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theses

Carotenoids are associated with several health benefits, mainly as an antioxidants. The consumption of carotenoid as mean of prevention and correction of health conditions is in sync with the growing functional foods shift in the world of food and wellness. However, carotenoids are conventionally extracted using solvent based methods which is facing a number of challenges, the greatest being the regulatory restrictions on the use, storage, waste management and percentage of contamination in final product. Social, environmental and economical reasoning have triggered a wide spread interest in green, convenient and economical alternatives. SPI is a GRAS material that is widely used in the food industry for functional and nutritional purposes. Thermal treatment of SPI results in denaturation of native protein structure exposing the hydrophobic core that has the ability to act as a site for adsorption of molecules or ions. DSC measurement demonstrated two endothermic peaks at 42oC and 72oC corresponding to the two major protein fraction, β-conglycinin and Glycinin respectively. Rheological measurements of SPI during thermal treatments at concentration below heat-gelation critical limit revealed details on the molecular level regarding protein-protein interaction during phase transition. UV/visible spectroscopy of SPI suspension as a function of temperature at 280 nm clearly coincided with DSC results and rheological measurements where protein hydrophobicity increases at or above the denaturation point of the least heat stable fraction, 7S at 42oC. Thermal denaturation of SPI in mango juice solution was the proposed thermal treatment required to achieve unfolding of protein, exposing the hydrophobic core and allowing adsorption of mango carotenoids. Examined thermal treatment of heating to 95oC for 30 min was confirmed safe as it resulted in 6% loss in total carotenoids; such reduction was statistically insignificant (p<0.05). Adsorption measurements of β-carotene, α-carotene, β-cryptoxanthin, Zeaxanthin, and Violaxanthin demonstrated similar order of adsorption magnitude as a function of SPI concentration with the exception of violaxanthin that reported lower percentages. Adsorption maxima were reached at 15 g/L of SPI for all carotenoids with the exception of violaxanthin where maximum adsorption capacity is reached at 20 g/L of SPI with 98.06% retention. Overall results suggest that SPI has the ability to adsorb carotenoids present in aqueous medium during thermal denaturation treatment, this solvent-free method results in a nutrient dense functional ingredient.

ETD_4927

M.S.

Includes bibliographical references

by Maha Alshehab

doi:10.7282/T3XG9P57

ETD graduate

The author owns the copyright to this work.