Peels for profit

A study on the range of agricultural waste, (cassava and yam) solutions in Ghana has revealed cassava peels can be used as alternative substrate for cultivating quality mushrooms. Samuel Doe Ablordeppey and Ama Amankwah Baafi have been studying the report and write 

Unlike the mushrooms that are only collected from the wild in forest regions during the wet season; March-September, cultivated mushrooms are available all year round.

But researchers say the availability of wild mushrooms is being threatened as a result of high rate of bush burning, deforestation and over-exploitation of timber and non-timber forest products in Ghana.

Therefore, the potential use of cassava peels as a supplement (and not a complete replacer) of mushroom cultivation is promising. Mushroom has high nutritive and medicinal value. It is a rich source of proteins, minerals and vitamins.

Gradually, there is a shift from overdependence on consumption of wild mushrooms that are collected to the consumption of cultivated mushrooms in Ghana. This presents enormous opportunities for mushroom growers, subsequently cassava farmers.

The opportunities include; growing demand for value added organic products, especially, in the food services industry like hotels and restaurants; opportunities for public-private partnerships in establishing large mushroom farms and cultivation of mushrooms for export.

There is also a growing health consciousness of consumers; increased processing sites and therefore opportunities exist for bulk volumes of peels at processing concentration sites; and employment generation opportunities.

Again, it will augment government policies and focus on agri-business and entrepreneurial development as engines of economic growth.

The study on the agricultural waste solutions was conducted by the Food Research Institute (FRI) of the Council for Scientific and Industrial Research (CSIR), under the Gains from Losses of Root and Tuber Crops (GRATITUDE) project, in collaboration with the Natural Resources Institute (NRI, UK), to reduce physical and economic losses of yam and cassava.

GRATITUDE, a four-year European Union (EU) funded project in Ghana, Nigeria and Vietnam, also seeks to add value to the tubers by processing them into other forms of finished and preserveable products.

One of the key focuses of GRATITUDE which is on the theme, “Reducing Post-Harvest Losses for Increased Security”, is improved utilisation of wastes (peels, liquid waste) to produce products for human consumption such as snacks, production of mushrooms and improved animal feed.

Although there are different types of substrates available for mushroom cultivation in Ghana, the use of sawdust is the most popular but has several limitations, including unavailability due to rapid deforestation, inaccessibility, high cost of transporting sawdust from wood processing sites and longer periods of composting.

Cassava (Manihot esculenta) is cultivated in all the agro-ecological zones in Ghana due to its tolerance to pests and disease and resilient to harsh climatic conditions.

Total production of cassava was estimated at 14.3, 13.5 and 12.2 million tonnes in 2011, 2010 and 2009 respectively. Over 90 per cent of farmers in Ghana cultivate cassava, a major staple food in Ghana with per capita consumption of approximately 153 kilogrammes per annum (MoFA-SRID 2011).

About 50 per cent of cassava that is produced is utilised fresh while the rest are processed into various products including gari (25 per cent), agbelima (18 per cent) and kokonte (five per cent) and (one per cent) industrial purpose (Adjekum, 2006 and Onumah et al., 2008).

Yam production estimates for 2009, 2010 and 2011 were 5.7, 5.96 and 5.85 million tonnes respectively. Its production is concentrated in the Brong Ahafo and the Northern Regions. Last year, Ghana exported approximately 27,000 metric tonnes of yam (MoFA-SRID, 2012).

The GRATITUDE study primarily, focuses on where waste are generated along the value chain (transportation and storage) and the ability to collect in large quantities from the processing points, either at the household level, village level or factory / industrial level. Insignificant proportion of peels generated at processing level are utilised for animal feed.

The survey findings show that over 90 per cent of the peels generated were either burnt or just left unattended to at dumping sites. Extraction of starch from liquid waste was limited.

In the case of yams, wastes are mostly generated at the consumption (households, chopbars and food vendors) levels since yam processing is very limited, only done by few small and medium enterprises (SMEs).

Yam peels constitute about 14 per cent of the volumes of yams consumed in Ghana and approximately, five per cent of volumes of yams traded go waste. However, the study proved bulking of yam waste at the household level will involve a lot of work; therefore, it makes economic sense to concentrate effort now on the potential use of cassava waste (particularly peels).

It recommended that cassava peels could be composited before using for the cultivation of mushrooms and even after the production of mushrooms, the spent substrate, which is rich in nutrients can be used for the preparation of animal feed (poultry and small ruminants) and bio-fertilizers for crop cultivation (Chang 1997).

Mushrooms thus have the capacity to convert nutritionally valueless substances into high protein foods (Hafiz et al 2003). Form the study four different methods of mushroom cultivation in Ghana were identified; (i) traditional method (ii) the high bed method (iii) the low bed method and (iv)the plastic bag method.

Currently number of mushroom growers in Ghana is estimated at 2500 and they are mostly concentrated in Greater Accra (close to 50 per cent), Brong Ahafo, Ashanti, Eastern, Volta, Western and the Central Regions of Ghana. Mushroom growers in Ghana can be categorised into micro, small and medium (highly commercial) scale growers.

Some of the growers produce and sell fresh mushrooms only, others sell both fresh mushrooms and compost bags while others sell fresh, dried as well as value added mushroom products.

In Ghana, mushrooms for food may be cooked fresh after harvesting, dried before utilising for food preparations and milled mushroom used for shito. At least 50 per cent of Ghanaian households consume mushroom (Apetorgbor et al., (2005).

The same study showed that approximately 41 per cent consume mushrooms due to the taste, 20 per cent due to availability and 12 per cent for medicinal purposes.

Other consumers use mushrooms as delicacies in soups and stews. Some mushroom growers indicated exportation of their products to other neighbouring countries but these are quite informal and not captured in the Ghana trade statistics. GB