Physicochemical studies of sunflower oil based vitamin D nanoemulsions

Abstract

The cumulative scientific information available on the digestibility of cooking oils and their nutritive values has spurred interest in replacing synthetic oils with natural oils to encapsulate lipophilic bioactives in nanoemulsion form. Our aim was to design stable nanoemulsions that encapsulate maximum concentration of cholecalciferol (vitamin D₃) into edible oil for improved stability and bioaccessibility. Among the four cooking oils tested, sunflower oil nanoemulsions formulated by a low energy method were found to be stable and highly miscible with Tween 85 and isopropanol (1:1) surfactant mixture. Mean droplet size of these nanoemulsions encapsulating 0.1–0.% (w/v) of cholecalciferol varied from 57.7 ± 1.9 to 158.13 ± 1.8 nm, and the ζ-potential maintained beyond −30 mV with entrapment efficiency ranging from 94.1% to 95.7%. Nanoemulsions were found to be stable over a period of 28 days upon storage at 4, 25, and 40 °C with no significant change in vitamin D₃ content. Bioaccessibility studies using a simulated gastro-intestinal digestion model revealed release of 98% of the encapsulated vitamin D₃. This method reported here to fabricate cooking oil based nanoemulsions for encapsulation of VD₃ using simple formulations and inexpensive tools can have economic importance in therapeutic and food based approaches to enhance the quality of vitamin D nutrition.

Graphical Abstract

Keywords:

• Cooking oils
• ternary phase diagram
• emulsion phase inversion
• encapsulation efficiency
• simulated GIT digestion

Acknowledgements

The authors are grateful to the Department of Science and Technology, Science and Engineering Research Board (DST-SERB), Government of India, for funding Dr. Bodiga Vijaya Lakshmi's study (YSS/2015/001115). Mrs. Inapurapu Santhi Priya (09/459/(0016)/2015-EMR-I) received a JRF fellowship from the Council of Scientific and Industrial Research (CSIR), Government of India.

Authors’ contribution

SPI carried out all of the study's experiments and prepared the manuscript. in vitro simulated digestion experiments were supported by RP. SB contributed to the study's design, giving suggestions and comments on the experiment design, drafting the manuscript, and performing the statistical analysis. PSY contributed in VD₃ quantification. As the principal investigator, VLB planned, guided, and organized the report, as well as providing conceptual and technical guidance for all aspects of the paper and assisting in the drafting of the manuscript. The final manuscript was read and approved by all authors.