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Research article2023Peer reviewedOpen access

Green Chemistry to Modify Functional Properties of Crambe Protein Isolate-Based Thermally Formed Films

Newson, William R.; Capezza, Antonio J.; Kuktaite, Ramune; Hedenqvist, Mikael S.; Johansson, Eva


Proteins are promising precursors to be used in productionof sustainablematerials with properties resembling plastics, although protein modificationor functionalization is often required to obtain suitable productcharacteristics. Here, effects of protein modification were evaluatedby crosslinking behavior using high-performance liquid chromatography(HPLC), secondary structure using infrared spectroscopy (IR), liquidimbibition and uptake, and tensile properties of six crambe proteinisolates modified in solution before thermal pressing. The resultsshowed that a basic pH (10), especially when combined with the commonlyused, although moderately toxic, crosslinking agent glutaraldehyde(GA), resulted in a decrease in crosslinking in unpressed samples,as compared to acidic pH (4) samples. After pressing, a more crosslinkedprotein matrix with an increase in beta-sheets was obtained inbasic samples compared to acidic samples, mainly due to the formationof disulfide bonds, which led to an increase in tensile strength,and liquid uptake with less material resolved. A treatment of pH 10+ GA, combined either with a heat or citric acid treatment, did notincrease crosslinking or improve the properties in pressed samples,as compared to pH 4 samples. Fenton treatment at pH 7.5 resulted ina similar amount of crosslinking as the pH 10 + GA treatment, althoughwith a higher degree of peptide/irreversible bonds. The strong bondformation resulted in lack of opportunities to disintegrate the proteinnetwork by all extraction solutions tested (even for 6 M urea + 1%sodium dodecyl sulfate + 1% dithiothreitol). Thus, the highest crosslinkingand best properties of the material produced from crambe protein isolateswere obtained by pH 10 + GA and pH 7.5 + Fenton, where Fenton is agreener and more sustainable solution than GA. Therefore, chemicalmodification of crambe protein isolates is effecting both sustainabilityand crosslinking behavior, which might have an effect on product suitability.

Published in

ACS Omega
2023, Volume: 8, number: 23, pages: 20342-20351