Use of red onion (Allium cepa L.) residue extract in the co-microencapsulation of probiotics added to a vegan product

Abstract

This study aimed to develop a functional strawberry pulp containing the combination of Lactobacillus casei and bioactive compounds from red onion peel extract into the microparticles formulations to improve bacteria survival during storage and product consumption. To achieve this goal, the addition of different concentrations of red onion peel extract added to the microparticles was evaluated: 5, 20 and 40 %. Microparticles were morphologically characterized and the encapsulation efficiency of the bioactive compounds were evaluated. The physicochemical and microbiological characteristics of the fruit pulp were within the required standards, regardless of the formulation evaluated. As for the pulp added from the microparticles, their physicochemical and microbiological features and probiotic survival under simulated gastrointestinal conditions and storage were analyzed; the size of the microparticles ranged from 136.00 to 305.00 µm. The encapsulation efficiency of both, probiotics and compounds was satisfactory over the different treatments. Indeed, the results pointed out values in the range from 77.77 to 92.11 % for probiotic bacteria; from28.88 to 50.18 % for reducing compounds; 35.72 to 69.01 % for flavonoids; and 25.39 to 60.00 % for total monomeric anthocyanins. The formulations of alginate microparticles and alginate +5 % extract had the best results of L. casei probiotic viability in strawberry pulp under simulated gastrointestinal conditions and during storage at -18 °C for 60 days. In conclusion, red onion peel extract at low concentrations can help the survival of the probiotic L. casei under different conditions.

Keywords: Antioxidant; Co-encapsulation; External gelation; Microparticles; Probiotic.