Determination of Alcohol and Total Dry Extract in Slovenian Wines by Empirical Relations

Abstract

The possibility of fast determination of alcohol and total dry extract from given relative density and refractive index in wine was examined on fifty eight samples of Slovenian white and red still wines. Calculated relation values obtained from literature were compared to values determined experimentally using official methods (pycnometry and hydrostatic balance). Determination of alcohol and total dry extract together by means of calculation was the most accurate for the group of white wines (according to the concentration of reducing sugars) with up to 5 g L–1 and the least accurate for the group of white wines with over 15 g L–1. For alcohol calculation the standard deviations and coefficients of variation for literature and our relations were different (literature relations: SD = 7.37–8.53, CV = 8.33–9.52 %, our relations: SD = 7.18–13.94, CV = 7.96–16.55 %) and they were higher for the total dry extract (literature relations: SD = 16.39 16.76, CV = 45.14–49.49 %; our relations: SD = 13.70–16.73, CV = 42.68–49.16 %). The most accurate relations for separate groups of wines (white wines with different reducing sugars content or red wines) have already been published (2–6). Our own relations for calculation of alcohol level and total dry extract were obtained by means of multiple linear regression analysis. The experiment has shown that none of the results are accurate enough to be obtained using only one relation for different wines.

Keywords

• wine
• alcohol
• total dry extract
• official method
• rapid method
• empirical relations