Ivana Tomaz

Recovery of Flavonoids from Grape Skins by Enzyme- Assisted Extraction

Abstract Grape skin contains large amounts of different flavonoids so it can be used for their recovery. Optimization of enzyme-assisted extraction of flavonoids was conducted using oenological enzyme preparations with respect to enzyme dosage, temperature, extraction time, pH, and enzyme preparation. Optimal conditions were obtained using enzyme preparation Lallzyme EX-V, at the temperature of 45°C, time of 3 h, pH 2.0, and enzyme dosage of 10.52 mg/g. The new optimized extraction method is less expensive, simple, accurate, and selective for the recovery of simple flavonoids. It is based on an environmentally-friendly extraction solvent which may provide a valuable alternative to conventional methods.

Determination of 2-aminoacetophenone in white wines using ultrasound assisted SPME coupled with GC-MS

The unpleasant odor of an off-flavor is mostly caused by only one or, sometimes, several volatile compounds with very low odor threshold values giving the typical unpleasant odor taint of the spoiled food product. 2-Aminoacetophenone is an aroma compound which causes the untypical aging off-flavor in Vitis vinifera white wines. Ultrasound assisted headspace solid phase microextraction (UA-HS-SPME) and direct immersion solid phase microextraction (DI-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) were tested and optimized for determination of 2-aminoacetophenone in Riesling wines fermented by different yeast strains.

Multi-response optimisation of ultrasound-assisted extraction for recovery of flavonoids from red grape skins using response surface methodology

INTRODUCTION For the characterisation of grape cultivars, the profile and content of flavonoids are important because these compounds impact grape and wine quality. To determine the correct profile and content of flavonoids, the use of robust, sensitive and reliable methods is necessary. OBJECTIVE The object of this research is to develop a new ultrasound-assisted extraction (UAE) method for the recovery of flavonoids from grape skins using response surface methodology. METHOD Optimisation of UAE was performed using a complementary study combining a Box-Behnken experimental design with qualitative analysis by high-performance liquid chromatography. RESULTS Optimal extraction conditions were obtained using the extraction solvent composed of acetonitrile:water:formic acid (26:73:1, v/v/v) at an extraction temperature of 50 °C, an extraction time of 15 min in a single-extraction step and with a solid-to-solvent ratio of 1:80 g/mL. The calculated relative standard deviations for the optimal extraction method were very low, measuring less than 5%. CONCLUSIONS This study demonstrates that numerous factors have strong effects on the extraction efficiency, including the type of organic modifier and its percentage in the extraction solvent, the number of extraction steps, the solid-to-solvent ratio, the extraction time and temperature and, finally, the particular nature of analyte and their position within the grape skin cell.

Influence of Different Yeast Strains on Metabolism of Tryptophan and Indole-3-Acetic Acid During Fermentation

The effect of supplementation of Riesling (Vitis vinifera L.) must with ammonium sulphate (AS) on tryptophan (Trp) and indole-3-acetic acid (IAA) metabolism during alcoholic fermentation with four commercial yeast strains (Uvaferm CEG, Lalvin Cross Evolution, Anchor VIN 13 and Anchor exotic SPH) were examined. AS addition reduced Trp uptake by yeasts from 1% to 15%. Wines produced by Anchor VIN 13 and Uvaferm CEG yeasts with AS addition had the highest concentrations of Trp (0.60 and 0.59 mg/L respectively). Concentrations of total and bound IAA decreased during all treatments. At the end of fermentation the highest concentration of free IAA was measured in the control must inoculated with Anchor VIN 13 yeast (35.83 μg/L) and the lowest in the sample inoculated with Uvaferm CEG yeast (13.08 μg/L). Anchor VIN 13 yeast showed the strongest change in metabolism due to AS addition during fermentation. 2-Aminoacetophenone (2-AAP) formation was not observed in all the studied wines.

Polyphenolic Composition of the Berry Skin of Six Fungus-Resistant Red Grapevine Varieties

Phenolic compound profiles were investigated by high-performance liquid chromatography-diode array detector in three vintages to assess genotypic variation in berry skins of six resistant grapevine varieties: “Cabernet Cortis,” “Chancellor,” “Léon Millot,” “Maréchal Foch,” “Monarch,” and “Regent.” The research has revealed a significant difference among the varieties in the total phenolic content, anthocyanins, flavanols, and flavan-3-ols. A clear differentiation of all varieties by means of the polyphenol profile using discriminant analyses has been achieved. “Regent” reached the significantly highest total polyphenol content, as well as total anthocyanin and total flavonol content. The polyphenol profile of “Chancellor” was quite different from all of the other studied varieties. Although being closely related, “Maréchal Foch” and “Léon Millot” showed qualitatively and quantitatively quite different polyphenol contents. No clear connection between the genetic origin of the varieties and their polyphenol profiles has been found.

Extraction Methods of Polyphenol From Grapes: Extractions of Grape Polyphenols

Abstract The grape is one of the most important horticulture crops in the world and a reliable source of polyphenolic compounds. Nowadays, there are many papers concerning the analysis and especially the extraction of polyphenolic compounds from various parts of the grape berry. Numerous extraction techniques are applied for the recovery of polyphenolic compounds from grape berries including solid-liquid extraction, ultrasound-assisted extraction, microwave-assisted extraction, enzyme-assisted extraction, etc. For all of these techniques, there are numerous published methods, but there is no standardized one. Thus, the aim of this chapter is to unify the known data concerning the extraction methods for the recovery of polyphenols from grapes.

Influence of Pectolytic Enzymes and Selected Yeast Strains on the Chemical Composition of Blackberry Wines

Abstract The aim of this study was to determine concentrations of individual o rganic acids, polyphenolic and aromatic compounds in blackberry wine, and to define the influence of different yeast strains (Uvaferm BDX and Lalvin 71B) and pectolytic enzymes (L allzyme OE and Lallzyme EX-V) on the chemical composition and quality of the wine. Blackberry wines were produced in five variants, depending on yeasts and enzymes used: BDX OE, BDX EX-V, 71B OE, 71B EX-V, and Control without the addition of selected yeasts and enzymes. All blackberry wine variants were defined by a relatively high sum of organic acids. The citric acid was the predominant one, which concentrations ranged from 5.42 to 7.31 g/L. The concentration of gallic acid ranged from 19 to 37 mg/L and was in dependence of the yeast strain used. The concentration of procyanidin B2 which was the predominant flavan-3-ol compound, ranged from 103 to 117 mg/L, and there were no significant differences between individual wine variants in the experiment. Rutin is the predominant compound in the flavonol group, followed by quercetin-3-O-glucoside. The predominant one among the anthocyanins was cyanidin-3-O-glucoside whose concentrations ranged from 134 to 229 mg/L. According to the obtained results, the yeast strain and pectolytic enzymes had a significant impact on the concentration of individual anthocyanins in the analyzed wines. The predominant group of aromatic compounds was monoterpenes, among which linalool was the most prominent in all of blackberry wine variants, except in Control.