:1, 1:2, 1:3, and 1:4), and treated under pressure to make their uniform solution. Then they were dried to powder by spray drying and freeze-drying scientific processes to make the microencapsulated NSO powder. By studying these microencapsulate NSO powders, scientists found that WPI outperformed SPI and PPI, showing superior solubility, emulsifying capacity, and rehydration properties, resulting in microcapsules with the highest encapsulation efficiency (EE) and oxidative stability. A higher protein to MLD ratio (1:4) enhanced the flowability and bulk density of microcapsules. Spray drying produced microcapsules with smaller particle sizes, higher EE, and improved oxidative stability, making it a more effective drying process than freeze drying. In contrast, freeze drying process produced porous structures leading to reduced EE and lower oxidative stability. This study advances the stabilization of bioactive-rich oils, making them highly beneficial ingredients for adding in functional food and health products. This finding will benefit the USA niger seeds growers and processor.

Technical Abstract: In this study, the influence of protein isolate types (whey, soy, and pea protein isolates), protein-to-maltodextrin (MLD) ratios (1:1, 1:2, 1:3, and 1:4), and drying methods (freeze drying and spray drying) for enhancing stability and functional properties of microencapsulated niger seed oil (MNO) was investigated. The protein isolate type and MLD ratio significantly influence the physicochemical properties, encapsulation efficiency (EE), and oxidative stability of MNO. The whey protein isolate (WPI) exhibited superior solubility, emulsifying capacity, and rehydration properties than the soy and pea protein isolates. The MLD ratio impacted viscosity, bulk density, and oxidative stability, with the higher MLD ratios (1:4) resulting in lower viscosity and bulk density whth higher flowability. The spray drying produced microcapsules with smaller particle sizes, higher EE, and enhanced oxidative stability while freeze drying resulted in more porous structures with lower EE. The encapsulation process significantly improved the oxidative stability of niger seed oil (NSO), with WPI-based microcapsules exhibiting the highest stability. The results suggest that the optimization of protein-to-MLD ratio and drying method are important in maximizing the EE, particle size, and stability of MNO powder.