Greg Petersen

Mr. Greg Petersen


Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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18 February 2022 in Foods
Verified
Journal Article
Open access
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Ozan KahramanOzan Kahraman
Ozan Kahraman
GPGreg Petersen
Greg Petersen
CFChristine Fields
Christine Fields
According to the Food and Agriculture Organization (FAO), protein demand is expected to increase globally by around 40% by 2030 as a response to the world’s population growth. Due to their clean label, vegan or vegetarian based applications, nutritional value, and cost-efficient properties, plant-based proteins have been widely studied. However, most of the alternatives currently found in the market have some challenges because of their poor solubility, emulsifying, gelling, and foaming attributes. Hemp seed protein has gained increasing attention due to its unique amino acids and fatty acids profiles. In this study, commercial HPC mixtures were adjusted to pH 2, 4, 6, 8, 10, and 12 followed by ultrasonication (US) for 5 min (5 s on: 5 s off) and incubated for an hour before neutralizing to pH 7. Following the treatments, the samples were analyzed for their hydrodynamic diameter, conductivity, zeta potential, polydispersity index, surface hydrophobicity, solubility, electrophoresis (SDS-PAGE), free sulfhydryl group, and optical characteristics. The samples treated with ultrasound at pH 8 and 10 significantly (p < 0.05) enhanced the solubility of the hemp seed protein by 12.12% and 19.05%, respectively. Similarly, the samples treated with ultrasonication and pH shifting at pH 6, 8, and 10 also significantly increased the amount of free sulfhydryl content (p < 0.05) to 41.6, 58.72, and 46.54 mmol/g from 32.8 mmol/g, respectively. This study shows that the application of ultrasonication and pH shifting is a promising alternative method to modify the functional properties of HPC and widen their applications in the food, cosmetics, and pharmaceutical industries.

1 May 2019 in Journal of Ethnopharmacology
Verified
Journal Article
Open access
GPGreg Petersen
Greg Petersen
YTYijin Tang
Yijin Tang
CFChristine Fields
Christine Fields
Kava and kava extracts have shown great potential as a way to minimize anxiety-associated symptoms and to help alleviate pain. Hepatoxicity has been associated with the consumption of kava products. The chemical compounds, kavalactones (KL) and flavokavains (FK) have been implicated in kava's psychotropic and possible hepatotoxic properties. To investigate the kavalactone and flavokavain content and in vitro toxicity of KAVOA™, a supercritical carbon dioxide extraction (SFE) of kava. Kavalactone and flavokavain content of SFE kava and noble kava root were determined following extraction in acetone, cell culture media, and water using ultra high-performance liquid chromatography (UHPLC). Using water extractions of the kava products, the cell viability and toxicity on the human hepatocellular carcinoma cell line (HepG2) were determined using luminescent and fluorescent assays, respectively. The half maximal inhibitory concentration (IC50) of the SFE kava and noble kava root, extracted in cell culture media, were determined utilizing a luminescent cell viability assay. Quantification of the KAVOA™, a SFE extract of kava and kava root showed similar profiles of kavalactone and flavokavain content. Water extracted SFE and root kava did not show a negative impact on cell viability and toxicity when compared to the vehicle control treated cells. IC50 values were determined for the SFE kava and kava root extracted in cell culture media in respect to cell viability, 78.63 and 47.65 µg/mL, respectively. KAVOA™, a supercritical carbon dioxide extract of kava displays a similar kavalactone profile to a noble variety of kava. In relation to total kavalactone content, KAVOA™ also has a lower content of the cytotoxic compound FKB. Aqueous extractions of KAVOA™ and noble kava root had no significant negative impact on cell viability and toxicity on HepG2 cells when compared to vehicle controlled treated cells. Results indicate KAVOA™ demonstrates a similar in vitro safety profile to that of noble kava root when experiments are normalized to kavalactone content.

10 September 2025 in Sustainability
Verified
Journal Article
Open access
PDF file
Ozan KahramanOzan Kahraman
Ozan Kahraman
GPGreg Petersen
Greg Petersen
CFChristine Fields
Christine Fields
The global challenge of food waste presents an opportunity to explore the untapped potential of agricultural by-products. Coffee pulp, a major by-product of the coffee industry, is a promising source of functional polysaccharides such as coffee pectin, which can be valorized for sustainable applications in food systems. This study investigates the microencapsulation of hemp seed oil—rich in essential fatty acids and bioactive lipids—using coffee pectin and maltodextrin as wall materials via spray drying. Emulsions with varying oil-to-wall ratios were formulated and characterized for viscosity, particle size, and zeta potential. The resultant microcapsules were analyzed for physicochemical properties, encapsulation efficiency, oxidative stability (peroxide value), and in vitro release in simulated gastrointestinal fluids. Encapsulation efficiencies ranged from 63.27% to 70.77%, with lower oil content formulations exhibiting higher efficiency. The peroxide values indicated enhanced oxidative stability, with the lowest value (10.69 meq O2/kg oil) observed in the most efficient encapsulation formulation. Microcapsule morphology analysis confirmed the formation of spherical particles with varying degrees of surface roughness. Release studies demonstrated controlled oil delivery, with higher retention in gastric conditions and progressive release in intestinal fluids. These findings demonstrate the potential of upcycled coffee pulp-derived pectin as a functional, sustainable encapsulant, aligning with circular economy principles and supporting the development of stable bioactive delivery systems for nutraceutical and food applications.