Guava (Psidium guajava L.) is an important tropical tree cultivated for its fruits. The fruit processing by-products, the leaves and the fruits themselves can be used to feed livestock though their nutritional value is low.
Guava is a fast growing evergreen shrub or small tree that can grow to a height of 3-10 m. It has a shallow root system. Guava produces low drooping branches from the base and suckers from the roots. The trunk is slender, 20 cm in diameter, covered with a smooth green to red brown bark that peels off in thin flakes. Young twigs are pubescent. The leaves grow in pairs, opposite each other. The leaf blade is elliptic to oblong in shape, 5-15 cm long x 3-7 cm broad, finely pubescent and veined on the lower face, glabrous on the upper face. The flowers are white in colour, about 3 cm in diameter, solitary or in 2-3 flower clusters borne at the axils of newly emerging lateral shots. The fruit is a fleshy, pyriform or ovoid berry that can weigh up to 500 g (Orwa et al., 2009). The skin colour is yellowish to orange. The flesh can be white, yellow, pink or red, sour to sweet, juicy and aromatic (Ecocrop, 2015; Orwa et al., 2009; Soetopo, 1991). The fruit contains a variable number of seeds (about 3-5 mm long) and its mesocarp is characterized by the presence of small (0.1 mm) and hard fibrous structures called stone cells (sclereids), which may cause damage to processing machinery (El Boushy et al., 2000; Weinert et al., 1988).
Guava is mainly grown for its edible fruits that are eaten raw or made into purée (pulp), jam, jelly, paste, juice, syrup, chutney, etc. (Murray et al., 1989; El Boushy et al., 2000). It is cultivated in orchards or in home gardens in many tropical countries. Guava is widely cultivated in Africa, and incorporated into agroforestry systems in India (CABI, 2013). Guava wood is useful for tool manufacturing, fences or firewood (it is a good source of charcoal) (Orwa et al., 2009). Handling of guava fruit is difficult and the rate of cull fruits is high (about 40% in Florida in the 1980s) (Murray et al., 1989). Guava processing yields 25% by-products that can be used in animal feeding (Azevêdo et al., 2011). For the production of guava purée the fruits are chopped and fed through a pulper, which removes seeds and fibrous tissues and forces the remainder through a finisher, which removes the stone cells. Guava waste from this process consists of a mixture of seeds, fibrous tissues and stone cells (El Boushy et al., 2000). Guava leaves can be used as fodder. Guava flowers are fragrant, and a good source of nectar for bees (Orwa et al., 2009).