Extraction and encapsulation of betacyanin from Opuntia stricta pulp: process optimization, in vitro biocompatibility and color stability

Purpose Scientists’ interest has turned toward eco-friendly food additives. This study aims to investigate the use of Opuntia stricta pulp–encapsulated extract, rich in betacyanin, as a stable, water-soluble pigment. Design/methodology/approach Microencapsulation studies were performed with different polymers (gum arabic, xanthan gum and modified starch) to evaluate the color obtained and its stability. Furthermore, the physicochemical characterization of pulp extracts (OS), such as pH, solubility, moisture and water activity, was assessed. Thermal degradation kinetics of betalains were evaluated at 60°C and 85 °C and in the presence of citric acid. The biocompatibility of pigments against human peripheral blood mononuclear cells (PBMC) was assessed. Findings The fruit pulp contained high levels of potassium (153.8 mg/kg), calcium (103 mg/kg) and sodium (27.38 mg/kg). Betacyanin degradation rates during storage increased with exposure to temperature, but considerable protection was demonstrated in pigment encapsulated with different gums. However, thermal pasteurization at 60°C seems to have a lower effect on color degradation, interestingly with the pigment encapsulated with gum arabic, with a retention color superior to 0.9 versus 0.7 in nonencapsulated pigment. Furthermore, the degradation of color had decreased after prolonged heating of different pigments added with citric acid. PBMC cells had significant proliferative activity when treated with the cactus pear pulp extract. Originality/value By embracing eco-friendly and economical alternatives, O. stricta–encapsulated pigments can be a promising option in pasteurized foods (milk, cheese, fruit juices, dairy products . . ..).