Influence of the fermentation parameters and optimisation of isomaltulose production from free Erwinia sp. D12 cells using response surface methodology

The food industry is constantly seeking novel ingredients to improve existing products or to allow for the introduction of new products. Isomaltulose is a reducing sugar with a sweet taste and very similar physical and organoleptic properties to those of sucrose. The strain Erwinia sp. is able to convert sucrose into isomaltulose. A two level rotatory central composite design and response surface methodology were applied to verify the influence and conditions for the production of isomaltulose by Erwinia sp. D12 free-cells in a batch process. The statistical analysis carried out at a confidence level of 90% gave a coefficient of determination of 0.90, and the polynomial model resulted in a response surface and contour curve that indicated the best parameters for the conversion of sucrose into isomaltulose as follows: temperature 35 °C, pH 6.5, wet cell mass 10% and sucrose 35%. The free-cells of Erwinia sp. D12 were recycled during repeated-batch processes to produce isomaltulose from sucrose obtaining high isomaltulose yields.