In botrytized wines

Various grape-picking strategies and techniques are applied in botrytized wine making. Regardless, a prolonged or late harvest is necessary a factor which implies risk of losing the crop to bunch rot, other infections or frost under adverse weather conditions. 

In addition to GC-MS, recent studies have focused on the identification and quantitative analysis of impact odorants in botrytized wines using gas chromatography-olfactometry (GC-O) analysis. Sarrazin et al. (2007a) investigated numerous botrytized and nonbotry-tized Sautemes wines. They could identify several key odorants that were responsible for the sensory differences between the wines, notably 3-mercaptohexan-l-ol, various furanons, ethyl-hexanoate, methional, phenylethanol, phenylacetaldehyde, sotolon, p-damascenone, and 2-methyl-3-furanthiol. 

Cessation of fermentation is one of the technical problems in botrytized wine production that needs further research and development. Dimethyldicarbonate (DMDC) is now considered a reliable inhibitor which could replace some of the S02. Although DMDC has proven suited for treating wines especially just before bottling, its use in Sautemes production has been investigated (Divol et al., 2005). The results showed that DMDC at a rate of 100-200 mg/1 stopped fermentation but did not replace the antioxidant functions of SO2. Sulfite addition was necessary to limit wine oxidation and yeast reactivation. 

TABLE 6.9 Occurrence of some biogenic amines in botrytized wines, in comparison with nonbotrytized wines... 

Kiss, J. and Sass-Kiss, A. (2005) Protection of originality of Tokaji Aszu Amines and organic acids in botrytized wines by high performance liquid chromatography, /. Agric. Food Chem., 53, 10042-10050. 

The main difference between botrytized wines and other nonfortified sweet wines, for example, late-harvest wines, icewines (eiswein), or straw wines, is the extreme range and richness of the aroma compounds produced by Botrytis. Marked differences also exist in some other components (e.g., glycerol, acid composition), due to the microbial activity. According to the descriptors most often applied to these wines, they are characterized by peach, apricot, pear, quince, raisin, and honey flavors, combined with distinctive "botrytis or roti aspects. Another typical feature of botrytized wines is their high acid contents. These prevent them from appearing cloying, even if the sugar content is commonly over 200 g/1. 

Beside these basic characteristics, the various types of botrytized wines may possess marked differences in style, depending on the grape... 

Botrytized wines have been made for a very long time in Europe, and also are produced in increasing amounts in Australia, New Zealand and South Africa. Although only a few types of botrytized wines are regularly produced, their occasional production is possible in many regions, depending on the weather conditions. 

Numerous y- and 8-lactones were identified in Tokaji aszu grapes (Miklosy and Kerenyi, 2004 Miklosy et al., 2004). The odor notes of the y-lactones were described as resin- and caramel-like, roasted, or honey, while the 8-lactones exhibited characteristic notes of coconut, chocolate, and peach. The same lactones had been identified earlier from botrytized wines but not from normal wines (Schreier et al., 1976). Lactones are mostly found in oxidatively aged wines but seem to develop in fruit due to the oxidizing effect of B. cinerea, water loss, or Maillard reactions (Miklosy et al., 2004). 

Due to the particular raw material, making botrytized wines is major challenge for winemakers. In addition to the uncertain nature of noble rot development, low grape and juice yield, technological difficulties, and the high risk of spoilage, make producing these wines one of the world s most expensive. 

The less labor intensive, but still expensive, harvest method involves waiting for as long as possible, and then picking the botrytized and healthy grapes together as whole bunches. This method is used all over the world in the making new-style botrytized wines. 

These results suggest that non-Saccharomyces species may contribute significantly to the fermentation of botrytized wines. C. zemplinina seems not to produce excess volatile compounds nor any specific aroma compounds (Toth-Markus et al., 2002). Its main contribution to the chemical composition might be an increase in glycerol content and in the G F ratio. C. zemplinina and C. stellata have proven to be very fructo-philic yeasts (Mills et al., 2002 Magyar and Toth, 2011 Magyar et al., 2008). 

With a few exceptions (Nisiotou et al., 2007), Saccharomyces strains dominate fermentation sooner or later, as in nonbotrytized wine. A special feature of botrytized fermentations is that, beside various S. cerevisiae races, S. uvarum (formerly known as S. bayanus var. uvarum) is typically isolated from these wines (Antunovics et al., 2003 Magyar et al., 2008 Minarik and Laho, 1962 Naumov et al., 2000, 2002 Sipiczki et al., 2001 Tosi et al., 2009). This species seems to be well adapted to sweet wine fermentations, particularly, but not exclusively, in cooler climates. 

The use of selected yeast starters for botrytized wine fermentation is strongly encouraged in Germany (Dittrich, 1977 Hoersch and Schlotter, 1990), in Sauternes (Dubourdieu, 1999 Ribereau-Gayon et ah, 2000), and is typical in the newer botrytized wines produced in Australia, and South... 

The unique chemical composition of botrytized must greatly impacts the products and by-products of alcoholic fermentation, as well as subsequent reactions. The changes have been extensively studied by German and French authors and have been reviewed by Dittrich (1977, 1989), Jackson (2008), Ribereau-Gayon et al. (2000), and Dittrich and Grossmann (2011). The chemical composition of some traditional (German and Hungarian) botrytized wine styles are illustrated in Table 6.5. 

The aroma of botrytized wines has been studied more extensively than that of the grapes. Mashuda et ah (1984) identified the lactone sotolon (4,5-dimethyl-3-hydroxy-2,(5)-furanone) as a principal compound in a botrytized aroma. Sotolon is also a key aroma compound in flor wines, for example, vin jaune, sherry (Dubois et ah, 1976 Martin and Etievant, 1991 Moreno et ah, 2005). However, Sponholz and Hiihn (1993) found no correlation between the degree of Botrytis infection and sotolon... 

The main aroma compounds identified as specific botrytized odorants are indicated in Table 6.6. It seems that while the terpene content decreases, numerous hydroxy-, oxo-, and dicarboxylic acid esters, acetals, and lactones form, all typically in lower concentrations or absent in normal wines (Miklosy and Kerenyi, 2004 Miklosy et al., 2000, 2004 Schreier et al, 1976). 

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