Application of rotating packed bed for in-line aroma stripping from cell slurry

Abstract

BACKGROUND

Nowadays, biotechnological production receives increasing interest as an alternative source of natural aromas. Unfortunately, especially for hydrophobic and semi-volatile aromas, the heterogeneous product partitioning between all phases present in fermentation makes recovery challenging. Additionally, when an aroma displays an inhibitory effect on the production microorganism, product removal during fermentation is recommendable. In-line aroma stripping offers an elegant way to deal with such challenges. This study reports the use of rotating packed bed (RPB) technology for the intensification of stripping of α-ionone, a key aroma of raspberry, from a model fermentation slurry containing Saccharomyces cerevisiae cells in a concentration of 250 g-CWW L−1. RESULTS

Throughout all experimental investigations, yeast cells were robust towards both the chemical stress from aroma exposure at a concentration of up to 400 mg L−1 and the mechanical stress from peripheral equipment and rotation of up to 2750 rpm, as a maximum of 11.3 ± 0.5% disrupted cells were measured during continuous processing in an RPB. An increase in the rotation speed led to an enhanced transfer of α-ionone from the fermentation slurry to the gaseous phase. CONCLUSIONS

RPB technology is found to be promising for the intensification of in-line stripping of biotechnologically produced aromas from crude fermentation broth without cell separation. The use of subsequent RPBs equipped with custom packings and flexibly adjustable rotation speed displays a holistic aroma recovery process supporting the way to commercial competitiveness of biotechnological aromas. © 2020 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.