ABSTRACT
I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
II. Unfreezable Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
III. The Concept of “State Diagram” in Food Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
IV. Measurement of the Glass Transition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
A. Sample Preparation and Moisture Determination . . . . . . . . . . . . . . . . . . . . . . . 39
B. Conventional Differential Scanning Calorimetry . . . . . . . . . . . . . . . . . . . . . . . . 39
C. Modulated Differential Scanning Calorimetry . . . . . . . . . . . . . . . . . . . . . . . . . . 40
D. Rheological Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
1. Viscosity (h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 2. Dynamic Mechanical Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
V. Glass Transitions in Frozen Fruits, Fruit Juices, and
Model Carbohydrate Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
VI. Glass Transitions in Ice Cream and Other Fabricated Products . . . . . . . . . . . . . . . . . 47
VII. Tg Perspective of Collapse Phenomena, Chemical Reactions, and
Enzymic Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
VIII. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
High solid systems refer mainly to mixtures of biopolymers and co-solutes and as such are increas-
ingly popular in the industrial world [1]. The mixtures are used as a base to formulate products with
a variety of textures and sensory stimuli but mechanistic knowledge behind these properties has
been lacking. In recent times, the importance of the rubber to glass transition and the development
of the glassy state became widely appreciated in the understanding and controlling the quality of
materials [2]. The emphasis now is on mapping out the relationship between the kinetics of vitri-
fication and the metastability of systems to produce innovative methods of processing and product
formulations [3].
