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Assessment of Microbiological Quality of Processed Fruit Juice

M Abul Basar
Department of Microbiology, University of Dhaka, Dhaka 1000, Bangladesh

Sabita Rezwana Rahman
Department of Microbiology, University of Dhaka, Dhaka 1000, Bangladesh

Abstract/ Executive Summary:

The present study was performed to evaluate the microbiological quality of industrially processed packed juices such as mango, orange and lemon of five different local companies. Aerobic plate count (APC) in juice samples was nil when measured before and after neutralization of pH. However, after enrichment of couple of samples growth of bacteria was observed on nutrient agar and MacConkey agar media. Sample A showed 120 cfu/ml after 3 h on nutrient agar and 20 cfu/ml after 5 h on MacConkey agar medium. These findings indicate that manufacturers might use high amount of preservatives that had bacteriostatic effect on microbes. It can be suggested that processed juices should be prepared under hygienic condition without use of high amount of preservatives that might cause health hazard.

Keywords: Fruit juice, Bacterial count, Preservatives, Enrichment

Location: Department of Microbiology, University of Dhaka

Start Date:

End Date:

Program Area: Quality and Nutrition

Commodity: Juice

Objectives:

To measure microbiological quality of industrially processed fruit juices.

Methodology:

Five types of mango juices, three types of orange juices and two types of lemon juices were collected from different prevailed manufacturer in the Dhaka City for bacteriological analyses. At least 7 samples of each category were analyzed to overcome the sampling biasness. These samples were designated as A (mango), B (mango), C (mango), D (mango), E (mango), F (orange), G (orange), H (orange), I (lemon), and J (lemon). Total heterotrophic bacterial and yeast counts were taken to determine the overall contamination by mesophilic bacteria. Total coliforms and faecal coliforms counts were done for assessing the faecal pollution, while staphylococcal count was chosen to assess the hygienic quality of plant personnel12. For heterotrophic bacteria, total coliforms, faecal coliforms, staphylococcal and yeast counts, nutrient agar, MacConkey agar, mFC, mannitol salt agar and MYGP media were used respectively. Plating was performed by pour plate and spread plate methods using 1 ml and 0.1 ml sample. After inoculation the plates were incubated at 37°C for 24-48 h, except the mFC and MYGP plates that were incubated at 44.5°C and 28°C respectively. In order to avoid acidity of the processed juice, 5 ml original sample was neutralized by adding adequate amount of 0.1 N NaOH and then the neutralized sample (0.1 ml) was spread onto the surface of different media. To overcome the bacteriostatic activity of any added preservatives, the juice samples were first filtered through filter paper. Then the filter paper was placed on nutrient agar media, MacConkey and mFC medium and incubated overnight. Enrichment of sample was done by diluting 1 ml original sample in 9 ml nutrient broth medium and incubated at 37°C for 3-7 h. After time intervals (3, 5 and 8 h), 0.1 ml enriched sample was poured in nutrient agar medium and MacConkey medium and incubated at 37°C for 48 h.

Source of Information: Bangladesh J Microbiol, Volume 24, Number 2, December 2007, pp 166-168

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The low total viable count would not necessarily mean safe juice. Juice has to be free from unwanted preservatives. A preservative like sulphur dioxide (SO₂) is very detrimental to respiratory system of individuals.

Knowledge Management: Journal