Effect of enzyme hydrolysis of lentil and chickpea protein isolates on their physicochemical, functional properties and protein quality
| dc.contributor.advisor | Nickerson, Michael | |
| dc.contributor.advisor | Tanaka, Takuji | |
| dc.contributor.committeeMember | Korber, Darren | |
| dc.contributor.committeeMember | Ai, Yongfeng | |
| dc.contributor.committeeMember | English, Marcia | |
| dc.creator | Thirulogasundar, Akshaya | |
| dc.date.accessioned | 2023-01-31T17:44:14Z | |
| dc.date.available | 2023-01-31T17:44:14Z | |
| dc.date.copyright | 2023 | |
| dc.date.created | 2023-01 | |
| dc.date.issued | 2023-01-31 | |
| dc.date.submitted | January 2023 | |
| dc.date.updated | 2023-01-31T17:44:14Z | |
| dc.description.abstract | The overarching goal of this research was to investigate the effect of enzyme hydrolysis of lentil (LPI) and chickpea protein isolates (CPI) using varied levels of hydrolysis to improve the functional properties and protein quality. Initially LPI and CPI were hydrolysed using trypsin to achieve degrees of hydrolysis (DH) at 5%, 10%, 15% and 20% respectively. The protein contents of CPI and LPI hydrolysates were in the range of 69% – 73% and 80% – 83% respectively. The lipid contents of CPI and LPI hydrolysates were in the range of 15% – 17% and 1.5% – 2.0% respectively. The physicochemical properties were examined for each hydrolysed protein preparation. The surface charges of CPI and LPI hydrolysates were decreased by 3.3 – 7.7 mV at pH 7.8 and were increased by 6.5 – 9.7 mV at pH 4.5. The surface hydrophobicity of CPI and LPI was increased by 1.1 – 2.4-times relative to the untreated protein isolate at pH 7.8. At pH 4.5, it was observed higher increases in surface hydrophobicity by up to 3.3-times. The surface and interfacial tension showed no significant difference with hydrolysis at either pH or protein isolates. FTIR analysis was performed to study the relative spectral weights of β-sheet, β-turn, α-helix, A1 and A2 residues. The results showed significant changes in the relative spectral weights with increase in hydrolysis when compared to the untreated isolates. SDS-PAGE and capillary gel electrophoresis showed that the hydrolysis process broke down high molecular weight protein molecules into small molecular weight protein molecules. The functional properties were studied to identify the suitability of enzymatic treatments for modification of protein isolates for food applications. The solubility of CPI and LPI increased after hydrolysis by 10 and 30-times. The emulsion stability of CPI and LPI at pH 7.8 increased by 2% after hydrolysis whereas at pH 4.5 it declined. The foaming capacity and stability of CPI decreased with hydrolysis, whereas LPI hydrolysis increased them both at pH 7.8 and 4.5. Water holding capacity of CPI and LPI did not change with hydrolysis whereas oil holding capacity showed significant increase. The protein quality of the untreated and hydrolysed protein isolates was also analysed. The limiting amino acid for both CPI and LPI was found to be tryptophan. The limiting amino acid score was found to improve from 0.62 to 0.71 in the case of CPI proteolysis and decreased to 0.37 for LPI. There was no significant increase or decrease in the in vitro protein digestibility (IVPD). In vitro protein digestibility corrected amino acid score (IVPDCAAS) of untreated LPI, and CPI was decreased from 52% to 32% for LPI and increased to 60% in case of CPI. Overall, enzymatic hydrolysis increased surface hydrophobicity and zeta potential, and improved functional properties in solubility, emulsion stability, oil holding capacity and surface properties. Meanwhile the foaming properties and water holding capacity are negatively affected. Qualitative analysis of flavour compounds in the chickpea and lentil isolates showed the presence of various off-flavour components including aldehydes, alcohols and ketones. Enzyme hydrolysis is a type of protein modification which could improve the functional and nutritional properties for a value-added protein ingredient. These changes suggest that the enzymatic hydrolyzed protein isolates could be applied into food emulsification food applications. | |
| dc.format.mimetype | application/pdf | |
| dc.identifier.uri | https://hdl.handle.net/10388/14459 | |
| dc.language.iso | en | |
| dc.subject | protein isolate | |
| dc.subject | enzyme hydrolysis | |
| dc.subject | lentil | |
| dc.subject | chickpea | |
| dc.subject | trypsin | |
| dc.subject | FTIR | |
| dc.subject | functional property | |
| dc.subject | protein quality | |
| dc.title | Effect of enzyme hydrolysis of lentil and chickpea protein isolates on their physicochemical, functional properties and protein quality | |
| dc.type | Thesis | |
| dc.type.material | text | |
| thesis.degree.department | Food and Bioproduct Sciences | |
| thesis.degree.discipline | Food Science | |
| thesis.degree.grantor | University of Saskatchewan | |
| thesis.degree.level | Masters | |
| thesis.degree.name | Master of Science (M.Sc.) |