Akbari Sh., Alemyar S., Akimbekov N.Sh.

al-Farabi Kazakh National University, Almaty, Kazakhstan

Microbial analysis of bread samples from Afghanistan

Abstract

This study was conducted to detect the microbial community dynamics of the bread samples (market and domestic) from bakeries in Kabul and Takhar provinces, Afghanistan. Counting of colony forming units (CFU) on various nutrition media has been used as a traditional method to quantify fungal and bacterial populations. According to the results, the contamination with Bacillus sp., Staphylococcus sp., Еntеrococcus sp., Listeria sp., Aspergillus sp., and Pеnicillium sp. was detected. The surface of market and domestic bread has the highest microbial contamination than the core sides. Different ambient (temperature, humanity, oxygen concentration, etc.) and management (flour composition, chemical constituents, pH, processing mode, etc.) factors contribute the distribution and germination of saprophytic, opportunistic and pathogenic microorganisms. Therefore, the microbiological purity of raw materials is very important. They should be thoroughly cleaned throughout the processing and subsequently stored in proper conditions under the hygiene standards.

Introduction

Bread is the most important component of the food that is widely accepted as a very convenient form of food, which is desirable to the entire population of most countries, including Afghanistan. The origins date back to the Neolithic era and is still one of the most consumed staple. It is a good source of nutrients, such as macronutrients and micronutrients, which are essential for human health [1].

Bread and other bakery products are expose to spoilage problems. These include physical, chemical and microbial spoilage. Mould spoilage is a serious and costly problem for food industries, especially the species of Pеnicillium, Aspergillus, Rhizopus, Mucor, Еurotium and Monilia cause considerable damage of bread and bread products [2].

Rope spoilage is a bread disease consisting in bacterial decomposition of the breadcrumb and generally caused by Bacillus subtilis (formerly referred to as B. mеsеntеricus), but B. lichеniformis, B. mеgatеrium, B. pumilus and B. cеrеus can also be the causative agents. Ropinеss, which is the most significant spoilage of bread after moldiness, occurs particularly in summer when the climatic conditions favor the growth of bacteria. The incidence of wheat bread spoilage caused by Bacillus has increased during the last few years presumably because more bread is produced without preservatives and often raw materials such as bran and seed are added. Spoilage of bread by rope formation may constitute a health risk, high numbers of B. subtilis and B. lichеniformis in foods may cause a mild form of food illness [3]. The origins of Bacillus species are reported to be raw materials, particularly flour, and from the bakery atmosphere, equipment surfaces and other materials. Spores found in flour and other raw materials are resistant to heat and some of them can survive the baking process where temperature in the center of the crumb remains at a maximum of 97–101°C for only a few minutes. Failure to reach this temperature in all parts of the bread greatly increases the proportion of surviving spores. It has been found that all baking flours are contaminated with Bacillus spores because of cultivation and processing methods. As this type of spoilage only affects the central portions of the loaf in its initial stages it is seldom evidence to consumers at the time of purchase [4].

Materials and methods

Two samples of bread including market and domestic were bought from “bakery areas” in Kabul and Takhar provinces, Afghanistan, and transferred to the laboratory for microbial analysis. After 4 days 0,1 gram of each bread sample (from core and surface) is weighed out and added in 10 ml sterile water then homogenized. According to the protocol [5, 6], the samples aseptically inoculated onto Petri dishes with various media (Dextrose agar (DA), tryptone soya agar, endo agar (TSA), sabouraud dextrose agar (SDA), tryptonе glucose yeast extract agar (TGA)). The plats are incubated at 30-35°C temperature for 2-3 days [7, 8].

Results and discussion

The number of microbes in various types of bread was variable. In the surface of market bread, bacterial load showed 7,3x10⁴ CFU/mg and the core of it was 8x10² CFU/mg. The number of fungi and yeasts was 4x10² and 5x10¹ CFU/mg respectively. Bacterial populations of the domestic bread were 6,1x10³ CFU/mg on the surface and 1x10¹ CFU/mg in the core. Fungal population was less than market bread, thus 1x10¹ CFU/mg and 2x10² CFU/mg respectively.

Microbial load of market bread in different nutrients

Microbial load of domestic bread in different nutrients

These bacterial isolates were cultured, colonial characteristics were observed and their morphology was microscopically analyzed. Bacteria obtained are short and long sized rods as well as cocci. Different standing and spore analyses were done and the morphological-biochemical identification of the isolates showed the isolates belong to the Bacillus, Pseudomonas, Micrococcaceae and Lactobacillus.

Conclusion

The selected bacterial isolates were micro-and macroscopically studied as well as using different fast morphological and biochemical tests. Analyses reveal that strains mainly belong to genera Bacillus, Micrococcus Pseudomonas. The raw materials and ingredients for the processing of different breads must have the least possible amount of contaminants. Thus, whole production should be as hygienic as possible.

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