Improvement of Storage Quality of Pre-baked Frozen Bread Based on Trehalose Protection

Abstract

Pre-baked frozen bread is increasingly accepted and loved by consumers because of its convenience, but the quality of frozen bread is easily degraded due to temperature fluctuation during storage and transportation. In this study, the effects of different amount of trehalose added (0, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%) and different freezing-thawing cycles (0~5 cycles of freezing-thawing treatment) on texture, thermogravimetric properties, sensory quality, stomatal structure and microstructure of rebaked bread were investigated. The results showed that hardness and chewiness increasing continuously, while elasticity, resilience, cohesion and overall acceptability decreasing continuously during 0~5 freezing-thawing cycles, the addition of trehalose could effectively prevent the deterioration degree, and the addition of 0.6% trehalose had the most significant improvement effect. With the increasing of trehalose content and freeze-thaw cycle, the weight percentage of rebaked bread showed a decreasing trend, and in the range of 40 to 60 ℃, the weight percentage of rebaked bread decreased significantly, with the decreasing rate of 0.6%~1.0%. When the amount of trehalose was 0.6%, the transverse section of bread core was fine, the pore space was uniform, the structure was good, the stomatal air holding rate and stability were improved, the protein network was continuous, and the starch particles were evenly wrapped. With the change of freezing-thawing cycle, the cross section surface of the rebaked bread became dry and uneven, and the stomatal structure became loose. Although the gluten network was gradually reduced and discontinuous, the starch particles were evenly wrapped by the gluten network and seldom incomplete.

Keywords

• trehalose
• pre baked frozen bread
• thermogravimetric properties
• texture properties
• microstructure