Mohd Dona Bin Sintang

Mixed surfactant systems of sucrose esters and lecithin as a synergistic approach for oil structuring

In order to modify the self-assembly of sucrose esters (SEs) in sunflower oil, we added sunflower lecithin (SFL) as co-surfactant. It is hypothesized that SFL modifies the self-assembly of SEs by interrupting the extensive hydrogen bonding between SEs monomers. The addition of SFL into SEs induced gelation of the mixed surfactant system oleogels at all studied ratios. The 7:3 SEs:SFL combination showed enhanced rheological properties compared to the other studied ratios, which suggests better molecular ordering induced by SFL. The modifications might have been caused by interference in the hydrogen bonding, connecting the polar heads of SEs molecules in the presence of SFL. This effect was confirmed by thermal behavior and small angle X-ray diffraction (SAXD) analysis. From the crystallization and melting analyses, it was shown that the peak temperature, shape and enthalpy decreased as the SFL ratio increases. Meanwhile, the bi-component oleogels exhibited new peaks in the SAXD profile, which imply a self-assembly modification. The microscopic study through polarized and electrons revealed a change in the structure. Therefore, it can be concluded that a synergistic effect between SEs and SFL, more particularly at 7:3 ratio, towards sunflower oil structuring could be obtained. These findings shed light for greater applications of SEs as structuring and carrier agent in foods and pharmaceutical.

Investigating the rheological, microstructural and textural properties of chocolates sweetened with palm sap-based sugar by partial replacement

Palm sugar, a natural alternative sweetener which can be made from the nectar of several species of palm tree flowers, recently gains more interest. Due to its physicochemical characteristics, utilisation of palm sugar as chocolate sweetener results in different quality attributes of chocolate. In this work, a thorough investigation about the influence of palm sugar on the rheological, microstructural and textural characteristics of chocolate was carried out through partial replacement of sucrose as chocolate sweetener. Accordingly, five sucrose–palm sugar blends with different palm sugar (PS) proportion, namely PS0, PS25, PS50, PS75, and PS100 were used as chocolate sweetener. The results showed that the Casson yield value of chocolate containing palm sugar was lower than the Casson yield value of chocolate sweetened with pure sucrose which could be attributed to the presence of agglomerates in the chocolate suspension. However, palm sugar-sweetened chocolate exhibited a higher Casson viscosity and thixotropy which could be mainly attributed to the presence of glucose and fructose and the relatively high moisture content. These factors also influenced the hardness of the chocolate to some extent. A lower melting temperature and enthalpy value of the sugar phase in chocolate were observed by DSC, whereas visualisation using SEM, polarised and normal light microscopy indicated increased agglomeration due to the presence of moisture, amorphous sugar and chemical “impurities”. Rheological behaviour of molten chocolate, hardness and polarised–normalised light microscopy were evaluated at a constant temperature of 40, 20, and 50 °C, respectively, while the melting profile was measured from 20 to 200 °C at a rate of 5 °C/min.

Synergistic interactions between lecithin and fruit wax in oleogel formation

In this study, the effect of lecithin (LEC) on the crystallization and gelation of fruit wax (FW) with sunflower oil was researched. A synergistic effect on the gel strength was observed at FW : LEC ratios of 75 : 25 and 50 : 50, compared to the corresponding single component formulations (100 : 0 and 0 : 100). Even below the critical gelling concentration (Cg) of FW, the addition of lecithin enabled gel formation. Lecithin affected the thermal behavior of the structure by delaying both crystallization and gel formation. The phospholipid acted as a crystal habit modifier changing the microstructure of the oleogel, as was observed by polarized light microscopy. Cryo-scanning electron microscopy revealed a similar platelet-like arrangement for both FW as a single oleogelator and FW in combination with LEC. However, a denser structure could be observed in the FW : LEC oleogelator mixture. Both the oil-binding capacity and the thixotropic recovery were enhanced upon lecithin addition. These improvements were attributed to the hydrogen bonding between FW and LEC, as suggested by Raman spectroscopy. We hypothesized that lecithin alters the molecular assembly properties of the FW due to the interactions between the polar moieties of the oleogelators, which consequently impacts the hydrophobic tail (re)arrangement in gelator-gelator and solvent-gelator interactions. The lipid crystal engineering approach followed here offered prospects of obtaining harder self-standing structures at a lower oleogelator concentration. These synergistic interactions provide an opportunity to reduce the wax concentration and, as such, the waxy mouthfeel without compromising the oleogel properties.