Insect proteins as emulsifiers in oil-in-water emulsions

McColm, Christopher (2023) Insect proteins as emulsifiers in oil-in-water emulsions. PhD thesis, University of Nottingham.

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Insect protein was extracted using an alkaline extraction method with an ethanol defatting step from six species and two life stages of commercially available insect species. The protein extracts and whole insect powders were analysed for composition and protein structure, oil-in-water emulsions were produced from the protein extracts at 0.44 % protein with a sunflower oil dispersed phase.

The first study compared protein extracts from Acheta domesticus (house cricket), Gryllodes sigillatus (banded crickets), Gryllodes bimaculatus (black crickets) and Gryllus assimilis (silent crickets) by composition, emulsion formation and the emulsion stability over a 40-day period. Little difference was found in the protein secondary structure in either the protein extracts or the whole insect powders. The amino acid composition of the four cricket protein extracts was found to be similar. House cricket protein extract produced emulsions with a marginal but significantly lower droplet diameter. Emulsions produced from all four cricket protein extracts were stable to coalescence over the 40-day period. These results suggest that protein from an insect species within the order Orthoptera can be used interchangeably to stabilise oil-in-water emulsions.

The second study compared the composition from protein extracts form Tenebrio molitor (mealworm) larvae and adult beetles, Achroia grisella (waxworm) larvae and banded crickets and emulsions the proteins formed. No difference was found in between droplet diameter of emulsions at pH 7 when heat-treated emulsions or non-heat-treated, with or without non-ionic surfactants. Heat-treatment at pH 5 increased the droplet diameter of emulsions from all insect protein types, but not in the presence of a non-ionic surfactant. Banded cricket protein emulsions adjusted to pH 5 with a non-ionic surfactant showed an increase in droplet diameter, mealworm beetle protein emulsions did not, and the larval protein emulsion droplet diameter increased marginally. These results suggest that there are important differences between proteins extracted from different insect order when used in emulsions.

The third study investigates the reasons behind the difference in the emulsions from the banded cricket and mealworm beetle protein extracts. Differences in interfacial protein concentration, droplet charge and interfacial activity were found.

This research has shown that insect proteins emulsions are stable in a range of processing conditions and have potential to be used in food products.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Gould, Jo
Yakubov, Gleb
Keywords: insects, insect protein, animal nutrition, proteins in animal nutrition
Subjects: S Agriculture > SF Animal culture
Faculties/Schools: UK Campuses > Faculty of Science > School of Biosciences
Item ID: 76286
Depositing User: McColm, Christopher
Date Deposited: 21 Dec 2023 10:51
Last Modified: 21 Dec 2023 10:51

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