Feasibility of Using Sodium Alginate Gel to Increase the Shelf Life of Top Strudel

The staleness of baking products is considered one of the most important causes of waste of these products. It indicates a change in the taste, flavor, appearance, and texture of products and finally reduces their consumer acceptance. The strudel is one of the well-known fermented sweet layered products in Iran. In this product, after incubating and baking the layered dough, chocolate or oil-based filling is injected into the middle of the bread by a pump, and the final product is packaged. However, this product is prone to staleness and texture hardening during the storage period; therefore, the methods that preserve the product during the storage period are able to increase the storage time of the product and its marketability. Normally, hydrocolloids are widely used as additives to modify the rheological and textural properties of baking products. The high-water holding capacity of hydrocolloids enables them to prevent the staleness of baked products during long-term storage periods.

The production steps of the fermented layered product were carried out according to the method of Sheikholeslami et al. (2018) with the necessary changes. The moisture content, water activity, specific volume, hardness, color, microbial load, and sensory properties of the top strudel were determined during storage time (32 °C for 30 days). The experiments were performed according to a completely randomized design in factorial arrangement. Minitab 16 software was used to analyze the data, and the differences between means were determined by Tukey test at p < 0.05.

Although increasing the storage time caused a significant decrease in moisture and water activity of the samples, the samples containing alginate gel had more moisture and water activity than the control sample. The specific volume of the samples containing 1.25% and 2.5% of gel was 9.45% and 18.51% higher than the sample without gel (control). The hardness of the sample containing 1.25% gel was significantly lower than other samples. In general, the hardness of the samples based on 1.25% and 2.5% of gel was 30.21% and 8.58% lower than the control sample, respectively. The use of gel in the top strudel formulation decreased the brightness index (L*) and increased the redness (a*) and yellowness (b*) of the final product. The microbial results showed that the microbial load of the samples was within the standard range. According to the results of the sensory evaluation, the sample containing 1.25% of gel received the highest scores for color and appearance, aroma, taste, and overall acceptance.

Based on the results obtained in this research, the samples containing gel had higher moisture content, water activity, specific volume, texture softness, and sensory scores than the control sample. In general, the best level of sodium alginate gel consumption for use in top strudel formulation in order to achieve the lowest level of hardness and the highest overall acceptance score is 1.25% gel.