The simultaneous determination of the suitable level of homogenization pressure and modified starch is an important issue, which affects the quality of the industrial ketchup. In this study, ketchup was produced at different pressures of homogenization (0, 5, 8, 11, 14, 17, and 20 MPa) and different weight percentages of modified starch (0, 0.1, 0.4, 0.7, and 1 g/100 g). The viscosity of ketchup was measured at different temperatures. The results showed that the selected ketchup, which contains 1 g/100 g of modified starch and homogenized at a temperature of 25°C and a pressure of 14 MPa, has the optimum viscosity and consistency. After that, to evaluate the effect of homogenization on the physical properties of selected ketchup, additional tests such as the dynamic dispersion scale, the optical microscopy and the Fourier transform infrared spectrophotometer were done. The results indicated a smaller particle size, a more uniform, and a continuous structure of selected ketchup compared with the control sample. Consequently, several different rheological models were investigated for evaluating the rheological behavior of selected ketchup. The statistical measures indicated that the Cross model could predict the rheological behavior of selected ketchup well (R2 = 0.998).
Practical Applications
Viscosity and syneresis can have strong effects on ketchup quality. Also, reliable rheological data are necessary for designing and optimization of ketchup processing equipment such as pumps, piping, heat exchangers, evaporators, sterilizers, filters, and mixers. In this research, the simultaneous effect of the modified starch and pressure homogenization on the rheological data of ketchup was evaluated. The purpose of this study is to help the ketchup industry by determining the optimum level of homogenization pressure and the optimal dose of modified starch when used simultaneously. Paying attention to this subject is vital for loss prevention in the process and machine depreciation. Furthermore, the rheological behavior which is important during storage, processing, and the transport of ketchup in the industry is determined.