Effect of sonication pretreatment on physicochemical, surface, thermal, and functional properties of fibro‐proteic extracts from male date palm flowers

Abstract

This study aims to investigate the effect of the application of an ultrasound pretreatment on physicochemical, surface, thermal, and functional properties of two extracts from male date palm flowers. The obtained extracts were compared based on their structural and functional properties. It was proved that the application of sonication pretreatment has modified significantly (p < .05) the extract's characteristics. The protein yield, the essential amino acid content and the protein solubility were improved (29.61%, 29.22 g/100 g protein, and 91.1% for native sample against 35.26%, 41.04 g/100 g protein, and 100% for treated sample, respectively), while the protein content and the surfactant behavior at 1% were decreased due to the liberation of other compounds than protein. Moreover, the sonication has engendered some structural modifications such as the dissociation of some intermolecular bonds (FTIR) and the increase of crystalline region (X-ray), which influenced the protein unfolding and have led to the decrease of enthalpy (DSC) (272.2 against 228.6 J/g) and the decrease of water-holding capacity (11.62 against 9.51 g water/g of dry sample). Practical applications The male date palm flowers (MDPF) present a rich matrix composed mainly of dietary fiber, protein, and minerals. The protein fraction of MDPF was considered as an excellent source of amino acids supplying the human requirements. The dietary fiber fraction was composed essentially of insoluble dietary fibers which contribute to a balanced diet by creating satiety feeling and facilitating the intestinal transit. The fibro-proteic extract (FPE) of MDPF could be a potential functional ingredient for food applications. The physicochemical and functional properties of the FPE was changed by ultrasound pretreatment, which was beneficial to improve the protein yield, the amino acid profile, and the protein solubility. Nevertheless, both treated and non-treated samples showed promising nutritional and functional characteristics that could be used in the food industry to ameliorate food quality.