The emulsification properties of octenyl- and dodecenyl- succinylated inulins

Abstract

a b s t r a c tThe emulsification properties of a series of inulin samples modified using varying amounts of octenyland dodecenyl-succinic anhydride have been studied by determining the droplet size as a function of time, temperature and in the presence of electrolyte using laser diffraction. It was found that~2% modified inulin was required to stabilise 15% w/v medium chain triglyceride emulsions and that the minimum droplet size was achieved when the % hydrophobe content was >8 mol%. The dodecenyl derivatives produced emulsions with a smaller droplet size than the octenyl derivatives. Apart from OSAinulin with a low degree of modification, stability was maintained when stored for a period of up to 21 days at room temperature and at 50 C. The zeta potential of the emulsion droplets was determined by Laser Doppler Velocimetry and was found to increase from~5 mv to~60 mv as the pH increased from 2 to 7 due to the presence of carboxylate ions present in the linkage between the inulin and alkenyl chains. The droplet size was found to increase on the addition of electrolyte indicating that the adsorbed polymer layer was insufficient to provide a steric repulsive barrier and that stabilisation was mainly due to electrostatic repulsive forces.

Potential applications of hydrophobically modified inulin as an active ingredient in functional foods and drugs - A review

“…The same research group studied the emulsification properties of OSA inulin derivatives and DDSA-inulin derivatives in the presence of electrolytes and during storage. It was also revealed that the ∼2 % DDSA inulin derivative exhibited a smaller droplet size and produced stronger medium-chain triglyceride emulsions than the OSA inulin derivatives and Inutec®SP1 ( Kokubun et al, 2015 ). The high emulsion stability of OSA and DDSA inulin derivatives has been achieved due to the significantly shorter inulin chain and formation of electrostatic repulsive forces owing to the presence of carboxylate ions in the head group.…”

“… DDSA-inulin had much better emulsification properties than OSA-inulin and Inutec®SP1. Kokubun et al (2015) (2018) Inulin, coded Inutec H 25 P, Tween 20. Successfully synthesized in deionized water under alkaline conditions using ASA.…”

“…2 b). This effect may be due to the heterogeneous nature of the modified inulin samples ( Kokubun et al, 2015 ). However, the interfacial tension has been reported to be approximately 13 mN/m, 16 mN/m, and 8 mN/m for the Inutec®SPI, DDSA, and OSA inulin derivatives, respectively.…”

“…Moreover, various types of inulin derivatives have been produced by the reaction of inulin with fatty acid methyl esters (FAMEs), fatty acid chlorides, alkyl epoxides, and alkyl isocyanates ( Exerowa & Platikanov, 2009 ; Exerowa, Gotchev, Gotchev et al, 2009 Gotchev et al, 2011; Khristov & Czarnecki, 2010 ; Stevens, Meriggi, & Booten, 2001 , 2001b ). In consideration of environmental issues with the development of industrialization, a green methodology has been established to synthesize different types of inulin derivatives with varying alkenyl chain lengths and varying degrees of substitution (DSs) by using alkenyl succinic anhydrides in an aqueous environment under mild alkaline conditions ( Han, Ratcliffe, & Williams, 2015 ; Han, Ratcliffe, & Williams, 2017 ; Kokubun, Ratcliffe, & Williams, 2013 ; Kokubun, Ratcliffe, & Williams, 2015 ; Kokubun et al, 2018 ; Morros, Levecke, & Infante, 2010 ; Morros, Levecke, & Infante, 2011 ). It was revealed that these types of inulin derivatives adsorbed at the liquid-liquid interface, solid-liquid interface, and air-water interface and produced micellar-like structures in the solution above a critical concentration.…”

The interfacial, emulsification and encapsulation properties of hydrophobically modified inulin

“…It is evident for Inutec SP1 that droplet aggregation is prevented through steric repulsive forces arising from the interaction of the carbohydrate moieties (Nestor et al, 2005;). For the OSA-and DDSA -inulin samples, which have a significantly shorter inulin chain compared to Inutec, stabilisation will be achieved by electrostatic repulsive forces due to the presence of the carboxylate ions in the head-group (Kokubun, Ratcliffe & Williams (2015)). This is supported by the zeta potential measurements reported above which show that the droplets acquire a significant negative charge as the pH is increased.…”