In this study, a comprehensive assessment of the factors that determine the suitability of specific indigenous wood species for specific food contact materials was conducted using a survey research on a representative community sample of manufacturers, suppliers, retailers and consumers (end-users) of wooden food contact materials. This approach was reasoned to comprehensively elucidate the underlining reasons that dictate the choice of specific wood type for the manufacture, sale and utilization of specific food contact material.
The critical first step towards the potential use of a specific wood for food contact purposes is species identification. Wood species identification is important because: the intrinsic suitability of any wood for food contact purposes is species-dependent; the dose and types of beneficial or deleterious wood phytoconstituents that may augment or preclude its food contact use are species-specific; the commercial values of wooden food contact materials are species-dependent. The reason for which you need reliable identifications in order to make conclusions.
The reliance of species identification on acquired indigenous wood knowledge encompassing specific colour, distinctive texture, unique grain pattern and characteristic smell of species suggest guess-work is involved in the distinction between closely related species or in the identification of different species that have similar physical features
. In addition to the demonstrated low consumer indigenous knowledge of wood and its reflection in the disparate choices of species for selected food contact items made by consumers’ (end-users’) relative to that made by the combined group of manufacturers, suppliers and retailers, it is reasonable to conclude that visual identification of species cannot be reliably used by end-users for species distinction of marketed products. Although older consumers (end-users) will have much more experience and a relatively higher aptitude to make reliable purchases of historically proven species, most consumers (end-users) will be susceptible to species misrepresentation by unscrupulous retailers. Since the reliability of wood species identification through indigenous knowledge ultimately impinges on food quality and food safety, the implication of any deficiency in wood species identification, as observed in 15% of consumers (end-users), is not just the loss of chemical benefits from beneficial species but also potential exposures to chemical hazards from potentially toxic species phytoconstituents from toxic historically unproven species
[22–28]. For example, ethanolic extract of the stem-bark of Nyamedua (Alstonia boonei) impairs reproduction in male albino rats
 and contributes to nephrotoxicity in guinea pigs
. But the continued use of Nyamedua (Alstonia boonei) for food contact purposes belies its potential for toxicity if indeed its wood has similar phytoconstituent composition as its stem-bark.
For all types of food contact materials, species availability was found to be a key factor that determines the range of marketable products. But species availability has been adversely affected by rapid deforestation and the scarcity of some species including Odum (Chlorophora excelsa), Mahogany (Khaya senegalensis), and Sapele (Entandrophragma cylindricum) has placed a price premium on them and has also necessitated the use of alternatives species including Teak (Tectona grandis) and Kyere (Pterygota macrocarpa)
. But it is unknown to end-users, through the scant available historical knowledge, whether or not the lesser-known or lesser utilized alternative wood sources or the newly introduced species in response to the dwindled pool of previously available ones represent a more or a less physiologically beneficial alternative. These critical questions can convincingly be settled by scientific research that thoroughly examines the health-related consequences of wood-species derived bioactive compounds. Nevertheless, for all wood species in use for food contact purposes, an important context-related question is: what are the criteria for wood type suitability for food contact use? Despite the heterogeneity in shapes and sizes of wooden food contact materials, some common suitability criteria proffered as answers to this question by manufacturers and consumers (end-users) include durability, consumers’ (end-users’) demand, availability, price, attractive grain pattern, odour, wood density, colour and ease of use. It is also apparent that consumers (end-users) preferred aesthetically pleasing wood at relatively low cost, as demonstrated by their choice of colour and attractive grain pattern.
Although the application of these suitability criteria, on a historical basis, by manufacturers and consumers (end-users) has successfully established distinct species of wood in current use for food contact purposes, a common observation is that none of the enumerated suitability factors included potential chemical benefits or likely chemical hazards of wood phytoconstituents. This observation emphasizes the notion that the choice of wood for the manufacture of food contact materials in Ghana is dictated primarily by reasons other than the chemical benefits or the chemical hazards presented by wood phytoconstituents. Despite increasing recognition of the possible chemical transfers from wood to food
[12–17], respondent groups failed to indicate any awareness of chemical benefits or chemical hazards associated with the use of wood food contact materials. In fact given the opportunity to consider this health-related option in the questionnaire, neither chemical benefits with implied knowledge of medicinal bioactivities of wood phytoconstituents nor chemical hazards with implied toxicological knowledge of wood chemicals were chosen by respondents in their respective wood type suitability assessment. In all cases, respondents made erroneous assumptions that all species of wood used for the manufacture of food contact materials in the market were non-toxic and that no direct negative health-related consequences could result from their use. The study, therefore, demonstrates in a community setting, that the knowledge of manufacturers, suppliers, retailers and consumers (end-users) on benefits and hazards of wood phytoconstituents or extractives of food contact items is abysmally low. And this observation translates into species suitability determinant system that gives little or no credence to the impact of potentially beneficial or toxic phytoconstituents migrant from wood to food on human health. Taken together, these observations support the prevailing assumption that does not consider domestic wooden food contact items as viable avenues for the transfer of beneficial and/or toxic active principles to food.
The observation that Danta (Cistanthera papaverifera) and Mahogany (Khaya senegalensis) are the only two species used for the manufacture of all surveyed food contact items is particularly interesting because neither the strength nor the durability of both species are exceptionally high to justify the observed multiple usage. It is reasonable to assume that the phytoconstituents of Mahogany (Khaya senegalensis), valued for its myriad curative properties in ethnomedicinal practices, likely accounts for its preferences for all food contact items. In fact, Mahogany (Khaya senegalensis)-derived bioactive extracts are produced and marketed nation-wide as dietary supplements
The stem-bark extracts of Mahogany (Khaya senegalensis) contain alkaloids, saponins, tannins, flavonoids
 and limonoids of angolensates, ring D-opened limonoids and mexicanolides.
[39, 40]. Some of these phytoconstiuents are also present in the wood of Mahogany (Khaya senegalensis) at relatively lower concentrations. The possible phytochemical migration from Mahogany (Khaya senegalensis) wood to food is unknown. Therefore, assertive conclusions cannot be made on whether or not Mahogany (Khaya senegalensis) phytoconstituents leach into food. The recommended detailed scientific investigation into phytochemical migrants to food is long overdue.
But given the general lack of awareness of respondent groups to potential chemical benefits of species, it is also doubtful that the preferences for Mahogany (Khaya senegalensis) for multiple items are informed by its numerous medicinal activities. This notion is perhaps supported by the additional choice of Danta (Cistanthera papaverifera), a species with no known or widespread medicinal value, for multiple uses. On an item-by-item basis, banku ladle and wooden spoons have a shared utility, namely, their use for prolonged periods at high temperatures. As a consequence, both items can potentially transfer high quantitative levels of bioactive phytochemicals to food at the earlier times of use (mostly between the first and the third time of use). Banku ladles are used mostly in aqueous environments and at temperatures high enough to facilitate the transfer of polar phytochemical functionalities to food
. Similarly, wooden spoons used at high temperatures in both aqueous and nonpolar milleu facilitate the transfer of a large spectrum of phytochemical functionalities to food
It is also interesting to note that grinding pestles undergo significant attrition and wear during use and may likely leave residual ground wood in the food during contact. Wood phytoconstitutuent migrants resulting from the grinding action of the grinding pestle are probably responsible for the impartation of the unique taste to ground pepper and tomato sauce prepared from the combined use of grinding pestle and grinding bowl. Published reports on the hygienic suitability of wood as cutting/chopping board are contradictory with some studies suggesting comparatively higher bacteria accumulation and retention even after cleaning
[42–44] and others positing that the combination of hygroscopic properties and antimicrobial bioactivities of wood extractives enable satisfactory hygienic performance
[45, 46]. It is apparent from both sides of the argument that the cutting/chopping board will exhibit the highest tendency, among the eight studied food contact items, to act as an incubator for bacteria growth and will probably facilitates the transfer of more pathogenic bacteria to food than any other wooden food contact item
[3, 4, 9, 45, 47–52]. The use of Mahogany (Khaya senegalensis) for a chopping board can likely be accounted for by its myriad biological activities including potential antimicrobial activities. Antimicrobial activities have not been reported in the wood of Mahogany (Khaya senegalensis). But since the wood contains secondary metabolites such as alkaloids, saponins, tannins and flavonoids that are frequent hallmarks of antibacterial activities, it can be reasonably assumed that Mahogany (Khaya senegalensis) wooden food contact items may possess antimicrobial activities. It is unknown whether the phytoconstituents of Danta (Cistanthera papaverifera) and Odum (Chlorophora excelsa), the two most preferred species for chopping boards, have intrinsic antibacterial properties. These observations emphasize the continuing importance of the use of chemically safe wood for food contact purposes.
Although respondent groups failed to indicate, overtly, any knowledge of possible wood phytoconstitutuent migration to food, the general practice of “priming” new food contact materials seems to contradict their stated perceived lack of knowledge in this area. New food contact items are “primed” prior to use by immersion in hot water and/or thorough washing with hot water followed by a purposeful disposal of the bits of food that makes first contact with the wood. People “prime” their utensils to reduce the amount of chemical compounds that transfers to foods at the initial stages of use. “Priming” is by default a practical demonstration of possible phytoconstituent migration to food. Implicit in this general practice is the recognition that some potentially toxic or unpleasant chemical substances might transfer from wood to the food at higher doses during the early stages of use of the food contact item. And that the practice of “priming” reduces the concentrations of such chemical substances to low, possibly non-toxic, levels prior to regular use. This observation is demonstrated by the reduction in the initial “bitter” taste that wood phytoconstituents impart to the food that makes direct contact with the wooden cookware. Despite its high prevalence in Ghana, the practice, however, lacks direct report or reference in the literature.
The transfers of chemicals from wood to food represents an area in which published research information is meager and thus, the nature and pattern of such chemical migration remain largely undescribed. However, mechanistic sketches of phytochemical migration from wood to food
[15, 53] can be deduced from that of the most thoroughly studied example of chemical transfers to food, namely that of plastic food packages
[54–57]. Net chemical intake by humans from food that has made prior contact with wood is likely dependent on the species-specific concentration and on the rate of the chemical compound’s diffusional transfer to food
. Wood phytoconstituent migrants may elicit a wide range of beneficial and/or deleterious physiological responses in humans even at very low doses
[18, 59–63]. So that low beneficial or toxic phytoconstituent concentrations in the wood species coupled with the phytochemicals low diffusional transfer rates to food may be just sufficient, in some cases, to attain biological significant concentrations of some chemical substances in the human body
. These observations underline the importance of using toxicologically safe and/or chemically beneficial species for food contact purposes. A critical unanswered question that remains within this context is whether or not the net chemical intake by humans from wooden food contact items constitutes a problem that warrants the level of caution alluded to in this study. This field of study is unquestionably a fertile one for research and definitive resolution of this and many related seminal topics and questions require carefully controlled experimentations.
For a start, food contact item regulatory bodies and researchers in Ghana can initiate biochemical research that uses molecular features including cellular wood anatomy to accurately identify all species in current use for food contact purposes
[33, 64–66]. This approach will eliminate much of the guess-work and subjectivity associated with species identification by direct visual inspection and will pave the way for the complete chemical and biological characterization of all indigenous species in current use for food contact purposes. The documentation of the chemical compositional differences, including the presence of specific bioactive extractives or group of bioactive extractive among species, will provide a better understanding of species commonalities and differences
[67–69]. Chromatographic separation, via Thin Layer and Column Chromatography, followed by phytoconstituent isolation and spectroscopic-methods based structural characterization of key bioactive constituents will lead to the identification of the molecular types of all wood phytoconstituents on a species-by-species basis and a classification of these molecular groups into potentially medicinal or toxic active principles
[2, 70–72]. GC/MS, LC/MS and HPLC/MS analyses will furnish the relative concentration of known bioactive phytoconstituents in all available species
. Analytical chemistry methodologies will provide the baseline concentration of wood phytochemical migrant in common local foods prepared in the normal manner using specific wood species of food contact items as well as establish the human exposure levels to specific types of wood phytoconstituents migrants. Molecular biological studies will establish whether the species-specific dose of wood phytochemical migrants in food is sufficient to trigger any biological response and if it is, will decipher whether the physiological response is beneficial or deleterious. And if warranted, mechanistic studies will identify the molecular target(s) and the biological mechanisms underlying the putative beneficial or toxicological action of specific phytochemical migrants.
In the long term practical sense, the dependence of wood species use on oral transmission of historical knowledge is unacceptable because cultural and economic acculturation pressures from modern society may endanger this practice. Regulatory bodies in Ghana can document and preserve this traditional historical knowledge in a curated database, cataloguing each species’ distinctive features and providing a comparative perspective on differences in structural features between species, the biological and chemical differences within and between species as well as specifying the potential for chemical hazard or the likely health benefits on a species-by-species basis. The adverse effect of deforestation on species availability suggests that the use of chemically safe and beneficial alternative species from sustainably managed forest should be encouraged by regulatory bodies. To facilitate informed purchasing decision by consumers (end-users), regulatory bodies must insist that retailers label each food contact item offered for sale with both the indigenous and scientific names of species.
Coupled with the comprehensive scientific analyses already suggested, this approach will provide a scientific qualitative knowledge base that will safeguard the indigenous knowledge on old and new wood species that are chemically safe and phytochemically beneficial for food contact uses and will permit the seamless translation of indigenous knowledge consistent with scientific understanding of food safety among wooden food contact items.