Natural coadjuvant for the alternative to sulphur dioxide for red and white wine making process

紅葡萄酒和白葡萄酒的制作過程中二氧化硫自然輔助劑的的替代品研究

Introduction 引言

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).

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涉及使用二氧化硫和/或亞硫酸氫鈉，鉀鹽他們的技術效率，抗氧化能力，抗菌劑，酶抑制劑，酶和非酶褐變反應，有利于發(fā)酵的控制和葡萄酒釀造過程中的不同階段顏色穩(wěn)定化效果。

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  (hyperoxigenation, flotation and tangential microfiltration). Nowadays neither validated
methodology has been developed. The object of this work was to develop a natural coadjuvant able to mimic the SO2 effects and to preserve the typical organoleptic
characteristics of white and red wines.

Qualitative and quantitative composition of the ALIWINE formulation (organic acids,flavonoids, catechins, and oligomeric proanthocyanidins) was defined on the basis of
microbiological, chemical, biochemical, sensory and toxicological data by using annnovative analytical approach based on the “Experimental Design”, a methodology
allowing to minimize the number of experiments and maximise the resources. The
ffectiveness 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
tability 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. The winemaking process includes multiple stages at which microbial spoilage can
occur, altering the quality and hygienic status of the wine and rendering it unacceptable

The faults caused include bitterness and off-flavours (mousiness, ester taint, phenolic vinegary, buttery, geranium tone), and cosmetic problems such as turbidity, viscosity, sediment and film formation. These spoilage organisms can also affect the wholesomeness#p#分頁標題#e#
of wine by producing biogenic amines and precursors of ethyl carbamate.

The judicious use of chemical preservatives, mainly sulphur dioxide during the winemaking process decreases the risk of microbial spoilage. Currently, the forms employed include
sulfur dioxide gas, and the sodium and potassium salts of sulfide, bisulfite or metabisulfite. In aqueous solution sulfur dioxide and sulfite salts form sulfurous acid, and
ions of bisulfite and sulfite (2).

SO2 +H2O =H2SO3

2H2SO3 = H+, HSO3- +2H+, SO32-

The relative proportion of each form depends on the pH of the solution, and at pH 4,5 or lower the HSO3- ion and undissociated sulfurous acid predominate. It has been shown
that sulfur dioxide  is most effective as an antimicrobial agent in acid media, and this effect is believed to result from undissociated sulfurous acid, which is the dominant from below
pH 3,0.

The enhanced antimicrobial effect of sulfur dioxide at low pH values may result because undissociated sulfurous acid can more easily penetrate the cell wall. Sulfurous acid
inhibits yeasts, molds, and bacteria, but not always to the same degree. This is particularly true at high pH values, where it has been suggested that the HSO3- ion is
effective against bacteria but not against yeasts.

Postulated mechanisms by which sulfurous acid inhibits microorganisms include the reaction of bisulfite with acetaldehyde in the cell, the reduction of essential disulfide
linkages in enzymes, and the formation of bisulfite addition compounds that interfere with respiratory reactions involving nicotinamide dinucleotide. Of the known inhibitors of non-
enzymatic browning in wine, sulfur dioxide is probably the most effective.

The chemical mechanism by which sulfur dioxide inhibits nonenzymatic browning is not fully understood, but it probably involves bisulfite interactions with active carbonyl groups.

Bisulfite combines reversibly with reducing sugars and aldehydic intermediates, and more strongly with a-dicarbonyls and a,b-unsaturated aldheydes.

These bisulfite addition products appear to retard the browning process, which when coupled with the bleaching action of sulfur dioxide on pigments, results in effective
inhibition of non-enzymatic browning; Sulfur dioxide also inhibits certain enzyme-catalyzed reactions, notably enzymic browning. Sulfur dioxide also inhibits certain enzyme-catalyzed
reactions, notably enzymic browing; the production of brown pigments by enzyme- catalyzed oxidation of phenolic compounds can lead to a serious quality problem in
winemaking.

Sulfur dioxide also functions as an antioxidant in wine and beer, avoiding the#p#分頁標題#e#
developments of oxidized flavours during storage. Also, sulfur dioxide in combination with buffering agents is applied to prevent browning and to induce oxidative bleaching of nathocyanin pigments: the resulting properties are desired in products, such as those used to make white wines and maraschino cherries.

Sulfur dioxide and sulfites are metabolized to sulphate and are excreted in the urine without any obvious pathological results. However, the safety-related aspects of sulfur
dioxide and its derivatives are undergoing extensive reviews because of reports of severe reactions in some asthmatics upon consumption of wine, and also because of potential
mutagenicity.

For these reasons, there is mounting consumer bias against chemical preservatives and the subsequent request of use of natural preservatives in complying with the consumers’
demand for “clean and green” products.

All food additives must have a demonstrated useful purpose and undergo a rigorous scientific safety evaluation before they can be approved for use: the aim of this work was
the study the molecular and functional characteristics of natural additives and the definition of the strategies for employing these compounds in the technological process of winemaking.

The natural vegetable products for wine processing should be able to mimic the effect of the SO2 in white wine making process, thus guaranteeing the antioxidant and antibacterial action.

The use of such products could decrease the amount of added sulphites during vinification and to obtain, as final result, a concentration of volatile sulphites lower than 10 ppm in
white wines. Both critical chemical and biochemical parameters of new formulation and experimental wines were assayed by conventional tests as well as analytical methods
based on high resolution chromatographic techniques in combination with structural analysis by mass spectrometry (GCMS, HPLC e HPLC-MS).

Classic oenological measurements

Classic parameters of wines were determined according to the international methods of the OIV (International Organization of Vine and Wine. 2005). All analyses were performed in
triplicate.

Total polyphenol concentration was determined w ith the FolinCiocalteu assay. witi) the microscale protocol previously reported (Arnous et al.. 2001). Total flavanol (F)
concentration was' measured with the vanillin assay employing the optimized protocol of Sun et al. (1998). adapted on a microscale.

Experimental activities and Results

The natural coadjuvant ALIWINE used for experimental activities consist essentially of SFE OPCs, Oligomeric Proanthocyanidin Complexes (ADD 1,2,3,4) from vitis vinifera seeds#p#分頁標題#e# composed by mixtures of organic acids, tannins, pectines, etc. used as stabilizer for the winemaking process with high antioxidant and antibacterial power. These products can
replace the traditional chemical treatments, thus enabling the improvement of organoleptic characteristics and the preservation of wine. Supercritical fluid extraction (SFE) and
supercritical fluid chromatography have been used in the chemical arts for many years; gases such as carbon dioxide or propane have proven to have excellent solvating properties
when pressurized, particularly above their critical point.

This so-called supercritical region occurs when a gas is pressurized to a point where it ould normally be liquid. At the same time it is heated above the boiling point, reduced by

the new condition of the solution, to prevent condensation; this "supercritical fluid" is neither a liquid nor a gas, but exhibits properties of both; in particular, supercritical fluids
possess excellent solvating properties with high selectivity for particular analytes.

This selectivity can be further adjusted by variations of pressure and temperature. When a gas is under a great amount of pressure, it changes state in order to become a liquid.
Above a certain pressure (the critical pressure) and temperature (the critical temperature), however, a gas may be pressurized further without condensation.