Effect of drying methods on the physicochemical properties and adhesion performance of water-washed cottonseed meal

Authors: LI, NINGHO - Kansas State University; PRODYAWONG, SAROCHA - Kansas State University; He, Zhongqi; SUN, XIUZHI - Kansas State University; WANG, DONGHAI - Kansas State University

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2017
Publication Date: 9/24/2017
Citation: Li, N., Prodyawong, S., He, Z., Sun, X.S., Wang, D. 2017. Effect of drying methods on the physicochemical properties and adhesion performance of water-washed cottonseed meal. Industrial Crops and Products. 109:281-287.

Interpretive Summary: Water-washed cottonseed meal (WCSM) showed the potential for being used as environment-friendly wood adhesives. However, the influence of WCSM preparation process on its adhesion performance is currently limited. Wet samples and products are frequently dried for stability and easiness in analysis, disposition and storage. Frequently used drying processes include freeze-drying, oven-drying and spray-drying. In laboratory, we have used freeze-drying to dry conttonseed meal products (WCSM and protein isolate) to ensure the physicochemical and stability of the products. However, freeze-drying usually takes an enormous amount of time, labor and expenses. Thus, oven- or spray-drying would be an option to lower the processing cost of WCSM if there is no difference in the adhesion performance between these WCSM products. The findings in this study suggested that the water-washed meal dried with spray dryer and freeze dryer are more effective to produce high quality cottonseed meal-based adhesives with improved bonding strength and water resistance. On the other hand, the more economic oven-drying may be applied to make WCSM product for bonding at higher press temperature (e.g. 170 oC) without undermining WCSM's adhesion performance.

Technical Abstract: Water-washed cottonseed meal (WCSM) showed the potential for being used as environment-friendly wood adhesives. However, the influence of WCSM preparation process on its adhesion performance is currently limited. This work studied the effect of different drying methods on the several key physicochemical features and adhesion performance of WCSM. Defatted cottonseed meal was washed with 8 folds of water for 3 cycles to remove the water-soluble components and dried with oven, freeze dryer, and spray dryer, respectively. Whereas the major chemical composition was unchanged, oven-dried WCSM showed protein degradation denaturation per sodium dodecyl sulfate polyacrylamide gel electrophoresis and differential scanning calorimetry data. With hot press temperature at 100 oC, oven-dried WCSM showed poor adhesion performance than its freeze- and spry-dried counterparts. However, the difference among the products with the three drying methods became smaller, and even none with the press temperature at 150 and 170 oC. The adhesion performance could be further improved by pH 4.5 adjustment and removal large residual hull particles. This study proved spray-drying and freeze-drying more suitable to make high quality cottonseed meal-based adhesives for a variety of operation conditions. On the other hand, the more economic oven-drying may be applied to make WCSM product for bonding at higher press temperature (e.g. 170 oC) without undermining WCSM's adhesion performance.