Modification of Oxalis tuberosa starch with OSA, characterization and application in food-grade Pickering emulsions

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ORIGINAL ARTICLE

Modification of Oxalis tuberosa starch with OSA, characterization and application in food-grade Pickering emulsions A. G. Estrada-Ferna´ndez1 • G. Dorantes-Bautista1 • A. Roma´n-Guerrero2 R. G. Campos-Montiel1 • J. P. Herna´ndez-Uribe1 • R. Jime´nez-Alvarado1



Revised: 3 September 2020 / Accepted: 9 September 2020 Ó Association of Food Scientists & Technologists (India) 2020

Abstract The emulsifying properties of Oxalis tuberosa starch (native and chemically modified) were evaluated in Pickering emulsions based on the emulsification index, emulsion stability over time and emulsion morphology. The best conditions of chemical modification were found by esterification of starch with octenyl succinic anhydride (OSA) at a concentration of 3% and a reaction time of 2 h, achieving a degree of substitution of 0.033 ± 0.001. The results obtained using Fourier-transform infrared spectroscopy, a Rapid Visco Analyzer, and differential scanning calorimetry, indicated that the starch underwent a change in its structure and that the insertion of the OSA groups was achieved. The amphipathic characteristics of OSA starch were evaluated by forming oil-in-water emulsions. Various concentrations of OSA-starch granules (1, 2.5 and 5 wt%) were used. A higher concentration of particles produced a smaller droplet size of emulsions (76.5 ± 0.9 lm) compared to those formed at a lower concentration of 1% (92.5 ± 1.0 lm). Therefore, the starch modified with OSA displayed the necessary characteristics to be adsorbed at the oil–water interface, achieving Pickering emulsion stabilization. Keywords Oxalis tuberosa  Chemical modification  OSA  Pickering emulsions  Water-in-oil emulsion

& R. Jime´nez-Alvarado [email protected] 1

Instituto de Ciencias Agropecuarias, Universidad Auto´noma del Estado de Hidalgo, Av. Rancho Universitario s/n km. 1, 43600 Tulancingo, Hidalgo, Mexico

2

Departamento de Biotecnologı´a, Universidad Auto´noma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Vicentina, 09340 Mexico, DF, Mexico

Introduction An emulsion is a dispersed system in which the phases include immiscible liquids and an emulsifying agent such as surfactant or solid particles. Solid-stabilized emulsions are known as Pickering emulsions. It has been proposed that low molecular weight emulsifiers and surfactants have a negative impact on gut health and inflammation when used in foods, being Pickering stabilizers from natural sources a good option to replace them (Marefati et al. 2017). Recently, the use of starch granules to stabilize Pickering emulsions has attracted the attention of researchers (Li et al. 2013; Marefati et al. 2017; FonsecaFlorido et al. 2018). The different types of starches differ from each other due to their granule size, microscopic appearance, and chemical constitution because the amylose-amylopectin ratio is not always the same and will depend on the species from which it is extracted (Palabiyik et al. 2017). Native starches have limitations for their use in the stabilization of Pickering emu