Studies on the phenolic content of Romanian Fetească neagră wines

The phenolic compounds in plants and the related foods inhibit the oxidation of lipoproteins with low density and reduce the plaquetary aggregation in blood vessels. Red wine is an excellent source of phenolic compounds, registering between 1000 – 4000 mg/L flavonoids with diverse biological effects [1]. Phenolic compounds also can contribute to the organoleptic characteristics of red wines.

Therefore, the study of the wine-making technology influence on the phenolic content of 8 Fetească neagră wine samples was considered important. The analyses were processed using high performance liquid chromatography coupled with a diode array detector.

Fetească neagră grape variety harvested in 2009 and 2010 from Uricani vineyard was used, as follows: V1 and V2 wine samples were processed according to classical red wine-making procedure; V3 and V4 were obtained by applying thermo-maceration on the grape marc; V5 and V6 resulted through thermo-maceration of grape marc in roto-tanks; V7 and V8 were blanc de noir variants. After fermentation, the wines were stabilised, conditioned and bottled.

All samples were analyzed on a Shimadzu Prominence 20 series HPLC system. Phenolic compounds were separated on a series of two Chromolith Performance RP-18e chromatographic columns, from Merck (2). Analyses were performed in triplicate and the data was presented as mean ± standard deviation (SD).

The quantity of phenolic compounds is influenced by the agricultural year as well as the processing technology (Table 1). The 2009 V3 wine sample obtained through thermomaceration registers a significant increase of concentration in caffeic, ferullic, p-hydroxybenzoic, gallic acids and a decrease of the syringic and gentisic acids.

Tab. 1: Concentration of polyphenolic constituents in mg/L in wine samples processed in 2009 (VI, V3, V5, V7) and in 2010 (V2, V4, V6, V8)

No.	Wine sample	protocatehic acid	p-hydroxybenzoic acid	vanillic acid	gallic acid	syringic acid	gentisic acid	caffeic acid	chlorogenic acid	p-coumaric acid	ferulic acid
1	FN V1	3.27	0.28	3.20	16.43	4.58	1.02	0.14	2.72	2.90	0.04
2	FN V2	3.16	0.50	3.82	22.73	5.36	1.04	7.42	2.39	4.24	0.64
3	FN V3	3.76	5.03	5.89	25.90	3.50	0.61	13.51	5.00	6.47	1.23
4	FN V4	4.25	022	3.79	29.01	5.33	0.74	7.70	2.39	5.30	0.91
5	FN V5	3.11	0.34	3.69	24.40	6.72	0.65	17.79	2.40	3.70	0.08
6	FN V6	5.05	8.67	3.09	18.93	4.28	2.12	6.44	2.40	4.09	0.05
7	FN V7	1.38	0.41	8.79	10.08	1.97	0.50	8.90	2.32	3.57	0.04
8	FN V8	1.17	1.05	9.79	12.39	3.06	1.38	8.23	1.98	3.91	0.03

References:

[1] Arnous, A., Makris, D. P., & Kefalas, P. (2001), Journal of Agricultural and Food Chemistry, 49, pp.5736 – 5742

[2] Castellari, M., Sartini, E., Fabiani, A., Arfelli, G., Amati, A., Journal Chromatography A, (2002), 973, pp.221 – 227