Sample Solution

nown weight of dry fibers under specified conditions. In general, the polysaccharide constituents of dietary fibers are strongly hydrophilic. Water is held on the hydrophilic sites of the fiber itself or within void spaces in the molecular structure. Viscosity is a physicochemical property associated with dietary fibers especially soluble dietary fibers such as gums, pectins, psyllium, and β-glucans. Viscosity, or gel-forming capacity, is related to a fiber’s ability to absorb water and form a gelatinous mass. Water soluble fibers are the major component that would increase the viscosity of a solution38. Thus, there is two way for asparagus powder to increase the elastic behavior of PC. One way is by absorbing the moisture of PC and forming a gel like solution and second way could be attributed to the formation of polysaccharide network throughout the casein matrix. With increasing concentration of asparagus, more intensive interactions between its fiber chains take place, leading to the formation of a denser network structure. Similar results were reported with k-carrageenan and ι-carrageenan39. Also, Ribeiro et al.40 reached similar conclusions, i.e. gel hardness and strength rise with increasing concentration of carrageenan. Other research reported that a pectin gel, which acted as a linkage with other ingredients in a processed cheese analogue, made the product more compact with less pores and as a result higher storage modulus41.

Dynamic rheology can provide useful information on the heat-induced changes that occur to imitation cheese viscoelasticity. Temperature sweep test of processed cheeses with different tomato and asparagus powder content from 25 to 80 °C were determined at frequency of 10 1/s and strain of 1%. For all products at 25 °C, the values of Gʹ were significantly (P < 0.05) higher than Gʺ (Figs. 4 and 5), indicating the dominant elastic character of the PC. Gʹ values decreased with increasing temperature from 25 to 80 °C, as has previously been observed in natural cheddar cheese42 and in imitation Mozzarella cheese43. This indicates that the cheese matrix became less elastic with increasing temperature. This may have been caused by liquefaction and deformation of the fat globules which may plasticized the protein matrix and weakening of protein-to-protein interactions within the casein network which, all of these, allowing the protein matrix to flow44. Gʹ and Gʺ of PCT samples at 25 °C was lower than those of control sample and samples with higher concentration of tomato powder, had lower Gʹ and Gʺ (Fig 4). These results showed that adding tomato powder in PC, decreased the firmness of that. Gʹ of PCT samples slightly incr