Application of computer vision for determining viscoelastic characteristics of date fruits

• A computer vision apparatus was designed to obtain actual contact surface area while fruit compression.
• Stress relaxation of date fruit was modeled using actual stresses.
• General Maxwell model predicted relaxed stresses of fruit more closer than Peleg and Nussinovitch models.

Date fruits are subjected to different environmental conditions from harvest to consumption. Since the rheological behavior of fruits are important for any processing operation, the viscoelastic characteristics of date fruits were studied at six moisture content, and four temperature levels of product, using a computer vision method. The whole date fruits were subjected to uniaxial compression for relaxing the stress during 300 s. As a new approach, a probe that equipped with a camera was used to measure the samples true contact area simultaneously. Three famous viscoelastic models were used to fit on experimental data. It was found that Generalized Maxwell and Nussinovitch models describe viscoelastic characteristics of date fruits appropriately, as compared to Peleg model. Furthermore, it was observed that moisture content of the product has dominant effect on viscoelastic characteristics of the fruits than temperature.