Estruturas supramoleculares de α-lactoalbumina e glicomacropeptídeo: produção, caracterização, propriedades funcionais e carreamento de vitamina B2 e quercetina

Abstract

This study aimed to produce, characterize and verify the technical and functional properties of α-lactalbumin (α-la) and glycomacropeptide (GMP) supramolecular structures, and their potential in the food industry. The α-la/GMP supramolecular structures were prepared in a molar ratio of 1: 0.689, respectively. This proportion was defined by isothermal titration calorimetry and differential scanning calorimetry aided in determining the temperature values used since the formation of supramolecular structures was verified at higher and lower values than the denaturation temperature of the α-la. For GMP could not be established denaturation temperature, because it has no defined tertiary structure. The circular dichroism and fluorimetry analysis showed that there was interaction between α-la and GMP molecules. The supramolecular structures, in general, kept the α-helix secondary structures, but the intensity of these secondary structures may vary in the different conditions tested. The supramolecular structures have hydrophobic core. The particle size of supramolecular structures ranging from nano to micrometer, demonstrating that can be controlled through variables tested: pH (3.5 to 6.5) Heating temperature (25 to 75 °C) and heating time. The stability of supramolecular structures was evaluated by monitoring the particle size and the ζ potential at temperatures of 4 and 25 °C for 60 days. The supramolecular structures formed at pH 6.5 have higher system stability with ζ potential absolute values of approximately -30 mV. The morphology of supramolecular structures was determined by transmission electron microscopy and it was observed that proteins associated forming spherical structures. The foaming ability of supramolecular structures was evaluated by homogenization method, determining the increased volume, stability and expansion of the foam. It was found that the structures formed at pH 6.5 and 75 °C showed higher foaming ability. The emulsifying properties of the supramolecular structures were determined by the emulsifying activity index and emulsion stability index, using the turbidimetric method. However, the variables tested (pH, temperature and time) showed no effect on emulsifying properties. The surface tension of the supramolecular structures, determined by the Wilhelmy method showed a mean value of 50.825 mNm-1, demonstrating that the supramolecular structures can be effective in stabilizing emulsions and foam products. The supramolecular structures were able to encapsulate quercetin and vitamin B2, with maximum encapsulation efficiency of 98.64% and 31.11%, respectively. The stability of carrier systems was evaluated by monitoring the particle size and ζ potential for 60 days. For quercetin, systems prepared at pH 6.5 were stable for 60 days, while for vitamin B2, the stability of 60 days was demonstrated by the systems prepared at pH 3.5.