Gelling agents are critical food additives which are responsible for the texture, stability, appearance, and nutritional quality of many products. Usually, polymeric substances are used for this purpose. Low-molecular-weight (LMW) gelators, in particular phenylalanine (PHEN), yield supramolecular gels and have been investigated for their potential use in pharmaceuticals, bioremediation, and cosmetics. PHEN's structural properties allow for the formation of three-dimensional networks through hydrogen bonding and π–π stacking interactions. However, the derivatisation of amino acids and use of organic solvents limit their use in food products. This study proposes new formulations of PHEN gels using GRAS substances, making them suitable for consumption.
Sol-gel systems consist of a mixture of PHEN, water, and propylene glycol. A 1% PHEN solution in 1:1 water/propylene glycol gels when cooled or stirred. Rheological behaviour was analysed at varying PHEN or propylene glycol concentrations. Also, to assess reactivity towards non-enzymatic browning, 1% or 10% xylose was added and the mixtures were heated at 60°C.
Mechanical spectra and viscoelastic properties of the gels were analysed. Pseudogel behaviour improved with PHEN concentration. The sol-gel transition temperatures of various formulations increased linearly with PHEN concentration and decreased with increased propylene glycol. The 1% PHEN formulation in 1:1 water/propylene glycol presented a transition temperature of 58.7°C. Systems with 1% or 10% xylose presented transition temperatures of 44°C and 49.6°C, respectively.
PHEN gel viscosity increases with stirring, rendering upscaling costlier; low stirring speed, high temperature, or composition changes must be considered. Lower stirring delays maximum viscosity linearly, and non-enzymatic browning follows first-order kinetics. Thus, the combined effects of these variables should be analysed in processing design and product development.
When mildly heated, PHEN gels release a floral aroma that could enhance tea-like blends, making them promising alternatives for food products, either desserts or appetisers with special texture and flavour.
