Application of FT-NIR spectroscopy in on-line monitoring of dough proofing and bread staling [Near InfraRed]
2004
Sinelli, N.; Dionigi, S. De; Pagani, M.A.; Riva, M. (Milan Univ. (Italy). Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche); Belloni, P. (Brueker Optics, Milan (Italy))
The kinetics of dough proofing and bread staling was monitored by a FT-NIR spectrometer, equipped with an optic probe working in diffuse reflectance. The dough leavening was carried out at different temperatures (25 and 35 deg C) and constant RH (80%). Bread storage was carried out at 25 deg C and RH = 80% on standard fresh samples stored for 4 days. Spectra were collected in the range of wave numbers from 10,000 to 4,300 cmE-1 directly on the samples, every 5 min during proofing, up to 3 hours, and every 2 hours during staling, up to 4 days. As reference methods, Image Analysis (IA) for proofing and differential scanning calorimetry (DSC) for staling were used. NIR spectra were corrected for scatter effect using standard normal variate (SNV) and transformed into second derivative. Both for leavening and staling, principal component analysis (PCA) was applied and a kinetics during process was calculated. PCA was performed on data set and "loadings" were calculated. For leavening, four absorption zones (8,900-8,800, 7,200-6,900, 5,250-5,050 and 4,700-4,450 cmE-1) were involved in describing the process. These bands show a phenomenological trend, similar to the one obtained by IA, which describes a fermentation phase, followed by a structural collapse of dough, influenced by process temperature. For staling, three zones were involved in describing kinetics; two zones were due to water absorption bands (7,200-6,900 and 5,250-5,050 cmE-1) and one to modifications of both protein network and starch (4,900-4,450 cmE-1). This kinetics of PCA scores and the trend of a selected wave number (4,860 cmE-1) is similar to the trend of re-crystallization of amylopectin observed by DSC method and can be modelled with an Avrami equation. The results show the feasibility of NIR spectroscopy to monitor dough leavening and staling
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