Whey disposal is one of the main problems for dairy industry due to its content of lactose. An interesting way to upgrade this waste is its use as substrate for fermentation using lactic acid bacteria (LAB). Further improvement could derive from the use of probiotic LAB, in order to obtain a cell biomass available for other applications. This study aimed the development of a fermentation control system based on NIRS, for a fast and accurate process monitoring. Whey powder was reconstituted at 7% with distilled water to reach the final lactose concentration of 4,5%. After sterilization, whey was inoculated with strains of Lactobacillus plantarum (1%), and incubated at 30°C ± 1°C for 48 h. Samples were collected at 0, 6, 8, 11, 15, 18, 24, 28, 32 and 48 h. Lactose (g/100g) and lactic acid (g/100g) contents were determined by HPLC, and microbial count determined in MRS agar (log CFU/mL). Spectra were collected in trasflectance mode with a NIRFlex N-500 spectrometer and controlled by the NIRWare 1.2 Operator software (BUCHI Italy, Assago, Milan) using an optic probe (pathlength = 0.08 mm) in the whole NIR range (1100-2500 nm). Data were processed by the Unscrambler software v.9.2 (Camo Inc., OSLO, Norway) and calibrations were built up applying partial least squares regression (PLSR) method. Preliminary results, obtained by PLSR, were satisfactory for all parameters, after pre-processing data with smoothing. Good NIR prediction ability in validation was highlighted, for each assessed parameter: for lactose (Rval=0.9133, RMSEP=0.1505); for lactic acid (Rval=0.9335, RMSEP=0.1404) and finally for microbial count (Rval=0.8644, RMSEP=0.2676). Based on these statistical indexes, these predictions are in agreement with reference data. The evaluation of statistical parameters obtained in this work, for the determination of lactose, lactic acid and microbial count indices, can confirm the suitability of NIR for their direct quantification in whey. The use of NIR probes could allow a complete process control in real time with benefits in terms of possibilities for intervention, affecting also positively on the waste disposal.
Remagni, M. C., Marinoni, L., Mora, D., Carminati, D., Cattaneo, T. M. P., The use of NIR spectroscopy for monitoring milk-whey biotransformation processes using, Paper, in Proceedings of 15th International Conference on Near Infrared Spectroscopy, (Cape Town, 13-20 May 2011), ICNIRS, Cape Town 2012: 439-443 [http://hdl.handle.net/10807/57392]
The use of NIR spectroscopy for monitoring milk-whey biotransformation processes using
Marinoni, Laura;
2012
Abstract
Whey disposal is one of the main problems for dairy industry due to its content of lactose. An interesting way to upgrade this waste is its use as substrate for fermentation using lactic acid bacteria (LAB). Further improvement could derive from the use of probiotic LAB, in order to obtain a cell biomass available for other applications. This study aimed the development of a fermentation control system based on NIRS, for a fast and accurate process monitoring. Whey powder was reconstituted at 7% with distilled water to reach the final lactose concentration of 4,5%. After sterilization, whey was inoculated with strains of Lactobacillus plantarum (1%), and incubated at 30°C ± 1°C for 48 h. Samples were collected at 0, 6, 8, 11, 15, 18, 24, 28, 32 and 48 h. Lactose (g/100g) and lactic acid (g/100g) contents were determined by HPLC, and microbial count determined in MRS agar (log CFU/mL). Spectra were collected in trasflectance mode with a NIRFlex N-500 spectrometer and controlled by the NIRWare 1.2 Operator software (BUCHI Italy, Assago, Milan) using an optic probe (pathlength = 0.08 mm) in the whole NIR range (1100-2500 nm). Data were processed by the Unscrambler software v.9.2 (Camo Inc., OSLO, Norway) and calibrations were built up applying partial least squares regression (PLSR) method. Preliminary results, obtained by PLSR, were satisfactory for all parameters, after pre-processing data with smoothing. Good NIR prediction ability in validation was highlighted, for each assessed parameter: for lactose (Rval=0.9133, RMSEP=0.1505); for lactic acid (Rval=0.9335, RMSEP=0.1404) and finally for microbial count (Rval=0.8644, RMSEP=0.2676). Based on these statistical indexes, these predictions are in agreement with reference data. The evaluation of statistical parameters obtained in this work, for the determination of lactose, lactic acid and microbial count indices, can confirm the suitability of NIR for their direct quantification in whey. The use of NIR probes could allow a complete process control in real time with benefits in terms of possibilities for intervention, affecting also positively on the waste disposal.
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