Novel Pickering emulsion stabilized by natural fiber polysaccharide-protein extracted from Haematococcus pluvialis residues

As an excellent source of natural astaxanthin, Haematococcus pluvialis (H. pluvialis) is rich in nutritional elements in the residues after extraction of astaxanthin. At present, the residues of H. pluvialis are only used as feed in the breeding industry, but its application in food industry is still a challenge. In this study, fiber polysaccharide-protein complex also known as aqueous protein extraction from H. pluvialis residues (APHRs) was successfully extracted from the aqueous extract of H. pluvialis residues (AHRs). The protein and carbohydrate contents of APHRs were 23.6% and 64.9%, respectively. The protein of APHRs was composed of β-sheet (57.6%) and turns, and the molecular weight of protein was about 10 kDa. What's more, APHRs had good emulsifying stability and oil holding capacity. Microscopic images showed that fibrous polysaccharides were connected around protein particles, which can form a stable structural cross-linking. The low energy emulsion formed by APHRs showed the smallest particle size and the best storage stability compared with crude polysaccharides of H. pluvialis residues (CPHRs) and AHRs. The emulsion creaming index of APHRs, CPHRs, and AHRs in high energy emulsion was 1%, 52%, and 61% respectively. Owing to the existence of fibrous polysaccharides, the stability of APHRs emulsion was superior to that of CPHRs and AHRs. In summary, APHRs have excellent safety and stability, and it is likely food-grade raw material for stabilizing Pickering emulsion.