INCIDENCE OF ICE CREAM CONTAMINATION WITH COLIFORMS AND FECAL COLIFORMS IN ASSIUT CITY

Assiut University web-site: www.aun.edu.eg

INCIDENCE OF ICE CREAM CONTAMINATION WITH COLIFORMS AND FECAL COLIFORMS INASSIUT CITY

YASSER S. WAFY

Fellow, Assiut University Hospitals

Received: 30 September 2019;     Accepted: 30 October 2019

INTRODUCTION

Milk and some milk products asice cream is a nutritionally enriched dairy product consumed by all ages especially children during summer (El-Sharef et al., 2006). Milk and some milk products asice cream is subjected to spoilage or contamination with pathogens during production, handling, processing and distribution.

Common sources of bacterial contamination, especially coliforms are faeces of animal or human origin, personnel, water, and containers. Further contaminations increase for some reasons including the cooling and storage temperatures plus holding time (Murphy and Boor, 2000). A high bacterial count reduces the shelf life of milk and enhances the risk of milk born bacteria infection, so a greater  deal of efforts have been made to produce clean milk and milk products to become safe for use and protect it from recontamination by any microorganisms specially from persons who work in production, handling, processing and distribution. The public health hazards of coliforms, fecal coliforms and E. coli has been emphasized by many authors; these enteropathogenic serotypes have been implicated in case of gastroenteritis, epidemic diarrhea in infants, sporadic summer diarrhea in children as well  as  in

Corresponding author: YASSER S., WAFY

E-mail address: yasserwafy2014@yahoo.com

Present address: Fellow, Assiut University Hospitals

case of food poisoning (kornacki and Marth, 1982).

Coliform are routinely used as indicator to the quality of the food products where their presence indicate careless method of handling and the use of insufficient sanitized equipment.

The microbial content of milk and dairy products are a major feature in determining their quality. Several routine examinations such as coliforms count, accepted to test the quality of milk and dairy products. As the coliforms may contaminate the milk which is used in manfacture of ice cream or may recontaminate it during handling by workers.

Therefore this work was planned to detect the incidence of coliforms and fecal coliforms in milk used in manufacture of ice cream and in ice cream after manufacturing in order to improve the sanitary conditions of ice cream.

MATERIALS AND METHODS

Collection of samples

A total of 90 random samples of raw cow's milk used in  small scale ice cream , small scale ice cream and large scale plain ice cream (30 samples each) collected fromAssiut city, Egypt, in the period between  April and September 2019. Each sample was   put in ice tank with thermometer to maintain temp. at 4C . The samples were dispatched to the laboratory with a minimum of delay where they were examined.

Preparation of samples (APHA, 1992a):

1-Raw cow's milk:   

11 ml of well mixed raw cow's milk were added to 99 ml of sterile peptone water 0.1% to make a dilution of 1/10 from which 10-fold serial dilutions were made.

2- Ice cream:

11 g. of well mixed ice cream samples after melting at room temperature (25°C) were added separately to 99 ml of sterile peptone water 0.1% and well mixed to prepare a dilution of 1:10; from which ten –fold serial dilutions were made.

Bacteriological examination for total coli forms and fecal coliforms count (APHA, 1992a):

1-    Total coliforms count (MPN) using lauryl sulphate tryptose (LST) broth and Brilliant-green Lactose Bile2%broth incubated at 35 to 37°C for 48 h.

2-    Faecal coliforms count using EC broth incubated at 44.5 C for 24 h.

3-    E. coli count using Eosine Methylene Blue agar (EMB) incubated at 35°C for 18 to 24 h.

4-    Biochemical test: Citrate utilization test - Indol production test- Methyl red test- Voges-Proskuer test-Citrate test.

RESULTS

Table 1: Statistical analytical results of total coliforms count (cfu/ml or g.) in the examined samples.

Table 2:Frequency distribution of the examined samples based on their total coliforms counts (cfu/ml or g.)

Negative tubes                                                                                                                                                        *

Table 3: Statistical analytical results of fecal coliforms (cfu/ml or g.) in the examined samples

Table 4: Frequency distribution of the examined samples based on their faecal coliforms counts (cfu/ml or g.).

Negative tubes                                                                                                                                                        *

Table 5: Statistical analytical results of E.coli true faecal type counts (cfu/ml or g.) in the examined samples.

Table 6: Frequency   distribution of the examined samples based on their E.coli true faecal type counts (cfu/mlor g.) in the examined samples.

Negative tubes                                                                                                                                                        *

DISCUSSION

The results in Table 1 & 2 show that 30 (100%), 22 (73.33%) and 8(26.66%) from examined  samples of raw cow's milk, (small scale) Ice-cream and (larg scale) Ice-cream samples were contaminated with coliforms and  the total coliform counts (cfu/ml or g.) in the examined samples ranged from 1.8x10² , 1.2x10²  and 3.7 x10  to 3.9x10⁴ ,3.7x10³ and 1.9x10²   with an average count of 2.4x10³, 2.8x10² and  1.56x10² (cfu/mlor g.), respectively.

The highest frequency distributions were 16 (53%), 14 (46.68) and 5(16.66) lied within the range of 10³-<10⁴, 10²-< 10³ and 3 -< 10¹in raw cow's milk, (small scale) Ice-cream and larg scale Ice-cream examined samples, respectively.

These results agree with those obtained by Sharma and Joshi (1992), El-Prince and Hussein (2000), Nawar (2001) and El-Kholy    et al. (2018).

Higher results of total coliforms in raw cow's milk were reported by El-Zubeir and Ahmed (2007), while lower results were reported by El-Kholy et al. (2015).

Higher results of total coliforms in ice-cream were reported by Çinar (2010), while lower results were revealed by Delia et al. (1980) and El-Essawy and Riad (1990). El-Kholy et al. (2015).

The stipulated results inTables 3&4 indicated that 18 (60%), 7 (31%) and 2(25%) of the examined samples of raw cow's milk, (small scale) Ice-cream and (larg scale) Ice-cream samples were contaminated with faecal coliforms and the total faecal coliforms counts (cfu/ml or g.) in the examined samples ranged from 1.1x10², 1.0x10²  and 9.4 x10¹ to 2.6x10^{4 ,}, 2.5x10³ and 1.7x10² with an average count of 2.1x10³, 1.9x10² and 1.32x10² (cfu/mlor g.), respectively.

The highest frequency distribution were 12 (40%),5 (16.67%) and 1(3.33%) lied within the range of 10³-<10⁴, 10²-< 10³ and 3-< 10² in raw cow's milk, small scale Ice-cream and larg scale Ice-cream examined samples, respectively. These results agree with those obtained by El-Kholy et al. (2018).

Higher results of faecal coliforms in raw cow's milk were reported by Meshref (2013), while lower results were reported by El-Kholy et al. (2015). Higher results of faecal coliforms in small scale ice cream were reported by Hassan (2003), while lower results were noticed by Salem (2017).

The presence of coliforms and faecal coliforms in milk and its products indicates either unsanitary conditions during production, processing or storage, (APHA, 1992b) or possibility of post-pasteurization contamination (Robinson, 2002).

Tables 5&6 show that 16 (53.33%), 5 (22.73%)  and 2(25%) of examined samples in raw cow's milk, small scale Ice-cream and larg scale ice-cream samples were contaminated with E.coli true faecal type and the E.coli true faecal type  count (cfu/ml or g.) in examined samples ranged from 4.8 x10¹, 5.8 x10¹ and 7.4 x10¹  to 1.8x10³, 2.3x10³ and 1.5x10²  with an average counst of 2.5x10², 3.3x10² and 1.12x10² (cfu/mlor g.),  respectively.

The highest frequency distribution were 10 (33.33%), 2 (6.66%) and 1(3.33%) lied within the range of 10³-<10⁴, 10²-< 10³ and 3-< 10² in raw cow's milk, small scale Ice-cream and larg scale ce-cream examined samples, respectively.

Higher results of E.coli in raw cow's milk were obtained by Mohamed (2017) and El Zubeir (2007) while lower results were noticed by Ali et al. (2010). Higher results of E.coli in small scale ice cream were showed by Sobeih et al. (2002), while nearly similar results were demonstrated by Hassan (2003), lower results were detected by Salem (2017) and El-Kholy   et al. (2018).

E. coli is a good indicator of fecal pollution and its presence in dairy products indicates presence of other enteropathogenic microorganisms which are considered of public health hazard (Singh and Prakash, 2008).

CONCLUSION

Milk contaminated with disease causing bacteria does not smell or look any different from non contaminated milk, and there is no obvious way for the consumer to know if the milk is contaminated (Julia, 2010). So great deal of effort must be done to protect clean milk from recontamination from different sources during production, handling, processing and distribution. It is valuable for considering the risk of contamination relating to health problem of the consumers.

The obtained results indicated that  unsanitary conditions during production, storage, handling and distribution of raw cow's milk,in dairy farm and manufacturing ofIce-cream (small scale) which   often has a poor bacteriological quality than the output of the large scale factory. Most of the examined samples are contaminated with coliforms, faecal coliforms and E.coli which considered as an indicator of poor sanitation and handling of the ice-cream during preparation and fecal contamination from either human or animal sources, and also its presence indicates poor sanitation.

So good hygienic measure must be taken during handling, transportation and  storage  of milk and avoid lack of cooling in facilities and unsatisfactory transportation means (Oghaiki et al., 2007)to improve the quality of milk and its products to be safe for consumers from exposure to the risk of food infection or intoxication.

Milk must come from dairy farm applied HACCP system in it. Also using of the refrigeration during production, storage, distribution and transportation of the raw milk in dairy farm. Moreover, enhancement of proper personal hygiene practices among all workers sharing in production, storage and handling of produced dairy products. Additionally, application of good manufacturing practices in milk manufacturing units and should be regarded by the regulatory authorities as basic or compulsory requirements. In order to obtain the best bacterial standard which is required, the utmost attention must be given to the cleaning and sanitation of all the plant and equipment used, to the personal hygiene of the entire operator, and to the general cleanliness of the factory.

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