Application of Peleg's equation to describe creep responses of potatoes under constant and variable storage conditions.

The application of Peleg's equation to characterize creep behavior of potatoes during storage was investigated. Potatoes were stored at 25, 15, 5C, and variable (fluctuating) temperature for 16 or 26 weeks. The Peleg equation adequately described the creep response of potatoes during storage at all storage conditions (R(2)  = .97to .99). Peleg constant k1 exhibited a significant (p < .05) decreasing trend with storage time (ts ) for samples stored under the experimental conditions whereas the constant k2 appeared to be unaffected much by ts except for samples stored at 25C. Under constant temperature storage, k1 was found to be a linear function of ts (R(2)  = .87 to .97). Also, the rate of change of k1 appeared to be temperature dependent described by a linear relationship between the degradation rate constant for k1 (α) and storage temperature (T). For the variable storage condition, a bulk mean temperature (Tbm ) was calculated to account for a series combination of storage time and temperature which the potatoes were subjected to. It was possible to describe the changes in k1 due to variable storage temperature in terms of Tbm and ts using stepwise multiple regression (R(2)  = . 94).

PRACTICAL APPLICATIONS: Precise description of the changes in the rheological properties of raw potatoes during storage could help predict the associated effect on the texture of cooked potatoes. Easy and simple methods of describing creep responses during storage or processing will be potentially helpful to better understand the phenomenon. The model parameters from such model could be used to relate rheological properties of raw and cooked potatoes. Moreover, the model parameters could be used to establish relationship between instrumental and sensory attributes which will help in the prediction of sensory attributes from instrumental data.