The study of bread staling using visible and near-infrared reflectance spectroscopy

The potential of visible and near-infrared reflectance spectroscopy (NIRS) as a fundamental tool for studying bread staling was investigated in this research. MRS was used to detect changes in bread during storage and results were compared to those obtained by a texture analyzer (TA). NIR spectra had a high correlation to TA firmness. NIRS measurements correlated better with the actual storage time and had smaller standard deviations than the TA firmness. The batch differences had less effect on NIRS measurements than on the TA firmness. Results indicate that NIRS could monitor changes during bread storage more precisely than the TA. The potential of NIRS was further investigated by studying starch, protein, and temperature effects on bread staling with the help of a differential scanning calorimetry. Results show that NIRS could be a useful tool to study bread staling. Three important wavelengths, 970nm, 1155nm, and 1395nm, showed that NIRS monitored moisture and starch structure changes in bread staling. The other two important wavelengths, 550nm and 1465nm, successfully classified the starch-starch (SS) and starch-protein (SP) breads based on color and protein content differences in SS and SP. Results also show that amylopectin retrogradation was the major factor for bread staling. The amylose-lipid complex contributed little to bread staling after one day of storage. Temperature significantly accelerated the bread staling process. Protein retarded bread staling by diluting starch and reducing starch retrogradation. The effect of protein on bread staling was limited when compared to the temperature effect.