Abstract
Utilizing an ultrasonic instrument known as the Solution Analyzer, a method was developed for the direct and simultaneous determination of alcohol and extract content of wines. No alcohol distillation is necessary. An indirect sound-velocity measurement, triggering frequency, is obtained through a wine sample at 30 and 65° C. From the triggering frequency values, alcohol content and extract, expressed as Brix°, may be obtained by direct read-out on the instrument panel, or in a simpler model with the aid of a nomograph. For calibration, alcohol analyses were made by the AOAC immersion refractometer method (at 24.0±0.02°C), and Brix analysis were made on the dealcoholized wine with a Brix hydrometer. Multiple regression analyses correlated known alcohol and Brix values with triggering frequencies obtained at each temperature. Separate pairs of equations, expressing these relationships, were required for wines in the ranges of 11-15% and 16-21% alcohol. A comparison of Solution Analyzer results with known analytical values from 23 different types of commercial wines showed an average difference of zero and a standard deviation of differences of ±0.05% alcohol and ±0.09° Brix. Total average test time per sample was 5 min. Determinations were simple, rapid, accurate, and reproducible.
- Accepted January 1970.
- Published online January 1970
- Copyright 1970 by the American Society for Enology and Viticulture
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