Microbial Contamination Of Vended Fruit

The pineapple

Ananas comosus

Bromeliaceae

It is one of the choicest fruit all over the world because of its pleasant taste and flavour. Pineapple is a good source of vitamin A and B and fairly rich in vitamin C and minerals like calcium, magnesium, and potassium and iron .It is also a source of

bromelain

2.4.2. History

Christopher Columbus and his sailors discovered pineapple in 1493

2.4.3. Cultivation and harvesting

Pineapples can be grown in a variety of soil types but prefer mildly acid soils within the pH of 5.5–6.5. However, there are certain requirements for successful pineapple production, which include: Preparing the soil, Removal of trees, stumps and stones, subsoil (rip) to a depth of 800 to 900mm under dry conditions, ploughing and tilling of the soil a number of times, to achieve a fine tilt, for effective plant rooting ridge the soil for better drainage, temperature and to improve aeration and have soil samples analysed at least 6 months before planting to determine fertilization and fumigation requirements. Unlike many other crops grown from seed, pineapples are grown by planting various parts of the plant according to the cultivar, where it is going to be produced, and the cultivation methods practised in the area. 

Although crowns are mostly used as planting material for the Cayenne cultivar, they are considered uneconomical for the Queen cultivar because of the length of time they take to bear.  Suckers are planted in the case of Queen Pineapple production. Pineapples are grown between July and December and they are grown on clayey loams or sandy soils (Sanewski and Scott, 2000).

Pineapples contribute to over 20% of the world production of tropical fruits and as a crop are second only to bananas as the most important harvested fruit. 
Harvesting should be done 7 to 14 days after yellowing. It is labour intensive because workers walk in the space between ridges to pick the fruit by hand, loading it into baskets, or onto a boom harvester.  After harvesting the crowns are broken off (not twisted) and left on top of the plants in the field or are placed in bags to be collected at a later date for planting.  It is ensured that the fruit is not too green or too ripe when harvested, not bruised or damaged and that it is not affected to a large extent by any physiological problems (Rohrbrach et al., 2007).

2.4.4. Diseases and Pests

The pineapple plant is most productive under xerophytic (dry) environments where low rainfall is supplemented by irrigation in well-drained soils. Once the root system (adventitious roots) is damaged or destroyed, it does not regenerate significantly. Several characteristics of the pineapple plant and commercial pineapple production systems have contributed to the severity of several pest and disease problems (Rohrbach et al., 2003).Common pests infesting vegetative propagates (crowns, slips, suckers) are mealy bugs, scale and pineapple red mites. In addition to these pests, the diseases termed heart rot, root rot, fruit rot and butt rot may be major problems when handling, storing or planting fresh pineapples (Pegg, 1993).     

The bacterial heart rot and fruit collapse is caused by a bacterium called Erwinia chrysanthemi. It causes water-soaked lesions on the white basal sections of leaves in the central whorl giving it an olive green colouration with bloated appearance. This disease progresses from the juice of the infected fruits and enters the leaves through the wounds made by ants. 
The butt rot, black rot and white leaf rot are caused by the fungus called Chalara paradoxa which causes a soft rot that begins from the area where the seed detaches from the mother plant; entire seed may be rotten; black rot of fruit causes a soft watery rot which darkens with time. The fungus survives in soil and pineapple residue. Marbling is another disease caused by a bacterium, Acetobacter spp Erwinia herbicola, which causes a yellow to red or very brown discolouration of fruit flesh. The infected tissues develop a granular texture with woody consistency and speckled colour and the emergence of the disease is favoured by warm, wet weather (Rohrbachet al., 2003).

These diseases can be prevented and controlled by the removal and destruction of infected fruits, use of insecticides to control ants; seed material should be properly stored and the removal of debris.

2.4.5. Nutritional value of Pineapple

The nutritional content of pineapple can vary significantly between varieties as illustrated by the Vitamin C content of the pineapple varieties. In addition to the fruit the pineapple plant also provides fibre (used in clothing and industry) and the enzyme bromelain (Arshad et al., 2014).

Bromelain’s medicinal uses include relief for arthritis sufferers, as a digestive aid, in the reduction of blood clotting, as an anti-inflammatory agent, and for skin debridement of burns (Chaurasiya et al., 2015). Bromelain also has industrial uses including meat tenderisation, clarification of beer, production of vegetable oils and the dehydration of eggs and soya milk. Bromelain content is known to vary by up to 50% between varieties.

2.5. CARROT
2.5.1. Introduction
Table 4: Scientific Classification of Carrot
Kingdom:     Plantae
Order:         Apiales
Family:     Apiaceae
Genus:     Daucus
Species:     carota
Subspecies:     Daucus carota subsp sativus
(Source: Simon, 2000)

The carrot (Daucus carota subsp sativus) is a biennial root vegetable usually orange in colour that belongs to the family of Apiaceae. It is related to celery, celeriac, coriander, parley, fennel and parsnip, which are all members of this family. It has a crisp texture when fresh and the most commonly eaten part is the taproot, although the greens are sometimes eaten as well. 

This crop grows a rosette of leaves in the first season and produce seeds in the second season. For root production the plant is grown as an annual and after germination there is a demarcation between the taproot and the stem. The carrot is a very important vegetable crop in many countries like Africa, Asia and Europe and it is consumed either as a salad or cooked in regional cuisines and restaurants (Simon, 2000). 

2.5.2. History

Carrots are likely to have come from Persia which remains the centre of diversity of the wild carrot (Daucus carota). A naturally occurring subspecies of wild carrot, Daucus carota subsp sativus has been selectively bred over centuries for the reduction of bitterness, increase sweetness and minimise the wood core (Rose, 2006). When carrots were first cultivated, they were grown for their aromatic leaves and seeds rather than their roots. The seeds were said to be found in Switzerland and Southern Germany between 2000-3000BC (Rubatsky, 1999). The root of the carrot was first mentioned during the 1st century (Simon et al., 2008). 

It was introduced into Europe via Spain by the Moors in the 8th century and in the 10thcentury; locations like West Asia and Europe produced the purple coloured carrots. Between the 11th and 16thcentury different countries like China, Japan began to cultivate carrots and most of them yielded different colours of carrots like yellow, purple coloured ones. But by the 17th century, orange- coloured carrots were cultivated in Netherlands and the European settlers introduced the carrot to colonial America but the purple carrots are still sold in most countries like Great Britain.