Soy Protein is an Efficacious Alternative to Whey Protein in Sorghum–Soy Fortified Blended Foods in Rats

Background Previously we found that extruded corn–soy blend (CSB) and sorghum–soy blend (SSB) fortified blended foods (FBFs) containing whey protein concentrate (WPC) were equally nutritious food aid products. WPC provides high-quality protein; however, it is the most expensive ingredient in these FBFs. Objectives The primary objective of this study was to determine if soy protein can serve as an alternative to WPC and the secondary objective was to evaluate different sucrose amounts in the FBFs. Methods Nine extruded FBFs were formulated: 1 CSB and 1 SSB, both containing 9.5% WPC and 15% sucrose, served as comparison FBFs. Three additional CSB and 4 SSB FBFs were formulated containing no WPC, but with increased soy flour to meet protein requirements and varying sucrose concentrations. The sucrose content ranged from 0% to 10% for the CSBs and 0% to 15% for the SSBs. Male weanling Sprague Dawley rats were individually housed and divided into 10 diet groups (n = 9–10) which consumed either AIN-93G or a dry FBF for 28 d. At study conclusion, blood, livers, and body composition data were collected. Results were analyzed using 1-factor ANOVA with Tukey's test. Results Outcomes were not significantly different between the SSB groups, with the exception of significantly higher protein efficiency for the WPC-containing group. Among the CSB groups, caloric and protein efficiencies were significantly higher for the WPC-containing CSB group. There were no significant differences in hemoglobin or hepatic iron concentrations between FBF groups, but hepatic iron concentrations were significantly higher in all FBF groups than in the AIN-93G group. Groups consuming diets with ≤10% sucrose had significantly higher bone mineral density than groups consuming diets with 15% sucrose. Conclusions These results suggest that extruded SSB, but not necessarily CSB, FBFs with soy protein and 5%–10% added sucrose are efficacious and cost-effective alternatives to WPC-containing FBFs.