A numerical model to simulate non-isothermal generalized Newtonian flow inside a deep-channel twin-screw cheese stretcher was developed. System variables (SME, MRT and TE) of the process were defined and mathematical models were developed to compute system variables from the flow field. The stretcher-cooker geometry and operating conditions strongly influence the system variables. Therefore, the stretcher-cooker geometry and operating conditions can be adjusted to control the process towards a desirable end. The technique developed in this study can help to improve the stretcher-cooker design and to optimize the pasta filata operation to obtain more desirable final product. (c) 2004 Elsevier Ltd. All rights reserved.