Household soybean processing, protein content, and caregiver acceptability of complementary porridges in rural Malawi

BACKGROUND: Child undernutrition remains a major public health challenge in Malawi, where inadequate dietary protein contributes to persistent stunting and poor child health outcomes. Soybean (Glycine max) is a locally cultivable and protein-rich crop with potential to strengthen complementary feeding in resource-constrained rural settings. However, the nutritional and practical effectiveness of soybean-based complementary foods depends on household-level processing methods and caregiver acceptability. METHODS: A community-based experimental study was conducted in Dowa District, Central Malawi, in July 2025. Four locally cultivated soybean varieties were subjected to five household-level processing methods: untreated (control), soaked, roasted, dehulled, and dehulled-and-roasted. Protein content was determined using the Kjeldahl method with triplicate laboratory analyses. Caregiver sensory evaluation was conducted among 60 caregivers attending under-five clinics using structured tasting sessions assessing aroma, flavour, texture, and overall acceptability on a 10-point Likert scale. Data were analyzed using Kruskal-Wallis H tests, Mann-Whitney U tests, repeated-measures ANOVA, and bootstrap resampling to estimate 95% confidence intervals. RESULTS: Measured protein content differed significantly across soybean processing methods (H = 12.68, df = 4, p = 0.013). Dehulled soybean flour demonstrated the highest measured protein content (21.26% ± 0.12; 95% CI: 21.12-21.40), while soaked soybean flour demonstrated the lowest (11.85% ± 0.11; 95% CI: 11.73-11.97). Caregiver sensory evaluation additionally differed significantly across processing methods (p < 0.05). Dehulled-and-roasted soybean porridge achieved the highest overall acceptability score (8.2 ± 0.2), followed by dehulled soybean porridge (7.8 ± 0.4). Integrated assessment demonstrated that dehulled and dehulled-and-roasted soybean processing methods produced the most favorable combined nutritional and caregiver acceptability outcomes. CONCLUSION: Household soybean processing methods substantially influence both measured protein content and caregiver sensory acceptability of soybean porridge in rural complementary feeding contexts. Dehulling, with or without roasting, represents a locally feasible household processing strategy with potential to strengthen soybean-based complementary feeding using existing agricultural resources. The findings highlight the importance of integrating nutritional quality with caregiver acceptability in the development of sustainable community-based child nutrition interventions in low-resource settings.