Effect of wheat germ protein isolate and xanthan gum as egg substitutes on the rheological properties of mayonnaise Rahbari, M. 1, Aalami, M. 2, Kashaninejad, M. 3, Maghsoudlou, Y. 3

Microbial spoilage and staling are the most important reasons for the amount of bread waste. In order to extend the bread shelf life, either different bread improvers such as hydrocolloids or appropriate specific packaging like modified atmosphere packaging (MAP) can apply. In this study, the effects of hydrocolloid on quality properties of Sangak bread were investigated. The gum Hydroxypropylmethylcellulose (HPMC) was added to the formulation at 0.5 and 1%) w/w of flour) concentration. As a control, no gum added formulations were used. Wheat bread samples were packaged in polyamid/ polyethylene bags with different gas combinations. Two gas concentrations tested included: air, and 100% CO₂. All packaged bread samples were stored at 25°C for 15 days. Quality and microbial features of bread such as moisture, texture, and mold and yeast count were assessed at intervals of three days during storage. Statistical analysis of the results of bread quality characteristics during storage revealed that, the gas in headspace of package did not significantly affect the product moisture content, while shear stress, maximum force and the microbial load of the samples were thoroughly impressed by it. So that with carbon dioxide, the growth of mold and yeasts was more limited. Also was observed all product quality characteristics change significantly during storage time. So that the reduced moisture were observed up to 12th day. Conversely hardness, shear stress and microbial load increased during the storage period. The breads containing 1% HPMC showed the lowest maximum force and shear stress. Control showed the highest moisture and mold and yeast count all over the storage period.