The fair trade (FT) movement significant rise in the last three decades draws attention to sustainability values and ethical consumption in society. Based on social, economic, and political concerns within developed and developing economies, the FT movement began in the mid-twentieth century by selling handcrafts to assist citizens in developing countries excluded from mainstream markets.
Established to build an alternative to the conventional trade model -considered to exacerbate inequality, impoverishment, and environmental damage -FT expanded to promote an alternative form of trade for production and distribution in a range of commodities including mainly foods. As an alternative movement, the FT challenge was to avoid the pitfalls of dominant economic growth models and contribute to development inspired on sustainability and social responsibility (FF, 2001; FLO, 2003 FLO, -2004 Raynolds et al., 2007; Nelson and Pound, 2009; Dragusanu et al., 2014) . As stated by the Fairtrade Foundation (FF), Fairtrade "challenges the conventional model of trade and offers a progressive alternative for a sustainable future" (FF, 2001, p.13) and "changes the way trade works through better prices, decent work conditions and a fairer deal for farmers and workers in developing countries" (FLO, 2016 (FLO, -2017 . While the economic benefits of FT are noticeable, it is "the empowerment and capacity building nature of Fair Trade that will prove the most important" (Raynolds et al., 2004 (Raynolds et al., , p. 1119 for sustainable development in the longer term.
Given current and emerging environmental and climate change challenges and the need to reverse harmful effects of unsustainable consumption and production patterns (Clay et al., 2007; Akenji and Bengtsson, 2014; Brizga et al., 2014) , the potential of the FT model as an alternative trade movement that prioritizes sustainable development is worthy of examination. In the FT model, a percentage of their floor price -a price that is higher than the market price -is intended to address sustainability targets such as environmental protection and socio-economic development. Given the growth of the movement and its diversification, however, the way this model is implemented under the term fair trade requires some clarification. Table 1 combines data about mainstream FT organisations and explains the use of terms that may otherwise lead to confusion. 
When written in block capitals, the term refers to the trademark used as a label on certified products from Fairtrade International. Fairtrade International This is the Non-Governmental Organisation that manages the FAIRTRADE label.
Launched in 1997, it is headquartered in Bonn, Germany, and adopted this brand name in 2002. The organisation is a multi-stakeholder association of 23 member organisations composed of 3 producers' networks and 20 national organisations.
This is the original name of Fairtrade International. Today, it is the formal name for the entity that sets FAIRTRADE standards and provides support for producers to meet such standards.
Launched in 2008, WFTO is a membership organisation that includes organisations and individuals from 75 countries. It was formerly called IFAT (International J o u r n a l P r e -p r o o f Federation of Alternative Trade), which mainly traded handcrafts. Today, WFTO trades a broader range of products based on the 10 principles of fair trade.
An offshoot of Fairtrade International that was formed around 2011. The first letters of both terms are capitalised and followed by USA and this constitutes the organisation's brand name -which uses the organisation Fair Trade Certified as its certifying body. Fair Trade Certified is Fair Trade USA's label and the organisation sets its own fair trade principles.
Fair trade (no capitals except at the start of a sentence) is how the overall movement is referred to in this article (instead of fair-trade). Fair trade encompasses Fairtrade, Fair Trade USA, FLO, WFTO and related organisations that abide by ethical consumption principles.
In recent decades, the increasing FT revenues suggest a positive response from consumers to production based on ethical standards, even when it requires increased prices. FT standards include:
no discrimination based on race, colour, sex, religion, political opinion, national extraction or social origin; no tests for diseases prior to employment; no gender based violence; no child labour; no compulsory work; documented regular payments; a stable income to producers set above the market price; and WHS (Work, Health and Safety) conditions based on ILO Convention 155 for all workers.
These are some of the FLO requirements for FT certification (updated as per May 2019). Note that Fairtrade International or FLO is the dominant in the market, to which other organisations have joined over the years. Yet, FT as a movement holds only a small share of the global international trade (Raynolds, 2017) , varying "from 0.1 to 1 percent of the global trade" (Fichtl, 2007, p. 30) in their product categories, which include food, beverages, textiles, flowers, and gold. In an economic growth perspective, this small percentage generated almost €8,5 billion in revenues in 2017 ( Fig. 1) . To date, a range of discretionary products including coffee, chocolate, flowers, wine, and gold are substantially addressed in the expanding literature on FT. Considering that the majority of FT products are foods (Raynolds et al., 2004) , our review analyses FT in the context of food systems.
While on the one hand, FT innovative model for sustainable consumption and trade show potential to enforce changes in agricultural production, community development, food security, and environmental protection. On another hand, given the volume and value of the global market in staple foods, the apparent minor role of staples in FT schemes may challenge the movement's goals in expanding sustainable development practices. While there are plenty of review articles covering a variety of themes related to FT history, aims, and core products, to date there are no reviews on FT that cover staple foods. This systematic literature review is the first to examine the status of staple foods in the FT movement and as such, our primary objective was to identify the literature on FT and staples.
A staple food, according to the Food and Agriculture Organisation of the United Nations (FAO) "is one that is eaten regularly and in such quantities as to constitute the dominant part of the diet and supply a major proportion of energy and nutrient" of a population (FAO, 2009 ) and this is the definition adopted in this article. The FAO states that "just 15 crop plants provide 90 percent of the world's food energy intake, with three -rice, maize and wheat -making up two-thirds of this" (FAO, 2009 ). Wheat, maize and rice are the most produced cereals worldwide, according to FAO (2009). As such, those grains were key search items in this systematic review. In addition, other staples identified by FAO such as soy, oats, potato and quinoa were included, given that staple foods may vary across regions and cultures. Our study investigates the approach to staples within FT practices and published literature to identify shortcomings and advantages for sustainable development. While FT sets itself the task of promoting sustainable development and social change, it appears to concentrate on niche markets. This article also reflects on this ambiguity and apparent ethical dilemma.
While we bring attention to analyse the opportunities in expanding the range and reach of FT products, we are mindful of the risks of mainstreaming that some authors already identified. As defined by Le Mare (2008) , "mainstreaming refers to both increasing markets for FT within commercial retailers like supermarkets, and the increased application of FT practices and values by conventional companies" (Le Mare, 2008 , p. 1929 . Redfern and Snedkern (2002) believe that mainstreaming FT can benefit the poorest and reshape conventional markets or even government policies given the movement's resonance worldwide (Redfern and Snedkern, 2002) . Based on empirical results concerning coffee supply chain governance (as per MacDonald, 2007) , Le Mare (2008) remarks that the mainstreaming of FT coffee resulted in empowerment of farmers. This J o u r n a l P r e -p r o o f achievement does not imply that FT is always the good alternative, for any product, producer or developing country. Moore (2004) raises the issue that the FT model "works" exactly because it is marginal. FT primarily aims to address production and trade inequalities, but mainstreaming FT carries the risk of dilution whereby the fairness goal becomes disconnected in the process of commercialisation (Moore, 2004; Renard, 2003; Raynolds, 2000) . Le Mare (2008) believes that more research is required to analyse the effects of mainstreaming across different commodities to test how replicable is the FT model "in order to consistently enforce positive outcomes across markets" (Le Mare, 2008 , p. 1929 ). This review is placed in this pathway, as an exploratory study to answer the research question: what is the role of staple foods in the FT movement?
Currently, "twenty commodities" are produced and distributed "according to Fairtrade International standards" (Raynolds, 2017, p. 1481) yet only two among those foods constitute staples: rice and quinoa. Therefore, staple foods represent 10% of the total range of Fairtrade International commodities, which is in contrast with the prominent role of staple foods in mainstream trade, and in people's everyday food intake (FAO, 2009) . Several authors state that FT favours the implementation of global production standards (Blowfield, 1999; Barrientos, 2000; Gereffi et al., 2001; Hughes, 2001; Raynolds et al., 2004) , with potential to address sustainable development aims (Murray and Raynolds, 2000) , although with limitations (Barrientos, 2000; Moberg, 2005) . According to Barrientos (1999) , FT can be considered as "a paradox of globalisation" (Barrientos, 2000, p. 559) .
Globalisation is considered here in general terms as the "greater integration of the national economies in the world" (Lloyd, 1998, p. 161) . It is an "integrated international production system" (UNCTAD, 1993), which involves great advantages but also pitfalls. Globalisation has facilitated the world's production and consumption of goods and services, increased interconnectedness, and technology sharing, and lowered the prices of goods (Legarde, 2017) . It is widely recognised that globalisation has intensified economic, social, and cultural relations among nations. However, it has also generated remarkable side effects such as unemployment in industrialised economies, increased inequality, and income concentration (Cornia, 2003; Cappelen and Bjorvatn, 2004) , with significant negative environmental impacts (Panayotou, 2000; Wheeler, 2001 J o u r n a l P r e -p r o o f
The FT movement seems an attempt to address social and environmental values neglected by neoliberal globalisation via mainstream trade, which prioritises lowering production and input costs and prices for profit maximisation. While FT standards can be considered by some authors as an obstacle to globalisation and free markets or an "anti-globalisation" initiative (Moberg, 2005, p. 17) ;
for others it is a "new form of globalisation" (Raynolds et al., 2007, p. 7) that is able to respond to the "competitive 'downward spiral' in labour conditions in export sectors" (Barrientos, 2000, p. 559) . We see the FT initiative offering opportunities for social change in the emerging paradigm of corporate social responsibility (CSR), circular economy (CE), and new forms of governance (Lévy, 2007; Scherer and Palazzo, 2007; EMF, 2017; Murphy-Gregory, 2018) . FT relies on the conventional market to differentiate their products and create an added value that might work as a CSR model despite not constituting a complete substitute of conventional market practices.
Two opposing views on trade are usually found in the literature: liberalism versus protectionism. It is of note that unrestricted trade is found less often even in countries more open to liberalism such as the USA, which practiced "domestic interventionism" (Ruggie, 1994, p. 3) on post-World War Two.
Conversely, countries such as Canada, Australia, New Zealand, and European nations sought to eliminate internal trade barriers (Harris, 1989) . Many other countries practice a managed trade (Bagwell and Staiger, 1988; Ethier, 1991) , which means to restrict trade in some level (Kuttner, 1990) . We see fair trade as a type of managed trade that integrates social and environmental dimensions. And we argue for the increase of the FT socioeconomic and environmental impacts with stringent certification requirements to enforce the promotion of sustainable development not only on the small producer's side. Greater engagement with staple foods seems a logical next step and this matters as data from the FAO already demonstrated that small farmers make up half of the world population subjected to hunger (FAO, 2012) , hence excluded from globalisation potential benefits (Ribeiro-Duthie, 2019b).
In the context of general international trade, FT model may decrease the comparative advantage in price because buyers pay more for a FT-labelled product. However, this is a mutually voluntary initiative: producers choose to become fair trade certified, and consumers retain their purchasing choices. The increased value added by FT is recognised by consumers and FT foods are submitted to trade conventions equally to other goods in the marketplace. It is anticipated that the existing international trade order is likely to be recalibrated due to the Covid-19 crisis, and fair trade may face new challenges if nations seek increased protection for their markets. Despite the complexity of national and international markets and their intermediaries, which adds difficulty to the identification of suppliers' origin, the four major players in global markets for staple food products -the so-called ABCD companies -can be identified, as per Table 2 , and this may shed some light to our research questions.
Major companies in the staple foods market.
Archer Daniels Midland Co.
Trades over 40 million tonnes of grains and oil seeds and is the world's third largest processor of corn, wheat, cocoa, oil seed. The fact that the major staple food producers are giant transnational corporations headquartered in developed nations is a feature that may add barriers to the FT initiative in broadening the engagement with staple foods market in favour of small producers, due to asymmetric power relations. To map and analyse FT movement interaction with staple foods, we undertook this systematic literature review, which is structured as follows: materials and methods are presented at section 2; results constitute section 3; discussion and analysis of findings are set at section 4, together with thematic analysis of the reviewed literature. The conclusion outlines the limitations and contributions of this study, also suggesting areas for future research and development.
For the general materials' selection process, our approach was to retrieve all articles, papers, media briefings, studies, reports or published documents addressing staple foods in a fair trade modelvideos or podcasts were not a target nor included in the totals. Concerning FT organisations, the present systematic review included all FT models and associated organisations that released online CSR, sustainability, annual or financial reports. Two processes ran in parallel (Fig. 2 ).
Our methodological approach was adapted from Cochrane's Handbook for Systematic Reviews (Higgins and Green 2011) . Despite initially developed for Health, Cochrane's protocols allow wide use for conducting systematic reviews, from Engineering to Social Sciences. In addition, we considered recommendations for addressing qualitative results and synthesizing findings (Cooper and Hedges, 1993; Petticrew and Roberts, 2005) .
Considering FT organisations' official releases, the first stage was collection of available reports. The second stage was screening reports to find any mention of FT certified staples, or potential evaluation of certification for staple food products. Appendix A lists all reports reviewed. The search was undertaken in March 2019.
To collect general literature, the first stage was the search across the databases Business Source Ultimate (EBSCO), Google Scholar (GS), Scopus and Web of Science (WOS). In this stage, the target was the collection of all documents including either the terms 'Fairtrade' or 'fair trade' plus one term representing staples. The parameters of staple foods were drawn from FAO list of staple foods most consumed worldwide, to which synonyms were added to form our search string.
Boolean operators were applied to narrow our search as it follows: ("Fairtrade" OR "fair trade") AND ("staple" OR "rice" OR "soy" OR "corn" OR "maize" OR "wheat" OR "flour" OR "oat" OR "potato" OR "quinoa" OR "grain"). In the case of GS, as the operators showed inaccurate results, producing tens of thousands of hits that often did not include one term of each group; we employed a combination of terms in pairs without Booleans. By including GS, we observed some new results were added to our materials.
The literature retrieved included published academic papers, reviews, book chapters, thesis, conference papers, working papers, commissioned reports, and press releases. Therefore, when we refer to literature in this article, this includes academic and grey literature. Not all documents were available online and, in some cases, contacting authors or organisations was necessary to obtain a copy of a conference paper, thesis or article. A snowball approach was adopted to broaden the search by scrutinising reference lists of the literature retrieved.
After retrieving all materials, the PRISMA method (Moher et al., 2009 ) was a guideline to frame the screening process and remove duplications or findings which were out of the research scope. In some cases, despite the presence of the keywords, their mention was casual and did not refer to staples in J o u r n a l P r e -p r o o f cohort study; and expert opinion based on theory. In some entries, more than one approach is applied.
The selected entries draw mainly on field-work research using ethnographic, survey, and interview techniques to gather data, but also statistical analysis to assess impacts. The rich diversity of methods also brings obstacles to generalise findings.
In total, nine review articles about fair trade were found through our research strategy, none of these reviews included staple foods category. Therefore, those reviews are not listed among our findings as they did not fulfill our eligibility criteria, albeit being studied to inform on FT in general. The results confirmed there is no review that cover staple foods: a gap that the present study addresses. In 2009, Nelson and Pound's meta-review concluded that "no impact studies on Fairtrade were found for cotton, sugar, tea, rice, nuts or other commodities for which there are Fairtrade standards" (Nelson and Pound, 2009, p. 5) . Although that review was limited to FLO and referred to impact assessment studies commissioned by the Fairtrade Foundation, the work constitutes a source for assessing the research agenda on FT.
The outcomes of our comparative analysis structured into five thematic topics are presented in the discussion; and Table 3 Turning to the 20 FT organisations' business reports in our sample, we mapped the variety of staples within FT schemes over the years and assessed the FT movement's approach to staple foods. The results are set out in Fig. 4 . It should be noted that the terms "staples", "grains", "maize" and "oats"
were also identified in these reports though in the context of companies, products, and meals rather than related to FT certification. Hence, they were not included in this qualitative synthesis (Fig. 4) . Overall, the results indicate that studies on FT and staple foods are exiguous. Not only are there few staples included in FT schemes (Fig. 2) , there is no theorized explanation as to why this is so among the studies retrieved. Although staple foods are not core FT products, some are included in the FT system as our analysis confirmed. One FF report details prospective studies on the inclusion of soybeans in the scheme, but there was no reference to it in subsequent reports (Fig. 4) . Possible barriers to engagement with soy in the FT model, as indicated in the reviewed literature, can be issues of "reduced opportunities for direct branding through consumer-facing label" (Potts et al., 2014, p. 2); its use as an intermediary input such as livestock feed; environmental standards (organic production is prioritized within FT schemes); forest protection (largest soy producers are in the Amazon region); and market demand where China is the main purchaser and its requirements for production practices are already in place (Potts et al., 2014) . Our review also indicated previous attempts to include other staples such as sweet potato in the FT model. However, such food product was not mentioned in subsequent reports, what seems indicative that their inclusion did not proceed.
Among the FT staple food products, rice is the most well-known, followed closely by quinoa. Van food, our analysis reveals that rice is also considered a high-end product. The aroma and flavour characteristics of some rice types grown in Malawi and the Philippines have facilitated FT certification Smith, 2014) . The inclusion of speciality rice in FT accords with other existing successful well-known FT commodities with speciality characteristics such as coffee, cocoa, and wine. This reinforces the notion that FT is a niche, even luxury, market.
Quinoa is an Andean cereal named by some consumers as a 'super grain' for its high nutritional value.
The international market for quinoa has expanded since the 1980s. Whereas rice is clearly a staple food, quinoa is a regional staple, and in Fairtrade reports, rice and quinoa sales are always presented together, therefore quinoa was included in this investigation about staple foods in the FT initiative, together with corn, maize, soy, potato, oats, and wheat.
These findings raise additional research questions about FT strategy and staple foods: why are staple foods not broadly included in the FT model? Is FT destined to remain a mere niche rather than mainstream market strategy? While it is likely that the FT certification of products follows some strategic rationale, it is not clear which of its identified priorities -sustainable development, poverty alleviation and addressing North-South market inequalities -take precedence.
Our aim in reviewing the FT reports and the academic literature on FT and staples was to determine the status of this sector within the movement. Our study provides an evidence base for understanding the nexus between FT and staple foods and raises a range of questions regarding the FT movement's aspirations, strategic focus, governance, reach, and environmental impact. To facilitate the discussion of those identified aspects, we structured our analysis into five interrelated thematic topics: supply, demand, governance, sustainability, and globalisation. These discussions propel a research agenda to J o u r n a l P r e -p r o o f better understand the shortcomings, advantages, and potential of the FT movement in engaging more intensively with staple foods regarding sustainable development aims.
Our literature review highlights a number of explanations for why producers of three staples (rice, quinoa and soy) find it difficult to obtain FT certification. Explanations offered included that (i) producers lack capacity due to low literacy, numeracy, and marketing skills related to procurement, logistics, planning, and sales; (ii) NGOs can be inefficient and add an additional layer of bureaucracy that increases costs (Lunardi, 2017; Smith, 2014) ; and (iii) the absence of government support can limit access to credit, processing facilities, and seed storage ( A factor that may affect prices of raw materials is government policy of subsides (or their removalthat may be required by trade agreements) driving the production with effects on availability and consequently, prices. As prices are subject to economic principles of supply and demand, this will affect inputs for staples and non-staples alike. Weather is another important factor that may increase or reduce the availability of raw materials in the market. To exemplify, heat waves are phenomena that can affect production and, as a result, price dynamics 1 . Therefore, climate change should be considered, as well as studies to address remediation and prevention of its adverse effects. Initiatives that look at reducing environmental impacts are necessary steps.
Supply side explanations, however, do not account for how the FT movement has overcome such obstacles in the non-staples sectors. While it is possible that coffee, cocoa and tea producers would benefit enormously from capacity building, NGO efficiency and government assistance, these factors are not clarified to the establishment of FT certification in these discretionary commodities. Are there features of staples production that are significantly different from non-staples production that might explain their limited FT presence? Possible differences include the following:
• The difficulty of obtaining a reasonable price premium for staples compared to non-staples;
• A lack of awareness and expertise among local FT representatives, certifiers, and consultants about the potential of staples; • A set of technical factors that make it difficult to grow the required volume of a staple crop to make it viable to meet international markets demand; • Difficulties in setting a higher floor price on basic foodstuffs as profits on staples come from large-scale sales unlike discretionary products.
1 Case studies report a heat wave in Russia that affected wheat production leading world prices to increase by 40% in 1988. A decade later, with optimal weather conditions, Russia's production returned to capacity and world prices went down by 15% (Karlin, 2018; Macrotrends, 2020) . This is an example of the volatilities in the staple foods market. Fair trade standards propose to protect producers from volatilities by setting a floor price above the market price (Dragusanu et al., 2014) , which is an important selling point of fair trade for producers.
Such factors, individually or collectively, may explain why staples are not the focus of the FT schemes. The major way FT does this for coffee, cocoa, and tea is to brand these otherwise 'like products' as preferable because they return a fair wage to producers and encourage more democratic and sustainable forms of production. The examples in our study are suggestive of how this could be done with regard to staples like rice, quinoa, and soy, but more research is required to examine if there are specific issues in branding staples as FT certified compared to non-staple discretionary food products.
It may be that FT is partially a victim of its own success in that small producers (and consumers) have come to view it as focusing almost exclusively on discretionary foods and that staples like rice, maize, wheat and potatoes are to be produced for domestic, not international, consumption. Such a perception might be associated to a lack of expertise by local FT practitioners in non-traditional FT products like rice, quinoa and soy -whose markets are dominated by large enterprises. It would thus be interesting to research initiatives where producers of maize, oats, potato, wheat, and other staples explored the FT option but ultimately did not pursue it. This aspect would be better reflected through interviews with FT practitioners or producers, a future step in our research agenda. Such study could enlighten on the specifics or technical production difficulties that producers experienced in marketing food commodities such as staples.
Turning to the demand side, some explanations as to why consumers are not apparently demanding FT staples in the same way as FT coffee, chocolate, and wine include:
• Consumer willingness to pay a price premium is indeed limited to discretionary goods;
• An actual absence of supply giving rise to an absence of demand;
• The 'invisibility' of many staples as components of processed foodstuffs.
On the consumer side, one possible explanation is the different pattern in consumer behaviour when purchasing speciality goods like coffee, chocolate and wine in comparison to necessities like rice, corn, oats and wheat. It may be that consumers are prepared to pay a price premium for an occasional and non-necessary purchase whereas they are not when it comes to purchases of everyday goods which are regarded as non-negotiable basic requirements that may compromise their income in the long-run. Investigate the way FT movement brands and advertises itself in consumer markets can shed light to the way consumers are conditioned to think about FT: referring to discretionary purchases and not staples? As it is known, FT is a premium product that does not necessarily aim to compete with normal market products but to challenge the conventional trade practices. The premium price is a hallmark of FT approach designed to support producers and their communities. The added value of FT increases the value of the product.
Studies have shown that smaller margins between a premium product and market product can reduce the sales volume of the premium product (Shapiro, 1983; Anderson et al., 2003; Bhattacharya and Sen, 2004; Schollenberg, 2012) . The effects of increased premium price on how consumers value the experience and the product are well established in the beverage sector for discretionary goods such as wine (Florkowsji et al., 2008) and coffee; the latter being FT's flagship product. Little is known about staples, but from our systematic review, indicates a similar approach to an heirloom variety of FT certified rice: the "grain's unique taste and its arsenic-free, high-antioxidant content" being considered a key selling point. In this case, the higher price was associated with a lower volume of production.
A range of issues around the structure and operation of the FT market can be anticipated as militating against sales in FT staples. The lack of supply of FT staples would induce a lack of demand since consumers cannot 'vote with their wallets' and purchase what is not available. More importantly, perhaps, it could be that the FT system depends on selling goods at a significant price mark-up in order to make the entire supply chain viable and such a mark-up is not viable for staple goods, unless a high volume sales is assured. To secure high volume sales, small producers have to be well organised, and usually cooperatives can better deliver this level of procurement and logistics skills. It would be very important to research whether this is a (perceived) limitation of the mechanism and how it can be overcome -since FT appears to be capable of making a major contribution to meeting the SDGs with special regard to small producers. Finally, the "invisibility" of staples as ingredients in many processed foods also needs to be considered, given that an important buyer of staples is the food processing industry. When people buy bread made from wheat, they usually have no idea of the complex supply chain that links their purchase to the welfare of producers thousands of miles away. This invisibility and disconnection from the producer and environmental effects of production may add obstacles to marketing strategies of the FT movement.
In regard to FT governance, the reasons for the lack of FT staples may include:
• Past experience within the FT movement linked to unsuccessful trials;
• A need for strategic focus on what is already working;
• A lack of resources and risk appetite to undertake new initiatives;
• Movement domination by non-staple producers and consumers;
• Consumer willingness to pay a higher price for staples insufficiently investigated.
It is unclear in the literature what steps the FT movement has taken to engage with staples. One reason to suspect limited engagement is that staples have not been identified as a separate category within the FT system, which instead appears to engage in a commodity-by-commodity analysis of its operations.
While this approach is understandable given the specificity of the factors influencing supply and J o u r n a l P r e -p r o o f demand, it could be that considerable effort has been invested into recruiting staples producers with only very limited success in rice, quinoa, and soy. Interviews with country-level FT movement organisers and consultants would help to answer this topic.
It is also possible that the FT movement is cognisant of the staples issue but has chosen to focus on the tried and tested discretionary goods for strategic reasons. A rationale may be that expanding the FT consumption of coffee, tea, chocolate, and wine is a means to generating wider awareness of the system to create future opportunities for other products. These strategic issues raise, in turn, the way in which the FT movement is governed, and decisions made. Raynolds (2016) highlights that the FT movement's governance arrangements have changed since its inception and it is interesting to reflect on the intersection between FT governance and its strategic plans and focus. Does the organisation have the capacity for deep self-reflection about its overall vision and purpose or is it more reactive to current interests represented by its board?
How much scope is there for mainstreaming FT and in which direction: expanding the range or boosting the existing commodities? This must be a constant question for any successful business: specialise or diversify? If mainstreaming FT is the answer, authors such as Renard (2003) , Moore (2004), Redfern and Snedkern (2002) have stressed the risks. The capacity of the movement for selfcriticism is important and it can be observed in the claim for increasing impact assessment studies of the system. Many of the existing impact assessment studies are the ones commissioned by FT organisations. Thus, they are not free of bias and this constitutes an important avenue for the FT research agenda. The capacity of the movement to address criticisms and renew its approach is important for the future of FT, a scheme that defines itself as promoting social change. Within our reviewed literature some key points of concern were identified including the complexity of standards; intensive use of intermediaries (NGOs); the limited responses to climate change, environmental protection, and food security.
We observe that the socioeconomic dimensions are some steps ahead of the environmental actions in our findings. This must reflect that FT's engagement with the environment has been piecemeal until recently and the organisation has placed more emphasis on socioeconomic than environmental impacts in their requirements for certification. We note, however, that this may be about to change following recent changes to Fairtrade International's standards (on April 2019) that relate to the environmental performance of small producers. Therefore, there is potential for the FT movement to boost their environmental performance. We see the establishment of targets and tangible indicators considering local contexts as a way of securing change and stimulating creative strategies to improve protection to the environment.
Drawing from our findings, Tayleur et al. (2017) recommends that areas in need of poverty alleviation projects are matched to areas targeted for biodiversity conservation through certification, based on J o u r n a l P r e -p r o o f their proposed tools for geographical location. In other studies reviewed, environmentally positive impacts of FT were identified in its support for organic production and the training of farmers in environmentally friendly techniques. Socioeconomic benefits associated with these changes were also identified, which included a guaranteed income for small farmers, capacity building, recognition of small producers' work, opportunities to acquire and share knowledge, and securing access to education for the children of small scale producers (Udomkit and Winnet, 2002; Barker, 2007; Becchetti et al., 2011; Lyon, 2015; Carimentrand et al., 2015; Vent et al., 2015; .
As observed, income is the most common dependent variable to assess the impact of FT and it is treated independently from the movement's other benefits. When quantitative studies are employed, it is important to pay close attention to the dependent variable. Such a limited dependent variable is no longer appropriate in the new era of the Anthropocene and as the world makes a just transition to the sustainability paradigm (Gale, 2019) . The early seeds of such a paradigm shift are beginning to sprout with the emphasis to responsible production and consumption (Akenji and Bengtsson, 2014) ; adoption of CE (Xavier et al., 2019) ; technology transfer; environmental governance (Murphy-Gregory, 2018) ; and the use of renewables in developing countries. Therefore, when attempting to assess whether a project, process, or practice is delivering sustainability actions, analysts need to contextualise any income effects within a broader set of differently measured social and environmental benefits (Schmelzer, 2006) . Hence, focus on shared value or sustainability value would be more appropriate (Porter and Kramer, 2011) .
A noteworthy environmental benefit of FT and staple foods in comparison to other FT products was identified in the study by Makita and Tsuruta (2017) . This study highlighted a successful initiative in Thailand to connect urban consumers to rural farmers by making household food waste available for agricultural compost production. The example demonstrates some potential for FT to support the transition towards a CE paradigm -which entails the use of waste as an input for another stage of the food production when the desirable avoidance of waste is impossible. Applied to food systems, CE principles highlight the potential for food redistribution; and food waste use for compost or energy generation (EMF, 2017; Ribeiro-Duthie, 2019a) . The incentive to reduce the costs through environmentally friendly techniques as, for instance, the use of solar powered pumps for irrigation is another valid incentive for a cleaner production. Biogas digestors and the production of biochar from waste have potential to be used where suitable, and that adds value to production process and reduces waste and environmental impact -another example that can be aligned to the principles of CE. Nelson et al. (2010) argue that climate change poses a variety of challenges and opportunities for Fairtrade and they identify a number of potential impacts that the organisation and its producers should focus on. These include producer standards, trader standards, capacity building and networking, policy, advocacy governance and research (Nelson et al., 2010) . Vent et al. (2015) discuss the importance of rice within the Cambodian diet and the efforts made to increase rice production for food security (subsistence) and for exports by using the agroecological methodology of J o u r n a l P r e -p r o o f System of Rice Intensification (SRI) to meet, among other aims, organic and FT requirements. The relevance of SRI is that rice is the primary user of water, and the "main source of methane emissions" in Cambodia (Vent et al., 2015, p. 73-74) ; in addition, climate change and other environmental issues affect rice production. As there are many negative effects from conventional rice production on producer's health and the environment, SRI could be an example of how FT applied to staple foods could address climate change even though SRI is not an exclusive FT practice.
We see the example of Cambodia's SRI, and Thailand's cultural dimensions integrated to a FT certification system showing that stringency regarding environmental standards can bring robust results when local contexts are recognised and integrated into the FT model. Disposal and reuse of waste, gas and energy generation are existing practices within food systems that could improve FT's environmental footprint, which also addresses the so claimed CE principles. The adoption of initiatives as such would allow FT producers, and the movement, to increase their environmental credentials.
While the alternative trade model aims at promoting sustainable development, it also provides an opportunity to address the globalisation pitfalls of intensive production associated with lower prices and its impacts to increase inequality. This is thoroughly discussed in the literature concerning quinoa Carimentrand et al., 2015; Lyon, 2015; Trinley, 2017; Lunardi, 2017) . Sharma et al. (2018) note that the globalisation of food chains has been "unfair for the grass root rural livelihoods" (Sharma et al., 2018, p. 450-451) , harming the environment and being unsustainable in the long run. Recognising the sustainable development potential of FT, Sharma et al. (2018) studied FT's association with sustainability parameters using a sample of rice farmers from India. They found that "farmers with FT systems score significantly higher when compared with farmers following conventional system on all indicators of sustainability dimensions except vulnerability" (Sharma et al., 2018, p. 464) . For farmers from Ifugao Province, turning Tinawon rice into an export commodity brought "implications for social organization, local development, and sustainability" (Sekimoto and Augustin-Jean, 2010, p. 182) .
Some studies, such as Wilkinson (2011) , argue in favour of less dependence on South-North trade as a means of economic advancement for peasant farmers. Makita and Tsuruta (2017) identify opportunities within Asia for a new kind of globalisation that matches organic consumers to organic producers. This could engage produces in countries like China, India, Thailand, Indonesia, the Philippines, and Vietnam which practice "large scale cultivation for export" (Makita and Tsuruta, 2017, p. 99) with consumers in Japan, South Korea, Taiwan, Hong Kong, and Singapore that are consumers of organic production (Makita and Tsuruta, 2017) . Likewise, Winkel et al. (2012) suggest that globalisation of the quinoa market is driving change towards research cooperation: "the J o u r n a l P r e -p r o o f increasing competition in the international quinoa market requires a shift towards more ethical economic relationships with exporters and ethical research cooperation with quinoa producers" (Winkel et al., 2012, p. 318) . The effects of globalisation over producers, communities and the environment with quinoa's peak in market and exports volume are a key lesson learnt from the staples group of commodities, even though not only related to FT effects. From those studies it is of note the key role FT system can play to address unsustainable consumption and production practices.
This initial exploratory research has pointed to compelling questions. What are the identifiable determinants of the FT choice of products? Are there past unsuccessful attempts to include staple foods in the FT system that are non-reported? Is the choice of products related to FT's governance strategies? These aspects constitute future directions to be explored in further studies using other methodological approaches.
While there is a well-established link between a cup of fair trade certified coffee and the social change it encompasses for consumers voting with their wallets, how does the FT movement approach staple foods to which a greater number of consumers are exposed to? What does the existing literature and the main FT organisations report about FT and staple foods nexus? Our systematic review confirms the scarcity of publications, and the need for broader understanding of the rationale of the FT system in selecting their products. This systematic review demonstrates that while 29 studies and 20 reports mention FT staples, only a handful analyse staple foods features within the FT model. As this article focused on FT and staples, only literature relating to FT staple foods was reviewed.
The findings from this review demonstrate a diversity of methodologies and disciplinary areas that make it almost impossible to generalise data -which can be seen as a limitation of the review's outcomes. Notwithstanding, they pave the road as a preliminary study on the relations of staples and the FT movement. If there is a role for staple foods within the FT model, it is not clearly stated nor This review has also sought to contribute by analysing the obstacles and opportunities for broadening the range and reach of FT system via the inclusion of FT models for staple foods to further FT goals of contributing towards sustainable development. We recognise that there could be many reasons for J o u r n a l P r e -p r o o f the lack of emphasis on staples, however as it stands, the literature tells us very little about what those reasons are and whether they are linked to a lack of FT strategy or to structural features and dynamics of staples production and distribution.
While there are hints to be gleaned about the general relationship between FT and staple foods in the studies we analysed in this article, it is unclear whether these are country or commodity specific. It appears necessary to step beyond the bounds of the literature and directly engage with the FT movement itself. As a follow up study, we intend to interview FT producers, practitioners and experts to further explore the relationship between FT and staples. It is important to undertake more research to answer the raised issues since there are good reasons to believe that FT constitutes an alternative model of trade that is better adapted to delivering the SDGs than the current energy and inputintensive industrial global market exchange model. We believe that FT can make a more significant contribution to sustainable development if the perceived and real barriers regarding staples are overcome. This systematic review mapped out the state of knowledge on FT certified staple foods and it can contribute by informing decision makers, policy makers, businesses interested in sustainable development practices, NGO's, producers, and consumers.
To the Australian Government for the Research Training Program Scholarship provided. To the anonymous reviewers for their careful reading and insightful suggestions.
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. J o u r n a l P r e -p r o o f Table 1 . FAIRTRADE When written in block capitals, the term refers to the trademark used as a label on certified products from Fairtrade International. Fairtrade International This is the Non-Governmental Organisation that manages the FAIRTRADE label.
Launched in 1997, it is headquartered in Bonn, Germany, and adopted this brand name in 2002. The organisation is a multi-stakeholder association of 23 member organisations composed of 3 producers' networks and 20 national organisations.
This is the original name of Fairtrade International. Today, it is the formal name for the entity that sets FAIRTRADE standards and provides support for producers to meet such standards.
Launched in 2008, WFTO is a membership organisation that includes organisations and individuals from 75 countries. It was formerly called IFAT (International Federation of Alternative Trade), which mainly traded handcrafts. Today, WFTO trades a broader range of products based on the 10 principles of fair trade.
An offshoot of Fairtrade International that was formed around 2011. The first letters of both terms are capitalised and followed by USA and this constitutes the organisation's brand name -which uses the organisation Fair Trade Certified as its certifying body. Fair Trade Certified is Fair Trade USA's label and the organisation sets its own fair trade principles.
Fair trade (no capitals except at the start of a sentence) is how the overall movement is referred to in this article (instead of fair-trade). Fair trade encompasses Fairtrade, Fair Trade USA, FLO, WFTO and related organisations that abide by ethical consumption principles. J o u r n a l P r e -p r o o f Major companies in the staple foods market.
Source: UN Food and Agriculture Organisation (FAO 2003) , Murphy et al. (2012) . Table 3 .
Selected literature: staple foods, reference, type of literature, methodological approach, and disciplinary areas of the findings.
Mainstream FT Organisations' Reports reviewed:
J o u r n a l P r e -p r o o f