ABSTRACT
I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 535
II. Evaluation of Prefreezing Treatments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 536
A. Blanching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 536
B. Freshness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 536
C. Irradiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 536
III. Methods to Assess Differentiation of Fresh from Frozen . . . . . . . . . . . . . . . . . . . . . 537
A. Measurement of Enzyme Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 537
B. Measurement of Volatile Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 538
IV. Methods to Assess Nutritional Degradation during
Freezing or Frozen Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 538
A. Ascorbic Acid and Organic Acid Measurements . . . . . . . . . . . . . . . . . . . . . . . 538
B. Glucosinolate Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 539
C. Folate Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 539
V. Methods to Assess Lipid Degradation during Freezing or Frozen Storage . . . . . . . . 539
VI. Methods to Assess Protein Degradation during Freezing or
Frozen Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 544
VII. Methods to Assess Carbohydrate and Pigment
Degradation during Freezing or Frozen Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . 550
VIII. Chemical Measurements to Monitor Chemical and
Microbial Additives/Contaminants in Frozen Foods . . . . . . . . . . . . . . . . . . . . . . . . . 550 IX. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553
Chemicals are the building blocks of foods and hence are responsible for the physical and sensory
properties of those foods. During freezing and frozen storage, chemical reactions occur; while they
are slower than those occurring at higher temperatures, they often have undesirable consequences.
To quantify those changes, analyses have been developed that target either substrates or products of
the reactions. This chapter provides an overview of those chemical measurements that assess degra-
dation of vitamins, lipids, proteins, carbohydrates, and pigments. This chapter presents a brief
description of the methodology as well as a number of examples of studies where those measure-
ments have been incorporated. The use of chemical measurements to differentiate fresh from frozen
product is also presented.
