European food research and technology vol:226 issue:1-2 pages:33-43
The firmness of green bell pepper (Capsicum annuum) was studied under different processing conditions. Thermal texture degradation kinetics of pepper tissue between 75 and 95 degrees C could be accurately described by a fractional conversion model. The firmness of pre-processed pepper increased when the samples were submitted to several heat, pressure, and combinations of heat/pressure and calcium soaking pre-treatments. Pre-heating at 55 degrees C during 60 min and mild heat/high-pressure treatments (200 MPa at 25 degrees C, 15 min) yielded the best results, which were further improved when combined with calcium soaking. These pre-treatments significantly slowed down thermal texture degradation of pepper at 90 degrees C, a typical temperature used for pepper blanching prior to freezing. The above-mentioned pre-treated samples showed a significant reduction in firmness when frozen by regular freezing at 0.1 MPa. The same samples showed no changes in firmness when frozen by high-pressure shift freezing at 200 MPa. When freezing was carried out by high-pressure shift and after frozen storage (-18 degrees C) for 2.5 months, pressure pre-treated pepper showed a better retention of texture than thermal pre-treated pepper.