Promoting food security and enhancing Nigeria's

Food Research International 76 (2015) 986–991

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Food Research International journal homepage: www.elsevier.com/locate/foodres

Promoting food security and enhancing Nigeria's small farmers' income through value-added processing of lesser-known and under-utilized indigenous fruits and vegetables O. Charles Aworh Department of Food Technology, University of Ibadan, Nigeria

a r t i c l e

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Article history: Received 11 January 2015 Received in revised form 28 May 2015 Accepted 3 June 2015 Available online 5 June 2015 Keywords: Food security Lesser-known indigenous fruits and vegetables Value-added processing

a b s t r a c t In Nigeria and other African countries, there are hundreds of lesser-known indigenous crops as well as other food plants gathered from the wild that contribute to food security and play vital roles in the nutrition of the people particularly the rural populace. These native crops and wild food plants that have received little research attention or extension activities and have been largely neglected by the mainstream of international science include a wide variety of wild indigenous fruits and vegetables that enrich the diet of the rural populace and could thrive with little care and without the use of costly agricultural inputs such as fertilizers, herbicides and pesticides. Among them are numerous fruits of Nigerian trees that grow wild in the rain forest and the woodland savanna zones or are cultivated on small, compound farms. These fruits that are consumed fresh are rich sources of nutrients including ascorbic acid, provitamin A carotenoids, minerals and nutraceuticals with health-promoting benefits. There is the need to promote the cultivation and utilization of many of these indigenous fruit trees including African star apple (Chrysophyllum albidum), African mango (Irvingia gabonensis), African or native pear (Dacryodes edulis) and hog plum (Spondias mombin) that are also of considerable environmental significance and protect them from uncontrolled wood felling activities that result in deforestation. Laboratory studies have shown that good quality fruit leathers, jams, juices and other drinks can be produced from several lesserknown and under-utilized Nigerian fruits and vegetables including African star apple (C. albidum), African mango (I. gabonensis), hog plum (S. mombin), tamarind (Tamarindus indica) and roselle (Hibiscus sabdariffa) using simple procedures suitable for small-scale commercial production including osmotic dehydration, openkettle jam-making process and mechanical juice extraction followed by hot water pasteurization. Removing the constraints to the development of small-scale food industries which include inadequate electricity supply, use of inappropriate technology, inadequate working capital, high interest rates, and limited access to banks and other financial institutions would facilitate commercial production of these value-added foods in rural communities thereby reducing post-harvest losses, promoting food security, enhancing small farmers' income and contributing to sustainable rural development. © 2015 Elsevier Ltd. All rights reserved.

1. Introduction Nigeria spans a total land mass of 923,768 km2 with 60–70% of the 170 million population involved in farming. Poverty is pervasive in Nigeria and it is estimated that about 70% of the Nigerian population lives on less than $1 a day (Canagarajah & Thomas, 2001; Oshewolo, 2010). Food insecurity is a major challenge in Nigeria; protein-energy malnutrition in children and micronutrient deficiencies (the hidden hunger) including Vitamin A deficiency and nutritional anemias remain important public health problems with dire consequences for productivity, maternal and infant health and intellectual development. For example, Nigeria and other West African countries have one of the highest under-5 mortality (168 per 1000) in the world (Murray, Laakso, Shibuya, Hill, & Lopez, 2007). Low food production, seasonal food shortages, high post-harvest losses, poverty, high food prices,

http://dx.doi.org/10.1016/j.foodres.2015.06.003 0963-9969/© 2015 Elsevier Ltd. All rights reserved.

high unemployment, poor health facilities, low level of nutrition education and cultural factors and taboos that reduce access to food contribute to food insecurity in Nigeria (Aworh, 2010). Agricultural production is very inefficient in Nigeria and crop yields are very low compared to the developed countries. Small, resource-poor farmers, often with holdings of less than 1 ha, account for over 90% of the output of most crops grown in the country with Nigeria spending about $8 billion annually on food importation (Aworh, 2010). Increasing productivity and improving post-harvest techniques and supply chains will increase Nigeria's smallholder farmers' income and therefore help fight poverty and secure better food and nutrition. In Nigeria and other African countries, there are hundreds of lesserknown indigenous crops as well as other food plants gathered from the wild that contribute to food security and play vital roles in the nutrition of the people particularly the rural populace (Aworh, 2014; NRC, 1996,

O. Charles Aworh / Food Research International 76 (2015) 986–991

2006; Stadlmayr et al., 2010). These native crops and wild food plants have received little research attention or extension activities and have been largely neglected by the mainstream of international science. Moreover, they suffer considerable post-harvest losses because of poor post-harvest handling practices, reducing their contribution to food security (Coursey, 1983; Joseph & Aworh, 1992; Olorunda & Aworh, 1983). Prominent among these native food plants are a wide variety of wild and cultivated indigenous fruits and vegetables of considerable horticultural and nutritional significance that enrich the diet of the rural populace and are available at certain critical periods of the year providing sustenance to millions of people when the more common sources are very scarce or completely unavailable (Aworh, 2014; Guarino, 1995; Okigbo, 1977; Schippers & Budd, 1997; Stadlmayr, Charrondiere, Eisenwagen, Jamnadass, & Kehlenbeck, 2013). They include green leafy vegetables such as Amaranthus cruentus, the most commonly grown Amaranth in Africa and other Amaranth species, water leaf (Talinum triangulare), Lagos spinach (Celosia argentea) and jute mallow (Corchorus olitorius). Other important lesser-known indigenous vegetables are the African eggplant or garden egg (Solanum aethiopicum, Solanum macrocarpon), which is widely distributed in the areas between the Guinea belt and the savanna, bitter leaf (Vernonia amygdalina), a perennial shrub frequently planted as a hedge or used as live fence in home gardens, fluted pumpkin (Telfairia occidentalis) which is commonly cultivated as an annual crop and is very popular in the diet of the Igbos, Ibibios, Efiks and other ethnic groups of southeastern Nigeria, Gnetum africanum, an important non-timber forest product in Nigeria and Cameroon, and leaves of the multi-purpose baobab tree (Adansonia digitata) popular in northern Nigeria and the savanna zone of other African countries including the Sudan (Aworh, 2014; Gebauer, El-Siddig, & Ebert, 2002; Yazzie, Vanderjagt, Pastuzyn, Okolo, & Glew, 1994). Prominent among fruits that grow wild in the rain forest of the humid tropics of southern Nigeria and in the woodland savanna that are consumed fresh are African star apple (Chrysophyllum albidum), African or native pear (Dacryodes edulis), African or wild mango (Irvingia gabonensis) and hog plum (Spondias mombin). C. albidum is a large berry, up to 6 cm long, that derives its name from the seed arrangement of its five large flattened seeds (Keay, 1989). It has an attractive fleshy pulp that varies in color from deep red through reddish or yellowish brown to light brown when ripe. The natural habitat of the African star apple is the lowland rain forest extending from Sierra Leone to East Africa (Keay, 1989). The fruits of African pear or safou (D. edulis) that are produced in hanging clusters on trees that may be up to 20–40 m tall are glossy in appearance and change from an initial pinkish color to bright blue and finally bluish black/black when mature (Keay, 1989; Okafor, 1981). The pulp is softened by dipping in hot water or hot ash for a few minutes before consumption. African pear is found naturally in the forest habitat extending from south-western Nigeria to Zambia and Angola, as well as in Sao Tome and Principe (Keay, 1989). In Nigeria, it is commonly planted in parts of the South-East but rarely in other parts of the country (Okafor, 1981). African or wild mango (I. gabonensis var. gabonensis), though a drupe with one large stone, is botanically unrelated to the conventional mango (Mangifera indica). The mature green fruits are 20.0–22.6 cm in circumference and weigh 131–184 g (Joseph & Aworh, 1991b). The ripe fruits have a fleshy, slightly fibrous, deep yellow/orange pulp with a characteristic turpentine-like aroma and a sweet taste relished by the rural populace in parts of southwestern Nigeria (Joseph & Aworh, 1991b). African mango grows naturally in the forest habitat of parts of Africa extending from Senegal to Sudan and south to Angola (Keay, 1989). Regrettably, these highly perishable fruits suffer considerable post-harvest losses minimizing their contribution to food security. There is also the need to protect them from uncontrolled wood felling activities resulting in deforestation. Numerous fruits of Nigerian trees that grow in the wild or on compound farms are not consumed in the fresh form, but rather are cooked, and together with a wide variety of wild and cultivated vegetables, form

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part of main dishes or are used as condiments imparting flavor and other desirable quality attributes to soups and sauces served with starchy staple foods made from roots, tubers and grains. A variety of the African mango (I. gabonensis var. excelsa) bears fruits with bitter, very fibrous inedible pulp surrounding an endocarp that bears two large, oil-rich cotyledons that are dried, milled and used in soups as a flavoring ingredient and to impart desired consistency on account of their stringy, gum-like properties. They may also be used for the preparation of dika fat (Okafor, 1981). The seeds of the African locust bean (Parkia biglobosa) are fermented to produce ‘dawadawa’, the most important food condiment in West and Central Africa (Campbell-Platt, 1980; Odunfa, 1986), while those of African oil bean (Pentaclethra macrophylla) are fermented to produce ‘ugba’ or ‘ukpaka’, a delicacy usually consumed with stock fish or dried fish mainly by the Igbo ethnic group of south-eastern Nigeria (Okafor, 1987). The shea butter nut (Vitellaria paradoxa) is a source of edible oil and has a number of other uses (Aworh, 2014). The seeds of several lesser-known species of the family cucurbitaceae are used as ingredients in soups. For example, melon (Citrullus lanatus) and fluted pumpkin (T. occidentalis) seeds are used for the production of soup flavoring condiments known as ‘ogiri’ or ‘ogili’ (Okafor, 1987). In addition, melon seeds are also used for the preparation of ‘egusi’ soup and oil may be extracted from the seeds and the residue fried as ‘robo’ (Aworh, 2014). The seeds of Lagenaria sicceraria are used for the preparation of ‘oseani’, a very popular soup among the Igbo-speaking people of Delta State, Nigeria (Badifu & Ogunsua, 1991). Promoting the utilization of lesser-known indigenous fruits and vegetables and other food plants through valueadded processing will increase their cultivation, reduce post-harvest losses and ensure that these important native crops and wild food plants that are part of Africa's rich biodiversity heritage are conserved.

2. Nutrient composition Tables 1 and 2 present the levels of some selected nutrients in some selected lesser-known Nigerian fruits and vegetables. Most of the fresh fruits and vegetables are good sources of fiber and are rich in carbohydrates but low in fat and protein with the exception of D. edulis that contains over 20% fat (Eka, 1980). However their nuts and seeds may contain high levels of protein and fat (Aworh, 2014). By and large, their main contribution to the diet is as sources of valuable vitamins and minerals that are vital for good health and wellness of the rural populace. In many localities, they are the most common and relatively abundant sources of ascorbic acid, folic acid and provitamin A carotenoids as well as other nutraceuticals including antioxidant pigments such as flavonoids that have ability to sequester or bind potentially toxic constituents and act as scavengers providing considerable health benefits (Okwu, 2005). In terms of mineral composition, potassium occurs in the highest concentrations in most lesser-known Nigerian fruits (Table 1) and vegetables (Table 2). Many of them are good sources of calcium and some that are good sources of iron include S. aethiopicum (18 mg/100 g), C. argentea (13 mg/100 g), T. occidentalis (10 mg/100 g), A. digitata fruit pulp (9 mg/100 g), A. cruentus (6 mg/100 g) and C. olitorius (6 mg/100 g). A. digitata (baobab) fruit pulp is very rich in vitamin C reported to vary from 162 mg/100 g in one tree to 499 mg/100 g in another (Sidibe, Scheuring, Kone, Hofman, & Frigg, 1998). Tamarindus indica (tamarind) and Dialium guineense (velvet tamarind) fruit pulp are much lower in vitamin C (less than 15 mg/100 g) than A. digitata fruit pulp (Table 1). Other lesser-known Nigerian fruits and vegetables that are among some of the best sources of vitamin C in the Nigerian diet include T. occidentalis (129 mg/100 g), C. olitorius (78 mg/100 g), G. africanum (56 mg/100 g), A. cruentus (56 mg/100 g), I. gabonensis var. gabonensis (54 mg/100 g), C. albidum (48 mg/100 g), A. digitata leaf (47 mg/100 g) and S. mombin (34–56 mg/100 g). They compare favorably with conventional tropical and sub-tropical fruits such as oranges, pineapples, papaya, mangoes and guava that are generally

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Table 1 Nutrient composition of selected lesser-known Nigerian fruits. Sources: Joseph and Aworh (1991a), Tiburski, Rosenthal, Deliza, de Oliveira Godoy, and Pacheco (2011), Adepoju (2009), Silou, Rocquelin, Gallon, and Molagui (2000), Eka (1980), Nour, Magboul, and Kheri (1980), Taylor (1987), Gebauer et al. (2002), FAO (1988), Ishola, Agbaji, and Agbaji (1990), Adeola and Aworh (2012), Okegbile and Taiwo (1995). Fruit

Moisture (%)

Carbo-hydrate (%)

Crude fiber (%)

Protein (%)

Fat (%)

Ash (%)

K (mg%)

P (mg%)

Ca (mg%)

Na (mg%)

Fe (mg%)

Vit C (mg%)

Irvingia gabonensis var. gabonensis Dacryodes edulis Chrysophyllum albidum Adansonia digitata fruit pulp Spondias mombin Tamarindus indica fruit pulp Dialium guineense fruit pulp

73.0 65.3 80.0 6.7 83.7 15–36 18.9

18.4 9.3 17.7 67.7 13.9 56–71 71.1

3.7 – – 5.3 1.9 2–5 4.9

1.8 3.0 0.6 15.2 1.1 2–9 1.6

2.2 21.2 0.2 0.2 0.6 0.5–7 2.1

0.9 1.2 1.5 4.9 0.8 2–7 1.4

300 142 – – 288 60 69

31 9.5 12.5 50.8 32.8 90 12

40 8.4 60 655 11.0 470 14

5.2 2.3 1.0 – 5.6 80 16

0.4 0.2 0.7 8.6 0.3 – 0.2

54 20 48 300 34–56 3–11 12

considered good sources of vitamin C (Baqar, 1980; Mudambi & Rajagopal, 1977; Thomas & Oke, 1980). While red palm oil is the best source of vitamin A in the Nigerian diet, many lesser-known Nigerian leafy vegetables such as C. olitorius (3130 μg/100 g), A. cruentus (2890 μg/100 g) and Hibiscus sabdariffa leaves (2580 μg/100 g) are good sources of β-carotene and contribute significantly to vitamin A intake (Stadlmayr et al., 2012). Consumption of traditional dark green leafy vegetables with fat significantly enhanced serum retinol and increased the percentage of preschool children with adequate retinol status in northern Ghana (Takyi, 1999). Lesserknown Nigerian leafy vegetables are among some of the best sources of folic acid (Stadlmayr et al., 2012). C. olitorius (118 μg/100 g), A. digitata leaf (118 μg/100 g) and A. cruentus (79 μg/100 g) are comparable in folic acid content with the better-known conventional herbage vegetables such as spinach (193 μg/100 g), broccoli (105 μg/100 g) and cabbage (66 μg/100 g). They, together with other traditional leafy vegetables, contribute significantly to dietary intake of this important vitamin that is present only in much smaller quantities in cereals and other Nigerian dietary staples (Aworh, 2014). 3. Value-added processing Small and medium enterprises (SMEs) are important components of the food processing sectors of the economies of the developed countries both in terms of number of companies and manufacturing value-added. Food SMEs that involve lower capital investment and rely on locally produced raw materials and improved traditional technology promote rural development and contribute to employment generation, poverty alleviation and food security (Aworh, 2010). The contributions that food SMEs can make to the Nigerian economy cannot be overstressed. Unfortunately, rapid growth and development of food SMEs in Nigeria is hampered by inadequate power (electricity) supply, adoption of inefficient or inappropriate technologies, poor management, inadequate working capital,

limited access to banks and other financial institutions, high interest rates and low profit margins. In addition, small-scale food industries rely on locally fabricated equipment, and non-standardization of equipment and lack of spare parts for equipment maintenance and repair are major problems constraining their growth (Taiwo, Oladepo, Ilori, & Akanbi, 2002). Laboratory studies have shown that good quality fruit leathers, jams, juices and other drinks can be produced from roselle (H. sabdariffa) calyx, tamarind (T. indica), African star apple (C. albidum), African mango (I. gabonensis var. gabonensis) and hog plum (S. mombin) using simple procedures suitable for small-scale commercial production including osmotic dehydration, open-kettle jam-making process and mechanical juice extraction followed by hot water pasteurization. 3.1. Production of fruit leathers/candies Osmotic dehydration allows for the development of a variety of new shelf-stable food products from perishable fruits thus reducing postharvest fruit losses and ensuring that seasonal fruit products are available throughout the year. Osmotic pre-treatment of fruits, by dipping them in sugar solutions, prior to hot-air drying produces relatively inexpensive intermediate moisture fruit products with good color, flavor and texture characteristics, and shelf stability at tropical ambient temperatures. Fruits dried with infused sugar are sometimes referred to as candies due to the large amount of sugar added to the fruit. They are also referred to as leathers because the infused sugar imparts a leathery texture to the dried product as opposed to the woody texture of nonosmosed dried fruit products. Fruit leathers/candies are moist enough to be eaten without re-hydration, yet shelf-stable (Cheman & Taufik, 1995). Laboratory studies on the production of fruit leathers/candies from African star apple revealed that the best products, from the standpoint of consumer acceptance, cost and energy savings, were obtained when ripe African star apple fruit pulps were immersed in sugar syrup

Table 2 Nutrient composition of selected lesser-known Nigerian vegetables. Sources: Chinedu et al. (2011), Mnzava (1995, 1997), Stadlmayr et al. (2012), Ajayi and Osifo (1977), Ladeji, Okoye, and Ojobe (1995), Taylor (1987), Ekumankama (1998), Ahmed and Mohammed (1995), Gupta, Lakshmi, Manjunath, and Prakash (2005), Sheela, Nath, Vijayalakshmi, Yankanchi, and Patil (2004), Omueti and Adepoju (1988), Babalola, Babalola, and Aworh (2001), Stadlmayr et al. (2012), Ogunlesi et al. (2010), Asaolu and Asaolu (2002), Atinmo and Akinyele (1983), Okegbile and Taiwo (1995), Keshinro (1985), Ishola et al. (1990), Adeola and Aworh (2012). Vegetable

Moisture (%)

Carbo-hydrate (%)

Crude fiber (%)

Protein (%)

Fat (%)

Ash (%)

K (mg%)

P (mg%)

Ca (mg%)

Na (mg%)

Fe (mg%)

Vit C (mg%)

Solanum aethiopicum Adansonia digitata leaf Vernonia amygdalina Telfairia occidentalis Gnetum africanum Corchorus olitorius Celosia argentea Hibiscus sabdariffa calyx Hibiscus sabdariffa leaf Amaranthus cruentus Talinum triangulare

89.3 76.7 82.8 80.0 83.8 80.2 87.6 86.7 86.7 85.0 91.2

4.1 9.2 5.5 10.5 6.7 6.5 – 8.9 4.1 6.0 2.9

3.0 7.2 5.1 1.7 4.0 3.4 – 1.3 5.0 2.1 0.9

2.2 3.5 4.4 6.1 3.2 7.3 3.2 2.0 2.8 3.4 1.9

0.5 0.5 0.6 0.6 1.9 0.2 0.3 0.3 0.2 0.4 0.1

0.9 2.8 1.6 1.7 0.4 2.4 2.7 0.8 1.2 3.1 3.0

483 391 437 154 – 480 476 276 437 208 143

38 85 67 20 – 78 35 15 65 26 26

378 313 162 75 128 291 188 195 212 136 193

217 6 6 68 – 83 240 1.0 6 92 89

18 3.9 2.8 9.6 2.7 5.7 13.2 4.7 4.1 6.4 3.2

26 47 27 129 56 78 26 30 33 56 22


[60°B; 1:4 ratio (w/w) of fruit pulp to sugar syrup] at tropical ambient temperature (27 °C) for 8 h followed by hot-air drying at 60 °C (Falade & Aworh, 2004, 2005). Fruit pulps dipped in sugar syrups of lower concentrations (44°B and 52°B) received lower scores for sensory quality attributes than those dipped in 60°B sugar syrup (Falade & Aworh, 2004, 2005). Similar studies with African mango indicated that coating African mango slices (10 mm thick) by immersion in 5–10% (w/w) gum guar solution prior to osmotic dehydration promoted water extraction from the fruit pieces but reduced solute (sugar) infusion into the fruit pieces (Falade, 2002). Although osmo-dried African mango slices received consistently better scores for color, taste, chewiness and overall acceptability relative to controls that did not receive osmotic pre-treatment, osmo-dried products from African mango were generally less preferred than those from African star apple (Falade, 2002; Falade & Aworh, 2005). Osmotic pre-treatment and drying inhibited microbial growth; osmo-dried products from African star apple and African mango were free of pathogenic microorganisms including intestinal pathogens (Salmonella and Shigella) and Staphylococcus (Falade, 2002; Falade & Aworh, 2004, 2005). 3.2. Jam-making Laboratory trials have shown that jams can be produced from lesserknown Nigerian fruits including African star apple, African mango and hog plum. Some of these fruits have sufficient pectin and acid that no other ingredients other than sugar and water need be used to produce good quality jam (Aina, 1991; Aworh, 2014; Inoh, Balogh, & Ngoddy, 1977). The recipes for production of some indigenous fruit jams containing 50% fruits are given in Table 3. After harvesting and washing, the fruits are peeled and cored followed by slicing, mashing and boiling with sugar addition in a steam-jacketed kettle. Jam made from African star apple by the open-kettle process has an attractive deep red color and that made from hog plum has a golden yellow color. Consumer acceptance tests, with over 50 assessors, indicated no significant differences in preference between hog plum jam and commercial pineapple (Ananas comosus) and mango (M. indica) jams (Adekoya, 1999). Using African star apple in combination with pineapple to produce a mixed fruit jam containing 50% African star apple and 50% pineapple improved consumer acceptance (Adekoya, 1999). In a comparative evaluation of jams made from African star apple (C. albidum), African mango (I. gabonensis var. gabonensis) and conventional mango (M. indica), African mango jam was less preferred, especially in terms of flavor and consistency (Table 4). Jam made from African mango had a somewhat gummy consistency and it would appear that the fruit has less prospects for commercial jam-making (Aworh, 2014). 3.3. Production of fruit juices and other drinks A variety of traditional beverages are prepared from lesser-known indigenous fruits and vegetables in Nigeria and many other African countries. Traditional beverages, which could be alcoholic or nonalcoholic, are beverages with localized consumption, made from indigenous crops and other locally available raw materials, whose methods of production are based on traditional technologies. Traditional

Table 3 Recipe for production of selected indigenous fruit jams (g of ingredient/kg of jam). Source: Aworh (2014). Ingredient

Chrysophyllum albidum jam

Spondias mombin jam

Irvingia gabonensis var. gabonensis jam

Fruit Sugar (sucrose) Water Citric acid Calcium chloride

500 596 100 – –

500 626 100 – –

500 638 100 6 5

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Table 4 Comparative evaluation of jams made from African star apple (Chrysophyllum albidum) and African mango (Irvingia gabonensis var. gabonensis) with commercial jam made from conventional mango (Mangifera indica)a. Source: Aworh (2014). Type of jam

Appearance Color Flavor Consistency Overall acceptability

African star apple jam 7.8a African mango jam 6.4b Commercial mango jam 7.3ab

7.9a 7.1a 7.5a

7.7a 5.1b 7.2a

7.1a 5.5b 7.4a

7.6a 5.7b 7.5a

a Rated on a scale of 1 = dislike extremely, 9 = like extremely. Means for each attribute followed by the same letter are not significantly different at 5% level by Tukey's test.

beverages are invariably of poor quality and the methods of preparation are not standardized, varying from one culture to another. The method of packaging invariably involves the use of discarded containers that have been previously used for other products such as discarded polyethylene water bottles. Consequently, they are often microbiologically unsafe, have very short shelf life and have been associated with food borne illnesses such as abdominal cramps, dysentery and diarrhea (Onyelucheya, Ojimelukwe, & Onyegbado, 2001). One of the most popular traditional beverages produced in Nigeria is ‘soborodo’ or ‘zobo’, a pinkish to wine-red or deep red drink made from red varieties of roselle (H. sabdariffa) by extracting the juice from roselle fruit calyx using fresh fruit or dried calyx. One procedure involves boiling 20 g of dried calyx/liter of water for 20 min, followed by filtering through a muslin cloth to obtain the juice (Babalola, 2008; Maliki, 2001). The acidic juice (pH 2.5–4.0) is usually sweetened by sugar addition and various flavors may be incorporated (Olawepo, Akoma, & Akoma, 2001). Roselle drinks produced in Nigeria vary widely in sensory, chemical and microbiological quality. Using an improved procedure suitable for small-scale industrial production that included sweetening with sugar and treatment with an aqueous extract from Aframomum danielli, a natural plant preservative, or with potassium sorbate and packaging in previously sterilized glass or polyethylene terephthalate (PET) bottles, roselle juices were produced from red, dark red and green varieties of roselle. The juices were of high nutritional, microbiological and sensory qualities and kept for up to 12 weeks at tropical ambient temperatures (Babalola, 2008). In northern Nigeria, several types of traditional drinks are produced from tamarind (T. indica) pulp using procedures that are slow, cumbersome, non-hygienic and variable depending on locality. ‘Tsimi’ is produced by soaking tamarind pulp in water for two days, followed by the addition of ground ginger, pepper and sugar. ‘Tsamia’ drink is prepared in the same manner as ‘tsimi’ drink, but without the addition of ground ginger and pepper. An improved process for small-scale industrial production of tamarind beverage reduced processing time from 10 h for 10 l of beverage (traditional method) to 2 h for 250 l of beverage (Adeola & Aworh, 2010). The improved beverage was superior in color, aroma, taste and overall acceptability to the traditional beverage and compared favorably with a commercial ginger beverage. In addition, the improved beverage was microbiologically safe, had a longer shelf life than the traditional product, and was considerably cheaper than similar products from conventional sources (Adeola, 2009). Fruit juices can be produced from other lesser-known indigenous fruits including African star apple and hog plum using simple procedures suitable for home preparation or small-scale commercial production. The procedure developed for African star apple juice involves first blanching washed fruits in hot water to facilitate manual peeling with knives. Juice extraction may be with a home blender or a pulper/finisher after removal of the seeds. The extracted juice which has an attractive deep red color but a rather harsh flavor is then pasteurized (Okoro, 2001). Similarly, hog plum juice was highly rated for color but lowly rated for taste in sensory evaluation tests. Blending African star apple juice or hog plum juice with pineapple (A. comosus) juice considerably improved the taste (Ogunmuyiwa, 2001).

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4. Conclusion Lesser-known indigenous fruits and vegetables play vital roles in the nutrition of the people particularly the rural populace in Nigeria. Laboratory studies have shown that good quality fruit leathers, jams, juices and other drinks can be produced from several lesser-known and under-utilized Nigerian fruits and vegetables including African star apple (C. albidum), African mango (I. gabonensis var. gabonensis), hog plum (S. mombin), tamarind (T indica) and roselle (H. sabdariffa) using simple procedures suitable for small-scale commercial production including osmotic dehydration, open-kettle jam-making process and mechanical juice extraction followed by hot water pasteurization. Removing the constraints to the development of small-scale food industries which include inadequate electricity supply, use of inappropriate technology, inadequate working capital, high interest rates, and limited access to banks and other financial institutions would facilitate commercial production of these value-added foods in rural communities thereby reducing post-harvest losses, promoting food security, enhancing small farmers' income and contributing to sustainable rural development.

References Adekoya, F. O. (1999). Quality attributes and consumer acceptability of jam made from African plum (Spondias mombin). M.Sc. Thesis Ibadan, Nigeria: University of Ibadan. Adeola, A. A. (2009). Production, quality attributes and storage stability of beverage from tamarind (Tamarindus indica L.) fruits. PhD thesis Ibadan, Nigeria: University of Ibadan. Adeola, A. A., & Aworh, O. C. (2010). Development and sensory evaluation of an improved beverage from Nigeria's tamarind (Tamarindus indica L.) fruit. African Journal of Food, Agriculture, Nutrition and Development, 10(9), 4079–4092. Adeola, A. A., & Aworh, O. C. (2012). A comparative evaluation of the chemical properties of wild tamarind (Tamarindus indica L.) fruits in Nigeria. Food, 6, 49–57. Adepoju, O. T. (2009). Proximate composition and micronutrient potential of three locally available wild fruits in Nigeria. African Journal of Agricultural Research, 4, 887–892. Ahmed, M. K., & Mohammed, E. I. (1995). Indigenous vegetables of Sudan: Production, utilization and conservation. In L. Guarino (Ed.), Traditional African vegetables. Proceedings of the International Plant Genetic Resources Institute (IPGRI) International Workshop on Genetic Resources of Traditional Vegetables in Africa: Conservation and Use, Nairobi, Kenya (pp. 117–121). Aina, J. O. (1991). Quality attributes of jam made from low usage tropical fruits. Food Chemistry, 40, 345–351. Ajayi, O. A., & Osifo, B. O. A. (1977). Home preservation of fruits and vegetables in Nigeria. Proceedings of the Launching and First Annual Conference of the Nigerian Institute of Food Science and Technology, 1 (pp. 56–60). Asaolu, M. F., & Asaolu, S. S. (2002). Proximate and mineral compositions of cooked and uncooked Solanum melongena. International Journal of Food Sciences and Nutrition, 53, 103–107. Atinmo, T., & Akinyele, L. (Eds.). (1983). Nutrition and food policy in Nigeria (pp. 217). Kuru, Nigeria: National Institute for Policy and Strategic Studies. Aworh, O. C. (2010). Food technology and national development. Ibadan, Nigeria: Ibadan University Press. Aworh, O. C. (2014). Lesser-known Nigerian fruits and vegetables: Post-harvest handling, utilization and nutritional value. Ibadan, Nigeria: Ibadan University Press. Babalola, S. O. (2008). Chemical evaluation of roselle (Hibiscus sabdariffa L.) and effects of variety, preservatives and packaging materials on quality of roselle juices. PhD thesis Ibadan, Nigeria: University of Ibadan. Babalola, S. O., Babalola, A. O., & Aworh, O. C. (2001). Compositional attributes of the calyces of roselle (Hibiscus sabdariffa L.). The Journal of Food Technology in Africa, 6, 133–134. Badifu, G. I. O., & Ogunsua, A. O. (1991). Chemical composition of kernels from some species of Cucurbitaceae grown in Nigeria. Plant Foods for Human Nutrition, 41, 35–44. Baqar, M. R. (1980). Vitamin C content of some Papua New Guinean fruits. Journal of Food Technology, 15, 459–461. Campbell-Platt, G. (1980). African locust bean (Parkia species) and its West African fermented food product, dawadawa. Ecology of Food and Nutrition, 9, 123–132. Canagarajah, S., & Thomas, S. (2001). Poverty in a wealthy economy: The case of Nigeria. Journal of African Economies, 10(2), 143–173. Cheman, Y. B., & Taufik, A. O. (1995). Development and stability of jack fruit leather. Tropical Science, 35, 245–250. Chinedu, S. N., Olasumbo, A. C., Eboji, O. K., Emiloju, O. C., Arinola, O. K., & Dania, D. I. (2011). Proximate composition and phytochemical analyses of Solanum aethiopicum L. and Solanum macrocarpon L. fruits. Research Journal of Chemical Sciences, 1, 63–71. Coursey, D. G. (1983). Post-harvest losses in perishable foods of the developing world. In M. Lieberman (Ed.), Post-harvest physiology and crop preservation (pp. 485–510). New York, USA: Plenum Publishing Corporation. Eka, O. U. (1980). Characteristics and potential of lipid from fruits of African pear tree (Dacryodes edulis). Nigerian Journal of Nutritional Sciences, 1, 117–119.

Ekumankama, I. O. (1998). Nutritional evaluation of selected indigenous vegetables: Strategy for promoting food security in Nigeria. Proceedings of the 22nd Annual Conference of the Nigerian Institute of Food Science and Technology, 1: Technical papers (pp. 92–93). Falade, K. O. (2002). Drying, sorption, sensory and microbiological characteristics of osmotically pretreated African star apple (Chrysophyllum albidum) and African mango (Irvingia gabonensis) fruits. PhD thesis Ibadan, Nigeria: University of Ibadan. Falade, K. O., & Aworh, O. C. (2004). Adsorption isotherms of osmo-oven dried African star apple (Chrysophyllum albidum) and African mango (Irvingia gabonensis) slices. European Food Research and Technology, 218, 278–283. Falade, K. O., & Aworh, O. C. (2005). Sensory evaluation and consumer acceptance of osmosed and oven-dried African star apple and African mango. Journal of Food, Agriculture & Environment, 3, 91–96. Food and Agriculture Organization of the United Nations (1988). Fruit bearing trees. Technical notes, FAO-SIDA forestry paper 34, FAO, Rome, Italy (pp. 165–167). Gebauer, J., El-Siddig, K., & Ebert, G. (2002). Baobab (Adansonia digitata L.): A review of a multipurpose tree with promosing future in the Sudan. Gartenbauwissenschaft, 67(4), 155–160. Guarino, L. (Ed.). (1995). Traditional African vegetables. Proceedings of the International Plant Genetic Resources Institute (IPGRI) International Workshop on Genetic Resources of Traditional Vegetables in Africa: Conservation and Use, 29–31 August 1995, Nairobi. Gupta, S., Lakshmi, A. J., Manjunath, M. N., & Prakash, J. (2005). Analysis of nutrient and antinutrient content of underutilized green leafy vegetables. LWT—Food Science and Technology, 38, 339–345. Inoh, P. G., Balogh, E., & Ngoddy, P. O. (1977). Agbalumo pectin: Extraction and properties. Proceedings of the Launching and First Annual Conference Nigerian Institute of Food Science and Technology, Lagos, 1 (pp. 61–67). Ishola, M. M., Agbaji, E. B., & Agbaji, A. S. (1990). A chemical study of Tamarindus indica (Tsamiya) fruits grown in Nigeria. Journal of the Science of Food and Agriculture, 51, 141–143. Joseph, J. K., & Aworh, O. C. (1991a). Chemical attributes of little known varieties of wild mango fruits (Irvingia gabonensis). Nigerian Food Journal, 9, 159–166. Joseph, K., & Aworh, O. C. (1991b). Composition, sensory quality and respiration during ripening and storage of edible wild mango (Irvingia gabonensis). International Journal of Food Science and Technology, 26, 337–342. Joseph, K., & Aworh, O. C. (1992). Post-harvest treatment of wild mango (Irvingia gabonensis) for improved shelf life. Food Chemistry, 44, 45–48. Keay, R. W. J. (1989). Trees of Nigeria. Oxford, UK: Clarendon Press. Keshinro, O. O. (1985). The unconventional sources of ascorbic acid in the tropics. Nutrition Reports International, 31, 381–387. Ladeji, O., Okoye, Z. S. C., & Ojobe, T. (1995). Chemical evaluation of the nutritive value of leaf of fluted pumpkin (Telfairia occidentalis). Food Chemistry, 53, 353–355. Maliki, K. (2001). Production and evaluation of sobo drink from roselle calyx. Proceedings 25th Annual Conference of the Nigerian Institute of Food Science and Technology, Lagos (pp. 66–67). Mnzava, N. A. (1995). Vegetable crop diversification and the place of traditional species in the tropics. In L. Guarino (Ed.), Traditional African Vegetables. Proceedings of the International Plant Genetic Resources Institute (IPGRI) International Workshop on Genetic Resources of Traditional Vegetables in Africa: Conservation and Use, Nairobi, Kenya (pp. 1–15). Mnzava, N. A. (1997). Comparing nutritional values of exotic and indigenous vegetables. In R. Schippers, & L. Budd (Eds.), African indigenous vegetables. Proceedings of the International Plant Genetic Resources Institute (IPGRI) International Workshop on Indigenous Vegetables, Limbe, Cameroon (pp. 70–75). Mudambi, S. R., & Rajagopal, M. V. (1977). Vitamin C content of some fruits grown in Nigeria. Journal of Food Technology, 12, 189–191. Murray, C. J. L., Laakso, T., Shibuya, K., Hill, K., & Lopez, A. D. (2007). Can we achieve millennium development goal 4? New analysis of country trends and forecasts of under5 mortality to 2015. Lancet, 370, 1040–1054. National Research Council (1996). Lost crops of Africa. Volume I. Grains. Washington, D. C., USA: National Academy Press. National Research Council (2006). Lost crops of Africa. Volume II. Vegetables. Washington, D. C., USA: National Academy Press. Nour, A. A., Magboul, B. I., & Kheri, N. H. (1980). Chemical composition of baobab fruit (Adansonia digitata L.). Tropical Science, 22, 383–388. Odunfa, S. A. (1986). Dawadawa. In N. R. Reddy, M. D. Pierson, & D. K. Salunkhe (Eds.), Legume-based fermented foods (pp. 173–189). Boca Raton, Florida, USA: CRC Press. Ogunlesi, M., Okiei, W., Azeez, L., Obakachi, V., Osunsanmi, M., & Nkenchor, G. (2010). Vitamin C contents of tropical vegetables and foods determined by voltammetric and titrimetric methods and their relevance to the medicinal uses of the plants. International Journal of Electrochemical Sciences, 5, 105–115. Ogunmuyiwa, J. D. (2001). Chemical, microbiological and sensory evaluation of pineapple and African plum juice blends after storage. M.Sc. thesis Ibadan, Nigeria: University of Ibadan. Okafor, J. C. (1981). Woody plants of nutritional importance in traditional farming systems of the Nigerian humid tropics. PhD thesis Ibadan, Nigeria: University of Ibadan. Okafor, N. (1987). Upgrading local technologies of food processing with emphasis on fermented foods: The case of oils and fats. Proceedings 11th Annual Conference of the Nigerian Institute of Food Science and Technology, Port Harcourt (pp. 61–74). Okegbile, E. O., & Taiwo, E. A. (1995). Nutritional potentials of velvet tamarind (Dialium guineense Willd). Nigerian Food Journal, 8, 115–121. Okigbo, B. C. (1977). Neglected plants of horticultural and nutritional importance in traditional farming systems of tropical Africa. Acta Horticulturae, 53, 1–31. Okoro, J. I. (2001). Quality attributes of blends of fruit juices from African star apple (Chrysophyllum albidum) and pineapple (Ananas comosus). M.Sc. thesis Ibadan, Nigeria: University of Ibadan.

O. Charles Aworh / Food Research International 76 (2015) 986–991 Okwu, D. E. (2005). Phytochemicals, vitamins and mineral contents of two Nigerian medicinal plants. International Journal of Molecular Medicine and Advance Sciences, 1, 375–381. Olawepo, O., Akoma, O., & Akoma, A. O. (2001). Changes in quality attributes of preserved zobo. H. sabdariffa during ambient storage. Proceedings 25th Annual Conference of the Nigerian Institute of Food Science and Technology, Lagos (pp. 72–74). Olorunda, A. O., & Aworh, O. C. (1983). Quantitative assessment of post-harvest losses of perishable vegetables in the Nigerian marketing system. Nigerian Journal of Science, 17, 41–49. Omueti, O., & Adepoju, E. (1988). Preliminary assessment of the effect of processing and storage on the quality of five local vegetables. Nigerian Food Journal, 6, 67–71. Onyelucheya, N. E., Ojimelukwe, P. C., & Onyegbado, C. O. (2001). Traditional beverages in Nigeria: A historical perspective and challenges for the future. Journal of Sustainable Agriculture and the Environment, 3, 141–148. Oshewolo, S. (2010). Galloping poverty in Nigeria: An appraisal of government interventionist policies. Journal of Sustainable Development in Africa, 12(6), 264–274. Schippers, R., & Budd, L. A. (Eds.). (1997). Proceedings Workshop on African Indigenous Vegetables, 13–18 January 1997, Limbe, Cameroon. Organised by Natural Resources Institute (NRI), U.K., International Plant Genetic Resources Institute (IPGRI) Sub-Saharan Office, Nairobi, and the Centre for Plant Breeding and Reproduction Research, Wageningen, The Netherlands. Sheela, K., Nath, K. G., Vijayalakshmi, D., Yankanchi, G. M., & Patil, R. P. (2004). Proximate composition of underutilized green leafy vegetables in Southern Karnataka. Journal of Human Ecology, 15, 227–229. Sidibe, M., Scheuring, J. F., Kone, M., Hofman, P., & Frigg, M. (1998). More on baobab's homegrown vitamin C: Some trees have more than others—consistently. Agroforestry Today, 10, 10. Silou, T., Rocquelin, G., Gallon, G., & Molagui, T. (2000). Characterization of safous (Dacryodes edulis) in Central Africa. Part II. Chemical composition and nutritional

991

characteristics of safous from the district of Boko (Congo Brazzaville). Variation between trees. Rivista Italiana delle Sostanze Grasse, 77, 85–89. Stadlmayr, B., Charrondiere, U. R., Addy, P., Samb, B., Enujiugha, V. N., & Bayili, R. G., et al. (Eds.). (2010). Composition of selected foods from West Africa. Rome, Italy: Food and Agriculture Organization of the United Nations (FAO). Stadlmayr, B., Charrondiere, U. R., Eisenwagen, S., Jamnadass, R., & Kehlenbeck, K. (2013). Nutrient composition of selected indigenous fruits from sub-Saharan Africa. Journal of the Science of Food and Agriculture, 93, 2627–2636. Stadlmayr, B., Charrondierre, U. R., Enujiugha, V. N., Bayili, R. G., Fagbohoun, E. G., Samb, B., et al. (2012). West African food composition table. Rome, Italy: Food and Agriculture Organization of the United Nations (FAO). Taiwo, K. A., Oladepo, O. W., Ilori, M. O., & Akanbi, C. T. (2002). A study on the Nigerian food industry and the impact of technological changes on the small-scale food enterprises. Food Reviews International, 18(4), 243–261. Takyi, E. E. K. (1999). Children's consumption of dark green leafy vegetables with added fat enhances serum retinal. Journal of Nutrition, 129, 1549–1554. Taylor, O. A. (1987). The nutrient composition and uses of fruits and vegetables. Proceedings of the First National Agricultural Extension and Research Liaison Service Home Economics Workshop, Zaria, Nigeria (pp. 1–17). Thomas, P., & Oke, M. S. (1980). Vitamin C content and distribution in mangoes during ripening. Journal of Food Technology, 15, 669–672. Tiburski, J. H., Rosenthal, A., Deliza, R., de Oliveira Godoy, R. L., & Pacheco, S. (2011). Nutritional properties of yellow mombin (Spondias mombin L.) pulp. Food Research International, 44, 2326–2331. Yazzie, D., Vanderjagt, D. J., Pastuzyn, A., Okolo, A., & Glew, R. H. (1994). The amino acid and mineral content of baobab (Adansonia digitata L.) leaves. Journal of Food Composition and Analysis, 7, 189–193.