ABSTRACT
Tomato (solanumlycopersicum), is one of the most
important vegetable crop of the solanaceae family, grown all over the world for
food and other economic purposes. The microbial spoilage of canned tomato of
varying product brands was investigated in this study. It was observed that the
total aerobic and anaerobic counts were less than 103 cells which
were within acceptable limit. Two of the canned product had no microbial count,
while the others had counts varying from 2 x 101 to 5 x 101
for aerobic count of freshly opened tomato, and 1 x 101 to 2 x 101
for anaerobic count. However, aerobic count of spoilt canned tomato product
ranged from 4.2 x 104 to 9.1 x 104 across all six
products investigated. Anaerobic count of spoilt canned tomato ranged from 2.5
x 104 to 6.8 x 104. Isolated organisms obtained from
spoilt canned tomato samples revealed the presence of Bacillus ploymyxa, Staphylococcus aureus, Streptococcus lactis,
Pseudomonas, sp., Clostridium
sporogenes,Bacillus coagulans,Saccharomyces sp., Candida sp., Mucorsp., Aspergillus niger, and Penicilliumsp. These organisms were
implicated in the spoilage of canned tomato products sold in Lokoja City. When
these products are consumed immediately after opening, they are safe because
the microbial load on fresh product is within acceptable regulatory standard
CHAPTER ONE
1.0
INTRODUCTION:
Canned tomatoes are tomatoes usually peeled
that are sealed into a canned after having been processed by heat. This product
are considered important world wide (Robinso, et al, 1994). In Nigeria tomato
paste is the most important tomato product because of its
wide spread use for preparation of various food/menus. It contain on the
average about 6.4% total solids, of which 3.5% is invert sugar, 0.5% citric
acid,0.6% ash, 0.9% protein, 0.53% crude fibre and about 0.05% fat. When spoil
as a result of the life processes of bacteria, yeast and molds, the sugars
are rapidly used up being changes into acetic acid, lactic acid,
alcohol and carbon dioxide, the amount of these substances depending on
the types of organism which are most active in the particular sample in
question.
Until recent years, nearly all the
tomato paste consumed in Nigeria was important from European countries with
Italy being the leading country. However, today, limited brands are produced
locally. Although both the imported and the local brands are available on the
market, consumers prefer the former in spite of its relatively
higher cost.
In general, adequate heat processing is
given to tomato paste to achieve commercial sterility (speck, 1984), but
subsequent abusive post-process handling/storage may lead to undesirable
microbiological changes (Anon, 1980). It is public knowledge that
can of tomato paste often show external evidence of spoilage under tropical
retail conditions. In addition, and interestingly, these d effective products
are sold (especially to the less informed) at the same cost as the normal
(non-defective- product.
The structural systematic
approach for the control of food safety “Hazard Analytsis and critical
control point-HACCP” identifies, evaluated and controls hazards that are
significant for food safety. The control parameters include various
factors such as time of harvesting, temperature and moisture during
storage, selection of agricultural products prior to processing,
decontamination conditions, addition of chemicals at final product storage
((Sango, 1995).
1.1 Tomato:
Tomato (Lycopersicumesculentum) belongs
to the family Solanaceae and subilasspolypetalae of the dicotyledenous group of
plants. Tomato is a slight modification of tomato the name used by the Indians
of Mexico, who have grown the plant for food since prehistoric times. Other
names reported by early European explorers were tomato, tumatle and tomatas,
probably variants of Indian words (Wener, 2004).
1.2 Origin:
The precise origin of tomato
remains a mystery but there is reason to believe that the original tomato came
from Peru called tomato, it was taken to Mexico by migrating Peruvians. It
found its way to Italy through the explorations of Christopher Columbus.
Tomatoes were taken back to Europe along with silver and gold and they were
grown on the continent as a pretty curiosity (Fallagatter, 1999). Though,
tomato has become one of the most popular and widely grown vegetables in the
world (Chung, 1998), until the 19th century, it was grown chiefly as
an ornamental plant for its colourful fruit (Villareal, 1980). This is because
it was regarded with suspicion due to the reputation of Solanum-like fruits
being poisonous (Philips and Rix, 1993)
Statement of problem
Canning destroys the microbial
contaminants, however, products undergo microbial spoilage and could cause food
The common garden tomato (Lycopersiconesculentum)
is borne illness as a result of under processing, inadequate botanically
classified as a fruit, although, some persons think of cooling contamination of
the can resulting from leakage and it as
a vegetable [1]. The United States Department of preprocess spoilage [6].
Canned foods have been reported to
Agriculture [2] for example, defined it as a vegetable. Tomato be contaminated
mainly by spore forming bacteria of the
is widely used as condiment or as food dietary supplement in genera Bacillus, Clostridium and Desulfotomaculum [7]. If the various
part of the world and also valuable in the food industry contaminant is a
pathogen and the food is capable of [3].
supporting its growth, a health hazard exists [8]. Bacillus Canene-Adams et al.
[4] reported that tomatoes are the coagulans
and Bacillus stearothermophilus have
been implicated in fourth most commonly consumed fresh vegetable and the most
canned tomato juice and milk causing flat sour spoilage with frequently
consumed canned vegetable in the Nigeria diet acid but no gas production from
carbohydrate [9, 10.
1.5 Aims and objectives:
- To carry out
a microbiological analysis of expired canned tomato paste.
Specific objectives:
- To determine microbial load of expired canned tomato paste.
- To
characterize and identify bacteria and fungi isolate in this sample
- To determine
the frequency of occurrence of bacteria and fungi species in this sample.
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