Ultrasonic Treatment of Food Colloidal Systems Containing Oleogels: A Review

Enhancing the Oxidative Stability of Beeswax-Canola Oleogels: Effects of Ascorbic Acid and Alpha-Tocopherol on Their Physical and Chemical Properties

The choice of antioxidant to be used in the formulation of an oleogel is crucial to determine its oxidative stability and functionality, as these factors can also affect the physical, chemical, and rheological properties of the oleogel. In this study, the effect of two antioxidants (ascorbic acid, AA, and alpha-tocopherol, AT) and their concentration (0.01, 0.02, and 0.03%) on the physical and chemical properties of beeswax and canola oil oleogels were evaluated. The results show that the type and concentration of antioxidants did not affect the thermal properties of the samples, and in FTIR analyses, no noticeable changes in spectra patterns are observed. Rheological analyses showed that the oleogels containing AA exhibited higher elasticity and resistance to deformation. Accelerated oxidative stability tests (storage at 50 °C and the Rancimat test) showed that AA effectively delayed oxidation. The induction time increased by 2.61-fold at higher concentrations, while AT did not significantly affect oxidation resistance. Overall, it was observed that AA improved oleogel firmness and OBC (up to 1.75-fold and 2.8%, respectively), whereas AT resulted in a softer and less stable gel structure. These results show the importance of antioxidant selection, indicating that hydrophilic antioxidants have promising applications in the formulation of beeswax oleogels.

Analysis of Oleogel Volatile Profile Formation under Ultrasonic Treatment

Under certain conditions, ultrasonic treatment of certain foods and ingredients can contribute to the appearance of an extraneous odor, which is not usual for them, especially in fat-containing products. Since the food sector uses high-intensity ultrasound to control the crystallization of fats, the development of foreign smells and secondary fat oxidation products may impact the quality and safety of such items. In this work, we studied the volatile compounds' profiles of oleogels structured with individual fractions of beeswax using ultrasonic treatment. For this work, six samples of oleogels were obtained. Sunflower oil was used as a fatty base, and three fractions of beeswax were used as gelators: hydrocarbon fraction (>99%), monoester fraction (>95%), and a mixture fraction of wax di- and triesters (10.1%), free fatty acids (40.1%), and free fatty alcohols (49.8%). The influence of ultrasonic treatment on the properties of oleogels was assessed using light microscopy in polarized light, texture analysis, gas chromatography with flame ionization, and mass spectrometric detection. Ultrasonic treatment affected the crystallization of oleogels and led to the formation of smaller crystals. At the same time, sonication led to both an increase and a decrease in the firmness of oleogels, depending on the composition of the gelator. As regards volatile compounds, a total of 121 fragrant substances were identified in all samples, including such groups as alkanes, alkenes, alkadienes, alkynes, alkadiynes, alcohols, ketones, aldehydes, terpenes, alkyl alkane, and alkyl benzene derivatives. Ultrasonic treatment caused formation of new volatile unsaturated compounds. Some of them are known to have an unpleasant odor and thus might be responsible for the extraneous odor formation in studied fatty systems. Those were mainly (E)-2-octene, 1-heptene, 1,3-butadiene, and 1,3-octadiene in all oleogel samples. Sonicated samples B and C additionally had but-1-en-3-yne, pentenyne, and 1,3-butadiyne, whose odor can also be characterized as extraneous and distasteful. Several volatile compounds, supposed to be products of lipid oxidation, were also identified. Here we assume a reasonable approach is needed when selecting sonication conditions to prevent undesirable taste and flavor in oleogels and oleogel-based food products.

Bigels as Delivery Systems: Potential Uses and Applicability in Food

Bigels have been mainly applied in the pharmaceutical sector for the controlled release of drugs or therapeutics. However, these systems, with their intricate structures, hold great promise for wider application in food products. Besides their classical role as carrier and target delivery vehicles for molecules of interest, bigels may also be valuable tools for building complex food structures. In the context of reducing or even eliminating undesirable (but often highly functional) food components, current strategies often critically affect food structure and palatability. The production of solid fat systems that are trans-fat-free and have high levels of unsaturated fatty acids is one of the challenges the food industry currently faces. According to recent studies, bigels can be successfully used as ingredients for total or partial solid fat replacement in complex food matrices. This review aims to critically assess current research on bigels in food and pharmaceutical applications, discuss the role of bigel composition and production parameters on the characteristics of bigels and further expand the use of bigels as solid fat replacers and functional food ingredients. The hydrogel:oleogel ratio, selected gelators, inclusion of surfactants and encapsulation of molecules of interest, and process parameters (e.g., temperature, shear rate) during bigel production play a crucial role in the bigel's rheological and textural properties, microstructure, release characteristics, biocompatibility, and stability. Besides exploring the role of these parameters in bigel production, future research directions for bigels in a food context are explored.