Classification of unelaborated culinary products: scientific and culinary approaches meet face to face

Abstract The ongoing academization of gastronomic studies indicates the necessity for a commonly accepted classification system for cooks that does not contradict scientific approaches. This work discusses the fundamentals used by chefs and scientists to classify unelaborated food products; proposes taxonomic gastronomy as a new interdisciplinary framework that studies the taxonomy surrounding gastronomy; and presents a categorization of unelaborated food products that follows commonly accepted culinary criteria yet avoids contradiction by scientific knowledge. As little literature focuses on these issues, and similar experiences are scarce, it is concluded that further cross-disciplinary endeavors such as this will continue to be greatly fruitful.


Introduction
One of the oldest and most significant endeavors that human beings have embarked on is to name and classify a myriad of objects surrounding them, especially those used for specifically relevant purposes (Berlin 1992). Outstanding among such entities are living organisms and mineral products used as food and drink, because they have been and continue to be particularly germane for survival and human evolution. In addition, the classification of foodstuffs has been highly important not only on a general scale, but especially for professional cooks, as well as-although often indirectly-for scientists in various academic fields.
We address in this paper unelaborated products, understanding by this food products that are used directly in cooking activities, not after a process that could transform them, or obtain from them, elaborated products; for instance, an orange is an unelaborated product, but its juice or a jam made with oranges are elaborated products.
Folk, professional, and scientific classifications of unelaborated food products (and their parts) are not necessarily always coincidental between themor even within them-as the ways in which distinct groups of people observe and conceptualize food can be remarkably different. At the same time, systems and outcomes of such classifications are, certainly, in constant evolution according to the knowledge and beliefs people have in a particular sphere and moment. As an example, the scientific classification of the elements of nature in three kingdoms, i.e., animals, plants, and minerals, proposed in 1675 by Nicolas Lemery (Lemery 1713), and popularized by Karl von Linnaeus (Linnaeus 1735), common in textbooks up to the second half of the nineteenth century (Hogg 1860;Haeckel 1866), was replaced by newer proposals with the development of microscopy, cell biology, and genetics amongst other disciplines, and with the incorporation of other major biological groups such as monera (bacteria), protists and fungi (Margulis 1974;Margulis and Schwartz 1982;Woese, Kandler, and Wheelis 1990).
New advances in science and cooking with the ongoing academization of gastronomic studies-reflected in many regulated studies for professional cooks, even at a university degree level-point to the necessity for a commonly accepted system of classification for cooks that does not contradict scientific approaches, yet very little has been done in this respect. Such a classification system could benefit from previous ones, in order to create a solid and robust categorization structure that is nevertheless flexible and adaptable to change. Furthermore, to our knowledge no attempt has been made to analyze and reconcile the classification of food products between scientific and culinary approaches. In fact, no scientific literature seems to address the caveats of classification systems within the sphere of professional cooks, while cooks have usually not addressed the lack of consensus within culinary classifications of food products. Based on these premises, the aims of the present work are: (i) to discuss the fundamentals used to classify unelaborated food products and their parts by professional cooks on one side, and by scientists (biologists studying organisms along with geologists) on the other; (ii) to propose a new interdisciplinary framework-termed here as taxonomic gastronomy-that studies and analyses the taxonomy surrounding gastronomy (e.g., products, tools, techniques), within a systemic approach to food studies; and (iii) to offer a consensual and flexible framework for the categorization of unelaborated food products (and their parts) derived from the direct collaboration of chefs and academics, which follows commonly accepted culinary criteria yet avoids contradiction by scientific knowledge.
In what follows, we present the methodology employed in this research, followed by the conceptual background on existing classification systems from both the culinary and scientific points of view. A taxonomy of gastronomy is proposed later, followed by the consensus classification system reached by co-authoring scientists and cooks, with concluding remarks.

Methodology
This work has been carried out transdisciplinarily by the elBulliLab culinary team (elBulliFoundation, led by Chef Ferran Adrià) and the UB-Bullipedia academic unit at the Food and Nutrition Torribera Campus of the Universitat de Barcelona (University of Barcelona). Academic collaborations from the Universitat de Barcelona included the Laboratory of Botany (Faculty of Pharmacy and Food Science), and the Laboratories of Animal Biology and Microbiology (Faculty of Biology), along with the Laboratory of Crystallography and Mineralogy (Faculty of Geology). Equally, the Botanical Institute of Barcelona (CSIC-ICUB), the Department of Animal and Food Sciences (Universitat Autònoma de Barcelona, Autonomous University of Barcelona), and the Department of Agri-Food Engineering and Biotechnology (Universitat Politècnica de Catalunya, Polytechnic University of Catalonia) also participated during the whole taxonomic process. These teams have defined the multifaceted nature of the resulting understandings and classification system. This classificatory process was begun in 2013 by a team of cooks from el-BulliLab and a small team from the UB-Bullipedia Unit-at that point recently created-with an initial analysis of the state of the art. Such an analysis was used to build a first proposal of classification that merged culinary and scientific perspectives. In March-April 2013 a team of experts from the UB-Bullipedia Unit was created in order to bring together the team of cooks from elBulliLab with academics from the UB-Bullipedia Unit. Eight meetings were organized, one every two months approximately. In light of the conclusions reached in these meetings, elBulliLab team created new versions of the classification, which were then sent to the UB-Bullipedia Unit experts for corroboration. Following this methodology, a first agreement was reached in September 2013; however, it was later adapted. The second and final agreement was reached in July 2014 and the classification was first presented in September 2014 in the new undergraduate joint degree in Culinary and Gastronomic Sciences offered by the Universitat de Barcelona and the Universitat Politècnica de Catalunya.
In this article, we propose a classification of food products (and their parts) with the idea of converting it into a collectively accepted classification by disparate types of professionals. Concretely, we focus here on unelaborated products (i.e., unprocessed foods such as the apple, brewer's yeast, chicken, or sea salt), leaving the classification of elaborated products (e.g., cider or jam), tools (e.g., pots and pans) and techniques (e.g., ethanol fermentation or jellification) for future work. Moreover, the main target group of this endeavor cannot go unmentioned, i.e., professional cooks. The proposed classification has been built from a culinary perspective and with a culinary purpose, that is, to organize the culinary products in an efficient, practical, and understandable way for cooks. However, this is not incompatible with a general and interdisciplinary consensus. Despite this clear cooking-oriented perspective, this classification has considered the scientific views of different fields. In addition, we have limited our scope here mostly to European cuisine, to further delimit our analysis of unelaborated food products.

Conceptual Background in the Taxonomy of Foodstuffs
Interestingly, neither culinary scientists, anthropologists, ethnotaxonomists nor other cognitive scientists have studied the food classification systems used amongst professional cooks, while folk taxonomies of food products or scientific classifications have been analyzed in much greater detail (Berlin 1967;Anderson 1980Anderson , 2014. We focus first on the poorly documented conceptual background in the professional classifications of food, followed by a few paragraphs on scientific taxonomies, while leaving aside folk conceptualizations from our scrutiny in this article, as they have been analyzed elsewhere (Messer 1981;Manderson 1986;Nichter 1986;Douglas 1997).
Theoretically, professional cooks' vocabularies, classifications, and categorizations could be considered intermediate between folk and scientific ones, in the sense that they are not carried out using a systematic scientific method, but require the application of certain technical aspects that are not necessary in folk thinking ( Figure 1). In addition, such gastronomic taxonomies are restricted to a small group of people; that is, they correspond to specialized or professionalized knowledge.
As previously stated, academically speaking little has been written about how chefs and professional cooks classify food. Historically, cookbooks are collections of recipes, generally only numbered and not grouped under any criteria, such as the Ancient Rome book De re coquinaria (Apicius 1541) or the medieval Libre de Sent Soví (Grewe 1979). From the first attempts to the present day, culinary classifications by professionals have been varied and heterogeneous, while following distinct systematization criteria: La Varenne (La Varenne 1651), for instance, listed seasonal meat products according to religious dates (e.g., meats from Easter to Saint John's Day); Menon organized foods according to elaborations (e.g., pâté) (Menon 1749); Escoffier classified them according to products, elaborations, or even the courses of meals without distinguishing between them (e.g., fishes, sauces, appetizers) (Escoffier 1903). Until recently, these classifications were not explicitly commented upon and were simply used as a base for structuring recipes in books.
More recently, the nouvelle cuisine chef Michel Bras, following the tradition of French cooks including the innovations of this school, classified dishes in categories such as vegetables, meats, soups, appetizers, and desserts (Bras 2002). Chef Joan Roca (Roca 2014), in turn, used the following categories: vegetables; fruits; herbs, spices, flowers, and sprouts; fish; seafood and cephalopods; and meats. After Ferran Adrià became chef of elBulli at 1985, his team showed an increased interest in the classification of culinary products and gastronomic knowledge in general. The initial volume of the first catalogue of dishes, already published, presents a classification of culinary products: waters, nuts, fish, eggs, preserved foods, and wines, among other categories (Adrià, Soler, and Adrià 2002). When Adrià ended elBulli's culinary activity (in 2011), he devoted himself even more to his reflection-shared with members of the academy-on several gastroculinary aspects, among them the classification of products, which he did not consider to be sufficiently resolved. An evolution of such ideas, reflections, and work is the classification presented in this article.
Classification systems of food products amongst scientists vary according to the discipline, be it biology, nutrition, food science and technology, agronomy, geology, chemistry, or physics. The bases for such taxonomies are in direct relation to the core subject in each discipline, varying from organisms to nutrients, agronomic units, minerals, and molecules, to name just a few. New approaches and methodologies allow constant evolution of such concepts and their categorizations. For instance, conceptual frameworks and categorization proposals for living organisms in science have varied greatly over time (Morton 1981). The first classification systems were far from using biological characters; Pedanius Dioscorides (first century ad), for example, classified plants, animals, and inorganic products by their uses. Later, artificial systems such as that created by Karl von Linnaeus for plants, started to consider biological traits, but only a few of them. The natural method-formulated in its more complete form by Augustin Pyrame de Candolle (nineteenth century)-aimed to use a representative diversity of traits for classification purposes. After Charles Darwin (nineteenth century), phylogenetic systems could adopt evolutionary concepts. Important efforts have since been made to incorporate to systematics not only morphological characters, but others such as chemical and cytogenetic as well as genomic (Stuessy 2011).
The above-mentioned classical classification of living organisms in a two-kingdom system was first questioned by Haeckel (1866), who, additionally to plants and animals, established the kingdom of protista, which comprised mostly single-celled organisms such as the protozoa, bacteria, and some algae and fungi. From then on, several changes have been made in this classification, with the proposal of different numbers of kingdoms (Margulis and Chapman 2009), which facilitate classifying all kinds of organisms into discernible groupings. Nevertheless, the biggest paradigm change in biological classification was facilitated by the discovery of the polymerase chain reaction (PCR) (Saiki et al. 1985), and its great potential in DNA sequencing, leading, from the 1990s, to molecular systematics. To summarize, nowadays, based on and developed from Woese, Kandler, and Wheelis (1990), living organisms are classified into three big domains (two of which are composed of prokaryotes, i.e., microorganisms without a nucleus), and what was classically considered as plants or animals are nowadays split into four kingdoms. Detailed-level classifications are today in process, such as the 'Tree of life project' (Maddison and Schulz 2007), but the simple long-established animal/plant dichotomy prevailing until the twentieth century is clearly no longer of use. For a thorough analysis of the evolution of taxonomic systems in biology during the last century, see Williams and Forey (2004). Mineral products are kept apart from living organisms, as has been the case from the onset of the three kingdoms of nature of Antiquity.

Taxonomic Gastronomy: A New Approach to Professional Cooking and Science
Over the past years, the gastronomic sciences have become a new frontier in academic fields and the professional world of cooks, with increasing holistic and transdisciplinary approaches to food and gastronomy (Caporaso and Formisano 2016). Nonetheless, the relationship between science and cooking is VOLUME 20 long-standing and has provided a foundation for the academization of cooking, although classification systems from the two sides have not yet converged. In the nineteenth century, explicit references already existed to such a relationship (Accum 1821;Liebig 1847;Kellogg 1893).
In the twentieth century, two crucial moments are the talk by Nicholas Kurti at the Royal Society titled "The Physicist in the Kitchen" in 1969, and when in 1992 the term "molecular gastronomy" was coined in the framework of the "Workshop on Molecular and Physical Gastronomy" by the scientists Harold McGee (1984), Hervé This (1993), and Nicholas Kurti and Giana Kurti (1988), the four most relevant figures of the molecular gastronomy movement. In 2007, Chef Ferran Adrià was the recipient of an Honorary Doctorate from the Department of Chemical Engineering at the Universitat de Barcelona and in the same year he delivered his first conference at Harvard University entitled "Cooking and Science with Ferran Adrià." This conference was the first step towards the launching in 2010 of the annual course on "Science and Cooking" in the Physics Department at Harvard University. Also worth mentioning is the emergence of the field of computational gastronomy, which consists in applying massive data analysis (big data) to gastronomic knowledge (Ahnert 2013). Specialized workshops such as "Computational Gastronomy: Food in the Age of Data" are proof of the interest in this new research field. Philosophy and arts are also turning their focus onto gastronomy; an example of this is the subject "Gustatory Aesthetics" within the undergraduate studies of Philosophy at the Universitat Autònoma de Barcelona.
Moreover, university-level studies on cooking and gastronomy are being created, such as those offered at the Università degli Studi di Scienze Gastronomiche (University of Gastronomic Sciences in Bra, Italy), the Master of Liberal Arts in Gastronomy at Boston University Metropolitan College, or the new Bachelor's Degree in Culinary and Gastronomic Sciences offered by the Universitat de Barcelona and the Universitat Politècnica de Catalunya. These are just a few examples of what we can call the emerging academization of cooking. Last but not least, another sign of the emergence of culinary science is the increase in SCI-and/or SSCI-indexed journals dealing with professional cooking and the science behind it, such as Flavour, Food, Culture and Society, Food Research International, Food Reviews International, and International Journal of Gastronomy & Food Science. This academization process has led to the emergence, in the intersection of the areas of science and cooking, of a thought collective (Fleck 1980), i.e., a community of people participating in a mutual exchange of ideas and intellectual opinion, which has been, among other things, the breeding ground of the consensus classification presented here. In fact, the above-mentioned academization process means the crystallization of a new academic discipline, which is interdisciplinary by nature and entails the need for a reconceptualization of concepts coming from other disciplines. For example, parsley is seen and has to be defined from a different perspective in integrative gastronomic sciences than in botany or in cooking, as considered separately. Gastronomic sciences cannot be the sum of their sibling disciplines, but require a change of paradigm and a process of distillation, to which the present paper-built by representatives of different approaches converging in the gastronomic sciences thought collective-aims to contribute.
Following this trend, we propose here a new branch within the systemic research approach to gastronomy: taxonomic gastronomy. Taxonomic gastronomy encompasses the scientific study of the description, identification, nomenclature, and classification of culinary products (unelaborated and elaborated), along with tools and techniques used for cooking. Such a definition is especially suited (but not exclusively) for systems of food classification by professional cooks in present and past times. As molecular gastronomy did (see above), taxonomic gastronomy requires a similar framework that combines contributions from two major human spheres: the culinary arts and a myriad of scientific disciplines, mainly physical, analytical, and organic chemistry, biology, geology, nutrition, and food science and technology.
Having set the background in previous sections, in the following paragraphs we present the taxonomic scheme of the classification agreed between chefs and academics, along with its different divisions, subdivisions, and components.

Consensus Classification for Unelaborated Culinary Products
The classification system consensually obtained by scientists and expert cooks for unelaborated products is based on consecutive subcategories, beginning with living beings vs. inorganic materials, further subdivided into worlds and, in the case of living beings, into specific organisms and their anatomical parts (Table 1).
Within unelaborated food products, two mutually exclusive categories were established: living beings and inorganic materials, the former with three subcategories (here known as "worlds") and the latter with two. On one side, the three living worlds include a joint category of plants and fungi (considered together, but as distinct groups, owing to the tradition of them being studied under the discipline of Botany), and two additional categories, that is, animals and microorganisms. A previous consensual arrangement following the kingdoms of living organisms was discarded, as complete agreement does not exist among biologists on the number and delimitation of these kingdoms and, in addition, we did not find any of those classifications to be, in our opinion, functional and simple enough for culinary products. We adopted the term "world" to define each unit, because it did not bear any biological taxonomical connotation and it is clear, evocative, and intuitive. Within each group of organisms, according to their main habitat along with morphological and phylogenetic relations, distinct categories can be found, where the primary level corresponds to the biological species in question (e.g., lemon tree or trout), and following levels vary according to distinct groups of organisms (e.g., peel of lemon or trout fillet). Such levels, which are very relevant to cooks, reflect one of the many contributions of gastronomy to the consensual taxonomy presented. On the other side, within inorganic materials two worlds were established: the VOLUME 20 ISSUE 3 SEPTEMBER 2017 world of waters and the world of minerals, and within them further categories were created according to their origin. For greater detail on the taxonomy and categorization within living beings see Table 2, and for inorganic materials see Table 3.

I. Living Beings
For all living beings, we basically follow the most recent biological classifications, some of them still in construction, at least at the lower taxonomic levels, according to the evolution of molecular datasets. Comprehensive projects, such as the Tree of Life (Maddison and Schulz 2007), along with some others restricted to specific biological groups, such as the Angiosperm Phylogeny Website for plants (Stevens 2013 , may provide ideas on the state of the art in biological systematics. However, this classification being conceived as a consensual one between different professional worlds (scientific and gastroculinary), these strictly biological scenarios could not be followed completely. For example, we could not use the structuring of life in several kingdoms (Margulis and Chapman 2009), because it did not work at a convenient and convincing level for both scientific and culinary professionals. Therefore, the classification of living beings was finally structured in what we called "worlds" (to avoid words such as "kingdom" or "domain", with a more biological connotation): plants and fungi (with both groups clearly mentioned); animals; and microorganisms. This classification does not strictly fit with current biological systematics and phylogenetics, but is understandable to all professionals and does not fall outside biological logics. As shown later, some major groups in the plant-and-fungi and animal domains have been established on the basis of habitats, which does not constitute a biological systematic criterion, but is adequate for cooking professionals, and makes easier the incorporation of new gastronomic groups, whenever necessary. In another case, cooks had to avoid the use of the term family for some food products (and to replace it with category or group), because such a term has a different and concrete sense in biological systematics. In the following paragraphs we explain and exemplify the solutions adopted for the different groups of living beings. The distinction between wild and cultivated (plants and fungi) or raised (animals), not relevant in biological classification (irrespective of the existence of infraspecific taxa and races), has been adopted, since it is meaningful for culinary professionals.
(a) Plants and fungi. Following the above-mentioned habitat criterion, within the world of plants and fungi (    Within terrestrial plants a distinction is made among grasses, subshrubs, shrubs, lianas, and trees. Within fungi, three groupings are proposed: Ascomycota, Basidiomycota, and lichens. Within macroalgae, three types are distinguished: green, red, and brown algae. Aquatic plants, all herbs, do not contain further subgroupings. It is to be noted that different criteria have been used in the classification of different organisms, for the sake of consensus. For plants the differentiation does not fit at all with taxonomical categories, but with life forms, which are much more intuitive. For instance, the distinction between pteridophytes and spermatophytes or that between gymnosperms and angiosperms has been avoided, as well as the lower categories (e.g., monocots, core eudicots, asterids…), because it was meaningless for cooking professionals. Conversely, for fungi and macroalgae, the basic biological categories have been followed (e.g., ascomycetes, red algae).
The aspects commented on above deal with what we have called the primary level, i.e., the whole plant or fungal organism. The secondary level consists of parts of plants or fungi (e.g. leaves, branches with leaves, fungal stipe) and the tertiary is composed of parts of parts of those organisms (e.g., seeds, peduncles). Those levels contain different categories depending on the primary level. These parts of plants or fungi, again, do not exactly fit plant and fungal morphology, but are not against it, and function without problems for culinary professionals. One case is the parts we named "fruits, fructifications and infructescences"; for cooking professionals, "fruits" was convenient, but they did not object to the larger and multiple term, which was correct from a scientific point of view (see Table 2 for greater detail and further examples than those provided here).
In some cases, the search for a compromise between scientific and culinary professionals led to the proposal of a neologism. Cooks termed "albedo" the white tissue found in figs (Ficus carica L.), by analogy with the similar part in citric fruits (Citrus sp.). This was not correct from a botanical standpoint, as oranges and their relatives are fruits, but figs are infructescences. Finally, we agreed in proposing the term "pseudoalbedo" for such a structure in figs. Nevertheless, terminological proposals of this kind also have to be further analyzed with linguists.
(b) Animals. The world of animals (Table 2) establishes an arrangement that, being scientifically correct, allows cooks to classify animals and their derived products easily and comprehensively. An agreement was reached to cluster animals according to their habitat: aerial, terrestrial, aquatic, and terrestrial-aquatic. In each environment up to four levels have been contemplated, from primary to quaternary.
A following step included taking into consideration the different groups with a culinary interest, to be included in each of these categories. In the primary VOLUME 20 ISSUE 3 SEPTEMBER 2017 level (whole organism), the zoological groups selected are presented in Table  2. Within each environment, the criterion used to arrange categories has been to consider the most consumed culinary groups. Such ordering allows us, as new gastronomic groups arise, to add to the corresponding type. In some cases, such a classification has required certain adaptations to reality. Insects are probably the most complex case, with several species being edible. When we think about insects we imagine terrestrial organisms that move in the air, hence being included within aerial organisms. But most edible insects have terrestrial larvae, which are generally more gastronomically valued than adults, while larvae live longer than adults. That makes it difficult to include them unquestionably within the aerial or terrestrial habitat, hence its being more practical to consider their aerial habitat when the adult is eaten, and the terrestrial in the case of larvae. Other examples include mollusks, which comprise terrestrial and aquatic organisms, and, within the latter, marine and freshwater. In such circumstances each species is located where it corresponds. On the other hand, reptiles, generally terrestrial (e.g., lizards, snakes), also consist of taxa such as turtles that can be terrestrial and aquatic. Marine turtles, though they have an aquatic life, reproduce on land. The opposite occurs amongst amphibians, most of which have a terrestrial life (e.g., toads, frogs) yet reproduce in aquatic environments.
While ordering groups within categories in each habitat, criteria of biological taxonomy have prevailed. This has been easier in certain cases but had to be adapted in others. Birds, for instance, are situated in the aerial environment. Within such a grouping, organization follows taxonomic criteria: Galliformes, Estrucioniformes, Passeriformes, Anseriformes, etc. The advantage behind such a structure is that, if a bird starts to have culinary interest and is not represented by the existing orders, it needs only to be added. Internal classification for mollusks has been simple as there exist three zoological groups: bivalves (e.g., clams), gastropods (e.g., terrestrial and marine snails), and cephalopods (e.g., squid, cuttlefish, and octopus). In the terrestrial environment all are gastropods, and in the aquatic there is only the need to differentiate marine vs. freshwater species. In other taxa, adapting to culinary criteria was more practical. Such is the case of mammals. In such a cluster, a biotaxonomic ordering was followed: bovids, porcines, etc. Nonetheless, for bovids-a group that includes most edible mammals (e.g., veal, sheep, goat, and buffalo)-such grouping under its taxonomic name, popularly evoking mostly the cow and related animals, is not discernible enough for a cook. In such case the taxon has been subdivided into bovine bovids (e.g., veal, cow, and ox), ovine bovids (e.g., sheep, lamb), caprine bovids (e.g., kid, goat) and other bovids (e.g., buffalo, bison). For crustaceans-all aquatic-we have opted for a practical classification, taking into account the means of locomotion. Three categories have been created: swimmers (moving in a water column, such as shrimp, lobster, and langoustine), walkers (moving on top of the substrate, such as brown crab and velvet crab) and cirripedia (living fixed to the substrate, such as barnacles). Not all crustaceans are marine; there are also freshwater species, such as the river crab. In the case of other groups with very specific characteristics, for instance echinoderms (sea cucumbers), tunicates (sea potato) or cnidarians (sea anemones, jellyfish), ordering has been easier.
The secondary level includes the morphological parts easily identifiable externally, into which the animal can be divided, i.e., head, body, and extremities. Nevertheless, not all animals have their bodies anatomically organized in the same manner and this affects the number and structure of pieces used in the kitchen. For instance, adult insects have their bodies divided into head, thorax (includes legs), and abdomen, while larvae have their head differentiated from the rest of the body. In crustaceans, decapods (the most valued, i.e., shrimp, crab) have their body divided into cephalothorax (fusion of head and thorax including legs) and abdomen (known as tail). For fish, the body is simplified and the head, body, and fins are recognized. The most complex case is for terrestrial vertebrates, such as birds and mammals, where the main parts are identifiable but their utilization requires the establishment of more parts. The neck belongs to the trunk yet gastronomically is treated separately. Further, a distinction is also needed between anterior extremities (wings, shoulders) and posterior (thigh) although, usually, combinations of parts occur (e.g., forequarter, hindquarter, and half carcass).
The tertiary level refers to the parts of the parts (secondary level), with examples such as the brain or the tongue as parts of the head. In the world of animals, in contrast to that of plants and fungi, a quaternary level was necessary. It corresponds to the tissues, such as tendons, which can come from different parts of the animal body. Not all groups of animals have the four levels described above. An interesting challenge has been to describe the derived products. At first, it seemed clear to define a derived product as a product obtained from an organism without causing it any injury. It could include some resins, pollen, or nectar in the case of plants, and eggs or milk in the case of animals. The problem appears when facing immature eggs or blood of animals, which cannot be obtained without damaging them. In this case we decided to treat them as quaternary-level items.
(c) Microorganisms. Even though it has some important representatives, the world of culinary microorganisms (Table 2) is much smaller. It has been structured in four groups: viruses, to date without culinary use; bacteria (including archaea), comprising organisms such as lactobacillus and the bluegreen algae or cyanobacteria (among which Arthrospira sp.-several species formerly included in the genus Spirulina and that maintain spirulina as the popular name-are well known in cooking); protozoa and microalgae, to which, for instance, Chlorella sp. belongs; and microfungi (unicellular and filamentous ones), including yeasts and molds. In this case the transactions for a consensus have led to consideration in the microbiological world of some animals (protozoa), some plants (microalgae), and some fungi (microfungi), apart from the genuine microorganisms (viruses, archaea, and bacteria). Their microscopic VOLUME 20 ISSUE 3 SEPTEMBER 2017 condition, clearly intuitive, has taken precedence over the strict biological classification, although not being in contradiction with it. As is logical, no different (primary, secondary…) levels are distinguished in this world.

II. Inorganic Materials
Regarding the inorganic materials classification (Table 3), two different worlds have been considered, i.e., waters and minerals. For the two cases, previously used classifications in gastronomic scenarios have been modified and adapted by applying scientific standards. As an example, scientific terms such as geological origin or crystal morphology and crystal size were employed in order to develop the classification of waters and minerals, respectively. The main criterion used to carry out such a classification distinction in both cases was the origin of the material. However, some additional aspects related to each world should be taken into account.
(d) Waters. Most commonly used classifications for potable waters are based on their composition in major cations (such as Na + , Ca 2+ or Mg 2+ ) and anions (CO 3 H − , Cl − , SO 4 2− , F − , SH − , etc.) (Domenico and Schwartz 1990), which strongly depends on the paths travelled through their evolutionary history. In the present work, we classified the world of waters (Table 3) according to their origin: superficial, subterraneous, and seawater. The superficial waters category includes river, lake, and glacier waters (all of them being non-carbonated waters), whereas the subterraneous waters category comprises natural mineral and natural spring waters, which can be non-carbonated or carbonated through natural and/or artificial methodologies. Subterraneous waters eventually emerge from below the Earth's surface or they can be forced by using specific techniques. Nevertheless, the main difference between natural spring and natural mineral waters resides in the fact that natural spring waters are not characterized by their mineral composition, thus they can become variable. As to natural mineral waters, only two actions are permitted: (i) to modify and normalize the carbon dioxide content; and, (ii) to reduce or eliminate the presence of unstable compounds in order to avoid unpleasant flavors and/or colors.
(e) Minerals. The most commonly used classification for the world of minerals (Table 3) is based on their chemical composition and structure (Gaines et al. 1997), where, according to new actualizations, biominerals, understood as minerals produced by the activity of living things (e.g., bones, shells), may also be considered. In the present work, we focused on common salt (sodium chloride, with the mineral name of halite), which is commonly used in cooking and, depending on its origin, may provide specific characteristics to the end food product. As an example, one may note that pink-or black-colored fossil salt may occur due to the presence of other mineral impurities. In the different types of salt obtained from salt lakes and salt flats, such as flower of salt or salt flakes, the different crystal morphologies may play dominant roles for determining certain physical properties (e.g., rapid solubility), which may be directly applicable to specific food products.
As in other scientific classifications from the periodic table of elements to the molecular taxonomy of living beings, the current classification will evolve according to new parameters and criteria, while maintaining its culinary application. Nonetheless, the essence of the classification will not change drastically.

Concluding Remarks
The existing gap in the taxonomy of professional cooking, with the interaction between cooks and scientists, has allowed the creation of a combined system of classification that is useful for cooks and consistent with scientific knowledge. Such a new taxonomy establishes five worlds (plants and fungi, animals, microorganisms, waters, and minerals) each with a variety of hierarchical subcomponents, which are mutually exclusive and subdivided into distinct levels according to their parts.
The resulting classification generates a flexible ordering, which is highly practical, that allows modifications and new introductions without changing its main structure. Hence, it is not a closed system but a taxonomy allowing all incorporations that may rise. Being conceived to be flexible enough to adapt to change when needed, it intends to be valuable for professional cooks as well as for food scientists, amongst others.
Despite major background differences between botanists, zoologists, microbiologists, mineralogists, nutritionists, food scientists, agronomists, chemists, linguists, cooks, and people from other disciplines, a diverse team has worked side by side on the project, obtaining overall agreement on the resulting classification.
We hope that this classification system will be useful in the classroom, as well as at home and in restaurants, for chefs, bartenders, and foodies. This classification is already part of the curriculum of the new undergraduate studies in Culinary and Gastronomic Sciences (Universitat de Barcelona and Universitat Politècnica de Catalunya) with the idea of later being included in other culinary studies.
We are now in the process of the categorization of most common ingredients in Western cuisine-numbering over a thousand-into the different ranks, levels, and categories. Future work in this taxonomic effort will involve the classification of elaborated products, i.e., those having undergone some kind of processing (e.g., bread or guacamole), in addition to cooking tools, techniques, and other culinary aspects. We are also working on the terminological analysis and standardization of all the terms that appear in the classification. We are focusing, at this point, on the Catalan language and we are working together with the linguistic services of the Universitat de Barcelona and TERMCAT, the center for terminology in Catalan of the Government of Catalonia. Barcelona, Prat de la Riba 171, 08921 Santa Coloma de Gramenet, Catalonia, Spain (perecastells@ub.edu).
Teresa Garnatje is a researcher on botany working on evolutionary botany and on ethnobotany, with particular attention to food plants. Correspondence may be sent to Institut Botànic de Barcelona (IBB-CSIC-ICUB), Passeig del Migdia s/n, Parc de Montjuïc, 08038 Barcelona, Catalonia, Spain (tgarnatje@ibb.csic.es).
Joaquim Gosálbez is a Professor of zoology, and is interested in the applications of animal science to food products. Joan Vallès is a Professor of botany whose research focuses on plant systematics and evolution and ethnobotany, with a special interest in food plants. Correspondence may be sent to Laboratori de Botànica (UB), Unitat associada al CSIC, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Avinguda Joan XXIII s/n, 08028 Barcelona, Catalonia, Spain (joanvalles@ub.edu).