Microencapsulação de polpa de araçá-vermelho (Psidium cattleyanum): seleção de material de parede e estabilidade de compostos bioativos

Abstract

The food industry has increasingly sought out various properties in food ingredients and such properties can often be provided through microencapsulation. A microencapsulation is a packaging technique that aims to protect and retain sensitive compounds during the processing and storage of products. In this work, a comparison of different wall materials in the microencapsulation of red guava pulp (active material) was carried out through lyophilization drying. A red apple pulp was characterized as soluble solids (12 ° Brix), pH (3.51), titratable acidity (1.71 g citric acid 100 g-1) and water activity (0.973 total phenolic compounds (3098,04 mg 100 g-1), total carotenoids (156,29 μg β-carotene g-1) and antioxidant activity (AA) (1418.16% for DPPH and 1156.24% for ABTS.) The polymers used as the wall material were hydrolyzed pinhão starch, tara gum and gum arabic. The pinhão starch was modified by acid hydrolysis (2.2 M HCl) at 45°C for a period of 10 hours. After the acid modification stage of the pinhão starch, seven formulations were prepared for the microencapsulation of red guava pulp, being fixed percentage of 50% of red guava pulp (core) and varying wall materials: (i) 50% modified pinhão starch (A), (ii) 25% modified pinhão starch and 25% tara gum (AGT), (iii) 25% modified pinhao starch and 25% gum arabic (AGA), (iv) 16,6% modified pinhão starch, 16% tara gum and 16,6% arabic gum (AGTGA), (v) 50% tara gum (GT), (vi) 50% gum arabic (GA), (vii) 25% tara gum and 25% gum arabic (GTGA). The microcapsules were evaluated for moisture content, aw, encapsulation efficiency (EE), water solubility, hygroscopicity, bulk density, total phenolics, total anthocyanins, total carotenoids, antioxidant activity and stability of antioxidant activity for 60 days in different environmental conditions. In the characterization, the microcapsules with starch in their coating (A, AGT, AGA, AGTG) presented higher moisture content, hygroscopicity and solubility. The efficiency of micrencapsulation was generally lower for anthocyanins than for carotenoids, and the highest EE was 80.42% for AGTGA. The amylose presents a helix conformation which contains in its interior a hydrophobic region, favoring the interaction with lipophilic compounds. The highest content of phenolic compounds was 891.33 g citric acid 100 g1 for sample A and the highest AA was A, being 817.86% inhibition of the radical DPPH and 739.74% inhibition of the ABTS. The antioxidant activity and the total phenolic compounds presented at high correlation, indicating that the higher content of phenolic compounds presented higher antioxidant activity. During storage, the AA is more stable during the first 30 days regardless of storage conditions. Therefore, it is concluded that the use of starch modified in conjunction the gums, generates beneficial properties such as increased stability and increased encapsulation efficiency, bringing great potential of the use of microencapsulated red guava pulp in food systems.