Food-Grade Bigel Systems: Formulation, Characterization, and Applications for Novel Food Product Development

Bigels are characterized as biphasic systems consisting of two structured phases of different polarity, namely the oleogel and hydrogel phases. These systems have been widely used in pharmaceuticals and cosmetics, owing to their enhanced physicochemical stability compared to other structured systems and their ability to simultaneously deliver both hydrophilic and lipophilic compounds. Considering the above advantages, bigels could have considerable potential for the food industry. This review aims to provide a detailed description of the edible components used for structuring the oleogel and hydrogel phases and the preparation methods applied for the formation of food-grade bigels with application-specific tailored properties. The impact of the processing parameters, such as the oleogel-to-hydrogel ratio, methodology used for component mixing, and cooling rates, is presented. Moreover, the most applicable bigel characterization techniques, such as rheology, DSC, texture analysis, etc., are critically discussed. Finally, different bigel applications in foods as animal fat substitutes or as complex delivery systems for both polar and non-polar bioactive compounds are examined.