ABSTRACT
I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 378
II. Influence of Product, Processing, and Packaging
(P-P-P Factors) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379
A. Product . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379
1. Agrotechnical Practices and Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . 379
2. Species and Variety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380
3. Technological Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381
4. Quality Assessment of Raw Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381
5. Nutritional Aspects of Raw Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382
6. Microbiological and Safety Aspects of Raw Material . . . . . . . . . . . . . . . . 383
B. Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384
1. Main Preparatory Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384
2. Blanching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386
a. Effects of Blanching on Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386
b. Nutritional and Microbiological Aspects of Blanching . . . . . . . . . . 389
c. Technological Aspects of Blanching . . . . . . . . . . . . . . . . . . . . . . . . . 390
i. Current Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390
ii. Emerging Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391
3. Freezing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391
a. Freezing Effects on Structure and Texture . . . . . . . . . . . . . . . . . . . . 392
b. Importance of the Freezing Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
c. Methods and Equipment for Freezing . . . . . . . . . . . . . . . . . . . . . . . . 394
d. Nutritional and Microbiological Aspects of Freezing . . . . . . . . . . . 396
C. Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398
III. Influence of Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399
A. Physical Changes during Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399
B. Chemical Changes during Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400
1. Changes Associated with the Appearance of Off-Flavors and Odors . . . . 400
2. Changes Associated with Alterations in Color . . . . . . . . . . . . . . . . . . . . . 400
3. Ascorbic Acid Oxidation and Changes in pH . . . . . . . . . . . . . . . . . . . . . . 402
C. Combined Effect of Time and Temperature during
Storage (T-T-T Factors) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403
D. Importance of Storage Temperature in the Freezing Chain . . . . . . . . . . . . . . . 407
E. Nutritional and Microbiological Aspects during Storage . . . . . . . . . . . . . . . . . 408
IV. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 410
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 410
Looking back over the historical development of quality requirements for processed foods, freezing
is undoubtedly the most satisfactory method for the long-term preservation of vegetable produce
when properly carried out. The low temperatures commonly prescribed for frozen foods
(2188C) can maintain initial quality and nutritive value practically unchanged, so that frozen and fresh vegetable products differ only in texture [1]. The freezing of vegetables immediately
after postharvest guarantees consumers a higher vitamin C content than could be attained by any
other form of preservation and distribution. Furthermore, if properly handled before freezing and
during distribution, there is no possibility of growth of microbial contaminants between freezing
and thawing [2].
