Sulphite-free organic additives to be used in winemaking process

Sulphites are extensively used as additives in many foodstuffs including wines, beer, cider, fruit juices, dried fruits, biscuits and vegetables. Currently all the wine produced in the world involves the use of sulphur dioxide and/or sodium, potassium salts of hydrogen-sulphite in various stage of winemaking process for their technological efficacy (antioxidant power, antimicrobial agents, enzyme inhibitors, control of enzymatic and non-enzymatic browning reactions, pro-fermentative and colour-stabilising effect). Sulphite additives were also implicated as the major cause of wine induced severe asthma attacks and anaphylactic reactions and presented some cytossic, mutagenic and antinutritional effects: for these reasons winemakers and researches are trying to obtain an added-sulphites free wines by using modern wine making techniques (hyperoxigenation, flotation and tangential microfiltration). Nowadays neither validated methodology has been developed. The final object of this research work was to develop a natural additive able to mimic the SO2 effects and to preserve the typical organoleptic characteristics of white and red wines. Qualitative and quantitative composition of the new formulation (organic acids, flavonoids, catechins, and oligomeric proanthocyanidins) was defined on the basis of microbiological, chemical, biochemical, sensory and toxicological data by using an innovative analytical approach based on the “Experimental Design”, a methodology allowing to minimize the number of experiments and maximise the resources. The effectiveness of the designed mixture was tested “on field” in real vinification process of several variety of white and red grapes. Polyphenols, tannins, procyanidins and other components and their influence on wine stability was assayed by conventional tests as well as advanced instrumental techniques (HPLC e HPLC-MS). The odorous compounds were analyzed by the analytical approach of solid phase micro-extraction (SPME) and headspace GC MS. All field tests showed a success in the use of this formulation to preserve wine avoiding oxidation and microbial spoilage. Also sensory analysis did not show defects and/or alterations in experimental wines.