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| Author(s): |
Izabela Dutra Alvim
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos |
| Defense date: | 2005-12-14 |
| Examining board members: |
Carlos Raimundo Ferreira Grosso;
Maria Ines Re;
Maria Célia Portella;
Maria Helena Andrade Santana;
Osvaldo de Freitas;
Alfredo Vitali
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| Advisor: | Carlos Raimundo Ferreira Grosso |
| Abstract | |
The microencapsulation is one technique for covering or evolving substances with the aim to provide protection and/or controlled release of the same ones. The microcapsules can be an alternative for attainment of a diet for feeding of the larvae of fish in the intensive aquaculture. Two methods of microencapsulation had been used for production of microparticles in the substitution of the alive food (rotifers and artemias) offered to the larvae of fish in the first periods of growing. The first one was based on the spray drying of one nutritionally and balanced liquid formulation. The dehydrated diet was agglomerated adjust the average size and solubility of the particles. The size of the agglomerated particles was increased efficiently. The solubilities in total soluble solids and soluble proteins of the diet without covering had been high with values (above 50%) for 120 minutes of permanence in water. The addition of oil to the dehydrated diet (OD) and the agglomation with pectate and calcium reduced the values of solubility. The aspect presented for the diet dehydrated without covering was characteristic of products dehydrated by spray dryer. The surface of the agglomerated particles presented some imperfections, which justified the low reductions of solubilities. The second process used was the complex coacervation between gelatin and acacia gum and as a core materials, a mixture of paprika oleoresin and vegetable soy oil and two hydrophilic composites (glucose or whey protein isolate). After, the lipidic microparticles were used as core material for microparticles obtained using complex coacervation. Using different types of microscopies (confocal, optical and scanning electronic microscopy) it was possible to characterize the coacervated microparticles that showed spherical geometry and multinuclear distribution of the core material. The microparticles containing paprika oleoresin of paprika and vegetable soy oil as core material had been crosslinked with glutaraldehyde or transglutaminase, and were dried using one oven with air circulation, spray dryer and freeze drying processes. The drying using oven did not allowed the attainment of a dry material presenting free flowing. The freeze drying, on the other side, allowed the attainment of microparticulated material showing spherical structure and free flowing for all samples including samples without cross-linking. The yield of the spray drying process was very low. This process did not work when non crosslinked samples were dried. The high level of cross-linking using 1.0mM/g of ptn showed the best results compared with transglutaminase or glutaraldehyde at 0.1mM/g of protein (reaction time of 18 hour for both) showing the maintenance of the moist microparticles structure. The release of the oleoresin was evaluated for the moist and dehydrated samples with and without crosslinking using ethanol as the release medium during 120 minutes. The core release observed was above 95% for moist coacervated without crosslinking, crosslinked using transglutaminase and for samples crosslinked with the low level of glutaraldehyde. The release level decreased when concentration of glutaraldehyde was increased. Dryed samples using freeze drying showed a great decrease on the release amount, not exceeding 35.4% after 120 minutes for all the treatments. The release of the core from the dehydrated microparticles using spray dryer was proportional to the maintenance of the integrity of particles. Again, cross-linking using high concentration of glutaraldehyde/g.ptn produced the best results.Lipídic microparticles had been incorporated successfully in the coacervated microparticles. The amount of released soluble composites using water solution was high to glucose and relative low for the protein after 20 hours of experiment. The acceptance of the microparticles was evaluated in a live biological assay using larvae of pacu. A diet agglomerated with calcium pectate and four coacervated microparticles using bovine gelatin or fish gelatin as the wall materials and vegetable soy oil or fat fish as core materials had been tested. Ranking of acceptance of the diets showed bigger values for the coacervated microparticles produced with gelatin/fat fish or gelatin/soy oil, followed by the microparticles produced with fish gelatin/soy oil, agglomerated particles and finally coacervate particles using fish gelatin/fat fish. The coacervation process showed interesting results but improvement on the nutritional balance needs to be done (AU) | |