To investigate the effect of ball mill treatment of microcrystalline cellulose (MCC) on the rheological properties of MCC-polymer suspension, the structure and physicochemical characteristics of ground samples with different milling time and the rheological behaviors of MCC-starch suspensions were determined and comprehensively analyzed. During the ball milling process, MCC underwent a morphological transformation from rod-like to spherical shape under the combined effect of breakage and an agglomeration regime. The particle size and crystallinity index of MCC exhibited an exponential declining trend with ball milling time. All of the milled MCC samples presented a crystalline cellulose Iβ structure whereas the MCC mechanically treated in a shorter time had better thermal stability. Rheological measurements of starch/MCC suspensions indicated that all the blended paste exhibited shear thinning behavior and ‘weak’ elastic gel-like viscoelastic properties over the whole investigated range owing to the formation of entangled network structure. The rheological behavior of starch/MCC pastes was strongly dependent on milling time and concentration of MCC samples. The increase in milling time of MCC samples resulted in the loss of rheological properties of starch/MCC pastes, where the size of the MCC playing a dominant role in affecting the properties of composite suspension. In addition, a possible network within starch/MCC suspensions was proposed.
24 June 2011 in International Journal of Food Properties
Flaxseed oil is rich in linolenic acid, and being accepted in diet by more and more people. The characteristics of flaxseed oil from two different varieties, namely fibre-flax seed and oil-flax seed, were evaluated. It was shown that fatty acids of flaxseed oil were mainly constituted by linolenic, oleic, linoleic, stearic, and palmitic acids, and the oil-flax seed oil contained more linolenic acid (58.03%) compared with the fibre-flax seed oil (47.37%). The fibre-flax seed oil showed a higher absorbance at 290–800 nm. Thermogravimetric curves showed that the oil-flax seed oil was more stable than the fibre-flax seed oil. Thermal profiles indicated that the fibre-flax seed oil had higher melting peak temperature and larger enthalpy. Rheological studies indicated that the apparent viscosity of the fibre-flax seed oil was higher than that of the oil-flax seed oil. It can be concluded that the oil-flax seed oil is better than the fibre-flax seed oil in terms of edibility.