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Modernization has led to a large convenience food market, and the demand for freeze-dried (FD) soup products is increasing in the Republic of Korea. FD soup products are easy to eat without cooking and can be stored for long periods. However, it is often difficult to ensure sensory satisfaction after rehydration of FD soup products; in particular, the ingredients are not evenly dispersed. Therefore, a stable dispersion or reconstitution of the FD soup products is required after rehydration. Here, the effects of high-speed shearing homogenization on the physical properties of a carbohydrate-binder mixture comprising maltodextrin, potato starch, and rice flour were investigated during hydrothermal gelatinization. To find a suitable treatment condition, different homogenization eras, speeds, and concentrations of the binder mixture were considered; in particular, the homogenization eras were set by considering the hydrothermal property of the binder mixture profiled using differential scanning calorimetry. The viscosity of the binder mixture and the compression strength and microstructure of the FD binder block, including the dispersion stability after rehydration, were evaluated. The quality of the FD binder block was improved by homogenization above 5000 rpm when the core temperature of the binder mixture reached approximately To at 14.5–21.8% concentrations. The improved FD binder block exhibited a fine surface and tiny porous microstructure compared with the control (with continuous agitation at 250 rpm). The control block was divided into two phases, whereas the improved block maintained the initial dispersion stability at 50 °C for 1 h. These results are expected to be referenced for the purpose of improving the quality of the FD soup products. [ABSTRACT FROM AUTHOR]

The amount of processed by-products such as crab shells is increasing, but industrial utilization is insufficient. In our previous study, crab shell extract (CSE) acted as a coagulant for tofu manufacturing. This study aimed to reduce freeze-dried (FD) tofu breakdown by improving its physical properties through adding sodium alginate (SA). FD state in tofu helps increase storage and availability, but FD tofu frequently fractures during processing, which is a concern for manufacturers. Tofu samples were prepared with either crab shell extract (CSE) or MgCl2, and SA, and freeze-dried. In the yields of FD tofu samples, there were no significant differences (p < 0.05). The brokenness of FD tofu samples was lower in CSE than in MgCl2 and was significantly reduced by SA in both tofu samples, which was affected by hardness. The water-holding capacity decreased after freeze-drying, and CSE reduced this decrease, regardless of SA addition. The microstructures differed depending on the coagulant and were dense upon SA addition. The FD tofu was packed into a multilayer film and stored at 25 °C or 45 °C for 6 months to investigate storage stability. During the storage, brokenness was unchanged in all tofu samples, indicating that they maintained their original structure. There were no significant differences in the volatile base nitrogen and thiobarbituric acid values according to the coagulant type and SA addition (p < 0.05). In conclusion, SA reduced FD tofu breakdown by improving the network structure, which may help increase FD tofu quality and decrease economic loss. [ABSTRACT FROM AUTHOR]