Development and Characterization of a Soy-Based Soft Pretzel Designed for Exercise Recovery

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Date

2020-02

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Research Projects

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Abstract

Soy has been shown to reduce inflammation in both exercise and disease states due to the presence of high-quality protein and anti-inflammatory compounds including isoflavones. Using wheat and soy proteins, the objective of this study was to develop a consumer acceptable soy soft pretzel (SP), intended for improving exercise recovery. It was hypothesized that SP would have high nutritional value and acceptability while maintaining similar physicochemical characteristics as traditional wheat pretzels.SP was developed using a blend of soy flour, soymilk powder, and vital wheat gluten to achieve an optimal protein, carbohydrate, and phytochemical content. A comparable wheat pretzel (WP) was developed to contain the same energy and lipid content as SP, for use as a control in clinical trials. Of critical importance when developing novel functional foods is to assure product quantity and stability of bioactives during processing as well as desired sensory characteristics. High performance liquid chromatography (HPLC) was used to quantify the isoflavone concentration in SP. The physicochemical properties of SP were compared to WP. Texture parameters were measured using texture profile analysis. Loaf volume was measured by displacement. To relate these findings to molecular changes occurring due to reformulation of traditional soft pretzels, scanning electron microscopy (SEM) was used to determine differences in internal microstructure and thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to determine moisture content and percent of “freezable” and “un-freezable” water in the samples. Finally, sensory evaluation was performed to ensure acceptability and feasibility of SP as a post-workout recovery snack in multiple populations including athletes and active/less-active non-athletes. The total sample of 131 panelists contained 71 males (including 42 collegiate male rugby players), and 60 females. SP contained 0.18 mg isoflavones per gram of pretzel. SP was found to have a 130% harder and 180% chewier texture than WP. The specific loaf volume of SP was reduced by 40%. SEM images showed smaller air pockets in SP and differences in protein strand conformation. The percentages of “un-freezable” water in WP and SP were not significantly different, however SP had a higher percentage of “freezable” water by approximately 9%. However, despite changes in the physicochemical properties, the median acceptability score of SP across all groups was a 7 out of 9, corresponding to “Like moderately” on a 9-point hedonic scale. Fifty-two percent of panelists said they would consume SP as a post-workout snack and 80% of consumers would consume it other times of day. The findings in this study showed SP to be acceptable in the target population, despite differences in physicochemical properties. Acceptability is an important metric for food-based clinical trial adherence. SP will be used in further clinical trials to assess its impact on symptoms of EIMD and the speed of muscle recovery.

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Poster Division: Food, Agricultural, and Environmental Sciences (FAES): 2nd Place (The Ohio State University Edward F. Hayes Graduate Research Forum)

Keywords

exercise recovery, Soy, Inflammation, Isoflavones

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