Submitted to: Journal of Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/2010
Publication Date: 7/8/2010
Citation: Xu, J., Cheng, W., Inglett, G.E., Wu, P., Kim, S., Liu, S.X., Tseng, Y. 2010. Micro-heterogeneity of Cellulosic Fiber Biopolymer Prepared from Corn Hulls. LWT-Food Science and Technology. 43(6):977-981. Interpretive Summary: As a new dietary fiber food product, Z-trim, has been developed as a fat replacement. The bio-based Z-trim can form a fat-like hydrocolloid gel. While fat has nine calories per gram, Z-trim has zero calories per gram. The Z-trim cellulosic biopolymer was produced from dry milled corn hulls. Recently, Distiller's Dried Grains with Solubles (DDGS) as a co-product of the bio-fuel industries, become widely available due to increased ethanol production. Approximately 3.2 to 3.5 million tonnes of DDGS are produced annually in North America. Because of the increased demand for ethanol, the production of DDGS is expected to double within the next few years. However, the usage of DDGS is limited. The Z-trim cellulosic biopolymer can also be prepared from DDGS, which opens another path for the DDGS applications. The basic physical properties of Z-trim have rarely been reported except some studies on its rheological property. In this study, a novel technique denoted as multiple-particle tracking (MPT) was used to investigate the micro-structural heterogeneities of Z-trim cellulosic biopolymer. This research gives more insight for cellulosic fiber biopolymer, Z-trim. The multiple-particle tracking (MPT) investigation on the micro-structural heterogeneities of Z-trim cellulosic biopolymer will help understanding the physical properties of Z-trim and their effects on applications in food products and pave the way for developing similar dietary fibers from DDGS, a co-product of ethanol production, which ultimately benefits the U.S. dry milling industry through value-added utilization of this increasingly abundant material from the bio-fuel production.
Technical Abstract: Z-trim is a zero calorie cellulosic fiber biopolymer produced from corn hulls. The micro-structural heterogeneities of Z-trim biopolymer were investigated by monitoring the thermally driven displacements of well-dispersed micro-spheres via video fluorescence microscopy named multiple-particle tracking (MPT). By comparing the distribution of the time-dependent mean-square displacement (MSD) of polystyrene micro-spheres embedded in three concentrations of Z-trim, we found that the degree of heterogeneity of the suspensions increased dramatically within a narrow range of concentrations. The ensemble-averaged MSD of 0.5% Z-trim biopolymer exhibited a power-law behavior that scaled linearly with time lag. This behavior was similar to that of homogeneous aqueous glycerol solution. But the MSD distribution for Z-trim was wider and more asymmetric than for glycerol. Increasing Z-trim concentration caused more deviation of microspheres colloidal dispersion from homogeneity as detected by the MPT.