METHOD FOR PRODUCING TARTARIC ACID AND A CONCENTRATE OF GRAPE PIGMENTS

Abstract: The disclosure pertains to a process for the production of tartaric acid and a grape anthocyanin pigment concentrate from winery by-products. This procedure is characterised by the removal of pigments present in the by-products through its adsorption onto an adequate polymeric adsorbent resin, before the production of the tartaric acid. Later, the tartaric acid is produced from potassium bitartrate by an ion exchange process using a gel type strong cation resin, especially developed for food applications, contained in a fixed bed. The present method also concerns the recycling of the used cation exchange regenerant solution and the ethanol used as regenerant for the adsorbent resin. As a result of this operation, it is possible to reduce substantially the quantity of effluents to be rejected from the system, increase the recovery of tartaric acid and the extraction of the anthocyanic pigments. Additionally, an exemplification of this method is presented schematically in figure 3.

Description: Description METHOD FOR PRODUCING TARTARIC ACID AND A CONCENTRATE OF GRAPE PIGMENTS The present invention describes a process for the production of tartaric acid and a concentrate of grape anthocyanin pigments, from winery by-products, by means of an operation of selective adsoφtion of the pigments onto a polymeric adsorbent resin and the use of an ion exchange process using a strong cation resin, contained in a fixed bed, to produce the tartaric acid. Although in the literature there is a description of some methods for the chemical synthesis of the tartaric acid (for example, R. J. Bosch and S. H. Ramsey in the Patent N° the 5.087.746 - USA (1992)), no industrial use for such procedures has been found due to the considerable availability of the traditional raw materials, namely, the by-products of wine making. Currently, tartaric acid can be produced from one or more of the following byproducts: 1 ) the wine lees, which are the slimy sediments at the bottom of the fermentation vats; 2) the press-filter cakes, which are the result of the filtration of the wine; 3) the diluted wine produced by the leaching of the grape pomace; 4) the crystalline crusts that form in the vats either during the secondary fermentation period or during storage before bottling. Traditionally, however, tartaric acid is produced industrially from only two sources, the wine lees and press-filter cakes, in a process involving two main steps: 1) the formation of the calcium tartrate from the potassium bitartrate through the use of diverse calcium compounds (Ca(OH) 2 , CaC0 3 , CaCl 2 , etc.) 2 KHQHΛ + Ca(OH) 2 + CaS0 4 - 2 + K 2 S0 4 + 2 H 2 0 2) the formation of the tartaric acid from a chemical reaction between the calcium tartrate and an aqueous solution of sulphuric acid CaC 4 H4θ 6 + H 2 S0 4 H 2 C 4 H4θ 6 + CaS Q 4 The tartaric acid thus produced is used as an acidifying agent in drinks (it is the only additive allowed in Europe for the correction of acidity in wines), grape juice, confectionery, jams and various industrialised food products. The traditional process presents, however, two disadvantages. The first, is due to the need of a great excess of the calcium compounds in order to ensure a good recovery of the calcium tartrate, the which generates high volumes of the solution in the final steps of the production of the tartaric acid. This would require an industrial plant calling for the type of financial investment that would not be justifiable unless the availability of winery by-products in the region were to be above one hundred thousand tons per year. Secondly, this process produces acidic effluents, besides other contaminants (namely, sulphates), that have been targeted for reduction with regard to the limits set within the European Union. In another process already described (Balazs in International Patent N° 9.712.028 - WO (1997)) tartaric acid and fodder yeast are produced by passing an aqueous suspension of wine sediments through a column containing a fluidised bed of an industrial grade cation exchange resin. Although this type of process of adsoφtion is very attractive from an economic point of view, it did not present any solution for the problem of the contaminated effluents (in this in case, the contaminants exist in the solution used for the regeneration of the resin). In relation to this procedure, there is also the question of the introduction of insoluble materials into the resin bed, which increases the complexity of the control of the column feed and makes the use of much more sophisticated and expensive equipment necessary. The presence of these solids, mainly grape skins and seeds, also requires more frequent and complicated resin cleanups. In addition to this technical problem, there is still the question of the anthocyanic pigment presence in the suspension where the extraction of the tartaric acid is suggested. If on one hand, the strong cation resins quickly adsorb these pigments, on the other it is impossible to remove them by using a practical volume of the regenerant solutions recommended by the manufacturers (HC1 - 50 to 150 g L or H 2 S0 4 - 50 to 250 g L). As a matter of fact, the contact of cation exchange resins with solutions containing pigments of this type causes a gradual reduction in the exchange capacity of the resin, requiring the use of greater excess of resin in each operation cycle. To overcome this problem, it would be necessary to use a much more concentrated regenerant solution, with a consequent decrease in the useful life of the resin. The present invention describes a method to produce tartaric acid from winery byproducts such as the wine lees, the press-filter cakes from wine filtration and the precipitate produced after the cooling of the leaching solution of the grape pomace, through the use of an ion exchange process with a gel type strong cation resin (hydrogen form) such as, for example, Amberlite SR1L (Rohm & Haas Co.), contained in a fixed bed, after the removal of anthocyanic pigments through two adsoφtion operations, using an adequate polymeric adsorbent resin as, for example, Duolite XAD761 (Rohm & Haas Co.). Both the cited resins were especially developed for food applications, and totally satisfy the requirements of the Council of Europe Resolution AP(89)2 and the FDA 21 CFR 173.25 (a) of the USA. Unlike the industrial exchange resins that can contain significant amounts of both organic (unpolymerised resin monomers and dispersion agents) and inorganic (in order to inhibit microbial growth, the resins beads are frequently saturated with NaCl and Na 2 C0 3 ) impurities, both the Amberlite SR1L and the Duolite XAD761 do not introduce the possibility of the contamination of the tartaric acid or the pigment concentrate yielded by the process described in the present invention. Such a fact is of special importance for the process, since the use of these two products in the European market is mainly in the wine and food industries. Thus, in the present invention, the anthocyanic pigments are removed in order to guarantee that the diluted solution of the potassium bitartrate (KHT) present in the by-products of vinification is transformed into tartaric acid without the reduction of the exchange capacity of the resin bed. Subsequently, the adsorbed pigments are eluted (regeneration of the adsorbent resin) with ethanol and the resultant solution is concentrated, under reduced pressure and a maximum temperature of 40°C. Such anthocyanic pigments are approved additives in the European Union (El 63) and United States of America (Grape Color Extract and Grape Skin Extract) for the coloration of some dairy products, ice-cream, candies, confectionery, tinned vegetables, meat products, soups and non alcoholic beverages. The present invention also concerns the recycling of the used cation exchange regenerant solution. Thus, while the elution of the regenerant solution through the resin bed occurs (regeneration of the cation resin), the conductivity of this solution is measured and, in accordance with the graph in Figure 1 , it is possible to control the addition of the exact amount of produced potassium chloride to reduce the solubility of the KHT, by the common ion effect (Figure 2), in the winery by-product that will be processed in the next cycle. Such procedure makes the total recovery of the potassium bitartrate (solid) contained in the winery by-product by filtration possible at room temperature. The remainder of the used regenerant solution is stored in order to be used as the first portion of regenerant solution in the next regeneration cycle of the cation exchange resin. Finally, the small amount of hydrochloric acid that comes with the potassium chloride, has a beneficial effect on the extraction of the pigments due to the increase in the solubility of the anthocyanins present in the solid sediments of the wine lees and filter cakes, as well as in the diluted wine produced by the leaching of the grape pomace. No harmful effect related to the presence of traces of hydrochloric acid hinders the use of the pigment produced that way, even because almost all the actual processes of extraction use various types of mineral acids, in higher concentrations, with the same objective. Example - Production of tartaric acid and a concentrate of grape pigment from wine lees (Figure 3) After adjusting the ionic concentration of potassium in 500 kg of wine lees (1), by the addition of the first 150 litres of the solution (2) (containing about 20 kg potassium chloride - KCl) eluted from column CC (described below) during the operation of regeneration (3), the resultant 650 litres of suspension (4) are filtered in a press-filter (5), at room temperature (18 - 20°C), the filtered solution (6) being introduced by means of an adequate pump (7) (flow of 13 litres/min.), in a fixed bed column CA (100 cm high X 30 cm diameter) containing 65 litres of the polymeric adsorbent resin Amberlite XAD761 (Rohm & Haas Co.) in order to remove the existing anthocyanic pigments. After this operation, the discoloured solution (8) is transferred to another tank (9). The cake (10) produced by the above filtration (125 kg), which has about 40% w/w of KHT, is then suspended in 1,500 litres of potable water (11) at 70°C, with the help of mechanical agitation, in a heating jacketed vessel (12), for 15 minutes and, after that, this suspension (13) is fractionated by filtration (14), yielding 1,550 litres of a coloured solution (15) containing 0.17 moles per litre of KHT and 75 kg of a solid composed mainly of grape skins and seed (SS). This coloured solution (15) is then introduced into the column CB by means of the centrifugal pump (16) (13 litres/min.). This column, of the same dimensions as the previously cited column CA, contains the same adsorbent resin and the temperature of the solution is maintained between 65°C and 75°C during the operation of adsoφtion by the circulation of warm water or steam inside a coil welded to the exterior of the column CB. The colourless solution (17) eluted from the column CB is pumped (18), while still hot and with a flow of 30 litres/min. into the fixed bed column CC through a piping system that can be closed in a way to make the recirculation of this solution (Re) possible. This column CC (100 cm high X 50 cm diameter) contains 175 litres of the strong cation resin Amberlite SR1L (Rohm & Haas Co.). After 2 hours of operation, the resultant solution (19) is transferred to a crystallizer (20) to be concentrated, at atmospheric pressure (maximum temperature of 60°C), until almost the water has evaporated. The wet crystals of tartaric acid (21) obtained are then dried with the aid of a fluidised bed dryer (22) (maximum temperature of 60°C). Later, tartaric acid (TA) containing a maximum of 0,5% w/w of moisture is packed up (23) (38 kg - 95% of recovery). Both the resin that composes the bed of the column CA as that of the column CB are regenerated (24), at room temperature, by passing the ethanol (Et) (94 - 96°) produced by the distillation (25) of the discoloured solution (8). The alcoholic solution (26) obtained is cooled at 5°C during 12 hours, with constant agitation and then filtered (27). Later, in the stage of concentration, the ethanol is recycled (28) at reduced pressure and 40°C, from the alcoholic solution (26) by adding a condenser (29) between the concentrator (30) and an appropriate vacuum pump (31). In this way 20 litres of a concentrate (30% w/v) of anthocyanin pigments of grape (GP) are produced. Finally, the cationic resin bed is regenerated (3) through the passing (by gravity) of 2,000 litres of solution (32) of hydrochloric acid 7,3% w/v, with a flow of 15 litres/min., followed by the rinsing of the resin bed with 700 litres of de-ionised water (33). The first 150 litres of the regenerant solution (2) eluted from column CC, are used for adjusting the potassium concentration in the next 500 kg of the wine lees to be processed, so that less than 1% of the potassium bitartrate will remain in the solution. The remaining volume of the regenerant solution (34) is recycled and will constitute the first portion of regenerant solution to be used in the next cycle of regeneration.

Claims: Claims 1 Process for the production of tartaric acid and a grape anthocyanin pigment concentrate from winery by-products, characterised by the removal of pigments present in the solution through its adsoφtion onto an adequate polymeric adsorbent resin, before the production the tartaric acid by a ion exchange process using a gel type strong cation resin, especially developed for food applications, contained in a fixed bed. 2 Process in accordance with claim 1 , in which a certain amount of the first portion of the eluted regenerant solution (rich in potassium chloride) from the fixed bed cation resin, in the previous cycle of regeneration, is added to the next amount of the winery by-product to be processed, with the objective to increase the efficiency of the first step of extraction of the anthocyanic pigments and the recovery of the potassium bitartrate, by filtration at room temperature, due to the reduction of its solubility related to the "Common Ion Effect". 3 Process in accordance with claim 2, characterised by the control of the amount of added potassium chloride solution, by measuring the conductivity of the regenerant solution eluted from the fixed bed cation resin. 4 Process in accordance with claims 1 and 2, characterised by the filtration of a suspension produced from the cake of the first winery by-product filtration, heated to 70°C, for the elimination of the solid particles before the second step of the anthocyanic pigments adsoφtion, and the operation of ion exchange in which an aqueous solution of tartaric acid is produced. 5 Process in accordance with claims 1 and 4, characterised by the ion exchange operation to be undertaken at an initial temperature of 70°C from an aqueous solution of KHT with a concentration higher than 0.15 moles per litre (28 g/L). 6 Process in accordance with claims 1 , 2 and 3, characterised by the recycling of the remaining amount of regenerant solution eluted from the fixed bed cation resin which, because it contains only a small amount of potassium chloride, can be used as the first portion of regenerant solution in the next cycle of regeneration. 7 Process in accordance with claims 2 and 3, characterised by an improvement in the process of extraction of anthocyanic pigments, by the increase in solubility due to the decrease in the pH of the winery by-product caused by the addition of the first portion of regenerant solution eluted from the cation resin bed which contain hydrochloric acid and potassium chloride. 8 Process in accordance with claim 1 , characterised by the production of a liquid grape anthocyanin pigment concentrate througli the elution of those pigments adsorbed onto the fixed bed polymeric adsorbent resin by means of ethanol 94 - 96°. 9 Process in accordance with claim 8, characterised by the removal of solid impurities from the ethanolic solution by cooling it at 5°C for 12 hours, under agitation, followed by filtration. 10 Process in accordance with claims 8 and 9, characterised by the recycling of the ethanol used as regenerant for the polymeric adsorbent resin by placing a condensation system between the concentrator and the vacuum pump.

Inventors: BRAGA FERNANDO GLENADEL, BRAGA, FERNANDO, GLENADEL
Applicants: BRAGA FERNANDO GLENADEL, SUBVIDOURO C R L, BRAGA, FERNANDO, GLENADEL, SUBVIDOURO, C.R.L.
Application year: 2000
Main classification: C12F3
IPC codes: C12F3