Introduction
Ice cream, a milk-based good, is an excellent medium for microbial growth owing to high nutrient value, virtually neutral pH value (~pH 6–7), and elongated storage interlude of ice cream. The components of ice cream may be of a diversity of amalgamations of milk, cream, condensed milk, dried milk, colouring materials, flavours, fruits, nuts, sweetening agents, eggs, and eggs products, and stabilizers. Any of these could add to microorganisms’ growth and influence the quality of the goods as evaluated by its bacterial load or the presence of different explicit bacteria species. Time reliant heating throughout the ice cream creation decreases principally the vegetative forms of the microorganisms. Conversely, spore-bearing bacteria might as well cause risks via consumption the milk products. In addition, the occurrence of bacteria in ice cream samples is mainly by means of tools and equipments, water, workers, environment, packaging materials and contaminations at some stage in the shipping and delivery of ice cream.
This particular study was carried out in Kars, Turkey to determine the microbiological quality of ice cream sold openly by retail outlets at the same time determining the specific prevalence of bacterial species in the ice creams.
Research design
The study was conducted between July and August 2004, and was designed determine Microbial quality of ice cream sold openly by retail outlets in Turkey. There were 73 samples collected, which were to be analyzed to verify the hygienic prominence of the ice creams and look for the occurrence of some Gram positive and Gram-negative pathogenic bacteria.
Materials
A total of 73 ice cream samples were acquired from retail stores from July to August 2004 in Kars city. The samples were transported in a freezer bag and analyzed.
Methods
The initial preparation of the samples was done in accordance with the method of Warke et al. Conventional microbiological techniques and media were utilized for the isolation and enumeration of total aerobic mesophile bacteria, coli forms, Enterobacteriaceae, Enterococci spp., yeast-mould and the pathogenic bacteria like E. coli, E. coli O157: H7, Yesinia spp., Salmonella spp., S. aureus, B. cereus.
The most probable number (MPN) technique was used to determine the number of E. coli. Three tubes with Brilliant Green Bile 2 % Broth (Oxoid, CM31) was inoculated with the E. coli. E. coli presence in the tubes was established by streaking the bacteria on Endo Agar (Oxoid, CM479). The colonies were characteristically greenish metallic in color. E.coli was further confirmed through biochemical tests: the indole, methyl-red, Voges Proskauer, and citrate utilization (IMVIC) tests. The S. aureus were identified through gram staining technique and confirmed through biochemical tests: catalase, coagulase, and latex agglutination (Oxoid, FT0203). B. cereus is identified through Gram stain, catalase, motility, nitrate reduction, tyrosine decomposition, anaerobic fermentation of glucose, Voges Proskauer reaction and production of acid from mannitol and arabinose. B. cereus colonies are usually pink-purple, and opaque.
For Salmonella, the colonies were subjected biochemical and serological tests : Triple Sugar Iron agar (TSIA) (Merck 103915) and Lysine Iron Agar (LIA) (Merck 111640), and agglutination (Oxoid FT 203) test. Yersinia spp., suspected colonies were subjected to Gram stain and biochemical tests: catalase, oxidase, urease, motility in SIM (Oxoid CM435) medium, growth on Kligler Iron Agar (KIA) (Oxoid, CM33). E. coli O157 : H7, colonies (colourless and sorbitol negative) were streaked on Fluorocult Violet Red Bile agar (Merck 1.04030) and incubated at 42 °C for 24-48 h. The grown colonies were then subjected to gram staining and biochemical tests: catalase, and IMVIC tests .The colonies were further confirmed via the use of Dryspot E. coli O157 latex agglutination (Oxoid, 200075) test and antisera O157 and H7 (Oxoid, Denka Seikan 210753 and 211057).
Results and discussions
This study intended to examine microbiological quality of ice cream samples sold openly by retail markets in Turkey. Of the 73 ice creams scrutinized, 4.1 % of the samples had intolerable hygienic quality consistent with the criterion (105 cfu/g) suggested in Turkish Food Codex (TFC), 78 % of the samples had the Enterobacteriaceae which had an advanced recognition rate than coli forms at 52 %, that is 102 to 106 cfu/g. The figures of coli forms were not consistent with the standard of TFC (95 MPN cfu/ml). Bearing in mind the percentage allocation of Enterococci spp. in the samples, 47 % of the ice cream samples (n=73) were inside the limits of 102 and 104 cfu/g. Entire yeast and mould tallies diversified between the ranges of 102-104 cfu/g and 18 % of samples could not be satisfactory, anchored in TFC level. The counts concerning the yeast and mould ice cream samples proposed the necessitation for a sufficient heat treatment and proper storage states.
E. coli was discovered and identified in 15 out of the 73 ice cream samples. However, E. coli O157 : H7 was fascinatingly missing within the samples collected. Yersinia spp was found in 9.6 % of the samples analysed. 6.8 % of ice cream samples had Salmonella spp. as 24 samples had S. aureus which is within the limits of 102 to 104 and 15 % of the samples do not satisfy the TFC standards (102 cfu/g). B. cereus was recognized in 19 % of the samples. However, the detection echelon for B. cereus (+) samples could not be considered potential hazard consistent with TFC (No: 24511) which is suggested it to be lesser than 1.0x104 cfu/g.
This research has designated that the hygienic quality of the examined open ice creams samples were insufficient. Bearing in mind the Enterobacteriaceae, coliforms, Enterococcus spp., yeast and mould counts, and the occurrence of S. aureus, E. coli, Salmonella spp., ice creams sold in the open may cause probable risk for public health particularly for vulnerable people (ages 24-28). This study backs the stipulation of offering hygienic safety measures by manufacturers and vendors and their control episodically in Turkey.
Limitations
The amount of sample collected was not broad enough to provide a longitudinal assessment of the Microbial quality of ice cream sold openly by retail outlets in Turkey.
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