Effect of ultraviolet/visible radiation processing on the quality of fruit juices Karla Aguilar Lara

177 Pages·2017·3.63 MB·English

by  Karla Aguilar Lara

Effect of ultraviolet/visible radiation
processing on the quality of fruit juices
Karla Aguilar Lara
h ttp://hdl.handle.net/10803/405804
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DOCTORAL THESIS
Effect of ultraviolet/visible radiation
processing on the quality of fruit juices
Karla Aguilar Lara
Dissertation presented to fulfil the requirements to obtain the degree of
Doctor by The University of Lleida
Doctoral Program of Agricultural and Food Science and Technology
Directors
Albert Ibarz Ribas
Alfonso Garvín Arnés
2017
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A los mexicanos que trabajan
por una vida mejor
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IV
¿En perseguirme, mundo, qué interesas?
¿En qué te ofendo, cuando sólo intento
poner bellezas en mi entendimiento
y no mi entendimiento en las bellezas?
Sor Juana Inés de la Cruz
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This thesis was undertaken in the Department of Food Technology of the
Technical Superior School of Agricultural Engineering at the University of Lleida
(Lleida, Catalonia, Spain). The research was funded by the Ministry of Science and
Innovation of the Spanish Government in the CTQ2011-26569 project. Part of the
research was performed with the Group of Studies on Processing and Engineering (Ge2P)
in the Department of Agrifood Industry, Food and Nutrition (LAN) of the Luiz de Queiroz
College of Agriculture (ESALQ) at the University of São Paulo (USP, Brazil). This piece
of work was part of project no.º 2014/16998-3, funded by the São Paulo Research
Foundation (FAPESP, Brazil), and project no.° 401004/2014-7, funded by The National
Council for Scientific and Technological Development (CNPq, Brazil).

My doctoral studies were sponsored by the National Council of Science and
Technology of the Mexican Government (CONACyT, Mexico) by means of a fellowship
for post-graduate foreign studies. The stay at the University of São Paulo was supported
by the Research Vice-chancellor’s Office of the University of Lleida.

Finally, this thesis has received a grant for its linguistic revision from the
Language Institute of the University of Lleida (2017 call).

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SUMMARY
Fresh fruit juices are nutritious refreshing beverages. For commercialization, they
need to be submitted to a process to inactivate microorganisms and enzymes. Thermal
pasteurization, commonly used for this purpose, alters the organoleptic and nutritional
quality of food. Besides, it does not eliminate mycotoxins and induces the formation of
the potentially toxic 5-hydroxymethylfurfural (HMF). Ultraviolet irradiation is an
alternative for fruit juice pasteurization due to its effectiveness at inactivating
microorganisms and enzymes as well as destroying mycotoxins. This work studied the
effect of ultraviolet-visible (UV-Vis) irradiation processing on the quality attributes of
clarified fruit juices.
The results showed that UV irradiation does not produce HMF and is capable of
degrading it. A three-stage mechanism related to the radiation absorbed by the liquid
sample was proposed to describe the photo-degradation of this compound. From this
mechanism, three kinetic models were developed to describe this process: first-order,
zero-order and/or pseudo-first-order. The fitness to the model depended on the initial
concentration of HMF. On applying the kinetic and thermodynamic compensation theory,
it was concluded that the HMF photo-degradation process is entropically controlled and
can be speeded up by changing non-thermal parameters such as agitation. On the contrary,
when a multi-wavelenght emission lamp was used, the photo-degradation of L-ascorbic
acid was insignificant.
After the UV-Vis treatments, most of the physicochemical parameters of the fruit
juices were practically unaltered. The enzymes polyphenoloxidase and peroxidase were
totally or partially inactivated, the higher the temperature the higher the inactivation. To
sum up, UV-Vis processing combined with mild-heating for fruit juice pasteurization is
an alternative to traditional methods, since it is effective inactivating enzymes, preserves
quality attributes of the product and does not produce HMF.

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