Abstract: Since, ice-cream harbors many potent pathogens, its microbial quality has always been crucially important in public health. In this study, 50 samples of ice cream produced by 30 different small-scale traditional ice cream manufacturers in Kazeroon were studied for Total Bacterial Count (TBC), Enterobacteriacea count, coagulase positive Staphylococcal count, E. coli search and Salmonella sp. search, in order to determine if the samples meet the Ice cream standard set by the Iranian National Standard Center. Out of total ice cream of Kazeroon 50 samples (100%), 50 samples (100%) and 18 samples (36%) exceeded standard value of mesophilic aerobic count, Enterobacteriacea count and coagulase positive Staphylococcal count, respectively. Also, according to the results obtained from E. coli search, it was determined that 26% of ice-eream samples examined were not fit bacteriologieally to the Iranian Ice-Cream Standard. However, non of the samples were found to be contaminated with Salmonella sp. In the case of coagulase positive Staphylococcal count, the microbial quality of grade 2 ice cream samples was poorer in comparison to grade 1 samples but these two grade samples did not show significant differences in other cases. However, this study shows that the overall microbial quality of traditional ice cream samples being sold in Kazeroon is poor.

INTRODUCTION

Ice cream is a frozen dairy food made by freezing a pasteurized mix. The mix is composed of a combination of milk products (milk, condensed milk, milk powder, cream), sugar, emulsifiers, stabilizers, f1avouring and coloring agents. Ice cream is a palatable, nutritive and healthful food. Therefore, ice cream production has increased rapidly in recent years in many countries of the world (Kocak et al., 1998). In Iran, the production of ice cream is made in two different ways: traditional methods and the industrial production. The traditional production method refers to the manufactoring of open/artisanal ice cream. This kind of ice cream is generally manufactured in small-scale production units, which do not follow completely a standard procedure for production of ice cream. As, ice cream can become contaminated, while adding some ingredients after pasteurization or by means of improper sanitation of the equipment and environment, many psychrotroph and psychrotolerant microorganisms like Listeria monocytogens, Staphylococcus aureus, Bacillus, Salmonella, Shigella, Streptococus, Pseudomonas, Campylobacter, Brucella sp. and coliform bacteria are generally present in this kind of product (Jay, 1992). Therefore, evaluation of the presence of microorganisms in these products can give us the information about the raw ingrediets quality and the sanitary nature of the processing and packaging stages. Therefore, there are lots of surveys on the bacteriological quality of ice crcam and related products (Massa et al., 1989). The present research was conducted to determine the sanitary quality of traditionally produced ice cream in Kazeroon (a city of Fars province) and comparing it to the Iranian Ice Cream National Standard.

MATERIALS AND METHODS

In this study, fifty samples of traditional ice cream collected randomly from 30 different local markets of Kazeroon. The markets which had hygienic and acceptable appearance (according to the Iranian Institute of Food Control and Inspection) were nominated grade 1 and those, which had poor appearance were called grade 2. The samples were collected in an ice box and immediately taken to the laboratory where they were kept at -20°C, untill they were examined for the bacteriological quality. Ice cream samples were prepared according to the Iranian Institute of standard and Industrial studies, 2001a. Bacteriological examination included the total bacteria, Enterobacteriacea and coagulase positive Staphilicoccus aureus counts, E. coli and Salmonella sp. search were also, done according to the Iranian Institute of Standard and Industrial Studies (1991, 1994, 1995a, b; 2001b), respectively. SPSS software (chi-square (χ²) and Fisher^,s exact test) were employed to statistically evaluate the data.

RESULTS AND DISCUSSION

Out of total 50 samples, 50 ice cream samples (100%) exceeded standard value of total mesophilic aerobic count, which is 5x10⁵ cfu g^-1 (Iranian Institute of Standard and Industrial Studies, 2001a). In case of total Enterobacteriacea count, 50 samples (100%) crossed the standard value which is 100 cfu g^-1. Similarly, 18 samples (36%) and 13 samples (26%) were found crossing the standard value of Staphylococcal count (100 cfu g^-1) and E. coli (0 cfu g^-1), respectively. However, none of the samples were found to be contaminated with Salmonella sp. The average counts for total mesophilic aerobic bacteria, Enterobacteriacea and coagulase positive Staphylococcus aureus were found to be 4.9x10⁶, 2.9x10⁴ and 1.55x10² cfu g^-1, respectively. In the case of coagulase positive Staphylococcal count, the microbial quality of grade 2 ice cream samples was poorer in comparison to grade 1 samples (p<0.05) but these two grade samples did not show significant differences in other cases (p>0.05). However, this study shows that the overall microbial quality of traditional ice cream samples being sold in Kazeroon is poor.

The bacteriological status of the samples are presented in Table 1 and the comparison of the bacteriological status of the samples (cfu g^-1) with the standard value is shown in Table 2.

Ice cream is a fairly complex food containing sugar, emulsifiers and fats. This investigation presents the current status of microbial quality of ice cream being sold in Kazeroon. From the total analyzed ice cream samples (n = 50), 100% exceeded standard value of mesophilic aerobic count, 100% crossed the standard value of total Enterobacteriacea count, 36% were beyond the standard value of staphylococcal count and 26% were found to carry E. coli, but none of the samples were found to be contaminated with Salmonella sp. These results are generally similar to the findings of other researchers and can be supported by the research of Massa et al. (1989) and Tamminga et al. (1980). Microbial quality of ice cream examined in Phillipines by Orallo et al. (1999) and Bangladesh by M-E Elahi et al. (2002) also showed the more or less comparable results.

Staphylococcus aureus is found to survive longer in ice cream (Gogov et al., 1984). Staphylococci might enter the milk products from food handlers which either suffering from acute pyogenic infections or being healthy carriers harboring the organisms in nose or throat. The presence of coagulase positive Staphylococcus, which is mainly S. aureus can lead to the staphylococcal intoxication as a result of the growth and toxin production of this organism. The presence of starch and protein can also encourage the toxin production of these organisms (Jay, 1992).

The survival rate of the organisms depended both on the specific peculiarities of the individual strains and on the composition of the ice cream mixture. Exceeding the standard value in terms of mesophilic aerobic count may be because of poor handling of retailers. However, in terms of total coliform it^,s cutting of standard value indicates the presence of fecal contamination of ice cream.

Table 1:	The bacteriological status of the traditional ice cream samples (cfu g-1)
*Standard value

Table 2:	Comparison of the bacteriological status of the traditional ice cream samples (cfu g-1) with the standard value
*TBC: Total Bacterial Count

This suggests, the possibility of the presence of other intestinal pathogens in this dessert. These microorganisms are transmitted via fecal-oral route.

The results show a negligence such as poor sanitation during the preparation or storage of ice cream including dirty premises, using bare hands in preparing the products, etc. Even, the raw milk could be a possible source of contamination. In the manufacturing processes, proper pasteurization is effective in destroying most of pathogenic bacteria. Automatic machines that are widely used for ice-cream production in dairy industry minimize direct hand manipulation and possibility of cross contamination.

The present study shows the sub-standard microbiological quality of open/artisanal ice cream and encourage the consumers to shift to the packed/industrial ice cream with consistently good quality. The study calls for actian in two fold:

ACKNOWLEDGEMENT

We acknowledge the Islamic Azad University, Kazeroon Branch who technically supported this project.