The role of buffering capacity in identification of wine dilution with water

Abstract

Studies of recent years demonstrate that introduction of water into
must or wine upsets the balance of ions, changes the values of physico-chemical, organoleptic and integral indicators. one of the most
important indicators to establish the addition of water is the buffering
capacity of wine (BC). Buffering capacity of wine is its ability to resist
changes in pH after addition of a strong acid or base. acid strength
is characterized by dissociation constant. its negative pKa logarithm
means pH value at which the non-dissociated and dissociated by stage
i acid forms ratio is 1: 1. We have modified the method for buffer capacity determination based on acidimetric and alkalimetric wine titration
results, which can be used to assess organic acids dissociation degree,
the ratio between their molecular and ionized forms, the state of metal
ions, the ability to control the chemical oxidation reactions and recovery rate. in our work we used genuine dry white and red base wines
obtained in conditions of micro-winemaking and production during the
wine-making seasons of 2017–2018 from grapevine cultivars ‘aligote’,
‘Chardonnay’, ‘Sauvignon verde’, ‘Kokur Belyi’, ‘Cabernet Sauvignon’,
‘Merlot’, ‘Sangiovese’. to study the effect of base wines dilution with
tap water, it was added in the amount of 10-70%. the sample size
made 131 samples. dilution of wine with water is the mixing of two
systems, one of which (wine) is a solution containing organic acids and
their acid salts, possessing a pH and buffering capacity. Water contains
hardness salts that determine its pH, but does not possess buffering
capacity comparable in quantity to that found in wine products. Certain
characteristics of wine-water mixture were studied: the ratio between
the acidic and alkaline components of the buffering capacity at which
the buffering properties of the system change their nat u re, which
corresponds to 70% dilution; mathematical models of the process of
water introduction into wine were described, allowing to determine
the values at any point of dilution, including the control. the entire
sample systematization allowed dividing samples into two clusters,
determining genuine and diluted wines by buffering property index
(PBi); the system buffering property values for genuine (50-80) and
diluted (80-100) wines were established.