Cereal Chem 62:223-226   |  VIEW ARTICLE
Measurements of Bread Firmness Using the Instron Universal Testing Instrument: Differences Resulting from Test Conditions.

P. A. Redlinger, C. S. Setser, and A. D. Dayton. Copyright 1985 by the American Association of Cereal Chemists, Inc. 

The Instron universal testing instrument (IUTM) was used to evaluate bread firmness as influenced by sample location, loci of compression, slice thickness, IUTM depth of compression, and presence of a crust. Crusted or crustless slices 13, 25, or 50-mm thick, cut from the center or 25 or 50 mm from the end of the loaf, were compressed 4 or 8 mm at the top, center, or bottom of the slice. Bread firmness measurements were influenced by slice thickness, depth of compression, presence of crust, and location of measurement. Deeper compression always gave higher firmness values regardless of the other factors. The larger value supposedly indicates firmer breads. Consistently, the thinnest slice (13 mm) had a higher firmness measurement when compressed 8 mm compared to 4 mm. When the two compression depths were compared, significant differences in firmness were found for both crusted and crustless slices 13 and 25 mm thick, regardless of location of measurement. The crust imparted resistance during compression, particularly when a compression depth of 8 mm was used with thin slices, and resulted in high firmness readings. No differences were noted in locations of measurement when the crust had been trimmed before compression. However, crusted samples cut 50 mm from the end of the loaf and compressed at the bottom exhibited higher values. A difference in firmness detected by the IUTM may have resulted from conditions of measurement rather than inherent differences within the loaf.