Microalgas como fonte de emulsionantes para aplicação alimentar

Abstract

The food industry depends on the use of emulsions and emulsifying agents for the production of creams, salad dressings, mayonnaise, and soups. Oil-in-water emulsions are formed by the homogenization of these two phases in the presence of one or more emulsifiers, e.g. proteins, compounds that have an amphiphilic character. Most of the emulsifiers used by the food industry are synthetic, motivating the searches for more natural and sustainable ingredients, apart from incentivising the study of the rheological properties of microalgae. Microalgae are a source of biomolecules, such as proteins, which have shown excellent emulsifying capabilities. Among microalgae, we can highlight Arthrospira platensis, Chlorella vulgaris, and Nannochloropsis oceanica, which may contain 18 to 77% protein. The extraction of this compound from the microalgae has been done through several techniques of cell disruption, such as ultrasound technology. Ultrasonic waves facilitate the breakdown and reduction of microalgal cell particles helping to improve the efficiency of the processes for protein extraction. Ultrasound probe and bath are the most widely used techniques among the ones currently available. Therefore the objective of this work is the extraction of proteins from the dehydrated biomass of the microalgae A. platensis, C. vulgaris and N. oceanica, using ultrasonic treatment with a probe and trough a bath equipment, combined with stirring in alkaline medium, characterization of the protein extract (total and protein yield, nutritional and energetic value, FTIR), evaluation of their functional properties (solubility, water and oil absorption capacity, foaming capacity, foam stability) and test of their use as an emulsifier. A. platensis showed the best results in terms of total and protein yield for both extraction methods. However, the extract obtained by ultrasound bath showed the higher concentration of phycocyanin (116,14 μg/mL), which is a photosynthetic pigment present at a content of 15 to 20% in this microalgae protein composition, also having the lower lipid content (0,44 g/100g ms). Due to the observed best results, the protein extract obtained by ultrasound bath was used to prepare emulsions, for which a procedure PFF (24-1) was applied to evaluate the effect of 4 process variables (oil/water ratio, concentration of protein extract, pH, and storage time) on the stability of the formed emulsions (zeta potential, particle size, creaming index, optical microscopy). All the prepared emulsions remain stable for up to 14 days.