Cold pressed Hemp (Cannabis sativa L) seed oil, which contains a favorable ratio of omega-6/omega-3 and a considerable amount of vitamin E, is a high nutrition value product with various health benefits. However, the presence of a large amount of chlorophyll makes the oil highly susceptible to photo-oxidation and limits its applications. Chlorophyll and other pigments in edible oils are commonly reduced through oil bleaching process. The objective of this study was to reduce the chlorophyll content in cold pressed hemp seed oil using ultrasonic bleaching and evaluate the impacts on carotene content, peroxide value, conjugated diene, total phenolic content and oxidative stability. The bleaching efficiency increased significantly as the ultrasound power (0 to 60% pressure amplitude) and concentration of bleaching clay (20 to 40 g/kg) increased. At 20% ultrasound power, the chlorophyll reduction (%) of different clays was found to be 99.4% (industrial clay) > 97.8% (activated bentonite) > 82.7% (sepiolite) > 47.1% (non-activated bentonite). Ultrasonic bleaching significantly reduced (p<0.05) the total chlorophyll content, total carotene content and primary oxidation products of hemp seed oil. During accelerated oxidation tests (40 and 60 ℃), the developments of peroxide value and conjugated diene were significantly (p<0.05) slower for hemp seed oil treated with ultrasonic bleaching compared to the control oil. Enhanced oxidative stability was observed in hemp seed oil after ultrasonic bleaching. In addition, another objective of this study was to evaluate the impacts of solvent and heat treatment on phenolic profile and antioxidant activity of cold pressed canola and hemp meals. For canola meal, a solvent-mixture of aqueous methanol (70%) and aqueous acetone (70%) in a ratio of 1:1 (v/v) extracted (p<0.05) slightly higher total phenolic content (11.3 mg SAE/g), while aqueous methanol (70%) extracts exhibited higher DPPH scavenging effect (40.4%). For hemp meal, aqueous acetone (80%) extracts exhibited higher total phenolic content (6.0 mg GAE/g) and DPPH scavenging effect (12.5%). Total phenolic content and antioxidant activity in canola meal extracts were significantly higher (p<0.05) than those in hemp meal extracts. After heat treatments at temperature from 140 to 180 ℃, canola and hemp meal extracts showed equal or lower total phenolic content and DPPH scavenging effect. / May 2017
| Identifer | oai:union.ndltd.org:MANITOBA/oai:mspace.lib.umanitoba.ca:1993/32207 |
| Date | 04 May 2016 |
| Creators | Jingbang, Liang |
| Contributors | Thiyam-Holländer, Usha (Human Nutritional Sciences), Eskin, N. A. Michael (Human Nutritional Sciences) Hydamaka, Arnold (Food Science) Narvaez, Claudia (Food Science) |
| Publisher | Lipid Technology, LWT- Food Science and Technology |
| Source Sets | University of Manitoba Canada |
| Detected Language | English |
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