Functional and bioactive properties of protein isolates and hydrolysates from camelina and sophia seed meals

Ngo, Na Thi Ty (2023) Functional and bioactive properties of protein isolates and hydrolysates from camelina and sophia seed meals. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Camelina and sophia meals, often seen as by-products from these oilseed crops, are promising resources in the battle against food waste due to their high nutrient content. These by-products, rich in proteins, fibers, essential amino acids, and antioxidants, could be repurposed as functional food ingredients or nutraceuticals, thus enhancing food's nutritional value. These meals align with sustainability goals, as they can decrease waste and promote a circular economy. The rising consumer interest in plant-based diets and alternative protein sources further highlights their potential as valuable food products. Further research could position these oilseed by-products as crucial players in reducing food waste and creating nutritious, functional, and sustainable food products. This research involved the acquisition of camelina protein isolates (CPI) and sophia protein isolates (SPI) through the application of traditional and ultrasonic-assisted extraction methods. We conducted a detailed examination of the protein isolates using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and explored their functional characteristics. It was notable that the application of ultrasonic extraction resulted in a substantial improvement in the functional properties of both camelina and sophia protein isolates, which included increased protein solubility, water holding capacity, oil absorption capacity, as well as emulsifying and foaming properties. Furthermore, this study focused on using sophia and camelina seed meals to produce protein hydrolysates through enzymatic processes (Alcalase and Flavourzyme). The antioxidant activities of these protein hydrolysates were examined using in vitro methods such as free radical scavenging activity, namely the 2,2’-azino-bis (3-ethylbenzothiazoline�6-sulfonic acid) (ABTS) radical cation, 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl radical scavenging ability, and oxygen radical absorption capacity (ORAC) as well as reducing power and bioactivities such as inhibitory activities against the oxidation of LDL cholesterol and DNA strand breakage. In addition, bioinformatics methods were employed to predict bioactive peptides. The research mainly investigated to release of potent antioxidative, angiotensin-converting enzyme (ACE) inhibitory peptides and dipeptidyl peptidase IV (DPP IV) inhibitors using in silico approaches. The protein hydrolysates derived from sophia and camelina exhibited superior radical scavenging activity compared to protein isolates, particularly against DPPH and ABTS radicals. Especially in the case of camelina peptide fractions, smaller-size peptides showed significantly higher radical scavenging activity and potency than larger-size peptides. The hydrolysates produced with the Alcalase enzyme demonstrated the highest capacity for scavenging hydroxyl radicals and exhibited excellent oxygen radical absorbance capacity. Additionally, the hydrolysates showed inhibitory effects on LDL cholesterol oxidation and protected against DNA damage caused by hydroxyl and peroxyl radicals. The study successfully employed bioinformatics methods to predict bioactive peptides, revealing that the selected peptides exhibited both ACE and DPP IV inhibitory activities. Importantly, all resistant peptides to digestion were found to be non-toxic. Furthermore, the in silico prediction based on physicochemical properties and Lipinski's rule of five suggested that most peptides possess favorable drug�like properties. These findings indicate that the protein isolates and hydrolysates derived from camelina and sophia seed meal have desirable functional properties and exhibit antioxidant activities. As a result, they are considered valuable sources of bioactive peptides for developing available food ingredients and nutraceutical products. Therefore, camelina/sophia protein hydrolysates show promise as functional food ingredients and nutraceuticals.

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