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Overview. IntroductionObjectivesMaterials and methodResults and discussionConclusion. Introduction. Introduction (con't). Objectives. Study the properties of moisture-sensitive product, including initial moisture content, critical moisture content, and moisture sorption isotherm;Determine water vapor permeability coefficient of of polymeric material and its dependence on environmental conditions;.
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1. Determination and Prediction of Shelf Life of Moisture-sensitive Post? Shredded Wheat Cereal Presented By:
Li Xiong
School of Packaging
Michigan State University
2. Overview Introduction
Objectives
Materials and method
Results and discussion
Conclusion
3. Introduction
4. Introduction (con’t)
5. Objectives Study the properties of moisture-sensitive product, including initial moisture content, critical moisture content, and moisture sorption isotherm;
Determine water vapor permeability coefficient of of polymeric material and its dependence on environmental conditions;
6. Objectives Learn to decide shelf life of moisture-sensitive product experimentally;
Try different mathematical methods to simulate moisture sorption isotherm, so that shelf life of the product can be decided analytically;
7. Objectives (con’t) Compare the validity and suitability of different analytical method.
8. Materials Moisture-sensitive product: post? shredded wheat cereal;
Polymeric material: LDPE film with thickness of 1.25 mil;
Package: 10 cm x 10 cm pouch made of 1.25 mil LDPE film
Aluminum dishes
The national vacuum oven
9. Materials (con’t) Saturated salt solutions;
Analytical balance (sensitivity ?0.00005 g);
Desiccant
Impulse sealer
10. Method Initial moisture content
Moisture sorption isotherm and GAB model
Critical moisture content
Water vapor permeability coefficient of LDPE film with thickness 1.25 mil
Experimental shelf life of moisture-sensitive product
11. Method (con’t) Simulated shelf life of moisture-sensitive product
Linear isotherm
Two-point method
Integrated GAB
Mid-point method
Log-method
12. Results and Discussion Moisture-sensitive post? shredded cereal
Initial moisture content: 3.69 % (vacuum oven method);
Critical moisture content: 9% (from literature review), which is related to crispness of the cereal product;
Moisture sorption isotherm at 20oC
17. Permeation property of 1.25 mil LDPE film (determined with pouch method)
Testing conditions: 23.7oC and 44% RH%
PH2O = 0.1682 g.mil/day/m2/mmHg
PH2O = 0.1496 g.mil/day/m2/mmHg (20oC, using Arrhenius equation)
18. Storage conditions for shelf life study
Temperature: 20oC
Relative humidity: 80% RH%
Package: 10 cm x 10 cm pouch made of 1.25 mil LDPE film
21. Conclusion The initial moisture content of the cereal is 3.69% (dry basis);
The critical moisture content of the cereal is decided to be 9%, which is considered crucial to crispness of the product;
GAB model was used to fit the experimental moisture sorption isotherm data at 20oC, the fitting was satisfactory (RMS 3.85%);
22. Conclusion The water vapor permeability coefficient of 1.25 mil LDPE film was measured to be 1.122 x 10-3 g.mil/day/m2/Pa at 20oC;
The shelf life of the cereal was determined to be 23 days experimentally at 20oC and 80% RH%;
Linear method, two-point method, mid-point method and Log method give good prediction of shelf life of the product;
23. Conclusion (con’t) Integrating GAB was not suitable for predicting the shelf life of the cereal, because the constant C in the GAB model is 16.15. GAB method is valid only if constant C is higher than 20.
24. Questions and Comments?