In the same year, the following variables were determined: density, alcohol, titratable acidity, volatile acidity, fixed acidity, pH, dry extract, reducing sugars, reduced dry extract, alcohol in weight/reduced dry extract, ashes, alkalinity of ashes, absorbance--420 nm (I 420) and 520 nm (I 520)--, color intensity (I 420 + I 520), hue (I 420/I 520), anthocyanins, tannins, total polyphenols index, volatile compounds--ethyl acetate, methanol, 1-propanol, 2-methyl-1-propanol, 2-methyl-1-butanol + 3-methyl-1-butanol and sum of higher alcohols.
In fact, high contents of amyl alcohols (2-methyl-1-butanol and 3-methyl-1-butanol) can be responsible for the vegetal or herbaceous character of wines.
The straight-chain higher alcohols are considered to have the most significant sensorial impact (1-propanol, 2-methyl-1-propanol (isobutyl alcohol), 2-methyl-1-butanol
and 3-methyl-1-butanol (isoamyl alcohol).
Identification and quantification was based on external calibration with standard solutions of acetaldehyde, 2-pentanone, 2-butanone, ethylacetate (Fluka, Buchs SG, Switzerland); ethanol (Arcus, Oslo, Norway); 2-methyl-1-propanol, 2-methyl-1-butanol, 2-methyl-1-butanal, 3-methyl-1-butanol, 2-methyl-1-butanol, 2-methyl-1-propanol, 3-methyl-1-butanal, 3-methyl-1-butanol, 2-methyl-1-butanol, 2-methyl-1-propanal, diacetyl, 2-propanol, 1- butanol, 2-butanol, acetoin, iso-butylacetate, acetone, 2,3-pentanedione, ethylacetate, acetone, isobutyl acetate and ethyl butyrate (Merck KGaA, Darmstadt, Germany).
The alcohols identified in Obushera, in order of decreasing quantity, included: ethanol, 3-methyl-1-butanol, 2-methyl-1-propanol and 2-methyl-1-butanol (Table 5).
The higher alcohols exceeded reported odour threshold values after 2 days of fermentation: 2-methyl-1-propanol (5.25 mg [kg.sup.-1]), 2-methyl-1-butanol (5.50 mg [kg.sup.-1]) and 3-methyl-1-butanol (4.75 mg [kg.sup.-1]) .
Fusel oil usually includes n-propanol, 2-methyl-1-propanol, 2-methyl-1-butanol and 3-methyl-1-butanol in various concentrations.
1979) that a 5% concentration of Carbowax 20M gives the optimum resolution of methanol, ethanol, n-propanol, 2-methyl-1-propanol, 2-methyl-1-butanol and 3-methyl-1-butanol.
The six peaks correspond to methanol, ethanol, 1-propanol, 2-methyl-1-propanol, 2-methyl-1-butanol and 3-methyl-1-butanol.