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Changes in the composition of aroma and phenolic compounds induced by different enological practices of Croatian white wine

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Tomasevic M., Lisjak K., Vanzo A., Basa Cesnik H., Gracin L., Curko N., Kovacevic Ganic K.

Polish Journal of Food and Nutrition Sciences

2019

tom 69

nr 4

The aim of this research was to investigate the effects of pre-fermentative maceration, Saccharomyces and non-Saccharomyces yeasts during alcoholic fermentation, and antioxidant additions (sulfur dioxide and glutathione) at bottling on the compositions of aroma and phenolic compounds of white wine Pošip (Vitis vinifera L.). Additionally, for the fi rst time the insight in volatile thiol precursors in Pošip grape was given, wherein higher concentrations of glutathionylated thiol precursors in comparison to cysteinylated ones were determined. Regarding the applied practices, signifi cant differences among produced wines were established: pre-fermentative maceration resulted in a decrease of 3-sulfanylhexyl acetate (3SHA) and a slight increase of C6 compounds; indigenous yeasts produced higher concentrations of terpenes and esters, while sequential fermentation with Torulaspora delbrueckii also infl uenced higher concentrations of esters. Most abundant phenolic compound was caffeic acid, except for wine produced by indigenous yeasts where trans-caftaric acid was predominant. Finally, combination of higher SO2 and glutathione resulted in higher concentrations of thiols.

Microwave-assisted extraction of different groups of phenolic compounds from grape skin pomaces: modeling and optimization

100%

Curko N., Kelsin K., Dragovic-Uzelac V., Valinger D., Tomasevic M., Kovacevic Ganic K.

Polish Journal of Food and Nutrition Sciences

2019

tom 69

nr 3

A microwave-assisted extraction (MAE) technique was employed on grape skin pomaces to enable the extraction of different groups of phenolic compounds (total phenolics, tannins, fl avonols, and hydroxycinnamic acids) and to obtain extracts with the highest antioxidant capacity (ORAC). The single-step extraction process was modeled and optimized by means of artifi cial neural network (ANN) and response surface methodology (RSM) coupled with full factorial design. Methanol concentration (20 to 100%, v/v), temperature (30 to 60°C) and duration (2 to 16 min) were MAE input parameters studied. Optimal parameters were further applied in multistep MAE cycles for the complete recovery of phenolic antioxidants. Results showed that methanol concentration was the most signifi cant parameter infl uencing the extraction of all groups of phenolics and antioxidant capacity of extracts. Moreover, a signifi cant effect of time and temperature was also noticed, except in the case of total hydroxycinnamic acids. The presented ANN model accurately predicted the effect of the three input parameters simultaneously on the output parameters (training R2 =0.9957; test R2 =0.9945; validation R2 =0.9965). Optimal parameters showed that higher methanol concentrations and lower temperatures (100%, v/v; at 40°C) were more convenient for the extraction of flavonols and hydroxycinnamic acids than for ORAC (78.1%, v/v; at 60°C) or total phenolics and tannins (62.7 and 65.3%, v/v; at 60°C). The number of MAE cycles was found to be a key factor for completing extraction of skin pomace phenolics and should always be considered prior to analytical determination.

Ograniczanie wyników

2 Polish Journal of Food and Nutrition Sciences

2 Curko N.

2 Kovacevic Ganic K.

2 Tomasevic M.

1 Basa Cesnik H.

1 Dragovic-Uzelac V.

1 Gracin L.

1 Kelsin K.

1 Lisjak K.

1 Valinger D.

1 Vanzo A.

2 2019

Wyniki wyszukiwania

Changes in the composition of aroma and phenolic compounds induced by different enological practices of Croatian white wine

Microwave-assisted extraction of different groups of phenolic compounds from grape skin pomaces: modeling and optimization