'Pepper' Aroma and the Sesquiterpenoid Rotundone
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Received: 27 November 2019 y Accepted: 12 March 2020 y Published: 30 April 2020 DOI:10.20870/oeno-one.2020.54.2.2947 May peppery wines be the spice of life? A review of research on the ‘pepper’ aroma and the sesquiterpenoid rotundone Olivier Geffroy*, Didier Kleiber and Alban Jacques Physiologie, Pathologie et Génétique Végétales (PPGV), Université de Toulouse, INP-PURPAN, 75 voie du TOEC, BP57611, 31076 Toulouse Cedex 3, France *corresponding author: [email protected] ABSTRACT Rotundone is the main aroma compound responsible for peppery notes in wines. Since its discovery in 2008, this potent and fascinating odorant has been the subject of many research studies worldwide. The aim of this review is to summarize these works. Rotundone is a rather ubiquitous molecule that has been detected in many grape varieties. As with other sesquiterpenes, the proposed biosynthetic scheme for rotundone involves both the methylerythritol phosphate (MEP) and the mevalonate (MVA) pathways. The production of the compound by the plant, which could be a response to biotic stress, is also affected by abiotic factors. In most cases, studies showed that rotundone was neutrally or positively perceived by consumers, which makes the peppery note a desirable character in vine. Practical ways were identified to modulate rotundone levels in wines using viticultural and enological techniques. Climate change, through the expected alteration of precipitation regime and a rise in temperature over the grape maturation period, should have a depreciative impact on rotundone accumulation. Adaptation strategies in this context, together with other perspectives of research, are discussed in concluding this review. KEYWORDS peppery aroma, rotundone, occurence, biosynthesis, consumer acceptance, modulation techniques OENO One 2020, 2, 245-262 © 2020 International Viticulture and Enology Society - IVES 245 Olivier Geffroy et al. INTRODUCTION 1. Generalities on pepper and pepper aroma The aromatic component of a wine is a key element Black pepper (Piper nigrum), native to the in its appreciation by consumers, as the olfactory Southeast coast of India, is one of the most widely assessment takes place just after the visual used spices in the world, with sensory qualities examination, which is seldom discriminatory. that have been recognized for millennia. It was the Aromas are also perceived in the palate through main spice imported by the Romans and during the the retronasal olfaction as the oral and nasal siege of Rome at the end of the Western Roman cavities are connected to each other. Thus, the Empire, the Visigoths claimed 3000 pounds of persistence of the aromas in the mouth, which is pepper as a ransom payment (Bury, 1889). In the one of the last sensory memories left by the wine Middle Ages, pepper was an essential commodity after swallowing or spitting it out, also contributes in the European economy, as tolls were paid in to the overall appreciation. With more than pepper in the South of France, Germany, Italy 800 compounds according to Robinson et al. and Poland (Schoell, 1834). This strong demand (2014), or more than 1000 according to other for pepper led to the trade development toward authors (IFV 2013), wine is one of the food products the East. In search of alternatives to the long and richest in volatile molecules. All these volatile perilous spice routes, Vasco de Gamma crossed the compounds do not necessarily have an odorant Cape of Good Hope and Christopher Columbus property and odorants are often characterized discovered America (Demolins, 1901). Today by a moderate molecular weight, low polarity, Vietnam, India, Brazil and Indonesia are the main good water solubility, high vapor pressure and a pepper producers in the world. lipophilic character (Meierhenrich et al., 2005). The bouquet of wine may involve 80 molecules Green, black, gray and white pepper are different (Dagan, 2006), originating from grapes for the forms of pepper products on the market (Variyar varietal aroma fraction or synthesized during pre- et al., 1988). Green and black peppercorns are fermentation operations, alcoholic and malolactic produced using green berries harvested before fermentations and aging. Most contributors to full ripeness is reached. The green peppercorn the varietal aroma of white wines have been berries are usually boiled, treated with sulfur widely studied, for example the monoterpenols dioxide and frozen or dried to preserve their color. responsible for floral notes in Muscat-like varieties Black pepper, the most noble pepper, is obtained (Terrier and Boidron, 1972), or the varietal thiols by fermenting these green berries. Red pepper imparting passion fruit and grapefruit aroma in is made of red-orange berries harvested at full Sauvignon wines (Tominaga et al., 1998). Until maturity. White pepper is traditionally obtained 2008, knowledge of the aromatic compounds that account for the varietal character of red wines, from red pepper that has been immersed in water especially free compounds directly extracted from for several days to eliminate the pericarp. The grapes without being released from a precursor, powdered gray pepper comes from crushing was limited to methoxypyrazines, responsible lower-quality black pepper berries. for undesirable green notes in wines (Lacey et Other species from the genus Piper are also used to al., 1991). The discovery in an Australian Syrah produce pepper. The berries of P. longum produce wine of rotundone, a sesquiterpene responsible long pepper, P. cubeba gives cubeb or tailed pepper for peppery notes (Wood et al., 2008), made a and P. borbonense is used to make Voatsiperifery major contribution to this knowledge. Despite its sensory significance, this molecule has remained pepper. By analogy, other spices misuse the undetected for a long time in wine and other food vernacular name of ‘pepper’. These berries are products, including pepper. Rotundone has been obtained from species with different botanical the subject of much research since its discovery, characteristics and that do not belong to the genus notwithstanding the lack of availability of Piper. Sichuan pepper (Zanthoxylum piperitum) commercial standards, a constraint that involves and pink pepper (Schinus terebinthifolius) are achieving its organic synthesis. This review article among the best-known of these ‘fake’ peppers. addresses the state of the literature on ‘pepper’ Because of their distinctive peppery flavor some aroma and especially on rotundone. In light of plant species are sometimes also described as the factors affecting rotundone concentration, ‘peppery’, such as peppermint (Mentha piperita), adaptation strategies are proposed that will assist which results from a spontaneous hybridization in producing wines with consistent rotundone between water mint (Mentha aquatica) and levels in the context of climate change. spearmint (Mentha spicata). 246 © 2020 International Viticulture and Enology Society - IVES OENO One 2020, 2, 245-262 Piperine and its stereoisomer chavicine are the and white peppers differed slightly (Chen et al., main active compounds of pepper (De Cleyn and 2011). Verzele, 1972). These cyclic secondary amines belonging to the piperidine family are the alkaloids The spicy or peppery character has always been responsible for the pungent character of pepper. associated with the world of wine. Spices were This sensation relies on the trigeminal nerve and commonly used at the time of the Roman Empire is independent of the chemical receptors located to elaborate the conditum paradoxum. The recipe in the buccal cavity responsible for the five basic for this spicy wine is given in the book De Re tastes (sweet, salty, sour, bitter and umami). Coquinaria, written in the 1st century AD by the This nerve provides both a sensory function gourmet Apicius. A wine, usually of poor quality, and the motor function for biting, chewing and was boiled with honey and then supplemented swallowing. In addition to the pungent sensation, with spices (pepper, mastic, nard, laurel and it is also involved in the sensations of touch, pain saffron) and dried fruits (dates). The product and freshness. During the storage of peppercorns, obtained was diluted with quality wine and hot chavicine is slowly transformed into piperine, coals were added to promote conservation. This which leads to a decrease in the pungent character tradition also existed in the Middle Ages with (Kozukue et al., 2007). Pepper also contains hypocras which was a beverage made from wine, many volatile compounds, mostly monoterpenes and sesquiterpenes (SQT) (Table 1). Before the honey, spices and herbs. Nowadays, the spicy discovery of rotundone (Wood et al., 2008), Jagella dimension has an important place in the aromatic and Grosch (1999) concluded that α-pinene, description of wine. The work led by Noble β-pinene, myrcene, α-phyllandrene, limonene, et al. (1987) classified the aroma of wine into linalol, 2-methylpropanal, 2- and 3-methylbutanal, 12 aromatic families, including a spicy family. butyric acid and 3-methylbutyric acid, were the These spicy notes (licorice/anize, black pepper and main odorants of Piper nigrum. Other research clove) imply a varietal origin clearly dissociable highlighted that the volatile composition of black from the woody notes. TABLE 1. Main volatile compounds identified in pepper Piper( nigrum). Monoterpenes Sesquiterpenes Other compounds α -Thujene α -Copanene Eugenol α -Pinene β-Caryophyllene Methyleugenol Sabinene β-Bisabolene Myristicine β-Pinene