Snack foods comprise a larger proportion of the diet in Western cultures than ever before, and many provide very few nutritional benefits. Soy, due to its unique nutritional and functional profile, was hypothesized to increase the nutritional quality of a model snack food, a soft pretzel, as well as increase the frozen shelf life, an important indicator of success in the market. In a narrower focus, the soy pretzel formulation was optimized for intestinal uptake of soy isoflavones while maintaining the physical properties. Using a variety of approaches encompassing physics, material science, food science, in vitro nutrition, and in vivo human nutrition trials, we showed that soy provides nutritional and functional benefits to the soft pretzel, a model snack food.;The dough for bakery products is often frozen for convenient storage and on-site preparation. Retention of the physical properties of the frozen dough is crucial for high consumer acceptability. Addition of soy to dough at 49% slightly mitigated changes in dough and baked soy bread with increased frozen storage time due to the hygroscopic nature of soy protein. The changes in the physical properties of the dough and bread were explained by observing impeded microscale migration of water from the “bound” to “free” state in soy dough compared to wheat dough.;Soy inherently increases the nutritional profile of the soft pretzel by contributing high quality protein, dietary fiber, and soy isoflavones. Glycemic index (GI) was selected as a metric to further characterize the novel pretzel’s nutritional profile because GI has been identified as a broad, key factor that can contribute to promoting or preventing chronic disease [1]. In 12 healthy human participants, the soy soft pretzel exhibited a low GI (39.1 ± 20.4) compared to the wheat pretzel (66.4 ± 15.3), suggesting it to be a more prudent option for people to prevent hyperglycemia. Notably, the soy pretzel was shown to have equivalent consumer-acceptability ratings as the wheat pretzel.;Soy isoflavones are phytochemicals that provide unique biological effects due to their weak affinity to the estrogen receptor. Therefore, the soy pretzel matrix was further optimized for the uptake of soy isoflavones by enterocytes. A two-fold increase in the proportion of aglycones was achieved by adding raw almonds as the lipid source due to efficient β-glucosidase activity during proofing. Meanwhile, the pretzel maintained moisture content and distribution and exhibited only a slight increase in hardness and chewiness. Approximately 75% of isoflavones from soy-almond pretzels were bioaccessible compared to about 82% in pretzels produced with other types of lipids, but it is hypothesized that this deficit can be overcome by consuming the soy food with lipid [2]. Conversion of the isoflavones from glucosides to aglycones promoted their uptake in an in vitro cell model, but neither the amount nor type of lipid greatly affected isoflavone uptake, metabolism, or transepithelial flux into the basolateral compartment.;In summary, soy ingredients increased the nutritional profile of the soy pretzel by contributing protein, fiber, and phytochemicals and decreasing glycemic index and, additionally, showed to aid in preserving the quality of dough during frozen storage.
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