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TEXTURAL PROPERTIES OF DEHYDRATED FOODS. RELATIONSHIPS WITH THE THERMODYNAMICS OF WATER VAPOR SORPTION
John G Kapsalis1, Birger Drake1, Birgit Johansson1
1U.S. Army Natick Laboratories, Natick, Mass., U.S.A.Swedish Institute for Food Preservation Research, Goteborg, Sweden.
Journal of Texture Studies
|April 4, 2017
Summary
The study investigated how moisture affects the texture of freeze-dried foods. Increased humidity made foods harder but less easy to bite, with strong links between heat sorption and sensory experience.
Area of Science:
- Food Science
- Materials Science
- Rheology
Background:
- Freeze-dried foods, including pre-cooked beef and space foods, are designed for convenience without rehydration.
- Understanding their textural properties under varying moisture conditions is crucial for product development and consumer acceptance.
Purpose of the Study:
- To determine the textural properties of pre-cooked, freeze-dried beef and space foods at different relative humidity levels.
- To correlate instrumental measurements of texture with sensory perceptions during consumption.
- To investigate the relationship between thermodynamic properties and food texture.
Main Methods:
- Instrumental analysis of mechanical properties (hardness, cohesiveness, crushability index).
- Sensory evaluation of texture, including 'ease of biting' and perceived heat during chewing.
- Moisture sorption isotherm analysis at various relative humidity points.
- Measurement of heat of sorption and other thermodynamic functions.
Main Results:
- Increased relative humidity led to increased hardness and cohesiveness.
- Higher relative humidity decreased the crushability index and the sensory 'ease of biting'.
- Strong correlations were observed between the heat of sorption and the sensory perception of heat during chewing.
- Good correlations existed between other thermodynamic functions and measured textural properties.
Conclusions:
- Moisture content significantly influences the textural characteristics of freeze-dried foods.
- Instrumental and sensory methods provide complementary data on food texture.
- Thermodynamic properties are closely linked to the perceived texture and eating quality of freeze-dried products.