1:00 pm - 2:00 pm
318-J Agriculture/Forestry Centre, Agriculture/Forestry Centre, Edmonton
A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES MSc Final Exam Seminar by Hung Vo. This seminar is open to the general public to attend.
Thesis Topic: Subcritical Water Hydrolysis of Citrus Pectin, Pea Protein Concentrate, and Their Mixture for Oligosaccharides and Peptides Production
MSc with Dr. Marleny Aranda Saldana.
Bioactive oligosaccharides and peptides have drawn great attention due to reported health benefits. The most common methods to produce oligosaccharides and peptides are enzymatic and acid hydrolysis which have multiple disadvantages such as environmentally harmful, time consuming, expensive, and use complicated procedures. Therefore, the main objective of this thesis was to evaluate subcritical water processing as an ecofriendly technology to hydrolyze pectin and pea protein concentrate to obtain oligosaccharides and peptides, respectively. In the first study, citrus pectin was hydrolyzed at 135-200oC/50 bar using subcritical water modified by either malic acid or citric acid to obtain hexuronic acids and pectic oligosaccharides. The contents of hexuronic acids, pectic oligosaccharides, rhamnose, and hydrolysate antioxidant activity were determined. The results showed that with increasing temperature, the content of hexuronic acid significantly enhanced in aqueous citric acid media. The main oligosaccharide in the hydrolysates was arabino-oligosaccharide with the highest content obtained at 160oC/50 bar/20 min with a molecular weight of 2.65 kDa. The main monosaccharide in the hydrolysates was rhamnose which content increased at elevated temperature. In the second study, citrus pectin was added as a catalyst for pea protein concentrate hydrolysis to obtain bioactive peptides. Subcritical water at 160-240oC/50 bar was employed. The degree of hydrolysis, peptide size distribution, hydrolysate antioxidant activity, amino acid profile, fluorescence intensity, and the total protein content were determined. The degree of hydrolysis improved with increasing temperature with the highest value of 64.8% using pectin as the catalyst compared to citric acid (27.2%). The peptide with molecular weight of 4.1 kDa was the dominant peptide in the hydrolysate. The DPPH– scavenging activity of protein hydrolysates using citric acid was significantly higher than the ones obtained with pectin. The hydrolysates with pectin, on the other hand, had significantly higher ferric reducing antioxidant activity than the ones obtained with citric acid, indicating that pectin and citric acid catalyzed the hydrolysis reaction in different patterns to produce peptides capable of accepting and donating hydrogen atoms, respectively.
Keywords: Bioactive oligosaccharides, bioactive peptides, citrus pectin, pea protein concentrate, subcritical water hydrolysis.