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

M.I. SANTOS , C. ARAUJO-ANDRADE, E.E. TYMCZYSZYN AND A. GÓMEZ ZAVAGLIA.

Rosario

Congreso; IX Congreso Argentino de Microbiología General SAMIGE. 5-7/8/2013. Rosario (Argentina).; 2013

Monitoring of industrial bioprocesses requires methodologies able to provide complete information in a fast way, and if possible in real time. In this regard, the potentiality of near infrared spectroscopy (NIR) in this matter has been deeply explored in the last fifteen years. The role of sugars as bacteria protectants is well known, and among them, the efficiency of certain prebiotics (i.e.: galactooligosaccharides -GOS-) as cryoprotectants has been reported recently. In this regard, this new function GOS as protective molecules opens up several valuable perspectives. Considering the relevance of starters and their combination with prebiotics as protectants, NIR can be a useful tool to monitor their efficiency The ability of galacto-oligosaccharides (GOS) and lactulose to protect Lactobacillus delbrueckii subsp. bulgaricus upon freeze drying and dessication was analyzed by NIR. Survival of L. bulgaricus in a glassy GOS and lactulose matrix was investigated after freeze drying and equilibration at different relative humidities (RHs): 11, 22, 33, 44, 52, 75 and 80%. All commercial prebiotics used were good protectant to preservation by freeze drying and desiccation over silica gel. At higher HRs a drastic viability loss was observed after 3 weeks of storage. The dehydrated samples were measured by NIR and multivariate analyses. The principal component (PCA) shown a good agrupation as function of RHs, but difference were observed between prebiotics. This observation could be explained by the water content of the sample and thermo-physical properties of each oligo-saccharides. The cell damage was measured by NIR during growing kinetic. Differences on the spectrum were observed for lag, log and stationary phase and different effect of cryoprotectant was observed. GOS containing tri and tetra sacharides was most efficient than GOS with lower degree of polimerization and the disaccharide lactoluse. These results coul be due to glass transition temperatures of prebiotics used as cryoprotectant. These results are important in the optimization of dehydrated functional foods containing pre and probiotics, and the application of new rapid method technology.