INSTRUMENTAL MEASUREMENT OF BREAD CRUMB GRAIN BY DIGITAL IMAGE-ANALYSIS

An instrumental system has been developed for direct quantitative asse ssment of bread crumb grain using digital image analysis technology im plemented on a personal computer. Software was developed for comprehen sive measurement of crumb grain features including cell area, cell den sity (cells/cm2), cell-wall thickness, cell-total area ratio, crumb br ightness, and uniformity of cell size. The system is completely object ive in all respects, including the critical step of crumb cell detecti on, where an adaptation of the K-means algorithm was used for image se gmentation by thresholding. Typical spatial resolution of the system u sing a conventional macroviewing lens was approximately (80 mum)2 crum b per pixel. Image processing time to compute the crumb cell structure for a single bread slice (307,200 pixels per image) was about 10 sec. The precision and accuracy of the system were tested by analysis of r esults of experimental breadmaking using control and oxidant-formula l oaves. Compared with control loaves, bread crumb containing oxidants w as determined to be 6% brighter and to have, on average, 21% more cell s/cm2, 17% smaller cells in cross-sectional area, 13% thinner cell wal ls, and 16% more uniform grain. These values were consistent with the finer crumb grain of bread containing oxidants, as observed visually. The proportion of crumb comprising gas cells for control and oxidant-f ormula bread was precisely identical (46%). The equivalence provides o bjective evidence that the predominant difference in the crumb structu re of bread prepared with and without oxidants relates almost exclusiv ely to the degree of subdivision or coalescence of gas cells.