Abstract
An automated procedure for photometric titration of red wine and associated instrumentation is described. The procedure was based on the flow-batch approach implemented employing multicommutation. The photometric detection was carried out using a homemade LED-based photometer. The mixing device, LED, and photodetector were attached to the titration chamber in order to form a compact and small-sized unit. The flow system comprised an automatic injector and three-way solenoid valves, which were controlled by a microcomputer through an electronic interface card. The software, written in Quick BASIC 4.5, was designed with abilities to accomplish all steps of the titration procedure including data acquisition and real-time processing to decide about the course of titration in the following step and so forth, until the titration endpoint was reached. The usefulness of the proposed titration system was demonstrated by analyzing red wine samples. When results were compared with those obtained using the AOAC reference method, no significant difference was observed at the confidence level. A relative standard deviation of ca () was obtained when processing a typical red wine sample containing 7.3 total acidity expressed as tartaric acid.
Highlights
The acids present in wines are formed during the fermentation process and tartaric acid is the major constituent [1]
This condition was not required when using the multicommuted process in the flow system [20,21,22], allowing true titration to be implemented for the first time [23, 24], which was done by exploiting a binary search strategy
This effect was probably due to the red wines, because the assays were carried out using different wine samples with similar profiles
Summary
The acids present in wines are formed during the fermentation process and tartaric acid is the major constituent [1]. Studies involving speciation model [8], astringency properties [9], and vineyard irrigation [10] have been elected as relevant parameters for total wine acidy In this sense, the availability of a reliable procedure for acidity determination is mandatory. The strategies adopted allowed titration endpoint detection; acidity quantification was dependent on an analytical curve, which was derived from measurements obtained by processing a set of standard solutions This condition was not required when using the multicommuted process in the flow system [20,21,22], allowing true titration to be implemented for the first time [23, 24], which was done by exploiting a binary search strategy. The strategy to find the titration endpoint was based on Fibonacci’s method, which was implemented by means of multicommutation process
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