Effect of modified atmosphere packaging on stability of three kinds of bread

Abstract

The study evaluates eff ect of ordinary and modifi ed atmosphere N2 and CO2 on bread packaging and changes of selected bread parameters, moisture content (MC) and water activity (Aw), in real storage time. MC has a signifi cant infl uence on physical properties of bread and Aw characterizes its microbiological stability. Both parameters are functionally dependent. Manometric method was used for measurement of Aw and gravimetric method was used for measurement of MC. Samples of three kinds of bread, gluten-free, Šumava bread, and Bavorský bread, packaged into barrier wrappers, were stored at the room temperature of 20 °C. MC and Aw were measured in real storage time in intervals of three days for all kinds of bread, always in crust and crumb separately. Individual measurements were fi nished when a mould were discovered in samples. The initial MC of crust was in the range of 21.01-29.26% MC (w.b.) and the fi nal MC in the range of 26.79-33.58% MC (w.b.) in tested breads. MC of crumb was in the range of 34.49-46.58% MC (w.b.) at the beginning and in the range of 32.92-44.21% MC (w.b.) at the end in tested samples. Minimum diff erences within values of MC showed gluten-free bread during storage time. Values of Aw were in the range of 0.863-0.948 at the beginning and in the range of 0.933-0.958 at the end of measurement in crust, for all samples. Values of Aw were in the range of 0.960-0.961 at the beginning and in the range of 0.952-0.961 at the end of measurement in crumb. Minimum diff erences within values of Aw showed gluten-free bread again. The highest shelflife has been achieved in CO2 atmosphere, for all kinds of bread. Mathematical models with ability for MC and Aw prediction in real time of storage were created for Šumava bread.