Effect of UV-C Irradiation on Quality from Fresh Grapes var. Bordô

The effect of irradiation through UV-C on the content of phenolic compounds, antioxidant activity, color, and texture profile was evaluated in Bordô variety grapes. Grapes were subjected to stress by irradiation at time of 0.5, 1.0, 4.0, 10 and 30 min that correspond at doses of 0.1, 0.3, 1.0, 2.4, and 7.2 kJ m^-2, respectively. The total phenolic and anthocyanins content, antioxidant activity, color and texture of the grapes were evaluated after storage at 22 ºC for 24 and 48 h. In general, samples irradiated did not show an increase in total phenolic content, anthocyanin compounds and antioxidant activity. Hue and Chroma values indicated that the color of grapes did not change when irradiated. Texture profile analysis suggested that UV-C treatment delayed grapes softening.

Keywords:
polyphenols; texture; color; anthocyanins; antioxidant activity

	L*	a*	b*	Hue	Chroma
Initial sample	29.41±1.77^a.b	-0.21±0.11^a.b	-1.13±0.49^a	250.03±3.02^a	1.15±0.50^a
24 h
Control	31.38±0.68^a	-0.45±0.11^b	-1.71±0.47^a	244.97±4.62^a	1.77±0.46^a
0.5 min	28.76±0.56^a.b	-0.05±0.05^a	-1.44±0.85^a	257.50±2.18^a	1.44±0.85^a
1 min	28.90±1.24^a.b	-0.20±0.09^a.b	-1.77±0.63^a	252.82±4.69^a	1.78±0.62^a
4 min	29.17±1.09^a.b	-0.22±0.12^a.b	-1.42±0.36^a	251.39±3.24^a	1.43±0.37^a
10 min	28.04±0.91^b	-0.20±0.13^a.b	-1.06±0.35^a	248.70±6.72^a	1.08±0.35^a
30 min	28.96±1.03^a.b	-0.16±0.07^a	-0.98±0.29^a	250.45±2.30^a	1.08±0.35^a
48 h
Control	28.13±1.52^b	-0.30±0.08^a.b	-1.31±0.31^a	246.54±5.37^a	1.34±0.30^a
0.5 min	27.63±0.78^b	-0.21±0.15^a.b	-1.08±0.55^a	243.05±20.63^a	1.13±0.49^a
1 min	28.86±0.83^a.b	-0.17±0.11^a	-1.77±0.63^a	253.89±4.53^a	1.78±0.63^a
4 min	28.62±0.67^b	-0.21±0.05^a.b	-1.41±0.31^a	251.55±1.92^a	1.43±0.31^a
10 min	27.77±1.39^b	-0.22±0.15^a.b	-1.53±0.58^a	252.50±2.61^a	1.54±0.60^a
30 min	28.71±0.70^b	-0.14±0.12^a	-1.57±0.62^a	254.71±3.43^a	1.58±0.63^a

Treatment	F_R (N)	D_R (mm)
Initial sample	3.44±0.29^d,e	9.74±1.21^a,b
	24 h
Control	3.74±0.19^a,b,c,d	8.98±2.07^a,b
0.5 min	4.02±0.06^a,b	9.14±0.83^a,b
1 min	3.48±0.09^d,e	8.63±0.74^a,b
4 min	3.55±0.21^c,d,e	8.78±0.57^a,b
10 min	3.92±0.13^a,b,c	7.38±1.67^b
30 min	3.69±0.09^a,b,c,d	8.14±1.36^a,b
	48 h
Control	3.23±0.19^e	8.20±0.94^a,b
0.5 min	3.66±0.03^b,c,d	8.80±0.99^a,b
1 min	3.48±0.15^c,d,e	8.98±1.00^a,b
4 min	3.92±0.11^a,b	10.06±0.50^a
10 min	4.00±0.25^a	7.82±0.90^a,b
30 min	3.61±0.04^a,b,c,d	8.58±0.91^a,b

Instituto de Tecnologia do Paraná - Tecpar Rua Prof. Algacyr Munhoz Mader, 3775 - CIC, 81350-010 Curitiba PR Brazil, Tel.: +55 41 3316-3052/3054, Fax: +55 41 3346-2872 - Curitiba - PR - Brazil
E-mail: babt@tecpar.br

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[1] *Correspondence: czapatan@ufrgs.br; Tel.: +55-51-33086673 (C.P.Z.N.)