Idaresit Ekaette | 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 Idaresit Ekaette. This seminar is open to the general public to attend.

Thesis Topic: Rutin as a co-modifier with thermal treatment in the modification of barley starch and the application of subcritical water, ultrasonication, and electrolysis technologies.

PhD with Dr. Marleny Aranda Saldana.

Seminar Abstract:

Barley grain is a rich source of starch and dietary fibre but over the years, its use in Canada has been more popular in animal feeding and brewing, than for food purposes. With the large barley production, and continual demand for starch by the food and biobased industries, barley starch becomes an item of economic value. Therefore, the objective of this research was to isolate barley starch and modify the barley starch properties for suitability in functional food applications. Towards the development of functional food, rutin, a flavonoid compound was selected to be added to the isolated barley starch. The incorporation of rutin into the barley starch matrix was enhanced by thermal treatments using subcritical water (SCW), ultrasonication and electrolysis technologies. Thermal treatment of barley starch with rutin at 80 ^oC and SCW temperatures of 100-160 ^oC/7 MPa/30 min added 0.19-0.87 mg rutin/g starch dry matter to waxy and high amylose barley starches. Comparison of barley starches with and without rutin showed a loss of amylose, for the 37% amylose starch at 100 ^oC, and 22% amylose starch at 120 ^oC, indicating that rutin was involved in V-amylose inclusion complexation.  The 37% amylose starch with 0.34 mg rutin/g starch dry matter had the highest observed expansion (specific volume) of 6.10 ± 0.12 mL/g at 160 ^oC, which was a 392% increase from 1.24±0.01 mL/g of native 37% amylose starch at room temperature (25 ^oC). The effect of acoustic cavitation (ultrasonication treatment) at 600 W was carried out on rutin hydrate (20.0±0.9 mg) in water, 0.01 g/mL citric acid, and 0.01 g/mL sodium chloride. Ultrasonication energy density (3.6-36 kJ/mL, 47 ^oC) and change in energy density (0.1-7.0 kJ/mL, 86 ^oC) showed an increase in total flavonoid content from 15-74%, with the water media (27 kJ/mL) leading at 74%. Quercetin, an aglycone of rutin was produced (with treatment in the citric acid media) as change in energy density increased from 0.1 kJ/mL (0.34±0.09%) to at 7.0 kJ/mL (2.23±0.04%). SEM images showed long, and slender strands of rutin nanocrystals (<500 nm) bound as agglomerates. According to DSC endotherms, new rutin polymorphs were formed from all solvent treatments at 3.9 kJ/mL, and 7.0 kJ/mL, and of water, 36 kJ/mL. Control rutin and new rutin polymorphs used in pyrodextrinization (2.2 M HCl, 90 ^oC, 1 h) of barley starch did not significantly change the quantity of malto-oligosaccharides (DP 1-7) produced from the control barley starch (without rutin). In another study, barley flour with zero amylose content was treated by electrolysis at voltages of 5-30 V, and electrode length of 4-8 cm. Starches isolated from the electrolysed barley flour slurry (1:6 w/w) had higher metal content (magnesium 2.9% and phosphorus 13.0%) compared to magnesium 0.8% and phosphorus 3.5% of the alkali-treated starch. The electrolysed starch- freeze dried gel had the highest absorption capacity in water as 1659±24%, observed for treatment at 15 V, and 8 cm. However, the effect of rutin addition in the freeze-dried starch gels inhibited rehydration. All electrolysed starches gels with and without rutin were opaque and exhibited no change of firmness at 40 days of storage at room temperature. The structural behavior of the electrolysed starches was related to re-alignment of amylopectin molecules by electrolysis. Based on the technologies utilized, modified barley starches loaded with rutin have been produced with the unique characteristics of expanded starch (lighter mass per volume), dextrin (as a soluble starch), and the opaque superabsorbent hydrogels (to enhance light protection of rutin). These starches can find applications in functional foods, cosmetics, and the pharmaceutical industry.