Microorganism Associated With Spoilage of Tomatoes (Canned Tomatoes)
Chapter One
PREAMBLE OF THE STUDY
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).
CHAPTER TWO
LITERATURE REVIEW
Canned tomato can be defined as thick paste that is made by cooking tomatoes for several hours to reduce moisture, straining them to remove the seeds and skin and cooking them again to reduces them to a thick rich concentrate (Gould, et. al.,1983).
HISTORY OF CANNED TOMATOES
It was traditionally made in part of Sicily southern Italy and Malta by spreading out a much reduced tomato sauce on wooden boards. The boards are set out door under the hot August sun to dry the paste until it is thick enough, when craped up, to hold together on a richly coloured dark ball. Today, this artisan product is harder to find than the industrial (much thinner) version (Efiuvwevwere, et al, 1991).
In the USA, tomato paste is concentrated tomato solids (no seeds or skin) and usually no added or seasonings, with a standard of identity.
In the UK, paste is referred to as puree or concentrate, depending on its manufacturing conditions, tomato paste can be the basis for making ketchup or reconstituted tomato juice (Sidhu, et. al., 1984).
TYPES OF CANNED TOMATO
WHOLE TOMATOES: These can be either as peeled or unpeeled. They can either be pack in puree or juice, the puree being a little bit thicker. They are used for sauce, chili, soups and stews.
CRUSHED TOMATOES: These are whole tomato cut up. Sometime extra juice has been added to the can. They are commonly used for pasta sauces, are made up adding ground tomatoes to a heavy medium made from tomato pasta (Guardia, et. al., 1990)
DICED TOMATO: This usually refers to tomatoes that have been diced. This has become increasingly common for application where a chunkier or more substantial product is needed. In recent years, the petite diced form (3/8 cut pieces) has become the fastest growing segment of canned tomato (Frazier, 1967).
In the united state retail environment, however, the term refers to canned chuks of plum tomato in tomato juice or tomato puree, sometimes seasoned with basil or garlic. This product is a relatively recent arrived in the processed tomato market and has become quite popular since its introduction in the mid 9os, probably due to American tastes for a chunkier tomato sauce (Sneath, et. al., 1986) calcium chloride is sometimes added to stabilize the cell structure of the canned tomatoes, giving the end product a firmer texture.
NUTRITION FACTS OF CANNED TOMATOES
Canned tomatoes are low in calories and free of fat and cholesterol. The protein, fiber and vitamin c content varies from brand to brand, so there is a need for checking of label.
The canning process which involves quickly steaming or boiling, does down some of the fiber and vitamin c. On the ftp side, canned tomatoes haves higher hycopene content than fresh ones.
CHAPTER THREE
MATERIALS AND METHODS:
PLACE OF EXPERIMENTAL WORK
:- This research project was conducted in Umudike
AIM OF STUDY:
- To determine the micro organism associated with canned tomato.
- To identify the isolates from both samples and the possible health implications.
MATERIAL / REAGENT USED
Gallenkarnp electronic colony conuter, melttler weighing balance, refrigerator, Autoclave, inoculating loop, sterile pipette, test tube, sterile petric dishes, carbolite oven and Ohams PH meter.
REAGENT USED:-
Potato Dextrose apar, lodine, nutrient agar, methylred, ethanol, safarmine, hydrogen peroxide, kovac regent, peptone water, glucose and sodium hydroxide.
COLLECTION OF SAMPLE:-
Three different brand of canned tomatoes were purchased from various retail outlets in railway police quarter Aba. All the brands that were selected for this project carried comparable expiry date (ie best before) the sample were well labeled and stored for further analysis.
CHAPTER FOUR
Table 4.0 MICROBIAL LOAD OF BACTERIA ASSOCIATED WITH CANNED TOMATO SPOILAGE
CHAPTER FIVE
DISCUSSION
The result of the study carried out shows that all the three canned tomato samples collected were found to be severely contaminated with bacteria and fungi.
The observed higher total viable count in samples suggest alteration of the hermetic condition normally associated with canned products. Consequently, favorable growth conditions not usually encountered must have occurred within the can, thereby enhancing the growth of diverse microflora and increased population. The preponderance of the isolates were sporeformers but other micro-organisms, including staphylococcus and lactobacillus were also isolated from the samples. This may be partly attributable to the heat resistance of these micro-organism.
CONCLUSION
The study conducted suggest bacteria specie to be the major cause of spoilage to canned tomato.
Among the three major bacteria isolates, Bacillus species constituted the highest proportion samples. Bacillus coagulans was the predominant organism among the Bacillus species.
Also mesophilic organisms are mainly responsible for flat sour spoilage of canned tomatoes, their high percentage of occurrence in the cans showing normal appearance may have led to the low pH and the absence of any visible manifestation of bulge due to their ability to from acid without gas.
RECOMMENDATION
Since tomato paste is the most important product because of its wide spread use for preparation of various food/menus for human consumption. Government should encourage refined production of tomato paste so as to help to minimized contamination. And also adequate preservative measures should be taken in order to help in storage canned tomato against quick spoilage and contamination of micro-organisms.
REFERENCES
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