Taísa Ceratti Treptow - UFSM

ABSTRACT
Master Dissertation
Graduate Program on Food Science and Technology
Federal University of Santa Maria
RADIATION UV-C IN NIÁGARA WHITE, TREBBIANO, ISABELLA AND
CABERNET SAUVIGNON
AUTHOR: TAÍSA CERATTI TREPTOW
ADVISER: CLÁUDIA KAEHLER SAUTTER
Place and Date of Defense: Santa Maria, February 29 th , 2012.
This study evaluated the UV-C irradiation in tissues of rachis with and without berries, and
berries with stems of Vitis vinifera and Vitis labrusca. In berries of cv. Isabella, the volatile
compounds were analyzed on days 2, 5 and 10 of storage at 20 ºC and the effect of UV-C
irradiation on the 5 th day of storage. The experiments were based on four treatments of UV-C
radiation (0, 1, 2 and 3 kJ m -2 ) with four cv. (Niagara white, Trebbiano, Cabernet sauvignon
and Isabella) and evaluation times (three in berries and four rachis). The rachis with and
without berries and the berries with stems remained stored at 20 ºC to evaluate physiological
parameters. Ethylene production rate, respiratory rate and total polyphenols were evaluated in
all tissues. Only in the rachis was determined by weight loss on days 1, 3 and 5, reducing
sugars, non-reducing sugars on the 5 th day. Berries and the juice from the cv. Isabella the 5 th
day of storage at 20 °C the total soluble solids (TSS), titratable acidity (TA), anthocyanins,
total phenols, sugars and the ratio (TSS/ TA) were measured. In berries of cv. Isabella on days
2, 5 and 10 storage and berries irradiated with UV-C in amounts of 0, 1, 2 and 3 kJ m -2 ,
volatiles were extracted by solid phase microextration. After desorption, the volatile
compounds were separated by gas chromatography, identified by mass spectrometry and
quantified by flame ionization detector. For the sensory analysis of the juice discriminatory
tests for paired comparison of difference and test ranking were used. The physiological
response of UV-C irradiation depends on the cv. and the irradiated tissue. Only the rachis of
grape Vitis labrusca ‗Niagara white‘ behaves climateric during storage in post-harvest and
may reduce the self life of table grapes. This study found a possible hormetic dose of 3 kJ m -2
only for the cv. Isabella berry. 84 volatile compounds were detected over the days of storage.
After 5 days storage, berries irradiated with UV-C 66 volatiles were found. And the dose of 3
kJ m -2 increased the concentration of esters and aldehydes, and 43,8% increase in the total
polyphenols in berry. In the paired comparison test of difference, the judges showed greater
intensity in the aroma of the juice from grapes irradiated. In the ranking test, the judges were
unable to discriminate between different doses of irradiation, though differing dose control (0
kJ m -2 ) of the irradiated treatments. The analytical test enabled by gas chromatography to
determine statistical differences between the different doses detected volatiles, especially at a
dose of 3 kJ m -2 , in which panelists found no difference.
Keywords: Vitis vinifera, Vitis labrusca, plant tissues, secondary metabolism, volatile
compounds.
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