Partículas de alginato e mucilagem de ora-pro-nobis (Pereskia aculeata Miller) recobertas com quitosana ou proteína do soro do leite para encapsulação de Lactobacillus acidophilus

Abstract

Because it is rich in arabinogalactan biopolymer, ora-pro-nóbis mucilage (MOPN) has broad technological potential applied to the food industry, including in the formation of particles by ionic gelation. However, studies show that spheres formed with MOPN and alginate have large pores, which can be reduced by coating these particles with biopolymers of opposite charge to the hydrogel, forming a polyelectrolyte complex. This combination of techniques is widely used in the food industry and one field of application is the encapsulation of probiotics for the production of functional foods. The objective of the present work was to synthesize microparticles of ora-pro-nobis mucilage (MOPN) and alginate (ALG) coated with whey protein concentrate (WPC) and chitosan (QUI) for the encapsulation of L. acidophilus ATCC 4356 applied in ice cream. The particles were produced by ionic gelation using a central rotational composite design to optimize the concentrations of biopolymers that provided greater encapsulation efficiency for the microorganisms. These spheres were characterized regarding morphology, size distribution, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and in vitro digestion test. Subsequently, the particles were added to ice cream and the viability of the probiotics was evaluated during 60 days of storage and also after recrystallization test. The results showed that L. acidophilus was successfully encapsulated in the synthesized microparticles with maximum encapsulation efficiency of 96.86% for uncoated spheres (SRp), 98.40% for particles coated with whey protein concentrate (WPCp) and 99.56% for treatments coated with chitosan (QUIp). The optimized concentrations of each biopolymer were 0.6% (m/m) for MOPN, 0.9% (m/m) for ALG, 5.25% (m/m) for WPC and 1.2% (m /m) for QUI. Zeta potential and FTIR analyzes confirmed the coating of the particles with WPC and QUI. The synthesized particles had a spherical shape and average Sauter diameters (D32) that ranged from 172.50 to 272.25 μm. The QUIp microspheres were more porous, less thermally stable and showed lower survival rates of microorganisms in the simulated gastrointestinal tract and in ice cream, when compared to the others. The SRp and WPCp microparticles showed the best viability results for the in vitro digestion test (68.65% and 67.45%); for storing ice cream (71.23% and 72.49%); and for viability after recrystallization cycles (93.32% and 92.47%). The results for free cells were lower than those presented for microencapsulated cells, confirming the ability of MOPN and ALG microparticles, coated or not, to protect probiotic microorganisms against adverse conditions. Finally, it was possible to attest to the potential of MOPN in encapsulating active ingredients, especially probiotics.