Fabrication of Oleogels via a Facile Method by Oil Absorption in the Aerogel Templates of Protein–Polysaccharide Conjugates

Abstract

In this study, a novel and facile method was developed to fabricate oleogels. The alginate/soy protein conjugates with excellent emulsifying activity and emulsion stability were prepared via Maillard reaction and freeze-dried to form the aerogel templates, which were then immersed in corn oil within 6 h to induce the oleogels. Compared with the alginate and soy protein solutions, the viscosity and elastic modulus G′ of the conjugate solutions increased, indicating the formation of a new macromolecule and strengthened gel network from Maillard reaction. The conjugate aerogels presented the morphology of serious aggregation and conglutination but the higher elastic modulus and better thermal stability, due to the increasing covalent interactions. These aerogel templates showed a good oil absorption of up to 10.89 g/g aerogel and holding capacity of 40%. The resulting oleogels loaded with thymol showed excellent antimicrobial activities against Staphylococcus aureus and Escherichia coli. This work suggests that the fabrication of oleogels is not limited to the choice of existing oleogelators but from a wide variety of protein–polysaccharide conjugates to form the aerogel templates for oil absorption.

Preparation of Protein Oleogels: Effect on Structure and Functionality

“…Similar to the emulsion-templated approach, also the foam-templated approach is based on freeze-drying of a previously prepared foam. After the drying step, oil is then added to the obtained dried foam-templates until saturation is reached [92,93], or the template is immersed in oil to let the dried foam absorb the oil in its voids [90,94]. As the oil is added later, the final amount of incorporated oil depends on the absorption capacity of the dried foams (aerogels).…”

“…Additionally for foams, it is important that the interfaces are stable enough to prevent coalescence of the air bubbles during drying. Although stable systems have been found with proteins only (gelatin, sodium caseinate) [90,92], additional polysaccharides are often added, such as xanthan gum [92,93], hydroxypropyl methylcellulose [90], and alginate [94]. In the case of the gelatin-based foam, additional polysaccharides were not a required component to obtain a sufficiently stable foam, but the addition of xanthan considerably increased the oil sorption capacity of the resulting cryogels [92].…”

“…These results suggest that the addition of polysaccharides does not necessarily lead to a more favorable network formation and could even result in weaker gels. However, in many other oleogels, polysaccharides contribute to gel strength or are required to make a stable system [85,[88][89][90]94]. The effect of polysaccharides on the gel strength therefore seems to depend on the specific composition used.…”

Effects of Grafting Degree on the Physicochemical Properties of Egg White Protein-Sodium Carboxymethylcellulose Conjugates and Their Aerogels

“…Certainly, a better aerogel structure can be achieved by introducing chemical cross-linking agents, although we cannot deny that the presence of these cross-linking agents is usually a great threat to people's health [32,35]. Recently, researchers have investigated the combinations of different proteins, such as whey [36,37], soy [38,39], and collagen [40], with various polysaccharides to improve the functional and mechanical properties of aerogels. Sodium carboxymethylcellulose (CMC-Na) is a food additive which contains COO − , an anionic polymer, which enables electrostatic interactions with some proteins in a positively charged state and contributes to a certain thickening and gelation effect.…”

Estructuración de aceites mediante el uso de hidrocoloides para sustituir grasas plásticas en los alimentos

“…Different protein-polysaccharide complexes have been formulated to develop hydrocolloids-based oleogels: soy protein-κ-carrageenan (Tavernier et al, 2017), sodium caseinate-xanthan gum, sodium caseinate-guar gum , and gelatin-xanthan gum (Abdollahi, Goli, & Soltanizadeh, 2020). Other studies have used protein-polysaccharide conjugates to develop aerogels such as alginate-soy protein (Chen & Zhang, 2020).…”