Scale-up of Sicklepod Processing

Authors: Harry O Kuru, Rogers

Submitted to: New Crops and New Uses
Publication Type: Book / Chapter
Publication Acceptance Date: 6/30/2007
Publication Date: 12/15/2007
Citation: Harry O Kuru, R.E. 2007. Scale-up of Sicklepod Processing. In: Janick, J., Whipkey, A., editors. Issues in New Crops and New Uses. Alexandria, VA: ASHS Press. p. 132-137.

Interpretive Summary: Sicklepod is a weed species in soybean and other crop fields in the Southeastern United States. Its eradication effort adds to the cost of farming faced by farmers. This weed is prolific, producing an abundance of seed/acre even for volunteer stands. The seeds of this plant contain a unique flour already in the market as an import for pet food formulation. Additionally, the seed contains other components with potential non-food industrial applications. This project is an effort at separating the components of the seed into clean classes that could expand the market and, thereby, facilitate commercialization of this underutilized plant in the area where it is endemic.

Technical Abstract: Sicklepod (Senna obtusifolia L) is an invasive weed species especially of soybean and other field crops in the Southeastern United States. The seed contains a small amount (5-7%) of a highly colored fat as well as anthraquinones, proteins and galactomannan polysaccharides. The character of sicklepod seed oil is such that a small amount of the weed seed present in a soybean crush lowers the quality of the soybean oil. Although cultivation of "round-up-ready soybeans" mitigates infestation of the crop by sicklepod, the latter is so prolific that even volunteer stands yield >1000 lb of seed per acre. Under this circumstance, agricultural prudence calls for tapping the potential of this weed as an alternative economic crop in the affected region. In earlier laboratory-scale work, we had shown the feasibility of separating the different components of sicklepod seed. However, at the kilogram and higher processing quantities, exigencies arose, which led to the modification of the earlier approach in order to efficiently separate components of the defatted seed meal. In one version for cleanly separating the proteins, the dried defatted meal was extracted with 0.5M NaC1 solution to remove albumins and globulins. Prolamines were extracted from the pellet, from the salt extraction, by use of 80% ethanol. Glutelins fractionation was obtained from the residual solids with 0.1N alkali. In a simpler (pilot scale) version, the polysaccharides were obtained from the defatted meal with deionized (DI) water via centrifugation. The pooled supernatants were heated at 92 degrees Celsius (15-20 min), filtered, cooled to room temperature, and passed through a column of amberlite XAD-4 to separate the polysaccharides from the anthraquinones.