Germination of sorghum grain results in significant changes in paste and texture properties
2017
Yi, Cuiping | Li, Yan | Ping, Junai
The changes in sorghum [Sorghum bicolor (L.) Moench] proteins during germination and the resultant effects on the physicochemical properties of sorghum flour were studied using non‐germinated grains as a control. Results showed that flour obtained from germinated sorghum grains had lower protein levels, higher protease levels, and higher free amino nitrogen content compared with the control. There was an increase in the albumin and globulin protein fractions and a decrease in kafirin. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis analysis indicated that this decrease was the result of a decrease in γ‐kafirins, while microscopy found that a continuous protein network was formed. Following the germination‐associated protein changes, the viscosities of sorghum paste decreased with germination from a peak viscosity value of 1,324 rapid visco units (RVU) down to 727 RVU in white sorghum (WS), and from 1,549 RVU to 1,295 RVU in red sorghum (RS). The hardness of the sorghum gels was significantly enhanced after germination, with WS increasing from 1,640 g to 5,374 g and RS from 970 g to 5,529 g. Thus, the study revealed that germination decreased the viscosity of sorghum paste and increased the strength of sorghum gel by changing the content and structure of sorghum protein, making it possible to design new foods that require thickening and gelling using germinated sorghum. PRACTICAL APPLICATIONS: Germination triggers the protease system of sprouting seeds, leading to the breakdown of proteins into simpler forms that decrease the viscosity of sorghum paste and improve the strength of sorghum gel, allowing the use of germinated sorghum to design new foods that require thickening and gelling.
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