title: Solid phase microextraction as a reliable alternative to conventional extraction techniques to evaluate the pattern of hydrolytically released components in Vitis vinifera L. grapes.
abstract: In present research, headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-qMS), was evaluated as a reliable and improved alternative to the commonly used liquid-liquid extraction (LLE) technique for the establishment of the pattern of hydrolytically released components of 7 Vitis vinifera L. grape varieties, commonly used to produce the world-famous Madeira wine. Since there is no data available on their glycosidic fractions, at a first step, two hydrolyse procedures, acid and enzymatic, were carried out using Boal grapes as matrix. Several parameters susceptible of influencing the hydrolytic process were studied. The best results, expressed as GC peak area, number of identified components and reproducibility, were obtained using ProZym M with b-glucosidase activity at 35°C for 42h. For the extraction of hydrolytically released components, HS-SPME technique was evaluated as a reliable and improved alternative to the conventional extraction technique, LLE (ethyl acetate). HS-SPME using DVB/CAR/PDMS as coating fiber displayed an extraction capacity two fold higher than LLE (ethyl acetate). The hydrolyzed fraction was mainly characterized by the occurrence of aliphatic and aromatic alcohols, followed by acids, esters, carbonyl compounds, terpenoids, and volatile phenols. Concerning to terpenoids its contribution to the total hydrolyzed fraction is highest for Malvasia Cândida (23%) and Malvasia Roxa (13%), and their presence according previous studies, even at low concentration, is important from a sensorial point of view (can impart floral notes to the wines), due to their low odor threshold (μg/L). According to the obtained data by principal component analysis (PCA), the sensorial properties of Madeira wines produced by Malvasia Cândida and Malvasia Roxa could be improved by hydrolysis procedure, since their hydrolyzed fraction is mainly characterized by terpenoids (e.g. linalool, geraniol) which are responsible for floral notes. Bual and Sercial grapes are characterized by aromatic alcohols (e.g. benzyl alcohol, 2-phenylethyl alcohol), so an improvement in sensorial characteristics (citrus, sweet and floral odors) of the corresponding wines, as result of hydrolytic process, is expected.
authors: CQM/UMa - Centro de Química da Madeira, Centro de Ciências Exactas e da Engenharia da Universidade da Madeira, Campus Universitário da Penteada, 9000-390 Funchal, Portugal.
authors: Rosa
authors: R
authors: Perestrelo
authors: Michael
authors: M
authors: Caldeira
authors: José S
authors: JS
authors: Câmara
mesh_terms: D000085:Acetates / Q000737:chemistry; D000438:Alcohols / Q000032:analysis; D004952:Esters / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry; D006868:Hydrolysis; D059625:Liquid-Liquid Extraction; D009812:Odorants / Q000032:analysis; D015203:Reproducibility of Results; D052617:Solid Phase Microextraction / Q000379:methods*; D013696:Temperature; D013729:Terpenes / Q000032:analysis; D027843:Vitis / Q000737:chemistry*; D055549:Volatile Organic Compounds / Q000032:analysis; D001617:beta-Glucosidase / Q000737:chemistry
chemical_list: D000085:Acetates; D000438:Alcohols; D004952:Esters; D013729:Terpenes; D055549:Volatile Organic Compounds; C007650:ethyl acetate; D001617:beta-Glucosidase