Effects of glazes on the keeping quality of bread

This work describes a study on the effects of different glazes on the keeping quality of bread in term of its crumb and crust properties. Four types of glazes which are corn starch, egg white, skim milk and shortening with four concentrations, i.e., 20%, 30%, 50% and 70% were applied on sweet bun surfaces to determine their effect on staling during six days of storage. The bread staling was measured in term of firmness, moisture content and water activity of crumb and crust. The corn starch, egg white and skim milk were found significantly reducing crumb firmness with no effect by the concentrations used. The egg white and skim milk is moderately retaining moisture content of the crumb while egg white showed the lowest crumb water activity compared to other glazed bread. The effect of varying concentrations of glaze materials shows that only shortening showed significant (p<0.05) different effects on crumb firmness. Bread glazed with corn starch (p<0.05) affected crumb moisture content whereas all the glaze materials except corn starch significantly (p<0.05) affected crumb water activity. For the crust, shortening gave poor effect to the crust firmness since they have lower firmness compared to other glazes and unglazed bread. As glazes, corn starch and egg white probably able to prevent the growth of mold because they have lower water activity value compared to control bread. All the glaze materials give significant (p<0.05) effect on crust firmness and water activity when used at different concentrations while for the moisture content the effect is contradictory. The firming rate of crust is generally lower than the crumb despite the record of highest crumb firming rate detected when using 30% concentration of glazes. In the two-way ANOVA, concentrations of glazes was found to be not significant to both crumb and crust firmness although the types of glazes displayed significant (p<0.05) effects to crumb and crust firmness. While for moisture content and water activities it is contradictory. In conclusion, the results show that application of glaze materials was able to slow down bread staling as well as improve the bread quality. The corn starch, egg white and skim milk were significant as glaze materials due to their capability in reducing crumb firmness and increase crust hardness. The effect on the moisture content and water activity of crumb and crust was not as clear as those to firmness when evaluating the glazing effects by comparing with the unglazed breads. Effectiveness of glazes in reducing staling rate of bread is within 5 – 49% compared to control.

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