Use of spent osmotic solutions for the production of fructooligosaccharides by Aspergillus oryzae N74.

In the food industry, osmotic dehydration can be an important stage to obtain partially dry foodstuffs. However, the remaining spent osmotic solution at the end of the process could become a waste with an important environmental impact due to the large amount of organic compounds that it might contain. Since one of the most important osmotic agents used in osmotic dehydration is sucrose, this spent osmotic solution could be used to be biotransformed to produce fructooligosaccharides by a fructosyltransferase. This study evaluated the production of fructooligosaccharides using the fructosyltransferase produced by Aspergillus oryzae N74, and the spent osmotic solution that resulted in the osmotic dehydration of Andes berry (Rubus glaucus) and tamarillo (Cyphomandra betacea). Assays were conducted at small and bioreactor scales, using spent osmotic solution with or without re-concentration. At small scale no significant difference (p > 0.05) was observed in the fructooligosaccharides production yield, ranging from 31.18% to 34.98% for spent osmotic solution from tamarillo osmotic dehydration, and from 33.16% to 37.52% for spent osmotic solution from Andes berry osmotic dehydration, using either the SOS with or without re-concentration. At bioreactor scale the highest fructooligosaccharides yield of 58.51 ± 1.73% was obtained with spent osmotic solution that resulted from tamarillo osmotic dehydration. With the spent osmotic solution from Andes berry osmotic dehydration the yield was 49.17 ± 2.82%. These results showed the feasibility of producing fructooligosaccharides from spent osmotic solution that is considered a waste in food industry.

Kinetic modeling of fructooligosaccharide production using Aspergillus oryzae N74.

In this study, the kinetic for the bioconversion of sucrose to fructooligosaccharides (FOS) by free cells of Aspergillus oryzae N74 was modeled. In addition, the effect of immobilized glucose isomerase (IGI) on FOS production yield was evaluated and considered in the kinetic model. The selected kinetic models were based on a proposed reaction mechanism described by elementary rate equations and modified Michaelis-Menten kinetic equations. The use of IGI allowed to increase the FOS production yield (FOS(Yield)) and to decrease the glucose/fructose (G/F) ratio. At shake flask scale, the FOS(Yield) was increased in 4.7 % (final yield 58.3 %), while the G/F ratio was reduced 6.2-fold. At bench scale, the FOS(Yield) was increased in 2.2 % (final yield 57.3 %), while the G/F ratio was reduced 4.5-fold. The elementary rate equation model was the one that best adjusted experimental data for FOS production using either the fungus biomass or the mixture fungus biomass-IGI, with an overall average percentage error of 7.2. Despite that FOS production yield was not highly improved by the presence of IGI in the reaction mixture, it favored the reduction of residual glucose in the mixture, avoiding the loss of material owe to glucose transformation to fructose that can be used in situ for FOS production by the fructosyltransferase.

Recent trends in fructooligosaccharides production.

Prebiotics are food ingredients that promote host health beneficially due to their effect over the growth and activity of probiotic bacterial species. Prebiotic properties have been demonstrated for inulin-type fructans, galactoolicosaccharides and lactulose. Fructooligosaccharides (FOS), considered as inulin-type fructans, represent an important source of prebiotic compounds that are widely used as an ingredient in functional foods. FOS are produced by the action of fructosyltransferase from many plants, fungi and bacteria, and they are mainly composed of 1-kestose, nystose, and 1-beta-fructofuranosyl nystose. Among them, 1-kestose has better therapeutic properties than those with a high polymeric degree (GF(n > 4)). FOS exhibited properties than those with a high polymeric degree (GF(n>4)). FOS exhibited properties such as low caloric values, non-cariogenic properties, decrease levels of lipids and cholesterol, help gut absorption of ions, and stimulate the bifidobacteria growth in the human colon. This review presents a summary of the patents related with FOS production by industrial sucrose biotransformation or the use of recombinant fructosyltransferase enzymes. Also, a brief description of recent FOS applications will be discussed.