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Cahiers Agricultures 1996; 5: 83-8 [This is an updated translation with updated bibliographic links. There are a few more important citations I’m trying to fill in.]
Summary [untranslated abstract]
Rum technology and typicality factors in the French West Indies L. Fahrasmane, B. Ganou-Parfait, F. Bazile, P. Bourgeois
Rum has been produced in the French West Indies since the 17th century. The changes in production since then have been influenced by technical, economic and qualitative factors.
Rum must not only have its typical organoleptic qualities but also be competitive on the international market, and this requires technological progress. Through yeast-strain selection, we have contributed towards improving alcoholic fermentation in cane-sugar-based media.
Rum production in the French West Indies is typified by the raw materials (molasses, cane syrup or juice), the microbiology of the fermentation media allowing bacterial activity, and the distillation equipment with its so-called “Creole columns” producing a range of aromatic strengths.
Until the end of the 19th century, slops and froth were used in making the musts. Following Pasteur’s work, a new understanding of hygiene led to these substances being replaced by water, with the result that Saccharomyces yeasts replaced the Schizosaccharomyces as alcoholic fermentation agents.
Distillation equipment has also progressed. That used today depends on the type of rum produced (figure 1).
Synthesis
Technology and typical elements of rums from the French West Indies
Louis Fahrasmane, Berthe Ganou-Parfait, Francius Bazile, Paul Bourgeois
L. Fahrasmane, B. Ganou-Parfait, F. Bazile: Inra, Station de technologie des produits végétaux, BP 515, 97165 Pointe-à-Pitre cedex, France.
P. Bourgeois Université des Antilles et de la Guyane, Laboratoire de chimie des substances naturelles, Campus de Fouillole, BP 592, 97159 Pointe-à-Pitre cedex, France.
Rum technology involves several unit operations [1] the preparation of the must (more specifically called “composition”), fermentation, distillation and maturation. In the 17th century, the mastery of alcoholic distillation as a production tool became a key factor in the emergence of rum production, which appeared as a way of using sugar refinery by-products, particularly those coming from processing sugars.
In the middle of the 19th century, agricultural rum appeared, the particularity of which was the use of musts made from sugar cane juice. This type of rum will become, in the French West Indies, an export product, a production in its own right, distinct from sugar, retaining, in certain aspects, an artisanal character and having markers of recognition of its typicality linked to practices and production conditions.
In Europe, rum has been defined, since 1989, by the community regulation relating to spirit drinks [R. (EEC) No. 1 576/89]: it is “the spirit drink obtained exclusively by alcoholic fermentation and distillation either of molasses or syrups resulting from the manufacture of cane sugar, or of sugar cane juice itself, and distilled at less than 96% vol., such that the product of the distillation perceptibly presents the specific organoleptic characteristics of rum”. The minimum acquired alcoholic strength by volume is set at 37.5% (vol).
French national regulations (decree of April 22, 1988 relating to rums with designation of origin) distinguish between “agricultural rum” coming from cane juice, “traditional rum” coming from molasses and syrup, and “grand arôme rum” which is a variant of traditional rum, higher in aromatic substances (table 1). “Light rum”, formerly defined by national regulations, is no longer defined today [2]. Distillates of different types can be delivered for consumption either in the form of white eau-de-vie, or after maturation and dilution to consumer strength. They can also be subject to longer maturation or aging in wooden barrels with a maximum capacity of 650 liters and for at least three years (decree of July 25, 1963). Their content of volatile elements other than ethanol must be at least 225 grams per hectoliter of pure alcohol.
2. Borghese T. Rhum, rhum agricole, rhum traditionnel. Définitions légales. In: Actes du Colloque sur les rhums traditionnels. Pointe-à- Pitre : CRITT-BAC, 1994: 51-4.
Origins of rum production
The art of distillation dates back more than three thousand years, and it is believed that the Persians discovered it and used it to make rose water. The first real distillation devices were designed by Egyptian Christians, before the 7th century AD.
The appearance of eau-de-vie seems to have been preceded by that of alcoholic perfumery, which began with the Arab doctor, philosopher and alchemist, Rhases (864; 932). Around 1360, Hungarian water based on rosemary appeared. Perfumery later developed with Jean-Marie Farina (1685-1766), an Italian chemist who manufactured the eau-de-Cologne created by his uncle Jean-Paul Feminis in 1690.
Wine eau-de-vie appeared in Europe, as medicine and elixir of life, with Arnaud de Villeneuve (1235-1313) and Raymond de Lulle (1233-1315). Under the influence of Northern Europe navies (particularly Dutch), alembic distillation of white wines from Charente became a common rural activity, leading to the development and marketing of cognac and Armagnac in 1630. In 1624, the corporation of distillers was organized in France, for manufacture and sale of spirits. From the 18th century, wine distillation became a prosperous activity in France.
Appearance of rum production followed development of sugar production based on cane (Saccharum officinarum L.), with natural hybrids, on the American continent, in the 17th century. Migration of sugar production from the Mediterranean area to the New World is linked to the capture of Constantinople by the Turks in 1453 and expulsion of the Moors from Spain in 1492. We then witnessed a decline in influence of Arab culture and, with it, that of cane, after approximately seven centuries of sugar cultivation and production in the islands and around the Mediterranean Sea [3, 4].
3. Meyer J. Histoire du sucre. Paris: éditions Desjonquère, 1989; 335 p.
4. Fahrasmane L. Canne à sucre et rhum à travers le temps. In: Actes du Colloque sur les rhums traditionnels. Pointe-à-Pitre : CRITT-BAC, 1994: 330-5.
Holders of Genoese and Venetian capital, in search of new areas suitable for growing sugar cane, followed Christopher Columbus to the Americas. The expansion of sugar cane on the American continent triggered rum production as an annex to sugar refineries.
One of the first authors to talk about alcohol production from cane is Father du Tertre who stayed in the West Indies between 1640 and 1657. Father Labat, who arrived in the West Indies in 1694, describes at length the making of guildive in his Nouveau voyage aux isles de l’Amérique. The main characteristics of rum making in the 17th and 18th centuries are:
—use of by-products, scum and molasses, from the draining of sugars (foam and deposits produced during defecation of cane juice in sugar factories and syrupy residues of non-crystallizable sugar from sugar manufacturing), as sources of fermentable sugar. Must composition at the beginning of the last century is shown in Table 2 [5];
—spontaneous alcoholic fermentation due to microbial germs having resisted the various sugar factory operations (concentration, cooking of syrups) and those brought in by the wooden vats used for fermentation. It lasted one to two weeks in the presence of an abundant bacterial flora associated with yeasts of the Schizosaccharomyces genus. This microbial complex, of low productivity and generator of products with a very strong taste, was favored by the addition of vinasses (residues from previous distillations) pre-fermented during storage, which lasted several weeks, and during which acidifying bacterial fermentations took place. Musts thus obtained were acidic, with high osmotic pressure. Only yeasts of the Schizosaccharomyces genus were active in such environmental conditions.
The first distillation devices put in place were batch stills operating by two distillations (figure 1a). Most of them consisted of a copper boiler, topped with a capital also made of copper; residence time of the fermented musts was long, which favored esterifications. These devices allowed elimination of negative volatile compounds from the “heads”, sulfur and amines, and part of the very heavy compounds constituting the “tails”. Product quality obtained was often mediocre or frankly bad, due to the inferior raw material quality, lack of care taken in fermentation, and non-rectification of the distillates which would have been necessary to eliminate substances responsible for bad tastes. The best quality rum “is that which is made only with molasses; but that in which the remains of the sugar cane, the scum, etc. are left in the fermentation, always retains an unpleasant acidic touch and often contracts the taste of empyreum, which means that it is rejected from commerce… [6]”.
6. Le Normand. L’art du distillateur des eaux-de-vie. Paris: éditions Chaignieau, 1817; 112 p.
During the 18th century, devices began to be used to obtain marketable product at the first distillation.
Rum technology, from the beginnings of the industrial era to the present day
Towards the end of the 19th century, cane varieties were selected for better adaptation to sugar technology. Saccharum officinarum carries many factors linked to sucrose richness, fiber content, vigorous and mechanically resistant stems.
The first artificial hybrid was produced by Fairchild in 1708. In 1880, rediscovery of cane fertility was at the origin of scientific initiatives, with Slotwedel, in Java in 1888, and Harrison and Bovell, at Barbados in 1889, through intra- and inter-specific crosses. Cane hybridization successes in Java, Barbados and Demarara, in Guyana, were at the origin of the proliferation of hybrid creation stations throughout the world. Modern varieties resulting almost exclusively from hybridizations reached the commercial stage eight to twelve years later, selection criteria including agronomic characteristics, sucrose richness, resistance to diseases, specific locality characteristics, etc. . In 1921, Jeswiet obtained a hybrid clone nicknamed “the marvelous” (POJ 2878), far superior to natural hybrid noble canes in its resistance to pathogens and its agricultural and industrial yields.
Increase in alcohol consumption among the working classes, economic liberalism and phylloxera crises which struck wine spirits catalyzed, during the 19th century, significant rum industry growth. Production, which had remained relatively low until the beginning of the 19th century (3 to 4 million liters on average per year for Martinique, Guadeloupe and Guyana combined), exceeded 21 million liters in 1892. At the same time as this growth, profound changes have affected rum industry structure and manufacturing techniques.
Central sugar factories appeared after 1865 and annexed distilleries for molasses processing. Price and quantity constraints led to the installation, in 1818 in Saint-Pierre, Martinique, in addition to batch column stills, of simple continuous columns (figure 1b), of the Creole type, to increase productivity. Creole columns make it possible to distill wines, or fermented musts, containing 4 to 5% (vol.) of ethanol. Ordinarily, they have three to five concentration plates, which makes it possible to obtain distillates containing 60-70% (vol.) of ethanol. Rum that is distilled at too high a degree loses its aromatic qualities. Exhaustion must include at least fifteen trays so that there is no loss of alcohol in the vinasses. The entire exhaustion part (base, sections and plates) can be made of stainless steel but it is very important that the concentration part (plates and swan neck) be made of copper. Oxidative catalysis of copper towards sulfur products has been demonstrated. This type of distillation device became widespread in the French West Indies around 1880; it no longer permitted the extraction of heads and tails in any significant way. Thus, spirits obtained reflected the quality of the fermented must, without the possibility of correcting organoleptic defects. Subsequent improvements to the devices, in particular the optimization of fractionation, multiple column device (figure 1c), made it possible to obtain products of a light nature, free from bad tastes, but stripped of interesting volatile esters.
Parallel to the central sugar factories, so-called “agricultural” distilleries emerged after 1883 in the West Indies and French Guiana, whose products acquired quite great importance. Some owners of old estates far from central sugar factories, rather than selling canes burdened with high transportation costs or seeking to obtain inferior sugar, found it more advantageous to transform their harvests into rum by fermenting juices either directly or after concentration, which gave birth to agricultural rum.
The post-Pasteurian hygienist wave at the beginning of the century concerned the rum industry and caused strong turmoil. It was concluded that it was necessary to replace spontaneous fermentations with pure fermentations [7] and, in 1913, a detailed study of rum yeasts [8] led to the advocating of pure fermentation with selected yeasts. Concern to improve productivity was decisive for researchers who believed that bacterial flora was detrimental to rum fermentation, while chemists attributed an important role to bacteria in the formation of the bouquet of grand arôme rums [9, 10].
7. Pairault E. A. Le rhum et sa fabrication. Paris C. Naud, 1903; 292 p.
8. Kayser E. Contribution à l’étude des ferments et de la fermentation des rhums. Ann Sci Agric 1917; 34: 297-322.
9. Allan C. Report on the manufacture of Jamaica. Sugar exp. Stat. Report, for 1905, 119-140. West Ind Bull 1906; 7: 141-2.
10. Ashby SF. Studies of fermentation in manufacture of Jamaica rum. Inst Sug J 1909; 7; 243-51 et 300-7.
Application of pure fermentations led to changes in conduct. We first contented ourselves with improving the operating conditions of the spontaneous yeasts, by lowering the must density and adding sulfuric acid, to lower the pH in order to limit bacterial activity, and ammonium sulfate, to supplement the environment with nitrogen nutrients. Then, the use of yeasts acclimated to certain antiseptics became widespread. Improvements in yield were obtained, but the aromatic product quality was significantly reduced as they became more and more neutral. Most producers subsequently renounced the use of selected yeasts and concluded, around 1920, the superiority of spontaneous mixed fermentations which made it possible to obtain fuller-bodied rums, with a more intense and more characteristic bouquet.
Use of scums and stillage in must composition was gradually abandoned and replaced by water as a means of dilution. Currently, stillage is no longer used, except in the preparation of musts for the production of grand arôme rums. For around fifteen years, the new element in rum technology has been the addition of alcoholic fermentation yeast flora, by adding dry baker’s yeast, cheap and widely available. We have selected a strain of yeast for cold fermenting (box 1).
Elements of typicality
White rums are presented in four types, three of which are defined in French regulations, by their non-alcohol content (or TNA) and the type of raw material used (table 1). If typicality is what characterizes a product and allows it to be recognized, it is necessary to look for elements of the typicality of rums in the non-alcohol, or all of the compounds other than water and ethanol which constitute it.
The TNA of aromatic rums from the French West Indies is generally higher than that of light rum, the latest of the four types, where bacterial presence and activity are low, or even non-existent. This parameter, however, remains lower than that of grand arôme rum which constitutes an archetype where bacterial activity reaches a significant level.
Bacterial flora is responsible for the production of volatile acidity and precursors of aromatic compounds such as esters. Rums from environments where bacterial activity exceeds acceptable limits with regard to product quality have a high volatile acidity (> 15 mEq/l) [13] and contain undesirable substances such as acrolein [ 14] and butanol-2, markers of bacterial problems. The level of formic acid in rums can also be an element of assessment of possible bacterial problems and, therefore, of quality [15].
14. Lencrerot P, Parfait A, Jouret C. Rôle des Corynebactéries dans la production d’acroléine (2-propénal) dans les rhums. Indus Alim Agr 1984; 101: 763-5.
15. Jouret C, Pace E, Parfait A. L’acide formique composant de l’acidité volatile des rhums. Indus Alim Agr 1990; 107: 1239-41.
Box 1
Saccharomyces cerevisiae var. cerevisiae 493 EDV, a specific rum yeast
The main technical characteristics of this strain are:
—optimal pH = 4.5;
—optimal temperature 33°C;
—yield of alcoholic fermentation = 0.595 liters of alcohol pure/kg glucose equivalent (I ap/kg glucose);
—ethanol productivity = 3.0 g/l/h.
This yeast improves productivity and fermentation yield, compared to spontaneous fermentations and those carried out with the addition of oenological or bakery yeast and shows, compared to this, a good adaptability and better rate of live cells. Possessing the “killer” character, it inhibits certain types of yeast. It maintains good activity at a temperature of 36°C and does not cause the appearance of bad tastes in products.
The yields of the sugar-alcohol transformation usually obtained in distilleries are relatively low (0.521 ap/kg glucose on molasses and 0.47 I ap/kg glucose on cane juice), while the optimum yield is of the order of 0.60 I ap/kg glucose.
We are working to improve yeast fermentation efficiency, by adding sterolic extracts, sugar factory defecation sludge, to the musts [11].
Yeasts constitute above all a factor in the technical efficiency of the sugar-alcohol transformation while having a part in the synthesis of components and flavor precursors. This is, for example, the case in the formation of volatile fatty acids, the synthesis of which is modulated, depending on the strain, by the citric acid content of the raw material [12].
11. Fahrasmane L, Bourgeois P. Apport d’extraits stéroliques de cire de canne à sucre en fermentation alcoolique. In: Actes du Colloque sur les rhums traditionnels. Pointe-à-Pitre : CRITT-BAC, 1994: 128-35.
12. Fahrasmane L, Parfait A, Jouret C, Galzy P. Production of higher alcohols and short chain fatty acids by different yeast used in rum fermentations. J Food Sc 1985; 50: 1427-36.
Rum chemistry reveals propionic acid as singling out rum within eaux-de-vie, due to the relatively high concentrations observed [16]. The level of propionic acid formation is linked to the activity of fermentation yeasts, which seems specific in media based on sugar cane derivatives [17]. Bacteria inventoried in the distillery environments contribute to the formation of propionic acid. These are Propionibacterium, Bacillus and Clostridium.
16. Suomalainen H. Quelques aspects généraux de l’arôme des boissons alcooliques. Ann Techno Agr 1975; 24: 453-67.
17. Fahrasmane L. Contribution à l’étude de la formation des acides gras courts et des alcools supérieurs par des levures de rhumerie. Thèse de doctorat de troisième cycle. Université des Sciences et Techniques du Languedoc. 1983; 171 p. [I have a couple pages of this somewhere.]
Alkylpyrazines seem to be of certain interest for the analytical differentiation between agricultural white rum and industrial white rum. Given the perception thresholds of these compounds, we think they contribute to the aroma of certain rums through olfactory notes of burnt, caramel and leather [18].
18. Jouret C, Pace E, Parfait A. Différenciation analytique des rhums agricoles et industriels par les alkylpyrazines. Annales des falsifications de l’expertise chimique et toxicologique 1994; 87: 85-90.
The distillation method, through the use of the continuous Creole type column, impacts the quantitative level of the TNA (it decreases when the degree of rectification increases) by the low number of concentration plates (three to ten) which, itself , acts upon the degree of flow of the distillate by limiting it (60 to 80% (vol.) of ethanol); regulations allow up to 96% (vol.) ethanol to be distilled.
Damascenone is present in molasses [19]. It has been shown that an isomer of this compound, with the same mass spectrum, has a characteristic rum odor [20]. This ketone and its presumed isomer, identified in other products of plant origin, could, on the basis of quantitative considerations, be a factor in differentiating rums within spirits.
19. Godshall MA. Minor constituents identified in the sugarcane plant and sugarcane products. SPRI short report 1984; 3; 9 p.
20. Dubois P, Rigaud J. Étude qualitative et quantitative des constituants volatils du rhum. Ann Techno Agr 1975; 24: 307-15.
Rum manufacturing conditions (fermentation microbiology and distillation) as well as the raw material therefore contribute to the development of their analytical typicity. There is sensory analysis work to be done to describe this typicity, by characterizing the components that must be monitored to improve the competitiveness of rums.
Perspectives and conclusion
In the French Antilles, rum production must, to remain competitive, adopt fermentation methods that do not leave room for the hazards of spontaneous fermentations. The concern to produce aromatic rums, whether from molasses or cane juice, must involve following rigorous protocols taking into account the following aspects: use of selected yeasts, control of the bacterial flora, rational choice of distillation parameters, quality management of raw materials, products and by-products (box 2).
Reasoned fermentation management by must acidification (in order to contain, within appropriate limits, the presence and activity of the bacterial flora), temperature control and the use of yeasts selected for rum making allow active fermentation with reduced latency. This way of operating leaves room for positive bacterial expression with regard to the quality and product authenticity.
The potential evolution of fractioning techniques, increase in the number of plates (twenty to thirty) in the concentration part of the columns, use of vacuum distillation, pervaporation and reverse osmosis—should allow the selective extraction of certain volatile compounds which, present in too large quantities, mask the expression of typical notes. We would thus be able to better express the latter, despite the reduction in TNA, according to pre-established product profiles in which ethanol increasingly becomes a vector of aromas [22, 23].
22. Escudier JL. La distillation des rhums: typicité et récupération d’arômes. In: Actes du Colloque sur les rhums traditionnels. Pointe-à-Pitre : CRITT-BAC, 1994: 187-205.
23. Cogat P. Technologies applicables à l’atelier de distillation pour éliminer les composés négatifs, pour composer le profile aromatique. In: Actes du Colloque sur les rhums traditionnels. 1994: 163-86.
We must also seek to make the most of quality signifiers (AOC, label, etc.) linked to regulations. If, originally, the rum distillery was an annex to the sugar factory, it is not the same with the agricultural distillery, in the French West Indies, which is a production structure in its own right whose qualitative needs in raw materials could be considered specifically, depending on fermentation considerations and the aromatic properties of the products. Indeed, agricultural rum production could benefit from a raw material better adapted to its particularities than the hybrids used in sugar production, by selecting varieties richer in non-sugars (nitrogen, phosphorus, magnesium, etc.) and in aromatic precursors, in order to better meet the nutritional needs of the fermentation agents and to reinforce the typicality linked to the raw material.
Thanks
Thanks are addressed to R. Pichy, M.L. Saint-Marc and C. Galas, from INRA in Pointe-à-Pître, whose technical collaboration was invaluable to us.
Box 2
Waste water treatment and environmental protection in rum factories
Rum production generates highly charged residues (stillage). polluting (250 kg of COD/m3 of pure alcohol in agricultural distilleries; 1,500 to 1,900 kg of COD/m3 of pure alcohol in molasses distilleries). This sector of activity is increasingly required to integrate environmental protection measures downstream of its work schedules. To treat rum wastewater, various processes can be used: evaporation-incineration, spreading-irrigation, anaerobic lagooning, biomass production and anaerobic digestion. This last route, while reducing the organic pollutant load, produces combustible biogas. In the case of a molasses rum production unit, it allows 65% of the effluent to be decontaminated with the production of recoverable biogas, providing 60% of the energy necessary for the operation of the distillery. The treatment of waste water from the agricultural distillery, whose COD varies from 15 to 25 g/l with a BOD/COD ratio of 0.5, is easier than that of water from the molasses distillery whose COD varies from 90 at 120 g/l with a BOD/COD ratio of 0.2 to 0.4 [21]. In fact, organic load purification rates of more than 90% are obtained.
21. Bories A, Bazile F, Lartigue P. Traitement anaérobie des vinasses de distillerie en digesteurs à micro-organismes fixés. In: Actes du Col- loque sur les rhums traditionnels. Pointe-à-Pitre : CRITT-BAC, 1994: 219-42.
References
1. Fahrasmane L. Rum. In: Encyclopedia of Food Science Food Technology and Nutrition. Londres: Academic Press, 1993: 3941-6.
2. Borghese T. Rhum, rhum agricole, rhum traditionnel. Définitions légales. In: Actes du Colloque sur les rhums traditionnels. Pointe-à- Pitre : CRITT-BAC, 1994: 51-4.
3. Meyer J. Histoire du sucre. Paris: éditions Desjonquère, 1989; 335 p.
4. Fahrasmane L. Canne à sucre et rhum à travers le temps. In: Actes du Colloque sur les rhums traditionnels. Pointe-à-Pitre : CRITT-BAC, 1994: 330-5.
6. Le Normand. L’art du distillateur des eaux-de-vie. Paris: éditions Chaignieau, 1817; 112 p.
7. Pairault E. A. Le rhum et sa fabrication. Paris C. Naud, 1903; 292 p.
11. Fahrasmane L, Bourgeois P. Apport d’extraits stéroliques de cire de canne à sucre en fermentation alcoolique. In: Actes du Colloque sur les rhums traditionnels. Pointe-à-Pitre : CRITT-BAC, 1994: 128-35.
16. Suomalainen H. Quelques aspects généraux de l’arôme des boissons alcooliques. Ann Techno Agr 1975; 24: 453-67.
17. Fahrasmane L. Contribution à l’étude de la formation des acides gras courts et des alcools supérieurs par des levures de rhumerie. Thèse de doctorat de troisième cycle. Université des Sciences et Techniques du Languedoc. 1983; 171 p. [I have a couple pages of this somewhere.]
18. Jouret C, Pace E, Parfait A. Différenciation analytique des rhums agricoles et industriels par les alkylpyrazines. Annales des falsifications de l’expertise chimique et toxicologique 1994; 87: 85-90.
19. Godshall MA. Minor constituents identified in the sugarcane plant and sugarcane products. SPRI short report 1984; 3; 9 p.
20. Dubois P, Rigaud J. Étude qualitative et quantitative des constituants volatils du rhum. Ann Techno Agr 1975; 24: 307-15.
21. Bories A, Bazile F, Lartigue P. Traitement anaérobie des vinasses de distillerie en digesteurs à micro-organismes fixés. In: Actes du Col- loque sur les rhums traditionnels. Pointe-à-Pitre : CRITT-BAC, 1994: 219-42.
22. Escudier JL. La distillation des rhums: typicité et récupération d’arômes. In: Actes du Colloque sur les rhums traditionnels. Pointe-à-Pitre : CRITT-BAC, 1994: 187-205.
23. Cogat P. Technologies applicables à l’atelier de distillation pour éliminer les composés négatifs, pour composer le profil aromatique. In: Actes du Colloque sur les rhums traditionnels. 1994: 163-86.
24. Maldonado O, Espinosa R, Rolz C, Humphrey AE. Technical details of a process to manufacture industrial alcohol from sugar cane. Ann Technol Agr 1975; 24: 335-42.
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