Functional and Bioactive Properties of Australasian Canola Meal Protein Isolate and Hydrolysates

Adeola Alashi

Research output: ThesisDoctoral Thesis

Abstract

In this study, the prospect of utilising canola meal protein as a food and/or nutraceutical ingredient for human consumption was explored. Over the years, food functional properties have become very prominent in food research globally, and as people become increasingly aware of the effects of food on health and well-being, the need to develop functional foods and/or nutraceutical products will continue to increase. On the other hand, to be able to meet the increasing global demand for food supply, undervalued food crops such as canola, will need to be utilised. In this study, the prospect of utilising canola meal protein as a food and/or nutraceutical ingredient for human consumption was explored. Over the years, food functional properties have become very prominent in food research globally, and as people become increasingly aware of the effects of food on health and ell-being, the need to develop functional foods and/or nutraceutical products will continue to increase. On the other hand, to be able to meet the increasing global demand for food supply, undervalued food crops such as canola, will need to be utilised. The hydrolysis process was shown to generate smaller-sized peptides with significantly (p<0.05) improved solubility at different pH values when compared to CPI. The surface hydrophobicity of all the hydrolysates, were also reduced, depending on the enzyme type and time of hydrolysis employed when compared to CPI. Hydrolysing proteins has the potential to produce peptides with bioactive properties, therefore the antihypertensive, antioxidant and antiobesity properties of the hydrolysates were examined. Antihypertensive properties were measured both in vitro (angiotensin converting enzyme [ACE] and renin) and in vivo with the use of spontaneously hypertensive rats. The hydrolysates had significantly higher ACE and renin inhibition when compared to CPI, while the enzyme type had synergistic effects on the renin and ACE inhibition properties with respect to their molecular weight (MW). Further purification of the hydrolysates showed that peptide molecular weight reduction led to improved ACE inhibition activities. Some of the hydrolysates reduced systolic blood pressure (SBP) significantly (p<0.05) in the rat models used when compared to captopril (a commercially available ACE inhibition drug). CPI however, had the most prolonged SBP reduction effect. Antioxidant properties of the hydrolysates and their membrane filtration fractions were investigated using various in vitro methods. The effective concentration that scavenged 50% (EC50) of the ABTS•+ was greatest for the <1 kDa pancreatin fraction at 10.1 μg/ml. The CPHs and peptide fractions scavenged DPPH•+ with most of the EC50 values being <1.0 mg/ml. Scavenging of superoxide radicals was generally weak, except for the <1 kDa pepsin peptide fraction. All canola protein hydrolysates (CPHs) inhibited linoleic acid oxidation with greater efficiency for pepsin and trypsin hydrolysates. The oxygen radical absorbance capacity of hydrolysates from Alcalase, chymotrypsin and pepsin was found to be significantly (p<0.05) better than that of glutathione reduced (GSH). The ability to inhibit pancreatic lipase and the development of adipocyte differentiation in Mesenchymal stem cells (C3H10T1/2) by canola protein isolate and hydrolysate was also studied as potential antiobesity agents. Results demonstrated that the Alcalase, chymotrypsin and trypsin hydrolysates were able to down-regulate the expression of PPARγ in adipogenic differentiation of C3H10T1/2cells at a concentration that was not toxic to the cells (60 μg/mL), while pepsin and pancreatin hydrolysates were both toxic at these concentrations after continued treatment. The relative quantities of the gene expression results indicate that CPI and its hydrolysates were able to inhibit the development of adipogenic differentiation of C3H10T1/2 cells at folds that were significantly less (p<0.05) than the positive control (adipocyte differentiated cells).
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Charles Sturt University
Award date01 Mar 2014
Place of PublicationAustralia
Publisher
Publication statusPublished - 2014

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