## 2 Food Ontologies  
In this section, we review the following food ontologies: FoodWiki [18], AGROVOC [19], Open Food Facts [20], Food Product Ontology [21], and FOODS (Diabetes Edition) [22]. Table 1 below presents a summary of these methods in terms of their various properties and characteristics. It is obvious that some ontologies are designed to serve a specific purpose, while others are intended to be an open project for collaboration and contribution. AGROVOC is the most mature database/ontology, covering almost all kind of food products. This is not surprising since AGROVOC started more than three decades ago and is supported by world organizations and government agencies. Open Food Facts is becoming a \"Wikipedia of food\" and follows the same structure of contribution, where contributors manage their own inputs and edits; thus, making it very dynamic with updates added almost every day. FoodWiki and Food Product Ontology are designed to integrate with national databases to track food products produced in their corresponding countries. While these ontologies are helpful, their use is only limited to people tracking packaged food included in some ministerial database. Finally, FOODS has recently evolved to a service targeting people with diabetes and their dietary needs.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Ontology name** & **Type of food** & \begin{tabular}{c} **National/** \\ **international** \\ **coverage** \\ \end{tabular} & **Technology** & **Availability** & **Advantages and disadvantages** \\ \hline FoodWiki [18] & Packaged food & National food products (Turkey) & OWL, RDF & Mobile App for end users & Comprehensive coverage for national packaged food products. Limited only to food products included in the ministry’s database. \\ \hline AGROVOC [19] & All kind of food & \begin{tabular}{c} Worldwide \\ \end{tabular} & \begin{tabular}{c} OWL, RDF, RDFS, OWL \\ SKOS and SKOS-XL \\ \end{tabular} & \begin{tabular}{c} Free and can be \\ integrated with \\ any application \\ \end{tabular} & \begin{tabular}{c} Comprehensive coverage for \\ international food products (over 50,000 products). Covers all major \\ languages. Only experts and \\ organizations can use it. \\ \end{tabular} \\ \hline Open Food Facts [20] & Packaged food & \begin{tabular}{c} Worldwide \\ \end{tabular} & \begin{tabular}{c} OWL, RDF \\ \end{tabular} & \begin{tabular}{c} Free and can be \\ integrated with \\ any application \\ \end{tabular} & \begin{tabular}{c} Comprehensive coverage of \\ international food product. Data \\ may contain errors. \\ \end{tabular} \\ \hline Food Product Ontology [21] & Packaged food & National food products (Russia) & \begin{tabular}{c} OWL, RDF \\ \end{tabular} & NA & Product coverage is not clear. \\ \hline FOODS (A & \begin{tabular}{c} Thailand, but \\ trusted sources) and SPARQL \\ \end{tabular} & \begin{tabular}{c} RDF, linked data (from \\ trusted sources) and SPARQL \\ \end{tabular} & \begin{tabular}{c} Web-based \\ developed for people with diabetes. \\ \end{tabular} \\ Ontology-Driven System [22] & of food & \
\begin{tabular}{c} Worldwide \\ \end{tabular} &
\begin{tabular}{c} Query Language \\ \end{tabular} & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of the studied “food ontologies”.  
With the above summary in mind, let us now take a look at the details of each of these ontologies.