Staling of wheat bread stored in modified atmosphere

Modified atmosphere packing (MAP) of bread is known to extend the microbial shelf-life. However, the effect of MAP on staling of bread is more questio nable, and conflicting results are reported in the literature. To investiga te the effect of BT AP, wheat bread was packed in modified atmosphere conta ining 100% CO2 and in a mixture gas of 50% CO2 and 50% N-2, respectively. T he control bread was packed in atmospheric air. No significant effects of M AP were found during storage of bread for 7 days at 20 degreesC compared to control bread. when changes in bread firmness and starch retrogradation me asured by differential scanning calorimetry (DSC) were used as parameters f or the staling rates. Ira addition, no significant differences were obtaine d in firmness between bread stored in 100% CO,, and in the mixture gas of C O2 and N-2 after 7 and 14 days, respectively. The present study thus demons trated that storage of bread in MAP could be used to extend the microbial s helf-life without affecting the staling rate. The development of bread firm ness during storage in 100% CO2 for 49 days was,found to be correlated to a mylopectin retrogradation arid to changes in the freezable water fraction o f the breads in a non-linear manner, suggesting that bread firmness is infl uenced by both the crystallisation behaviour of starch and by changes in hy dration. (C) 2001 Academic Press.