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Characterization Of Chemical, Nutritional, And Techno-functional Properties of Protein-rich Fractions Obtained From Canola Cold-pressed Cake

Date

2024-03-08

Journal Title

Journal ISSN

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Type

Thesis

Degree Level

Masters

Abstract

The present study explored proteins of canola cold-pressed cake (CCC) for value-addition prospects. The protein and fiber fractionation developed by Agriculture and Agri-Food Canada (AAFC) was applied to CCC as-it-is (N-CCC) and after de-oiling with ethanol (E-CCM) or hexane (H-CCM). De-oiling with hexane and ethanol provided < 1% oil containing meal with protein levels of 40.6% in E-CCM, 35.4% in H-CCM compared to 31.1% in N-CCC. The fractionation generated two protein-rich and three fiber-rich fractions of each meal. The napin protein isolates (NPI) had the highest protein content (96.2%-97.9%) followed by cruciferin protein concentrates (CPC) (55.3%-74.2%) and intermediate protein fractions (IPF) (25.2%-29.7%). The soluble sugar rich fractions (SSF), and seed coat fractions (SCF) had 15.0%-16.3% and 21.4%-24.7% protein, respectively. These fractions recovered 99.8%-99.9% of total meal dry matter and 102.4%-102.7% of starting meal protein. Total phenolic content (TPC) was found to be 1.3-1.4 mg/g in N-CCC, E-CCM, and H-CCM, and NPI from N-CCC showed higher TPC than the other fractions. De-oiling did not affect meal phytate content (2.5-3.0 g/100g). The IPF of all meals had higher phytate values (15.3-19.3g/100g) than other fractions. The amino acid composition of the meals and their respective protein fractions followed their signature compositions. The presence of napin and cruciferin in NPI and CPC, respectively was confirmed. Selected functional properties of NPI and CPC of all three meals were studied. Proteins of NPI gave solubility values of 80-100% at pH 4.0, 7.4, and 9.5, regardless of the meal origin while CPC had values between 14-59%. The surface hydrophobicity values and negative zeta potential values of proteins in CPC were larger than NPI. Both NPI and CPC of all meals had higher oil holding capacity than commercial soy protein isolates at the same protein level but lower water holding capacity for CPC (<2.2 g/g protein). NPI emulsified more oil than CPC under the conditions of 0.5 M NaCl, and 10% sucrose, regardless of the meal origin, however, the stability of formed emulsions was similar. NPI of ethanol de-oiled meal exhibited better foaming properties at pH 4.0 than N-CCC with a foam capacity and stability similar to commercial whey protein isolate at equal protein level. The proteins of NPIs showed denaturation temperatures that aligned with constituent proteins and denatured completely at ~100ÂșC. The AAFC meal fractionation process can successfully be applied to CCC with or without defatting to obtain highly pure NPI, however, product composition and functional characteristics of CPC fraction depend on the residual oil that is portioned from the meal. This process allows obtaining protein-rich products from CCC with unique protein types and functional properties.

Description

Keywords

Canola, Cold-pressed cake, Protein-rich fractions, Cold-pressed canola meal, Napin protein isolates, Cruciferin protein concentrate

Citation

Degree

Master of Science (M.Sc.)

Department

Food and Bioproduct Sciences

Program

Food Science

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DOI

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