Different approaches for improving the quality and extending the shelf life of the partially baked bread:: low temperatures and HPMC addition

The use of refrigeration or positive temperature storage as an alternative to frozen storage for extending the shelf life of partially baked bread is described. In addition, the effect of hydroxypropylmethylcellulose (HPMC) on the baking performance of those products is detailed. With this purpose, the quality and shelf life of the bread from partially baked bread stored at frozen temperatures (-25 degrees C) for 42 days was compared with those of that from positive temperature stored partially baked bread (2 degrees C) stored for 10 days. In both cases, batches in the presence and absence of HPMC were performed. The characteristics evaluated were the microstructure by cryo-scanning electron microscopy (cryo-SEM), the sensory quality, the technological properties (specific volume, moisture content, width/height ratio, crumb hardness), the crumb grain and the staling rate. The microstructure of the bread crumb from the positive temperature stored sample was almost intact compared with that of the bread from its frozen counterpart. The positive temperature storage led to bread with better specific volume, low crumb hardness and slower hardening rate during staling than the bread stored at frozen temperatures. Regarding the sensory quality, loaves from positive temperature stored par-baked bread did not differ in appearance and aroma, but had lower scores in taste and texture than the samples from frozen par-baked bread. The presence of HPMC improved the technological parameters and diminished the staling rate without affecting the sensory attributes. The beneficial effect of the HPMC was more evident on the samples from frozen par-baked bread, showing a microstructure without any damage due to ice crystals growth and similar to that observed in the samples from positive temperature stored par-baked bread. (c) 2004 Elsevier Ltd. All rights reserved.