Modulating process parameters to change physical properties of bigels for food applications

Abstract

The effect of the process parameters involved in the production of bigels was investigated through the study of structural, mechanical and rheological properties. Four level (2 4) Central Composite Rotational Design (CCRD) configuration was applied in order to study the organogelator concentration, hydrocolloid concentration, organogel:hydrogel ratio and shear of mixing. Gellan gum and high oleic sunflower oil with glycerol monostearate were used to produce hydrogels and organogels, respectively. All formulations were water-in-oil systems with gel-like behavior. FTIR and XRD results showed that bigels were formed only by physical arrangement with no chemical interactions, but gellan gum decreased the crystallinity of the systems due to its amorphous character. However, hydrogel particles acted as an active filler, reinforcing the structure in comparison to pure gels. Also, the glycerol monostearate present in the organogel could self-assemble at the interface in order to interact with the aqueous phase, improving the interaction and affinity between the phases. Moreover, depending on the composition, systems could be softer or harder and present some frequency dependence. CCRD showed that all parameters evaluated changed with organogel:hydrogel ratio and organogel concentration. Shear of mixing was also significant for some parameters; however, hydrocolloid concentration did not exert a significant effect on the range studied. From PCA analysis it was possible to distinguish different groups, which means that some conditions produced bigels with similar characteristics. Thus, it is expected that these results will allow customizing and fine-tuning properties of structured two-phase systems for diverse applications, ranging from food to pharmaceutical and cosmetic industries.

Novel Formulation of Bigel-Based Vegetable Oil Spreads Enriched with Lingonberry Pomace

“…With regard to the rheological properties, all samples revealed a typical gel network formation as the elastic modulus (G′) was always above the loss modulus (G″) and both moduli were separated by less than one logarithmic cycle (with the tan δ always below 1) ( Figure 6 ). Such behaviour was previously reported as typical for gels and spreads [ 31 , 38 , 39 ]. Additionally, a slight frequency dependence was observed for both moduli, suggesting that although the gels were strong, they showed a slightly weak network.…”

Food-Grade Bigels with Potential to Replace Saturated and Trans Fats in Cookies

“…In the images of bigels, the needle-like structure of BW cannot be easily seen as in the BW-O. This fact could suggest that the shear in the bigel preparation process may destroy the more ordered structure of the BW of oleogel or that the BW crystals would dissipate with the aqueous content within the mixture in accordance with what was found by Martins et al [ 3 ] and Fasolin et al [ 11 ] for bigels.…”

“…Other authors have reported different effects of mixing the two phases of bigels, changing the rheological behavior and mechanical properties of the original matrices, where the bigel components lead to changes in network strength; these changes could be related to interactions between the disperse and continuous phases [ 11 ]. For example, in bigels prepared with medium-chain triglycerides Neobee-beeswax (3 and 6%) oleogel and ALG hydrogel (at 2%), mixed at 600 rpm, the oleogel fraction disrupted the alginate network (forming oleogel-in-hydrogel matrix) and consequently decreased the mechanical properties of the bigels compared to the ALG hydrogel; however, the firmness of bigels was higher than that of the original oleogels [ 3 ].…”

“…In these fat-reduced systems, there is a part of water bound to carbohydrate particles by developing a gel structure. This results in a decrease in the amount of free water, and consequently the cookie dough is hard [ 11 ]. For this reason, to obtain a fat reduction without compromising the food quality, a partial substitution of fat is a good option.…”

“…Currently, bigels are mainly used for pharmaceutical and cosmetic purposes, but minor applications have already been found in the food area [ 10 ]. Some food-grade bigels have been studied showing that it is possible to tailor their mechanical properties, rheology, and thermal stability, directing their characteristics to allow for their use in food products as a fat replacer [ 3 , 10 , 11 ]. The potential of bigels as a fat replacer was shown for the first time in foods by Ghiasi et al [ 12 ], who found that low-fat beef burgers using bigels presented better cooking properties compared to animal fat burgers.…”