Tuesday, 21 March 2017

Studies On The Occurrence Of Moulds In Tomato Pastes Preserved By Different Methods


Result from this study revealed that many  plant- pathogenic mould are the subject intense study because they cause disease symptoms that have severe negative effect on the yield or quality of tomato (Solanum lycopersicum) and its products. The common mould associated with tomato paste were determined to get information on whether the mould the tomato paste originate entirely from the tomato or soil. The species found belongs to some fungal genera Alternaria, Aspergillus fusarium and Penicillium .The species are the types of species that may potentially produce mycotoxins.

Title page                                                                                                   
Approval page                                                                                         
Table of Contents                                                                                                                      
List of Table                                                                                                                          

1.0  Introduction                                                                                                              
1.1 Background of the Study                                                                                           
1.2 Classification:                                                                                                             
1.3 Tomato Variety                                                                                                           
1.4 Fruit Formation                                                                                                           
1.5 Cultivation                                                                                                                  
1.6 Picking and Ripening                                                                                                  
1.7 Potential Health Effects                                                                                             
1.8 Justification of the Study                                                                                           
1.9 Aim of the Study                                                                                                        
1.10 Objectives of the Study                                                                                              

2.0 Literature view                                                                                                            
2.1 Biology                                                                                                                       
2.2 Isolation of Mould                                                                                                    
2.3 Identification of Mould                                                                                            

3.0  Materials and Methods                                                                                               
3.1  Samples Collection                                                                                                     
3.2  Storage of the Tomato Paste                                                                                       
3.3  Preparation of media                                                                                                   
3.5  Serial Dilution                                                                                                             
3.6  Isolation of Mould from the Samples                                                                         
3.7  Identification of Isolates                                                                                            

4.0  Results                                                                                                                      

5.0 Discussion                                                                                                                   
5.1 Conclusion                                                                                                                
5.2 Recommendation


1.0  Introduction

1.1  Background of the Study

Solanum lycopersicum M. (Solanaceae) is one of the world’s most important vegetable crops with a current worldwide fresh weight production of 80 million tones from a cropped area of about 3 million ha. The fruit improves the supply of vitamins and minerals in human nutrition.  The species originated in Central and South America. The Nahuatl (Aztec language) word tomato gave rise to the Spanish word "tomato", from which the English word tomato originates (Domsch et al.,1980).

Numerous varieties of tomato are widely grown in temperate climates across the world, with greenhouses allowing its production throughout the year and in cooler areas. The plants typically grow to 1–3 meters (3–10 ft) in height and have a weak stem that often sprawls over the ground and vines over other plants. It is a perennial in its native habitat, and grown as an annual in temperate climates. An average common tomato weighs approximately 100 grams (4 oz) (Domsch et al., 1980).

Its use as a food originated in Mexico, and spread throughout the world following the Spanish colonization of the Americas. Tomato is consumed in diverse ways, including raw, as an ingredient in many dishes, sauces, salads, and drinks. While tomato are botanically berry-type fruits, they are considered culinary vegetables, being ingredients of savory meals  (Sabongari and Aliero 2004).

There are around 7,500 tomato varieties grown for various purposes having been selected with varying fruit types, and for optimum growth in differing growing conditions (Levy and Taylor, 2003).

1.2       Classification:

Kingdom: plantae

Subkingdom: tracheobionta                                                                                                   

Superdivision: spermatophyte

Division :magnoliophyta

Class: magnoliopsida


Order: solanales

Family: solanaceae

Genus: solanum

Species:Solanum lycopersicum (Sabongari and Aliero, 2004)

1.3 Tomato Variety

There are around 7,500 tomato varieties grown for various purposes [citation needed] having been selected with varying fruit types, and for optimum growth in differing growing conditions (Colakolu, 1983).

Tomato varieties can be divided into categories based on shape and size.

Beefsteak tomato are 10 cm (4 in) or more in diameter, often used for sandwiches and similar applications. Their kidney-bean shape, thinner skin, and shorter shelf life makes commercial use impractical (Colakolu, 1983).

Plum tomato, or paste tomato (including pear tomato), are bred with a lower water /higher solids content for use in tomato sauce and paste, for canning and sauces and are usually oblong 7–9 cm (3–4 in) long and 4–5 cm (1.6–2.0 in) diameter; like the Roma-type tomato, important cultivars in the Sacramento Valley. Cherry tomato are small and round, often sweet tomato, about the same 1–2 cm (0.4–0.8 in) size as the wild tomato.

Grape tomato are smaller and oblong, a variation on plum tomato (Levy and Taylor, 2003).

Campari tomato are sweet and noted for their juiciness, low acidity, and lack of mealiness, bigger than cherry tomato, and smaller than plum tomato.

Tomberries, tiny tomato, about 5 mm in diameter (Levy and Taylor, 2003). Oxheart tomato can range in size up to beefsteaks, and are shaped like large strawberries. (Levy and Taylor, 2003).

Pear tomato are pear-shaped and can be based upon the San Marzano types for a richer gourmet paste (Levy and Taylor, 2003).

"Slicing" or "globe" tomato are the usual tomato of commerce, used for a wide variety of processing and fresh eating.[citation needed] The most widely grown commercial tomato tend to be in the 5–6 cm (2.0–2.4 in) diameter range.

Tomato are also classified as determinate or indeterminate. Determinate, or bush, types bear a full crop all at once and top off at a specific height; they are often good choices for container growing. Determinate types are preferred by commercial growers who wish to harvest a whole field at one time, or home growers interested in canning. Indeterminate varieties develop into vines that never top off and continue producing until killed by frost. 

They are preferred by home growers and local-market farmers who want ripe fruit throughout the season. As an intermediate form, there are plants sometimes known as vigorous determinate or semi-determinate; these top off like determinates, but produce a second crop after the initial crop. The majority of heirloom tomato are indeterminate, although some determinate heirlooms exist (Sabongari and Aliero, 2004).

Early tomato and cool-summer tomato bear fruit even where nights are cool, which usually discourages fruit set. There are varieties high in beta carotenes and vitamin A, hollow tomato and tomato that keep for months in storage in 1973, Israeli scientists developed the world's first long shelf-life commercial tomato varieties (Sabongari and Aliero, 2004). 

Heirloom tomato are becoming increasingly popular, particularly among home gardeners and organic producers since they tend to produce more interesting and flavorful crops at the cost of disease resistance and productivity. The definition of an heirloom tomato is vague, but unlike commercial hybrids, all are self-pollinators that have bred true for 40 years or more. 

Quite a few seed merchants and banks provide a large selection of heirloom seeds Home cultivars are often bred for flavor to the exclusion of all other qualities, while commercial cultivars are bred for factors like consistent size and shape, disease and pest resistance, suitability for mechanized picking and shipping, and ability to ripen after picking Hybrid plants remain common since they tend to be heavier producers, and sometimes combine unusual characteristics of heirloom tomato with the ruggedness of conventional commercial tomato (Sabongari and Aliero 2004).

Most modern tomato cultivars are smooth surfaced, but some older tomato cultivars and most modern beefsteaks show pronounced ribbing, a feature that may have been common to virtually all pre-Columbian cultivars While virtually all commercial tomato varieties are red, some cultivars – especially heirlooms – produce fruit in green, yellow, orange, pink, black, brown, ivory, white, and purple. Such fruits are not widely available in grocery stores, nor are their seedlings available in typical nurseries, but they can be bought as seed. Variations include multicolored fruit with stripes (Green Zebra), fuzzy skin on the fruit (Fuzzy Peach, Red Boar), multiple colors (Raper and Fennell, 1965).

1.4 Fruit Formation

Pollination and fruit formation depend on meiosis. Meiosis is central to the processes by which diploid microspore mother cells within the anther give rise to haploid pollen grains, and megaspore mother cells in ovules that are contained within the ovary give rise to haploid nuclei. Union of haploid nuclei from pollen and ovule (fertilization) can occur either by self- or cross-pollination. Fertilization leads to the formation of a diploid zygote that can then develop into an embryo within the emerging seed. Repeated fertilizations within the ovary are accompanied by maturation of the ovary to form the tomato fruit.

Homologs of the recA gene, including rad51, play a key role in homologous recombinational repair of DNA during meiosis. A rad51 homolog is present in the anther of tomato (Solanum lycopersicum), suggesting that recombinational repair occurs during meiosis in tomato.

1.5  Cultivation

Tomato are often grown in greenhouses in cooler climates, and there are cultivars such as the British 'Moneymaker' and a number of cultivars grown in Siberia that are specifically bred for indoor growing. In more temperate climates, it is not uncommon to start seeds in greenhouses during the late winter for future transplant.

Greenhouse tomato production in large-acreage commercial greenhouses and owner-operator stand-alone or multiple-bay greenhouses is on the increase, providing fruit during those times of the year when field-grown fruit is not readily available. Smaller sized fruit (cherry and grape), or cluster tomato (fruit-on-the-vine) are the fruit of choice for the large commercial greenhouse operators while the beefsteak varieties are the choice of owner-operator growers.

Hydroponic technique is often used in hostile growing environments, as well as high-density plantings.

1.6 Picking and Ripening

To facilitate transportation and storage, tomato are often picked unripe (green) and ripened in storage with ethylene. Unripe tomato are firm. As they ripen they soften until reaching the ripe state where they are red or orange in color and slightly soft to the touch (Sabongari and Aliero 2004). Ethylene is a hydrocarbon gas produced by many fruits that acts as the molecular cue to begin the ripening process. Tomato ripened in this way tend to keep longer, but have poorer flavor and a mealier, starchier texture than tomato ripened on the plant (Yoltao, 2000). They may be recognized by their color, which is more pink or orange than the other ripe tomato' deep red, depending on variety (Yoltao, 2000).

A machine-harvestable variety of tomato (the "square tomato") was developed in the 1950s by University of California, Davis's Gordie C. Hanna, which, in combination with the development of a suitable harvester, revolutionized the tomato-growing industry. This type of tomato is grown commercially near plants that process and can tomato, tomato sauce, and tomato paste. They are harvested when ripe and are flavorful when picked. They are harvested 24 hours a day, seven days a week during a 12 to 14 week season, and immediately transported to packing plants, which operate on the same schedule. California is a center of this sort of commercial tomato production and produces about a third of the processed tomato produced in the world.

In 1994, Calgene introduced a genetically modified tomato called the FlavrSavr, which could be vine ripened without compromising shelf life. However, the product was not commercially successful, and was sold only until 1997. Slow-ripening cultivars of tomato have been developed by crossing a non-ripening cultivar with ordinary cultivars (Levy and Taylor, 2003).

1.7 Potential Health Effects

There is no conclusive evidence that the lycopene in tomato or in supplements affects the onset of cardiovascular diseases or cancer.

In the United States, supposed health benefits of consuming tomato, tomato products or lycopene to affect cancer cannot be mentioned on packaged food products without a qualified health claim statement. In a scientific review of potential claims for lycopene favorably affecting DNA, skin exposed to ultraviolet radiation, heart function and vision, the European Food Safety Authority concluded there was insufficient evidence for lycopene having any of these effect (Levy and Taylor, 2003).

1.8 Justification of the Study
Tomato are vital sources of nutrient to human beings. They give the body the necessary vitamins, fat, minerals, and oils in the right proportion for human growth and development.  Tomato however have serious challenges to their existence, these include changes in climatic condition, inadequate rainfall and fungal attack. However, their consumption is limited by mould contamination and spoilage especially when predisposed to these organisms before consumption. This study is aimed at identifying the mould isolates responsible for the spoilage of tomato for the purpose of educating the consumers on the risk or dangers associated with the consumption of contaminated tomato (Sahlin et al., 2003).

1.9  Aim of the Study

The aim of this study was to isolate and identify mould associated with the spoilage of tomato paste.   

1.10 Objectives of the Study

i. To Isolate and identify mould isolates associated with refrigerated and non-refrigerated tomato pastes.

ii. Preservative techniques done in the laboratory.

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