A total of thirty (30) canned food samples comprising of six samples each of Sardines, Milk, Tomatoes, Meat and mixed vegetables were randomly collected from super stores, kiosks and local markets. All samples are within expiry date, none of which is bloated, leaking and/or physically damaged. Samples were analyzed by standard methods for total plate counts (aerobic and anaerobic incubations), and for spoilage, pathogenic and coliform organisms. The total aerobic plate count ranges from < 10cfu/g to 1.4x103 cfu/g. Anaerobic plate count ranges from < 10cfu/g to 1.0 x 102. Bacillus subtilis, B. coagulans, B. cereus, Clostridium perfringens, C. sporogenes, Staphylococcus aureus, Klebsiella spp and S. epidermides were isolated from some of the samples. The need for effective HACCP (Hazard Analysis Critical Control Point) is recommended to prevent under processing, pre-process and post-process contaminations, inadequate cooling, contamination from leakage through seams and pre-process spoilag

Braide, W.

Oranusi, S. U.

Osigwe, GA

Covenant University Repository

Volume 1, Issue 1, pp 15-18; March 2012 Journal of Biological and Food Science Research ©2012 Online Research Journals  Full Length Research  Available Online at http://www.onlineresearchjournals.org/JBFSR  Investigation on the microbial profile of canned foods  Oranusi US*, Braide Wesley and Osigwe GA  Department of Microbiology Federal University of Technology Owerri, Imo State, Nigeria.  Downloaded February 19, 2012    Accepted 6 March, 2012  A total of thirty (30) canned food samples comprising of six samples each of Sardines, Milk, Tomatoes, Meat and mixed vegetables were randomly collected from super stores, kiosks and local markets. All samples are within expiry date, none of which is bloated, leaking and/or physically damaged. Samples were analyzed by standard methods for total plate counts (aerobic and anaerobic incubations), and for spoilage, pathogenic and coliform organisms. The total aerobic plate count ranges from < 10cfu/g to 1.4x103 cfu/g. Anaerobic plate count ranges from < 10cfu/g to 1.0 x 102. Bacillus subtilis, B. coagulans, B. cereus, Clostridium perfringens, C. sporogenes, Staphylococcus aureus, Klebsiella spp and S. epidermides were isolated from some of the samples. The need for effective HACCP (Hazard Analysis Critical Control Point) is recommended to prevent under processing, pre-process and post-process contaminations, inadequate cooling, contamination from leakage through seams and pre-process spoilage.  Key words: Canned food, coliforms, expiry date, HACCP, pathogenic organisms, spoilage organisms, total plate counts.   INTRODUCTION  Canned foods or shelf stable canned foods are packed in hermetically sealed containers and are commercially sterile [1]. Canning is intended to destroy harmful microbes in food, however, with improper handling, cans become breeding grounds for microbes. Canning destroy the microbial contaminants, however, products undergo microbial spoilage and could cause food borne illness as a result of under processing, inadequate cooling contamination of the can resulting from leakage and pre-process spoilage. Some canned foods receive low-heat treatments and as such are prone to contamination by large number of different microorganisms’ types. Defective containers is a common place due to fault or bottleneck in the manufacture, improperly closed can or cans damaged due to bad packaging/transportation in such a manner as to permit recontamination of the can contents following the heat process (post-processing contamination). Canned foods have been reported to be contaminated mainly by spore forming bacteria of the genera Bacillus, Clostridium and Desulfotomaculum [2]. If the contaminant     *Corresponding Author's Email: ulochika@yahoo.com; +2348152215183 is a pathogen and the food is capable of supporting its growth, a health hazard exists [1,3,4]. B. coagulans and B. stearothermophilus have been implicated in canned tomato juice and milk causing flat sour spoilage with acid but no gas production from carbohydrate [5,6]. B. cereus and B. licheniformis contaminate milk causing broken cream and soft coagulum with blown cans [6,7]. Food poisoning by C. perfringens has been reported, poisoning has been associated most often with meat and gravies, however, C. perfringens spores are also found in milk and cheese and could grow to cause food poisoning [8,9]. Toarmina and Diorsa (2004) reported on the putrefaction and excessive gas formation of canned meat and sea foods caused by Clostridium sporogenes [10]. Spoilage of fermented Spanish olives “Zapateria’’ and explosion (rancidity and off-flavour) of chocolate candies have been associated with C. bifermentans and C. sporogenes [11,12]. Thermophilic spore formers may be more prevalent in under processed foods than mesophiles because they are more heat resistant, C. thermosaccharolyticum and C. thermoaceticum have been implicated in spoilage of canned foods [13,14]. Botulism is the most dreaded form of food poisoning and the botulinum toxin from C. 16                  J. Biol. Food Sci. Res.    botulinum is one of the most potent [8]. The ICMSF (International Commission on Microbiological Specifications for Foods) (1986) do not support incubation tests for canned foods for obvious reasons.  It is however necessary for low acid canned foods that do not receive full botuninum cook; it is equally of use to manufacturers to monitor spoilage trends over long period of time and to monitor pathogens like staphylococci and Salmonella typhi that will not produce gas in many canned products [1]. The aim of this work is to determine the microbial profile (pathogen and spoilage organisms) in some canned foods within expiry date, with a view of educating the public on food safety.    MATERIALS AND METHODS  Sample Collection:  Thirty (30) samples of a canned foods comprising of two each of three different brands of canned meat, milk, mixed vegetables, sardines and tomatoes were examined. Samples within the expiry date as indicated on the container were randomly (without specific order) collected from kiosks and supper markets/shopping malls. Samples were taken to the laboratory for analysis. The information on the container/labels was recorded to include NAFDAC (National Agency for Food and Drug Administration and Control) number, manufacture and expiry dates, batch number, manufacturer’s address, preservative(s) and compositions.  Cans were examined for evidence of bloating, leakage and physical damage.   Sample Analysis:  Prior to analysis, the surface of the container was cleaned with 70% ethanol and tincture of iodine.  Containers were opened near the flame of the Bunsen burner to avoid contamination.  The PH of the samples was taken using pH meter (Jenway 3505, manufactured in England).  Ten gram (10g) portions of the foods was blended in sterile warring blender and inoculated into triplicate tubes of 90ml Brain Heart Infusion (BHI) broth (Oxoid) and Cooked Meat medium (Oxoid).  The tubes were incubated aerobically and anaerobically for 24-48 hours pre-enrichment at 150C for psychrophiles, 370C for  mesophiles and 550C for thermophiles. Triplicate plates of BHI agar and Nutrient agar was inoculated after pre- enrichment and incubated aerobically and anaerobically (Oxoid anaerobic Jar) at the same temperatures of the pre-enrichment broths.  Ten gram (10g) portions of the foods was blended in 90ml peptone water (Fluka, Germany), the homogenates was diluted 10-2 and plated via spread plate method on triplicate Plates of BHI agar, Nutrient agar, MacConkey agar and Eosine Methylene Blue (EMB) agar (Oxoid).  Incubation was as described     above, except however, for MacConkey and EMB agar that was incubated aerobically at 370C and 450C for Coliforms. At the expiry of incubation time, colonies were counted using colony counter (Stuart Scientific, UK).  Results were expressed as cfu/g.  Characteristics colonies on plates were Gram stained, purified by repeated subculture and stored on agar slants or agar stab if anaerobe, until further characterization. Tentative identification of isolates was done by Gram staining, indole test, urease test, catalase test, methyl red test, citrate utilization test, Voges proskeur test, gelatine liquefaction, starch hydrolysis, sugar fermentation tests, motility and  cultural characteristics on culture media. Confirmatory identification was based on the methods of [15,16].   RESULTS  No blown, leaky or physically damaged can was observed in all the samples analysed. Cultures from the pre-enriched samples yielded more organisms than the directly cultured samples without pre-enrichment.  Similarly aerobic culture produced more colonies than anaerobic culture. The mean total plate counts for the canned foods are as shown in Table 1. It revealed that mixed vegetables, Tomatoes and Sardines had higher microbial loads compared to milk and meat products. Incubation at 370C and 550C both aerobically and anaerobically yielded more counts than incubation at 150C. Coliform was implicated in a sample of Sardine and two samples of mixed vegetables. Table 2, shows the micro organisms isolated from the analysed samples. B. coagulans and S. aureus are the predominant microorganisms isolated. B. cereus and C. perfringens was implicated in meat samples.   DISCUSSION AND CONCLUSION  The absence of blown and leaky cans could suggest that all the samples analysed within expiry date from  manufacture is of acceptable quality for consumption. The canned foods examined had low microbial loads < 106 within acceptable microbiological quality [17]. The combined effects of high temperature treatment, pH, preservatives and anaerobic condition of canning could have been responsible for the low microbial loads. Mixed vegetables, Tomatoes and Sardines had higher plate counts; these could be a reflection of the quality of the raw materials, under processing, pre-process contamination and to the level of stringency in their production. The isolation of B. coagulans, B. cereus, B. subtilis, C. sporogenes and C. perfringens could be explained by the  Oranusi et al.                        17    Table 1. Mean pH and total plate counts of canned foods  Canned Foods Mean Total Plate Count cfu/g Aerobic incubation                 Anaerobic incubation 15oC     37oC          55oC          15oC        37oC           55oC  Coliform Count  Mean pH Meat - 5.0x101 < 10 - 1.0x101 <10 - 6.24 Milk - 1.0x102 - <10 - <10 - 6.20 Mixed Vegetables - 1.4x103 1.0x101 <10 1.0x102 <10 2.0x102 5.30 Sardine - 2.1x101 1.1x101 - 1.2x101 <10 <10 6.12 Tomatoes - 1.3x102 <10 - <10 <10 - 4.25  - = No growth at expiry of incubation time   Table 2. Microorganisms isolated from canned foods  Canned Foods Microorganisms isolated Meat B. cereus, B. subtilis, C. Perfringens Milk B. coagulans, Bacillus spp Mixed Vegetables B. subtilis, S. aureus, Klebsiella spp, B. circulans Sardine S. aureus, C. sporogenes, Klebsiella spp Tomatoes B. coagulans, S. aureus, S. Epidermides   fact that they are spore formers and known common environmental contaminants, they have been implicated in canned foods [2,6,7]. C. perfringens and B. cereus are pathogens that can cause infection and food poisoning, they are known to have extreme wide growth temperature of 20-500C [6,7,8]. The presence of B. cereus and C. perfringens in canned food, even though in very small amount, calls for concern as temperature abuse and poor storage conditions prevalent in kiosks and stores from where these products were purchased, could encourage proliferation of these organisms to unacceptable level. B. coagulans, B. subtilis and C. sporogenes have been reported as spoilage organisms in Tomatoes, Milk, Meat and Chocolate products, causing flat sour spoilage, putrefaction, rancidity and off-flavour [5,6,10,11,12], their presence in canned food portend possible spoilage if storage conditions become favourable due to abuse. S. aureus, S. epidermidis and Klebsiella are of human flora, they are known opportunistic pathogens. Contamination of canned foods could be via food producers/handlers and equipments. They are facultative and hardy organisms, thus their survival in canned foods could be explained.  Toxigenic strains of S. aureus have been implicated in food born illness and are known to proliferate in conditions of temperature abuse [18,19,20,21]. That the pre-enriched samples yielded more organisms than the direct culture could be explained by the fact that shelf stable canned foods packed in hermetically sealed containers are not absolutely sterile and thus contain injured and suppressed micro-organisms that could proliferate if storage conditions and integrity of the container is compromised. Regular surveillance and checks to monitor canned foods on sales is therefore necessary for effective food safety.   References  [1] ICMSF. Micro organisms in foods 2. Sampling for microbiological analysis. Principles and specific applications. Blackwell Scientific Publications. 1986.  [2] James MJ. Spoilage of miscellaneous food. In Modern Food Microbiology, 4th edition, Nostraned Reinhold, New York. 1992; pp 245-246.  [3] Stersky A, Todd E, Pivnick H. Food poisoning associated with post-process leakages (P.P.L) in canned foods. J. Food Protection 1980; 43: 465-467  [4] Put HMC, Van-Doren H, Warner WR, Kruiswijk JTH. The mechanism of microbiological leaker spoilage of canned foods: Rev. J. Appl. Bacteriol. 1992; 35: 7-27  [5] William C, Frazier D, Westhoff O. Food borne illness bacterial. In Food Microbiology 4th edition New York. 2006; pp 401-431  [6] Oomus SJ, Van-Zuylen AC, Hehenkamp JO.  The characteristics of Bacillus spores occurring in the manufacturing of canned products. Int. J. Food Microbiol. 2007; 120: 85-94   [7] Arun KB. Food borne microbial pathogen, mechanism and pathogenesis. Purdie University Indiana USA. 2008; P. 276  [8] Donnelly LS,  Busta FF. Anaerobe spore forming micro organism in dairy products. J. Dairy Sci. 1981; 64(1):161-166  18                  J. Biol. Food Sci. Res.    [9] Granum PE. Clostridium perfringens toxins involved in food poisoning. Int. J. Food Microbiol. 1990; 10: 101-111  [10] Taormina PJ, Dorsa WJ. Growth potential of C. perfringens during cooling of cooked meats. J. Food Protect. 2004; 67(7): 11537-1547  [11] Flacks L. Botulinum in New Zealand. New Zealand Med. J. 1985; 98: 892-893  [12] Frazier C, Westhoft DC. Food Microbiology 3rd edition New York. 1986; pp 306-317  [13] Bryan FL. What Sanitarian should know about C. perfringens food borne illness. J. Milk Food Technol. 1969; 32: 383-389  [14] Mario PF, Don F. Food Microbiology. In public health and spoilage aspects 2nd edition. Westport New York. 1976; 356-379  [15] Speck ML. Compendium of methods for microbiological examination of foods. American Public Health Association. Washington DC. 1976; pp 277-328  [16] Jolt JG, Krieg NR, Sneath PHA, Stanley JT, Williams ST. Bergey’s Manual of Systemic Bacteriology, 9th edition. Williams and Wilkins Co. Baltimore, Maryland. 1994; P. 786  [17] ICMSF (International Commission on Microbiological Specification for Food). Sampling for microbiological analysis. Principles and specific application.  University of Toronto Press. 1974; Toronto pp 1-18  [18] Oranusi S, Galadima M, Umoh VJ. Toxicity test and bacteriophage typing of S. aureus isolates from food contact surfaces and foods prepared by families in Zaria, Nigeria. Afr. J. Biotechnol. 2006; 5(4): 362-365  [19] Oranusi S, Galadima M, Umoh VJ, Nwanze PI. Food Safety Evaluation in boarding schools in Zaria, Nigeria, using the HACCP System. Sc. Res. Essays. 2007; 2 (10): 426-433  [20] Tambeker DH, Jaiswal VJ, Dhanorkar DV, Gulhane PB, Dudhane MN. Identification of microbiological hazards and safety of ready-to-eat food vended in streets of Amravati city, India. J. Appl. Biosci. 2008; 7: 195-201  [21] Yadev N, Saini P, Kaur D, Srivastava N, Pandey D. Microbial quality and safety of ready to serve street foods vended in Allahabad city, India. Internet J. Food Safety. 2011; 13: 6-10  

Investigation on the microbial profile of canned foods

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Investigation on the microbial profile of canned foods

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