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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Commodity Utilization Research » Research » Publications at this Location » Publication #384701

Research Project: Development of Novel Cottonseed Products and Processes

Location: Commodity Utilization Research

Title: Modeling and thermodynamic analysis of the water sorption isotherms of cottonseed products

Author
item He, Zhongqi
item ZHANG, DAVID - Former ARS Employee
item Cheng, Huai

Submitted to: Foundations
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/8/2021
Publication Date: 7/12/2021
Citation: He, Z., Zhang, D., Cheng, H.N. 2021. Modeling and thermodynamic analysis of the water sorption isotherms of cottonseed products. Foundations. 1:32-44. https://doi.org/10.3390/foundations1010005.
DOI: https://doi.org/10.3390/foundations1010005

Interpretive Summary: Defatted cottonseed meal (CSM), its water washed product (washed cottonseed meal,WCSM), and protein isolate (CSPI) have shown promising in enhanced utilization as renewable and green industrial raw materials. Thus, we conducted research to obtain moisture sorption isotherms of CSM, WCSM and cottonseed protein isolate at 15, 25, 35 and 45 °C, modelled and calculated the relevant thermodynamic parameters from these adsorption isotherms. Results showed a general trend of decreasing moisture content in the order of CSPI < WCSM < CSM at the water activity < 0.6, but a reversed order of CSM < WCSM < CSPI at the water activity > 0.6. There were fewer interactions between water molecules and CSPI and WCSM. The moisture adsorption of all three products was an enthalpy-controlled process, rather than entropy controlled while the entropy of moisture adsorption was strongly dependent on the moisture content. Information on these moisture adsorption behaviors of the three products is helpful in designing or selecting appropriate equipment for their handling, aeration, storage and processing.

Technical Abstract: Due to their hygroscopic characteristics, equilibrium moisture contents of agricultural products and byproducts are important factors of their quality. Defatted cottonseed meal (CSM), washed cottonseed meal (WCSM), and cottonseed protein isolate (CSPI) can be used as energy and protein sources of animal feedstuff or industrial raw materials. Information on their moisture adsorption behaviors is needed for their storage conditions and quality control. Thus, this work measured the equilibrium moisture sorption isotherms of CSM, WCSM and CSPI, at 15, 25, 35 and 45 0C. When the moisture contents of the samples were compared at a constant temperature, the general trend of decreasing moisture content was in the order of CSPI < WCSM < CSM at the water activity < 0.6, but the trend reversed to the order of CSM < WCSM < CSPI at the water activity > 0.6. Relevant sorption isotherm equations were tested for accurate fit to the moisture adsorption data. Modelling results indicated that the G.A.B. (Guggenheim-Anderson-de Boer) model was a consistently good fit for the data among all sample types and all temperatures. This work provides some insight on designing or selecting appropriate procedures for the handling, aeration, storage and processing of these cottonseed meal products.