Azeite Sacha inchi (Plukenetia volubilis L.) como recheio em micropartículas de alginato e cálcio recobertas com ovoalbumina

Abstract

In this work we evaluated the effects of different amounts of sodium alginate (0.75, 1.50 and 2.25% w/w) and calcium ions (1.50, 3.00 and 4.50%) on microparticle production and oxidative stability of microencapsulated Sacha inchi oil by ion gelation, coated by electrostatic interaction with egg albumin. The microparticles were produced at room temperature using a double fluid atomizer with 30 L/min the flow of air and 3.34 mL/min the flow of emulsion. The acidity index of the Sacha inchi oil was 6.50 (mg KOH/g), iodine 47.96 (100g I2 g -1 ) and peroxide 1.73 (meq Kg). The antioxidant activity of Sacha inchi oil, possibly determined by phenolic compounds, was 164.44, 211.29 and 668.21, expressed in µM Trolox/g when ABTS, DPPH and FRAP methods were used respectively. In its composition 90.5% (w/w) of polyunsaturated fatty acids (45.5% of linolenic acid, C18:3 (w/w), 35.1% of linoleic acid, C18:2 (w/w) and 15 other fatty acids present in small quantities). The amounts of calcium, determined by atomic absorption spectrophotometry, ranged from 117,2 a 185,94 mgCa/g.particles. The encapsulation efficiency, determined by Bligh and Dyer, was 72.38 %. The average size of particles without protein was 239 µm and 309 µm for particles with proteins while the largest mean diameter was obtained for particles produced with 1.5% sodium alginate and 4.5% calcium. The polydispersity (Span index) ranged from 2.32 to 3.37, with lower Span values observed for coated microparticles. Morphological evaluation of wet microparticles by light microscopy indicated that 0.75% of sodium alginate was not sufficient to produce spherical microparticles for the other sodium alginate concentrations (1.50% and 2.25%) at either concentration, the calcium microparticles were spherical, with continuous walls and encapsulated Sacha inchi oil distribution throughout the microparticle matrix. Uncoated microparticles showed zeta potential between -22.5 mV and -36.4 mV, and with pH 4 coating, subjected to a grinding to decrease their average size, presented zeta potential between -13.3 mV and -32.9 mV. High amounts of proteins were adsorbed by the microparticles, ranging from 51.8% to 70.9% (dry basis, crude protein), with higher protein adsorption observed when 1.5% calcium chloride and 1.5% sodium alginate were used. The high amount of adsorbed protein can improve protection against pH, light and oxygen conditions that may be deleterious to microencapsulated material. Oxidative stability analysis indicates an increase in peroxide indices as a function of storage for protein-free and protein-coated microparticles, with a decrease in values at the end of the analysis period.