Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/18/2003
Publication Date: 10/21/2003
Citation: Park, S.H., Bean, S. 2003. Investigation and optimization of the factors influencing sorghum protein extraction. Journal of Agricultural and Food Chemistry. 51:7050-7054. Interpretive Summary: Sorghum is a drought resistant, low input cereal grain grown through the Central U.S. While most of the U. S. sorghum crop is currently used for animal feed, worldwide, 30-40% of the crop is used for human food. Sorghum is an underutilized crop and has potential to be developed into a renewable resource for a number of products including ethanol, biodegradable plastics and human food. However, for this potential to be realized basic research must be carried out on the properties of sorghum bio-molecules such as proteins. Sorghum proteins are some of the most difficult cereal proteins to extract and analyze. This paper reports improved methods for extracting the proteins found in sorghum. The methods developed in this study reduced the time required to extract proteins which in turns allows a much higher number of samples to be processed. This will be beneficial to scientists working to study sorghum proteins to improve the utilization of sorghum.
Technical Abstract: To optimize the extraction of sorghum proteins, several variables were examined: sample to solvent ratio, detergent type and concentration, reducing agent type and concentration, extraction time, and buffer pH and concentration. Samples were quantified and characterized by RP-HPLC ,FZCE and nitrogen analysis. These studies revealed that pH, detergent type, reducing agent type and sample to solvent ratio all had significant effect on levels of protein extracted. Increasing SDS concentration (2%), and solvent to flour ratio (20:1) with multiple 5 min extracts reduced extraction time by 35-80% while still extracting the same levels of total protein relative to the control methodology. Reproducibility using the multiple extractions was found to be excellent with RSD's of less than 2% for consecutive extractions. The optimized extraction protocol should prove useful to scientists working with sorghum proteins and provides basic information on the solubility of sorghum proteins.