Use of Near Infrared Spectroscopy (NIR) to Monitor the Efficiency of Polyhydroxylated Compounds As Protectants

SANTOS MAURICIO; ARAUJO-ANDRADE C.; TYMCZYSZYN E,; GOMEZ ZAVAGLIA, A.

Rosario

Congreso; IX Congreso Argentino de Microbiología General SAMIGE; 2013

SAMIGE

Monitoring industrial bioprocesses requires methodologies able to provide complete information in a fast way, and if possible in real time. In this context, the potentiality of near infrared spectroscopy (NIR) has been deeply explored in the last fifteen years. Spectral features in the near infrared region (800-2500 nm) arise from combinations and overtones of the fundamental vibrations associated with C-H, O-H and N-H bonds. As a consequence, the diversity of spectral signatures composed of stretching and bending vibrations, provides a rich source of information that requires a reliable analysis. As in other vibrational spectroscopic techniques, multivariate calibration techniques (i.e.: principal components analysis, partial least squares, or artificial neural networks) are often employed to extract the desired chemical information. The strength of NIR resides in the quantitative information that can provide, together with the ability to identify constituents in multicomponent samples and also to monitor complex mixtures in real time. The aim of this work was to set up an experimental and analytical methodology to evaluate the feasibility of developing simple, accurate and quantitative models based on NIR and multivariate analysis [Principal Component Analysis (PCA) and PLS] to monitor the evolution of viable, damaged and/or dead bacteria along with the kinetics of growth of Lactobacillus delbrueckii subsp. bulgaricus previously dried over desiccators containing silica gel in the presence or absence of three different polyhydroxylated compounds (sugars), until no changes in water desorption were detected (as determined gravimetrically). The differences observed in the NIR spectra (i.e.: shifts in the bands) could be correlated with the bacterial stage of growth, and with the efficiency of each sugar as protectant. These results are relevant in the food industry because NIR could be implemented to monitor fermentations in real time. This would save a lot of time, which is particularly valuable at an industrial level.