3. Results and discussion
3.1. Physical and textural analyses
Table 1 summarizes the physical and textural results of the FPBFB according to storage time. Weight,specific volume and crumb porosity of frozen bread were lower than fresh one (0 days) (see Fig. 2). Specific volume of FPBFB had a significant decrease after 4 days of frozen storage compared with those of fresh one. After 2 days of frozen storage, there was also a
significant decrease of FPBFB weight. The values obtained in this paper are within those reported by Bent (1998) and Carr and Tadini (2003). The last authors observed a specific volume reduction of partbaked French bread frozen stored for almost a month.porosity. Mandala (2005) reported shrinkage and porosity reduction of frozen baked bread after thawing
by microwaves. The specific volume was more than 20% in all samples (control and added with hydrocolloids).
Storage time significantly affected firmness and chewiness of bread; however, differences of springiness
and cohesiveness were not significant. A tendency of decrease in chewiness and firmness up to the 4th day of
storage time was observed followed by an increase the rest of the time, denoting some change in crumb
structure. These results are comparable to those reported by Carr and Tadini (2003) and Fik and Suro´wka (2002). These last authors studied the effect of prebaking and frozen storage on instrumental texture of round-shaped bread for 11 weeks and they also verified more pronounced changes in bread quality at the beginning of the storage period. After 1 week frozen storage, sensory and textural changes were only slight. Another point of view is that the observed variations can be due to the non-homogeneous nature of the analysed material. Ba´ rcenas et al. (2004) verified that the hardness of bread crumb containing HPMC was not affected by frozen storage at 25 1C, but this parameter showed a progressive increase in the control bread with the time of frozen storage. According to them this decrease was mainly observed after a 7-day storage period and further storage did not produce great changes. Ba´ rcenas et al. (2004), studying the effect of hydrocolloids on bread quality, observed that bread volume at 0 days was in all samples higher than that obtained for
frozen stored samples; that could be attributed to the different freezing treatment, since 0 days samples underwent only the prefreezing stage and a partial freezing, whereas the other samples suffered a complete
freezing stage. Water loss during frozen storage can contribute to shrinkage, but in this work it was not observed because
steam baking was applied twice, maintaining the amount of water in the product. Although the ANOVA
indicated that frozen storage did not significantly influence crumb porosity, it indicated that all FPBFB
presented lower crumb porosity than the fresh one. The crumb walls surrounding air space can be damaged by ice crystals during storage and consequently reduce.