Evaluation of Microbial and Heavy Metal Contaminants in Local and Imported Packaged Biscuits Available in Islamabad Pakistan

Abstract

A set of fifteen locally manufactured and fifteen imported biscuit samples were collected from three different locations of Islamabad. All the thirty samples were quantitively analyzed for their microbial and heavy metal content. A structured questionnaire was devised, and a detailed survey was carried out prior to the sample collection. The survey was the basis of the brands we specifically targeted for the sample collection. First the samples were subjected to the microbial analysis where they were tested for total bacterial count, total coliform count and salmonella and shigella count using Nutrient agar, EMB agar and S.S agar respectively. The results of total coliforms, salmonella and shigella were negative for all the samples as no growth was observed on the EMB and S.S agar plates however certain growth could be observed for total bacterial count for all the samples on Nutrient agar plates. Almost all the samples contained total bacterial count within permissible limits according to the Pakistan standards i.e. 10,000 cfu/g however 7 samples showed uncountable total bacterial count and cannot be deemed safe for consumption based on their microbial analysis. After the microbial analysis all the samples were tested for the presence of nickel, cadmium, chromium and lead. The amount of each heavy metal was detected using Atomic Absorption Spectrophotometry and the results were statistically analyzed using SPSS software. Nickel is the most abundant heavy metal present in all the samples more than the permissible limit as provided by WHO i.e. 0.05 mg/l (ppm) except 2 locally manufactured biscuits that contain nickel in permissible amounts. Seven samples contained chromium more than the permissible limit i.e. 0.06 mg/l (ppm) while lead and cadmium were present in permissible amounts in all the samples.