Srujana Mekala | ALES Graduate Seminar

A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES PhD Final Exam Seminar by Srujana Mekala. This seminar is open to the general public to attend, either in person or online:

https://ualberta-ca.zoom.us/j/93608434736?pwd=Q0Y3YzkxYkYxbkRWTWRidVYxQ21xZz09

Meeting ID: 936 0843 4736
Passcode: 195698

Thesis Topic: Novel development of lentil protein and pectin-based vitamin delivery systems using high-intensity ultrasound and supercritical carbon dioxide technologies

PhD with Drs. Marleny Aranda Saldana and Lingyun Chen.

Seminar Abstract:

The demand for plant-based delivery systems has grown rapidly in recent years. Lentil protein and pectin are promising plant-based alternatives to develop delivery systems due to their abundance, biocompatibility, and functionality. The main objective of this PhD thesis was to develop lentil protein and pectin colloidal based lipophilic vitamin delivery systems using emerging technologies like high-intensity ultrasound (HIUS) and supercritical CO₂ (SC-CO₂) drying technologies and evaluate the physico-chemical characteristics, loading capacity and bioaccessibility of the vitamins.

In the first study, oil-in-water emulsion systems were prepared using HIUS technology and influence of HIUS nominal power on the stability of lentil protein concentrate (LPC) and whey protein concentrate (WPC) emulsions were studied. Steric stabilization mechanism was observed for LPC and WPC stabilized emulsions. The HIUS processes aided in formation of microemulsions and significant reduction of mean particle diameter of the emulsions, promoting emulsion stability. However, destabilization of the emulsions was observed after 24 h due to low viscosity of the continuous phase and aggregation of starch and dietary fiber for LPC emulsions. Then, to improve the storage stability, emulsion-filled hydrogel systems were developed with LPC and pectin to encapsulate a vitamin complex (β-carotene, cholecalciferol, α-tocopherol, and ascorbic acid). This second study aimed at investigating the chemical stability of the vitamin complex in LPC – pectin emulsion-filled hydrogels processed by HIUS. The impacts of HIUS nominal power, the addition of xylooligosaccharides (XOS) and ascorbic acid on the physico-chemical and functional properties were evaluated. The maximum retention capacities were observed for gels processed at 900 W for β-carotene and ascorbic acid, and 600 W for cholecalciferol and α-tocopherol after 21 days of storage.

Since the previous study showed the highest retention capacity for β-carotene, ultrasound assisted ethanolic gelation of lentil protein isolate (LPI) and pectin was investigated to load β-carotene in the emulsion gels as a model system in the third study. This study investigated the influence of HIUS nominal power, pH, and ethanol concentration on the physico-chemical and functional properties of the LPI-pectin emulsion gels. The HIUS process improved the overall stability by promoting LPI-LPI and LPI-pectin interactions. The β-carotene loading capacity (78 – 93%) and the bioaccessibility (2 – 50%) were significantly dependant on the HIUS nominal power used. Additionally, the β-carotene loaded emulsion gels were freeze-dried to form aerogels to improve the long-term shelf stability. In the last study, the interaction mechanisms of lentil protein and pectin gelation in HIUS and SC-CO₂ drying process were investigated. First, the influence of HIUS nominal power and the biopolymer concentrations on the physico-chemical characteristics of emulsion gels was studied. The emulsion gels formed in this study were thermo-reversible. Then, the emulsion gels were dried using SC-CO₂. Low density (0.0009-0.003 g/mm³) and semicrystalline aerogels  were formed with good textural and swelling capacity that can be explored to form tailor-made vitamin delivery systems.

Overall, the results obtained in this PhD thesis showed that HIUS process and SC-CO₂ drying are promising technologies for the development of vitamin delivery systems. Furthermore, the aerogels formed in this study could potentially be used in nutraceuticals and food formulations as fat replacers.