Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS) is an analytical technique based upon the “soft”ionization of a gaseous matrix, followed by mass spectrometric separation, performed at high time and mass resolution. PTR-ToF-MS allows to monitor in non-invasive fashion the changes in volatile release induced by fermentation, as already shown for the lactic acid fermentation of milk. In the present work a matrix constituted by heat-treated (30 minutes at 80°C) low-fat milk was inoculated with different yogurt starters. For the first time, the reaction was monitored in automated fashion by means of a multifunctional autosampler, adapted to PTR-MS analysis. In a typical experimental setup, this allowed to follow four different experiments, with a time resolution of four sampling points/hour and minimal need for manual operation. Our preliminary results show the possibility to monitor the kinetics of production and depletion of volatile compounds of major importance in the manufacturing of fermented dairy products, both from technological and sensory point of view (e.g. acetaldehyde, pentanedione). This provides an example of the applicability of PTR-ToF-MS as a valuable tool for the rapid screening of lactic acid bacteria (LAB) strains of industrial interest.
Online monitoring of lactic acid fermentation by means of Proton-Transfer-Reaction Mass Spectrometry
SPANO, GIUSEPPE;CAPOZZI, VITTORIO;
2014-01-01
Abstract
Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS) is an analytical technique based upon the “soft”ionization of a gaseous matrix, followed by mass spectrometric separation, performed at high time and mass resolution. PTR-ToF-MS allows to monitor in non-invasive fashion the changes in volatile release induced by fermentation, as already shown for the lactic acid fermentation of milk. In the present work a matrix constituted by heat-treated (30 minutes at 80°C) low-fat milk was inoculated with different yogurt starters. For the first time, the reaction was monitored in automated fashion by means of a multifunctional autosampler, adapted to PTR-MS analysis. In a typical experimental setup, this allowed to follow four different experiments, with a time resolution of four sampling points/hour and minimal need for manual operation. Our preliminary results show the possibility to monitor the kinetics of production and depletion of volatile compounds of major importance in the manufacturing of fermented dairy products, both from technological and sensory point of view (e.g. acetaldehyde, pentanedione). This provides an example of the applicability of PTR-ToF-MS as a valuable tool for the rapid screening of lactic acid bacteria (LAB) strains of industrial interest.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
