Development of a Cottonseed Dehulling Process to Yield Intact Seed Meats

With recent genetic advances in development of gossypol-free cotton varieties, there is interest in retrieving undamaged, dehulled cottonseed kernels for development of new food and feed products. Current methods used to dehull cottonseed provide a low turnout of undamaged kernels that would be desirable for new market niches where intact kernels are desirable.

The first objective of the described work was to develop a process for dehulling fuzzy cottonseed to render a high percentage of undamaged seed meats. A series of methods were tested and optimized to identify the suite of processes that provided the highest yields. The final process included steam conditioning, cracking and dehulling using roller mills, and finally separating kernels from hull material using a roller separator and air aspirator. The reintroduction of un-dehulled seed to the roller mills for a second pass significantly increased the final yield of undamaged seed meats. Lab-scale tests show that yields of 65% to 70% can be obtained using this process, representing a significant increase over conventional dehulling, which typically results in less than 5% yields of undamaged kernels.

The second objective of the research was to integrate components of the lab-scale milling process into a continuous-flow, pilot-scale system. The performance of the milling system with and without steam conditioning was evaluated. Pilot-scale, continuous-flow tests resulted in undamaged kernel yields of 67.9 ? 3.0% (mean ? 95% confidence interval) during wet milling, comparable to results of initial batch processing and far exceeding yields of whole kernels from current milling techniques. During dry milling, the efficiency of the system to extract all possible kernel material was found to be 68 ? 2.9%, but most of the resulting kernel material is in broken fragments between 3.35 mm and 0.706 mm in diameter.