Produção de galactooligossacarideos por linhagens fungicas / Production of galactooligosaccharides by fungi strains

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Actually, one of the most significant development in science are functional foods, connected with the development of dietetic supplement that affects beneficially the health. Among these, we can mention the galactooligosaccharides, that is a group of oligosaccharides considerated as non-digestible carbohydrates due to their resistance to hydrolysis of intestine enzymes. Among the benefits obtained with galactooligosaccharides ingestion are the increase of bifidobacteria population in the colon and, by their antagonistic effect, the reduction of the pathogenic bacteria level, over the increase of calcium absorption, immune system stimulation, intestinal diseases combat, serum cholesterol regulation and the reduction of colon¿s cancer risks. The production of galactooligosaccharides has been extensively studied in microorganisms, through the transgalactosylation reaction catalyzed by b-galactosidase enzyme. The aim of this work was the production of b-galactosidase enzyme by fungus strains to produce galactooligosaccharide. Firstly, the fungus were ramdonly removed from the microorganisms collection of Bioaromas Laboratory (Food Science Department ¿ UNICAMP) and isolated from honeycomb collected at Itapira-SP. After this, the microorganisms were tested for the production of the b-galactosidase enzyme and transgalactosylation activity. To study the fermentative process, it was selected 3 microorganisms with the largest transgalactosylation activity. An experimental design was realized, consisting of 9 treatments, to evaluate the effect of temperature (24, 30 and 36 oC), humidity (40, 50 and 60%) and lactose concentration (0, 7,5 and 15%) in medium to produce the enzyme. After, it was selected the best microorganism to characterize its enzyme to produce galactooligosaccharides. The studied variables were: temperature (35, 45, 55 and 65 oC), pH (4, 5, 6 and 7), initial lactose concentration (20, 30, 40 and 50%) and lyophilized brute extract concentration (52, 104, 156 and 208 U). Aliquots were took out from all tests after 6, 12, 24, 36, 48 and 72 hours of reaction. To evaluate the time influence in galactooligosaccharides syntesis, it was realized a kinetic curve to meansure the production in 3, 6, 9, 12, 18, 24, 36, 48 and 72 hours of reaction. The screening of microorganisms resulted in 5 galactooligosaccharides producer strains: Aspergillus sp (LB-01), Aspergillus sp (LB-32), Aspergillus sp (LB-36), Penicillium sp (LB-51) and Scopulariopsis sp (LB-35). The largest producer of 4¿galactosil-lactose was Aspergillus sp (LB-32), that has converted 19,17% of lactose actual midst and has produced 7,25% of the tetrasaccharide. The second best producer was Penicillium sp (LB-51) with 6,71% of production, followed by Scopulariopsis sp (LB-35) with 6,65%, Aspergillus sp (LB-01) with 5,22% and Aspergillus sp (LB-36) with 4,97% of galactooligosaccharides production. The study of the fermentative process was realized with the microorganisms: Aspergillus sp (LB-32), Penicillium sp (LB-51) and Scopulariopsis sp (LB-35). During the experiment, it could be noticed that some treatments promoted the growth of the microorganisms, while others were disadvantageous. The control treatment T9 (that consists of 30 oC, 0% of lactose concentration in medium and 50% of humidity) was the best, with the biggest activity values for all microorganisms. The other treatments showed enzymatic activity values significantly poorer (p<0,05) than the values obtained in control treatment. The results of the enzymatic characterization showed that, for the microorganism Aspergillus sp (LB-32), higher temperatures (65 oC) and lower pH values (pH 4) promoted the production of 4¿galactosil-lactose. The initial lactose concentration of 50% was disadvantageous because of lactose precipitation, being the best production of galactooligosaccharide with 40% of initial lactose. The increase in the enzymatic concentration was directly proportional to the increase of 4¿galactosil-lactose production, obtaining the best result with 208 U of enzyme. All the tests showed the best results in 48 hours of reaction. The kinetic curve showed that the production of galactooligosaccharides starts after 3 hours of reaction, and reaches the top of production in 48 hours. Our best result was obtained using 65 oC of temperature, producing 12,10% of 4¿galactosil-lactose throught 31,27% of lactose conversion

ASSUNTO(S)

prebiotics galactooligosaccharides functional food alimentos funcionais galactooligossacarideos prebioticos

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