Modeling viscoelastic behavior of selected foods using creep and stress relaxation tests | |
| Author | Wanintorn Wirojwaranuruk |
| Call Number | AIT Thesis no.PH-03-21 |
| Subject(s) | Viscoelastic materials Food texture |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | In this study, the viscoelastic behavior of potato and sausage was investigated using creep and stress relaxation tests. Several techniques for analying experimental creep and stress relaxation data were undertaken. On the basis of qualitative interpretation, the range of linear viscoelastic behaviors of potato and sausage were established using the data obtained from the tests with a crosshead speed of 60 min/mm. In order to investigate the effects of experimental test conditions, potato samples were tested at four different crosshead speeds of 5, 50, 100 and 150 mm/min with initial stress levels of 20, 25, 30 and 35 N for creep testing and initial strains of 10%, 12%, 14% and 16% for stress relaxation testing. Sausage samples were tested at four different crosshead speeds of 5, 50, 100 and 200 mm/min with initial stresses of 4.5, 5, 5.5 and 6 N for creep testing and initial strains of 4%, 5%, 6% and 7% for stress relaxation testing. Based on the fitting to experimental test data indicated by R2 values, the generalized Kelvin and Maxwell models with five elements in each were selected for representing creep and stress relaxation behavior. Both apparent (original) and corrected forms of the selected models were used and the results were compared. The statistical methods in the form of multiple comparison and stepwise regression were employed to investigate the effects of test conditions. Based on fitting the five-element Kelvin model in creep tests, the values of R2 ranged from 0.978 to 0.991 for potatoes and from 0.997 to 0.998 for sausages. The values of parameters obtained with the apparent equations were slightly different as compared to those obtained with the corrected equations. The values of R2 obtained by fitting stress relaxation responses with the five-element Maxwell model for potatoes and sausages were 0.994 and 0.996, respectively. There were slight differences between the values of model parameters obtained with the apparent and corrected equations. It was found that the crosshead speed affected the model parameters of both potato and sausage in creep tests for both apparent and corrected five-element Kelvin model fitting. However, the initial stress did not affect the model parameters both for potato and sausage. For potato, both crosshead speed and strain level influenced the model parameters in stress relaxation tests for the apparent five-element Maxwell model fitting. Neither crosshead speed nor initial strain affected stress relaxation when the corrected equation was fitted to represent stress relaxation behavior. For sausage, crosshead speed affected the model parameters of both apparent and corrected fiveelement Maxwell models. However, there was no effect of initial strain on the model parameters of both apparent and corrected models. Finally, a three-hidden slab backpropagation neural network showed satisfactory performance in predicting viscoelastic behaviors of both potato and sausage. Also, these results revealed the ability of ANN to generalize a massive and ambiguous data. |
| Year | 2003 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Postharvest and Food Process Engineering (PH) |
| Chairperson(s) | Jindal, Vinod K. |
| Examination Committee(s) | Athapol Noornhorm;Rakshit, Sudip K. |
| Scholarship Donor(s) | AIT Fellowship |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2003 |