Comparative study of the nutritional quality of potato steamed bread fermented by different sourdoughs

To study the nutritional effects of sourdough on potato steamed bread, five different sourdough samples were adopted to produce potato steamed bread. Compared to baker's yeast, sourdough fermentation led to a lower pH at around 4.0 (fermented for 12 hr). The protein and dietary fiber content of sourdough potato steamed bread (SPSB) were 13.42%-13.89% and 4.92%-6.66%, respectively, which were significantly lower than baker's yeast fermented one (Control). The minerals of SPSB were significantly lower than Control except for Na and Fe. Total amino acids determination suggested an equal protein quality of both SPSB and Control. The total polyphenol content of SPSB varied from 1.72 to 2.28 mg CAE/g and their antioxidant activity was inferior to Control. SPSB had higher (1.17-fold) resistant starch content and lower in vitro glycemic index which made SPSB healthy food products. Grey relational analysis validated that some sourdoughs can somehow improve the nutritional quality of potato steamed bread. Practical applications Potato steamed bread is emerging staple food in China due to the initiation of the national potato staple food strategy. Because of the incorporation of potato flour, potato steamed bread had some difficulties in industrialization and marketization. Since sourdough had been proved to have positive effects on fermentation, we used Chinese traditional sourdough to ferment potato steamed bread for the first time in order to improve the quality of potato steamed bread. Our previous study had testified the positive effects of sourdough on the technological properties of potato steamed bread while the nutritional effects are not clear. The results of this study can give enough support to the beneficial effects of sourdough on potato steamed bread and provide references to the nutritional evaluation of potato steam bread. Chemical compounds studied in this article Water (PubChem CID: 962); nitric acid (PubChem CID: 944); sulfuric acid (PubChem CID: 1118); sodium acetate (PubChem CID: 517045); sodium hydroxide (PubChem CID: 14798); hydrochloric acid (PubChem CID:313); acetic acid (PubChem CID: 176); glucose (PubChem CID: 79025); sodium chloride (PubChem CID: 5234); ethanol (PubChem CID: 702).