Impacts of Roasting Temperatures on the Structural and Quality Characteristics of Cottonseed Kernel and Its Butter Products

Roasting temperature is a critical parameter in plant butter production. In this work, we evaluated the impact of roasting temperatures on the structural and quality characteristics of glandless cottonseed kernels and the corresponding cottonseed butter products. The cottonseed kernels were roasted in a convection oven for 15 min at 110, 120, 130, 140, and 150 °C. Higher roasting temperatures made cottonseed darker but did not significantly (p > 0.05) impact the content of its major antioxidant tocopherols. Electron microscopic images demonstrated that roasting treatment disrupted or ruptured oil body membranes, thus making oil more available for extraction and digestion in cottonseed processing and consumption. Roasted kernels were then ground and homogenized with additional crude cottonseed oil, table salt, and cane sugar to produce cottonseed butter products. High roasting temperatures deepened the color of these butter products and increased firmness, spreadability, and adhesiveness values. Evaluated by an accelerated oxidation approach, the shelf life against oxidation was predicted to be 311 days at 25 °C and 541 days at 20 °C with the butter sample prepared from the 140 °C roasted kernels. It appears that the high tocopherol content in the crude oil played a major role in the extended shelf life by mitigating cottonseed butter oxidation. The information derived from this work would be helpful in optimizing the preparation protocol for cottonseed butter products. Future work on the impact of roasting on the flavor and sensory attributes is planned to gain more insight into the consumer acceptance of cottonseed butter.