ASSESSMENT OF THE MICROBIOLOGICAL QUALITY OF INDUSTRIALLY PRODUCEDAND STREET VENDED ICE CREAM OFFERED FOR PUBLIC CONSUMPTION IN DHAKA CITY.

Presented by # Md. Mahmudul Hasan Taskia Haque Sweety ID # 113-040-031 ID# 111-267-031 Department of Microbiology Primeasia University

INTRODUCTION:

Ice cream is a delicious, nutritious frozen dairy food. Consumed by all age groups specially during

summer season. Ingredient of ice cream are cream, condensed milk,

dried milk, coloring materials, flavors, fruits, nuts and sweetening agent.

Contaminated with microorganisms and ingredients have been added after pasteurization or improper sanitation of the equipment.

Microbiological quality of ice cream is determined by total viable bacterial count ,coliform count and presence of organism.

Materials and Method:

Sample collectionA total of 20 samples,10 of locally produced

and 10 of industrially produced ice cream like as Polar, Quality, Igloo, Savoy, Bellissimo purchased from hawkers and retail outlets.

Collected in a sterile container and bought the laboratory immediately for proper analysis.

Preparation of serial dilution1ml of each sample was pipette set out

aseptically and transferred into a sterile test tube containing 9ml of distilled water to give a dilution of 1: 10 , homogenized by vertex and dilutions were made upto 105.

Primary Isolation of Bacteria from Samples: Using the pour plate technique. Average of plates were counted and

recorded as the numbers of colony forming unit(cfu/ml)of each ice cream sample.

The bacterial plate counts per ml were recorded using :

n/v x r Where n= Number of colonies r= Dilution factor v= Value of the particular dilution being put

on the medium.

Total Aerobic Plate Count (APC):Performed according to ISO standard (ISO-4833:2003(E), Done by serial dilution technique followed by pour plate technique and Nutrient agar was used and incubated at 37 ºC for 24 hour.

Enumeration of Total Coliform Count (TCC):MacConkey agar is used for total coliform count. All the plates were incubated at 30 ºC for 48 hours.

Enumeration of Total Staphylococcal Count (TSC):1 ml of each tenfold dilution was transferred to Mannitol Salt Agar (MSA). All the plates were incubated at 37°C temperature for 48 hours.

Detection of Escherichia coli: Eosin Methylene Blue (EMB) agar to examine them for production of metallic sheen to confirm E. coli growth. A pure colony of each isolates was picked and Gram stainingwas performed.

Detection of Salmonella spp.: The samples were inoculated into Buffer peptone water for pre-enrichment and incubated at 35-37°C for 24±2 hrs. Salmonella-Shigella (SS) agar and Bismuth Sulfite Agar (BSA) using sterile inoculating loops and then dishes were covered, inverted and incubated at 35-37°C for 24±2 hrs.

Characterization and Identification of Isolates:

Bacterial isolates were grouped on the basis of- Colonial morphology Size of the colony Color Surface Edge Slope Elevation by gram staining.Some common ice cream flavors: Chocolate Vanilla Strawberry Lollies Fruital

Collection of Different Ice cream Samples from Dhaka city:SL NO

Name of sampling site

Branded Ice cream

Road Vendor Ice cream

1 Tejgaon Polar Poly Kulfi

2 Tejgaon Igloo Loli Green mango

3 Tejgaon Kwality Chocober

Poly Chocober

4 Banani Bellissimo Loli Kulfi Local

5 Banani Za’n Zee Fruital

Malai Local

6 Banani Savoy Cup Cone Local 7 Mohakali Kwality Cup Kulfi Local 8 Mohakali Igloo Malai Kulfi Local

Media used for isolation of microorganisms and their percentage (%) occurrence in Ice cream :

SL NO Parameters Media Used 1 Total Plate Count Nutrient Agar 2 Staphylococcus

aureus Mannitol Salt Agar

3 E. coli EMB Agar 4 Salmonella - Shigella SS Agar 5

Isolation of gram-negative enteric pathogens from fecal and other specimens.

XLD

SL NO Types of microorganisms

Percentage (%)

1 Coliform Count 100 2 Staphylococcus species

(cfu/g) 40

3 Salmonella species (cfu/g)

33

4 E. coli (cfu/g) 40 5 Shigella species (cfu/g) 53

Result:Table 1: Enumeration of microorganisms (APC), Total Coliform, E. coli, Staphylococcus aureus and Salmonella spp of brander ice cream samples.

Sample no

Brand Name

APC(cfu/m)

TotalColiform(cfu/ml)

S. aureus(cfu/ml)

E. coli /g

Salmonellaspp

1 Polar 72 x102

7 2 Absent Absent

2 Bellissimo

32 x 102

8 Absent

Absent Absent

3 Za’n Zee

92 x 102

10 5 2 Absent

4 Savoy 160 x102

12 9 3 Absent

5 Igloo 28 x102

2 Absent

Absent Absent

6 Igloo 35 x102

Absent

Absent

Absent

Absent

7 Kwality

120x102

9 4 Absent Absent

8 Kwality

90 x102

14 8 Absent Absent

FIGURE: FIGURE: Growth of E coli on EMB

FIGURE: Growth of colonies on XLD FIGURE: Growth of colonies on SS agar

Growth of colonies on nutrient agar

Result:Table 2: Enumeration of microorganisms (APC), Total Coliform, E. coli, Staphylococcus aureus and Salmonella spp of street vended ice cream samples.

Sample no

Local Sample

APC(cfu/m)

TotalColiform(cfu/ml)

S. aureus(cfu/ml)

E. coli

Salmonellaspp

1 Poly Kulfi 90 x 102

11 10 Absent Absent

2 Green mango

110 x 102

10 8 Present

Present

3 Poly Chocober

100 x 102

41 9 Present

Absent

4 Kulfi Local

150 x 102

32 Absent Present

Absent

5 Malai Local

130 x 102

10 10 Absent Absent

6 Cone Local

200 x 102

16 Absent Present Absent

7 Kulfi Local

170 x 102

19 31 Absent Absent

8 Kulfi Local

220 x 102

41 18 Present

Present

FIGURE: FIGURE:

FIGURE:

Growth of colonies on nutrient agar

Growth of E. coli on EMB

FIGURE: Growth of colonies on XLD Growth of colonies on SS agar

Discussion:

The quality of food depends on the total number of viable organisms as revealed by the total bacterial count. Total Viable Count (TVC) was within the limit for all industrially produced ice cream samples average 78.6 x 102cfu/ml. The street vendor samples from Tejgaon, Mohakali and Banani exceeded the standard that average 146.2x 102 cfu/ml.

As per standard, the coliform count in ice cream should not be more

than 10/gram. In the present study, the average number of coliform count in branded samples is 8/ml and vendor sample is 23/ml which cross the limit.

S. aureus is present in 5 branded sample ( 70%) and 6 vendor sample (75%) . The average number of S. aureus count in branded samples is 4/ml and vendor sample is 11/ml.

The presence of E. coli in branded sample is relatively low, absence in 6 samples out of 8 and presence in vendor relatively high, presence in 5 samples out of 8.

Salmonella spp. absent in branded ice cream and presence

in 2 sample out of 8 in road vendor ice cream. Consumption of contaminated ice cream has been the cause of several food poisoning outbreaks .The bacteriological analysis of the ice cream from the street vendor reflected the unhygienic vendor handling practices.

Conclusions: Ice cream is one of most popular and favorite food products all over

the world. It is ideal media for microbial growth due to high nutritive value and long storage duration. Several steps during production like as cross contamination or improper handling can cause bacteriological hazards.

To improve quality of ice cream, implementation Good manufacturing

practice (GMP), HACCP are mandatory at all with post pasteurization steps. Adoption of good sanitation practices and application of HACCP principles in system along with training of workers on personal hygiene will definitely improve the quality of ice cream.

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