ABSTRACT
Introduction ........................................................................................................ 116
Food Structure .................................................................................................... 116
Definition and Importance ....................................................................... 116
The Structure of Low-Moisture Foods ................................................... 117
Microheterogeneity .................................................................................... 118
Viewing the Microstructure of LMF ....................................................... 118
Quantifying Structure................................................................................ 119
Properties ............................................................................................................ 119
Properties Relevant to Foods ................................................................... 119
Structure-Property Relationships........................................................... 120
Texture ......................................................................................................... 121
An Example: Hardening of Legumes..................................................... 122
Effect of Moisture Content on Mechanical Properties of LMF................... 122
Crispness of LMF....................................................................................... 122
Effect of Moisture Content........................................................................ 123
Crispness and the Glass Transition......................................................... 124
Fracture of Polymers ................................................................................. 126
Fracture and the Glass Transition in LMF............................................. 126
Structure-Property Relationships in a Low-Moisture
Starch Model System............................................................................. 127
Microstructure and Auditory Sensations............................................... 129
Concluding Remarks and Future Trends....................................................... 130
Acknowledgment............................................................................................... 130
References ........................................................................................................... 130
Although food technologists have been dealing with functional structures
made from natural molecules since ancestral times, their impact in
biomaterials science has been limited. The problem has been an insufficient
basic understanding of how structures are formed and relate to desirable
properties. In their favor, it can be argued that foods are complex,
multicomponent systems where key structural components are beyond the
resolution of the naked eye and that some properties are quite subjective.
Only in the last 20 years with the development of food materials science,
which is application of concepts from polymer science, colloidal chemistry
and modern microscopy techniques, is a basic understanding emerging of
how food structures are created and how they perform. This trend will be
illustrated in this paper for the case of low-moisture foods (LMF). Although
LMF were originally produced to increase storage stability and safety (i.e.,
minimize microbial growth and reduce the rate of deleterious chemical
reactions) there are many other desirable physical properties of foods
associated with low water content.
