|
|
vol. 9, nr. 1 (2007)
|
Influence of water activity on texture of corn flakes
|
|
|
Piotr P. Lewicki, Agata Marzec, Małgorzata Kuropatwa
|
|
| (get PDF )
|
|
|
Department of Food Engineering and Process Management, Warsaw Agricultural University (SGGW)
ul. Nowoursynowska 159c, 02-776 Warszawa
e-mail: agata_marzec@sggw.pl
|
|
|
vol. 9 (2007), nr. 1,
pp. 79-90
|
|
|
abstract:
Commercial corn flakes were equilibrated to different water activities and subjected to mechanical deformation. Breaking of corn flakes was done in a plastic tube in which flakes were piled one over another. Sounds emitted during breaking were detected by a piezoelectric accelerometer and recorded after amplification. Deformation curves were jagged and very irregular, and their course depended on the water activity of the material. Crispness of corn flakes was independent from water activity at aw<0.3. At higher water activities crispness decreased fast and at aw>0.639 that property was lost completely. An antiplasticizing effect of water on corn flakes was observed in the water activity range from 0.516 to 0.639. Acoustic activity of breaking corn flakes was also dependent on water activity. The energy of acoustic signal decreased at aw>0.516. However, the number of acoustic events decreased abruptly in water activity range from 0.2 to 0.3. Crunchiness index was introduced, combining both mechanical and acoustic measures of crispness of the material. In the range of water activity from 0.3 to 0.5 the crunchiness index for corn flakes was constant. At lower water activities it decreased with increasing wetness of the material, but at higher water activities it was close to zero.
|
|
keywords:
breaking force, crispness index, acoustic emission, acoustic energy
|
|
original in:
English
|
|
|
|
|
|
