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Interaction Between Sorghum Protein Extraction and Precipitation Conditions on Yield, Purity, and Composition of Purified Protein Fractions
Author(s) -
Bean S. R.,
Ioerger B. P.,
Park S. H.,
Singh H.
Publication year - 2006
Publication title -
cereal chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.558
H-Index - 100
eISSN - 1943-3638
pISSN - 0009-0352
DOI - 10.1094/cc-83-0099
Subject(s) - chemistry , extraction (chemistry) , precipitation , chromatography , yield (engineering) , protein purification , composition (language) , ethanol precipitation , sonication , ethanol , sorghum , protein precipitation , biochemistry , agronomy , linguistics , physics , materials science , philosophy , meteorology , metallurgy , biology
Sorghum proteins have the potential to be used as a bio‐industrial renewable resource for applications such as biodegradable films and packaging. This project was designed to evaluate the effect of interactions between sorghum protein extraction and precipitation conditions on the yield, purity, and composition of sorghum protein fractions. Proteins were extracted with 70% ethanol under nonreducing conditions, with ultrasound, or under reducing conditions using either sodium metabisulfite or glutathione as the reducing agent. Several conditions were used to isolate the extracted proteins through precipitation, including lowering ethanol concentrations alone or in combination with lowering to pH 2.5, or by adding 1 M NaCl to the extract. Combinations of these conditions were also tested. All precipitation conditions effectively precipitated proteins and lowering the pH and adding 1 M NaCl to the extracts enhanced precipitation in some cases. However, the conditions that precipitated the maxium amount of protein or highest purity of protein varied according to how the proteins were initially extracted. Precipitated proteins were characterized by RP‐HPLC, SEC, HPCE, and SDS‐PAGE to compare the protein fractions composition. Nonreduced and sonicated samples had a much wider M w distribution than reduced extracts. Thus, extraction and precipitation conditions influenced the isolated proteins yield, purity, and composition. Because the extraction and purification processes influenced the composition, purity, and biochemical properties, it may be possible to prepare protein fractions with unique functionalities for specific end‐uses.