Germination of sorghum affects phenolic acid profiles and in vitro digestibility but compromises physical properties of sorghum-wheat composite breads

Sorghum is a promising crop due to its resilience to heat and drought, but digestibility can be impaired upon processing. The aim of this study was to investigate whether germination could be a strategy to overcome this phenomenon. The impact of germination of different sorghum cultivars on the chemical composition, physical properties, and in vitro digestibility of flours, germinated flours and sorghum-wheat composite breads (40:60) was determined. Germination increased the amount of soluble sugars, α-amylase activity, total phenolic content (TPC) and antioxidant capacity in sorghum flours. Decreased rapid and slowly digestible starch reflected elevated hydrolytic activity. Protein digestibility slightly decreased, while phytic acid content was not reduced after germination. Adding germinated sorghum flour to wheat-sorghum composite breads improved the nutritional properties compared to native sorghum flour. Slowly digestible starch increased, protein digestibility was maintained and the content of phytic acid was decreased. Although baking reduced TPC and antioxidant properties, they were higher after the incorporation of sorghum. Despite these nutritional benefits of germination on flours and breads, the physical properties of breads, which were negatively affected by sorghum addition in general, were even further deteriorated by the use germinated flour. Further research is necessary to evaluate and overcome these effects.