Micropartículas contendo β-caroteno aplicadas em coberturas comestíveis para frutas minimamente processadas

Abstract

Microencapsulation is a technique for entrapment of bioactive compounds aiming at its protection against degradation, increasing its bioavailability, and stability during processing and shelf-life, as well as controlling the delivery of the bioactive in the gastro-intestinal track. Since at least 15 years, microencapsulation technologies are being developed in several research centres from the biggest food companies. This shows that encapsulation is an applied Science, which goes from the paper to the laboratories to the supermarket shelves and finally to the human body. Therefore, this technology can effectively be used for preventing several human diseases. The choice of encapsulation technology to be used or developed depends on several factors: required mean particle size, the physic-chemical properties of the bioactive compound and of the final ingredient, the mechanism for bioactive release, the food production process and the costs. The aim of this work was to identify the most promising Technologies for encapsulating pro-vitamin A carotenoids from carrots, as well as to develop and apply on fresh fruits those Technologies. Using the retro-design approach the most promising Technologies were identified. A careful analysis of the problem is done considering the intended consumer benefit, the target market, the food production process and the food product characteristics. Then, the technical requirements (ingredient physical state, barrier properties, release triggers, dosage in the food product) for the encapsulation system are defined. This in turn allows one to select the feasible encapsulation technologies, taking into account additional factors such as local legislation. For the experimental part of the present work, we have produced carrot flour and β-carotene particles by the ionic gelation technology. Bioactive encapsulation efficiency was determined experimentally using a spectophometer method. The four most promising encapsulation technologies were applied to manioc edible coatings, which in turn was applied to minimally processed strawberries. Then it was studied the effect of the type of particle over the visual appearance, colour and texture of the fruits. In that second part of the study, four types of particles were used: 1) microgels (produced in the lab); 2) coacerved particles (commercial); 3) lipid solid particles (commercial); 4) carrot flour (produced in the lab, although it is not an encapsulation technology). The retro-design approach reveled to be an excellent tool for identifying feasible encapsulation technologies for solving a well defined problem. Four technologies were identified as most promising: ionic gelation, complex coacervation, solid lipid nanoparticles and interfacial polymerization. Microgels were developed by using carrot aquous extract and alginate solutions. Particles with means size lower than 80 m were produced when alginate content was 1%. Those particles showed a beta-carotene encapsulation efficiency of 67-100%. The microgels or the lipid particles were homogeneously distributed in the edible coatings and did not bring roughness to the surface of the coated fruit. Color and texture of the coated fruits were not affected by the presence of particles. However, the brightness of the coated fruits was higher for samples containing microgels as compared to the other particles. This was due the opacity of the coacervates and the lipid particles.