Encapsulação de compostos bioativos da acerola (Malpighia emarginata DC) por spray drying e nanoprecipitação usando carreadores proteicos: avaliação das partículas de acerola, estabilidade de armazenamento e aplicação em produtos alimentares

Abstract

Brazil is the world's largest producer and exporter of acerola (Malpighia emarginata DC.), one of the richest natural sources of ascorbic acid. However, the high perishability of the fruits and the fact that ascorbic acid is easily degraded when subjected to food processing and storage due to exposure to light, oxygen, high temperatures and extreme pH, compromise their commercial use. Therefore, processing techniques that preserve the bioactive compounds of acerola and create profitable value-added alternatives and diversification of products are of special interest to the industry. Therefore, this doctorate dissertation investigates two relevant encapsulation techniques - spray dying and organic solvente nanoprecipitation - applied to both acerola juice and pomace using protein carriers. The work was divided into two distinct approaches. Initially, spray dried acerola microparticles were produced with whey protein isolate, soy protein isolate and hydrolyzed collagen (isolated or combined) as drying carriers. Six experimental groups were investigated: acerola juice with isolated soy protein – ASP; acerola juice with isolated whey protein – AWP; acerola juice with collagen – ACO; acerola juice with a mixture of isolated soy protein/ collagen 1:1 – ASC; acerola juice with a mix of whey protein isolate/collagen 1:1 – AWC; acerola juice with a mix of whey protein isolate/soy protein isolate 1:1 – AWS. Treatments were evaluated for the process performance (solids recovery and polyphenol retention) and quality of the final product (total polyphenol content and solubility) and the best treatment was selected for the study of storage stability and subsequent incorporation into starch films produced by casting. AWC microparticles achieved good solids recovery (> 50%), polyphenol retention and total phenolic content (TPC; > 70% and 128.45 mg GAE/g, respectively), in addition to high water solubility (85.2%). AWC particles were selected to produce biodegradable cassava starch films with water vapor permeability of 0.29 g mm/m2 h kPa and antioxidant activity (measured by 2,2-diphenyl-1-picrylhydrazyl DPPH) of 6.57 μM TE/g, in addition to greater migration of polyphenol to water (6.30 mg GAE/g film) compared to acetic acetic. In the second part of this study, acerola particles were produced by spray drying and organic solvent nanoprecipitation from bioactive compounds recovered from acerola pomace (peel, seeds and pulp) using whey protein isolate. Acerola spray dried microparticles were developed using lab-scale drying with input temperature of 150 ºC. Nanoparticles were prepared by the nanoprecipitation technique using a core: encapsulating agent ratio of 1:4 (p:p), Tween 80 surfactant and stirring speed (17,000 RPM) during ethanol evaporation of. The influences of the two encapsulation processes were evaluated regarding solids recovery and encapsulation efficiency, in addition to the physicochemical characteristics (scanning electron microscopy SEM, particle size diameter, Zeta potential, infrared spectroscopy with transform Fourier analysis FTIR, solubility, and hygroscopicity) concentration of bioactives (total phenolic content and ascorbic acid) and DPPH antioxidant activity. Furthermore, the particles were evaluated for storage stability under controlled conditions and fortification in natural yogurts. Both encapsulation techniques showed solids recovery greater than 50%. The phenolic encapsulation efficiency was higher for nanoparticles (79.7 ± 4.1%) compared to spray dried microparticles (66.5 ± 2.5%). Both particles had spherical shapes, with nanoparticles showing a smooth surface in the nanometer scale (178.37 ± 39.70 nm), while spray dried microparticles showed wrinkled surfaces on the micrometer scale (1.87 ± 0.63 μm). The Zeta potential results showed moderately stable (pH < 3.5) and highly stable (pH > 6.9) nanoparticles, while spray dried particles were moderately stable (pH > 7.5). FTIR demonstrated the interactions of whey protein with acerola pomace extract through electrostatic interactions and new chemical bonds, suggesting encapsulation. The nanoparticles had higher TPC (52.24 ± 2.42 mg GAE/g) and ascorbic acid (671.3 ± 294 mg AA/100 g) compared to microparticles (TPC = 39.72 ± 0.61 mg GAE/g and AA = 358.74 ± 77.85 mg AA/100 g) (p<0.05). Yogurt fortified with acerola particles was stable for 14 days, when the TPC in yogurt with acerola microparticles (36.25± 2.96 mg GAE/100 g) was higher than yogurt with nanoparticles (22.02 ± 0.3 mg GAE/100 g). Overall, results show that encapsulation techniques are efficient strategies for producing ingredients and products with preserved phytochemical characteristics and improved attributes from acerola, both from acerola juice and pomace.