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Advisor(s)
Abstract(s)
Vegetables play a particularly important role in human diet and their stabilization
after harvesting and during sub-sequent storage is critical. Among several long-term
preservation processes, freezing is widely recognized as a proven and efficient method
for vegetables.
Most vegetables require a short heat treatment (blanching) prior to freezing to reduce
microbiota and inactivate enzymes responsible for deteriorative reactions. However,
detrimental effects occur during this process, such as alterations of plant tissues and
consequent texture changes, solubilisation of nutrients in the blanching medium, thermal
degradation of nutrients, weight loss and color changes, resulting in quality losses.
Therefore, a rigorous balance between enzyme inactivation (correlated to degradation)
and minimization of quality losses must be achieved in order to produce the highest final
quality of frozen product.
The increasing consumers demand for high-quality food standards, have stimulated
research on alternative and/or mild processing technologies that extend shelf-life without
the detrimental effects caused by severe heating. From an industrial perspective, thermal
processes are extremely energy consuming and have high environmental impact. Nonthermal
processes, or their combination with less severe heat treatments applied before
low-temperature storage, are emergent challenges with potential applications in the food
industry. The application of ultraviolet irradiation is an example of such processes.Ultraviolet radiation (UV) occupies a wide band in the non-ionizing region of the
electromagnetic spectrum, with a wavelength between 100 and 400 nm. Application of
UV-C radiation in the germicidal range (240-260 nm) as a non-thermal food processing
technology, by pulses or continuously to food right after thermal processing of frozen
vegetables, may improve the process‘ quality by reducing heat. It is generally claimed
that the main parameters influencing sensory and quality changes on food are the dose of
UV radiation applied (measured in intensity of flux in J/m2), treatment time, and the
distance between the UV source and product. UV-C pre-treatments present a high
potential to retain the vegetable quality after freezing process and storage.
Description
Keywords
Vegetables Food industry Safety and quality preservation Freezing Thermal and non-thermal processes Blanching UV-C radiation
Pedagogical Context
Citation
NEVES, Filipa I. G. ; VIEIRA, Margarida C.; SILVA, Cristina L. M. - Effects of UV pre-treatments on frozen vegetables quality. In RADOSEVICH, James A. (ed.) - UV radiation properties, effects, and applications. New York: Nova Science Publishers, 2014. ISBN 978-1-63321-090-5. (Physics Research And Technology). chap. 2, p. 13-35