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Emulsification properties of Puka Gum – An exudate of a native New Zealand tree (Meryta sinclairii): Effect of shear rate and Gum concentration
journal contributionposted on 2023-06-27, 02:49 authored by LM Riana, Ian SimsIan Sims, L Matia-Merino
This study investigated the effect of puka gum (PG) (crude and purified) concentration on its emulsification properties in terms of droplet size distribution, zeta potential, rheological and microstructural properties of the emulsions and their visual phase separation. Different concentrations of PG (1–10% w/w) were used to stabilize 15% w/w soybean oil-in-water emulsions. The effect of constant shear rate and time on the apparent viscosity of PG solutions was also tested. PG stabilised-oil-in-water emulsions exhibited monomodal size distributions with average droplet sizes (d32) below 2 μm at 4% w/w PG. The apparent viscosity of these emulsions was dependent on gum concentration exhibiting a Newtonian behaviour at low PG concentrations (≤4% w/w), with shear-thinning at higher concentrations, becoming slightly more pronounced above 100s−1 and especially at 10% w/w gum. The loss modulus (G”) was higher than the storage modulus (G’) at all concentrations indicating that the liquid-like behaviour dominated at all frequencies. The apparent viscosity of PG solutions, showed an irreversible loss of viscosity after shearing over a period of time, presumably resulting from chain breakage and molecular weight reduction. PG droplets were negatively charge with zeta-potential values in the range of −30 – (−45) mV. Furthermore, PG-stabilised emulsions remained stable against phase separation for at least 30 days. Crude and purified PG exhibited no major differences in terms of their emulsifying properties at 4% w/w suggesting that a purification process may not be required for food formulations. Overall, PG can be considered as a promising natural emulsifier for emulsion-based foods and beverage products.
Preferred citationRiana, L. M., Sims, I. M. & Matia-Merino, L. (2022). Emulsification properties of Puka Gum – An exudate of a native New Zealand tree (Meryta sinclairii): Effect of shear rate and Gum concentration. Food Hydrocolloids, 124, 107263-107263. https://doi.org/10.1016/j.foodhyd.2021.107263
Journal titleFood Hydrocolloids
4004 Chemical Engineering30 Agricultural, Veterinary and Food Sciences40 Engineering3006 Food Sciences4004 Chemical engineering4016 Materials engineering3006 Food sciencesFood ScienceMaterials Engineering not elsewhere classifiedFood Sciences not elsewhere classifiedChemical Engineering not elsewhere classified