Isolation and Identification of Microbes Associated With Spoilage of Bread

Isolation and Identification of Microbes Associated With Spoilage of Bread

Chapter One

Aim and Objectives

The aim of this study is to isolates and identify microbes associated with the spoilage of bread its shelf life determination. This aim will be achieve through the following specific objectives;

To determine the total fungal counts associated with the sample breads
To determine the fungal genera of public health important associated with sampled bread
To determine the shelf life of the sampled bread

CHAPTER TWO

LITERATURE REVIEW

Bread and Types

Bread is not only consumed in all countries of the world but is also the most acceptable form of food. It is an important staple food in the world and its consumption is increasing. It is made from wheat flour which is imported to Africa and Nigeria for that matter, making it relatively expensive. Due to its nutritional, sensorial and textural characteristics, ready to eat convenience as well as cost competitiveness it makes it an appealing food product (Khanom et al., 2016). Different bread types exist in the Wudil – Kano; it could be butter, sugar or salt based. These could all be made from either whole wheat or composite flours. Nonetheless, they all have wheat as the main flour base.

Composite Bread

Composite breads are made from blends of wheat and non-wheat flours. Several researchers have reported on different composite bread from various composite flours (Jard and Mishra. 2017). Composite bread; fababean, cotton seed, sesame, corn and barley- wheat composite bread; cassava, plantain and soybean- wheat composite bread; pumpkin, canola seed flour- wheat composite bread; soybean-wheat composite bread; full fat and defatted cocoa powder-wheat composite bread; peanuts, sunflower seed flour-wheat composite bread; beinseed-wheat composite bread; Sweetpotato-wheat composite bread; coconut-wheat composite bread

All these ingredients impart sensorial attributes and nutritional value which may be favourable in bakery product recipes and other food products. The composite flours are an advantage to developing countries because the use of locally made flour could reduce wheat imports and increase the potential use of locally grown crops. The idea of substituting part of wheat with other starchy crops is not new. Several institutions have carried out research designed to find ways of partially substituting wheat flour with other sources of flour or replacing wheat altogether (Kotula et al., 2022). With the constant increasing consumption of bread and other baked products in many countries, the composite flour programme promises to save significant amount of foreign exchange, provide a traditional nutritious food to more people at lower cost and to utilize indigenous crops to a greater extent. Bread is basically made from hard wheat flour, yeast, fat, sugar, salt and water. The consumption of bread in Nigeria as a staple food has steadily been on the increase, especially with explosions in population and changing life style patterns (John and Mishra, 2017).

Studies on the utilization of composite flour in Africa

According to Oluwajoba et al. (2022) three main market ventures exist for the cassava. The first and major business venture is the substitution of HQCF for wheat flour in baking. Another market opportunity is the use of cassava starch as a raw material for both food and non-food industries. Cassava can also be used to feed livestock in the form of chips and it can also be exported.

Mukunda et al. (2022) stated that if wheat flour is substituted with 15% cassava, Nigeria would be able to save US$14.8 million per annum. Cassava processors would be able to make an income of US$ 12.7 million whilst 4.2 million US dollars will also go to farmers. The findings from a survey conducted in Côte d’Ivoire and Nigeria showed that the bulk of bread eaten was made from composite flours of wheat and either maize, sorghum or cassava. It was also stated that in order to expand the use of cassava in Tanzania, most bakery products such as cakes, biscuits, chin-chin and croquettes were made with cassava flour in place of wheat flour. Moreover, stated that a lot of research is being conducted to study replacing wheat flour with other flours to help alleviate the problem of gluten allergy in certain populaces in the world.

CHAPTER THREE

MATERIALS AND METHODS

Collection of sample

Ten different types of bread samples sold in Wudil were purchased for the purpose of this study from different shops within Wudil town. The collected samples were brought in sterile polythene bags to the Microbiology Laboratory of Aliko Dangote University of Science and Technology, Wudil for analysis as described by Kuchenmuller et al. (2013).

Storage of Bread during Shelf Life Study

The coded bread samples were stored in plastic baskets under room temperature as being practiced by bakers and consumers, and a little elevated temperature conditions of the environment in the sun. Samples stored at elevated temperature conditions were brought back into the room after sunset as normally done. Visual observations were made daily on the stored bread samples, to check for mould growth and samples were taken daily for analysis in the morning (Ahaota et al.,2018).

Microbiological Analysis of the Shelf Stability of the purchased Bread Samples

The mycological analysis being carried out on bread samples during the shelf life study was Fungal count (yeasts and mould) as described by Amadi et al. (2014). This was carried out on fresh bread samples and daily for fungi (yeasts and mould count). Samples taken were stored at -20^oC in a freezer prior to analysis. The bread samples were mashed using a pistil and mortar. Ten grams of the mashed bread was mixed with Peptone water and sub samples were serially diluted decimally times and 1 mL aliquots were spread plated on Potato Dextrose Agar (PDA) for the enumeration of fungi. The PDA plates were inverted and incubated at room temperature (28 ± 2^oC) for 3 to 5days. The colonies were counted and expressed as colony forming units per gram (cfu/g) of samples.

CHAPTER FOUR

RESULTS

The results presented on table 4.1 shows the total fungal count as a measure of bread shelf life from day one (1) to day seven (7). At day one both sample B, D, and G revealed a low fungal counts of 10×10^-1cfu/g while the highest fungal count on day one was at sample H with 50×10^– 1cfu/g. However, at day seven (7) the highest count was at sample I with fungal count of 1910×10¹cfu/g while the lowest was at sample C with fungal count of 1170×10^-1cfu/g. This result indicated that the fungal count was proportional to the number of days for all the treated samples.

Table 4.2 shows the cultural and morphological characteristics of the fungi isolated from the treated samples of bread. Based on those parameters five genera of fungi were isolated viz; Aspergillus sp., Fusarium sp., Mucor sp., Penicillium sp., and Rhizopus sp.

The frequency and percentage of occurrence of fungi isolated was indicated in figure 4.1. In this figure, Aspergillus sp. And Penicillium sp. has the highest frequency and percentage of occurrence of 29% and 26% respectively. Fusarium sp. has percentage of occurrence of 18%, followed by Mucor sp., with 15% and Rhizopus sp. 12% showing the least counts.

CHAPTER FIVE

DISCUSSION, CONCLUSION AND RECOMMENDATIONS

Discussion

In this present research, the isolated and identified microorganisms have been determined to be the causative agents of certain diseases. These findings support earlier evidence that foodborne illnesses are prevalent worldwide and contribute to approximately one-third of global mortality (Khanom et al., 2016). Bread’s nutrient-rich composition fosters an environment conducive to microbial growth and metabolism, making it perishable. This creates the potential for harmful microorganisms like Aspergillus and Bacillus to persist within the bread matrix, leading to spoilage and rendering the product unsuitable for consumption. Implementing hygienic processing practices is essential to mitigate the risk of contamination and food poisoning, safeguarding consumers’ health (Hathout and Aly, 2014).

Our findings align with another study conducted in Bori Metropolis (River States, Nigeria), where Aspergillus spp., Penicillium spp., and Rhizopus spp. were also identified in bread samples. This underscores the presence of common foodborne microorganisms in bread and highlights the need for vigilant monitoring and control measures (Ezekiel et al., 2022). Of particular concern is the prevalence of Rhizopus contamination in the food chain. Rhizipus species are naturally occurring in the flora of both animals and humans, and they can easily be transmitted from handlers and animals in the food preparation area to the food products. This can lead to potential health risks if contaminated bread is consumed.

Addressing the issue of unhygienic practices in bread production is of paramount importance. For instance, bread vendors and hawkers may inadvertently contaminate the equipment used in bakeries and points of distribution, allowing contaminants to enter the bread during various stages of handling and transportation (Jard et al., 2021). By proactively addressing unhygienic practices and adopting stringent control measures, the risk of contamination and associated health hazards can be significantly reduced, safeguarding consumers and maintaining the quality and safety of bread products (Amadi et al., 2014).

The utilization of preservatives has emerged as an alternative approach to extend the shelf life of bakery products, despite not being favored by consumers. Commonly employed in the baking industry are propionates, sorbates, and sometimes benzoates (Hassan et al., 2014). However, despite their effectiveness, certain fungal species have displayed resistance even at the permissible maximum concentrations allowed in food. Notably, Fusarium species is one such resistant species, known to exhibit an extended lag phase followed by rapid multiplication, which could be a key factor contributing to its prevalence in deteriorated samples examined in this study (Khanom et al., 2016). Moro, Mukunda et al. (2022) demonstrated the resistance of Fusarium and Penicillium species isolated from moldy bread to propionic acid concentrations permitted for use in bread, as well as Aspergillus resistance to sorbic acid. Additionally, the same study revealed that both Aspergillus and Rhizopus species displayed resistance to elevated concentrations of acetic acid.

The selection of sanitization agents to combat spoilage fungi is a critical factor as the effectiveness of the process relies on the susceptibility of the fungi to the active components and the concentration of the sanitizer applied. A recent study by Oluwajoba et al. (2022) revealed variations in sanitizer sensitivity among strains of the same fungal species and even among different species isolated from spoiled baked goods. This underscores the significance of assessing the sensitivity of spoilage fungi causing losses in each individual bread industry.

Another crucial measure to prevent fungal spoilage is adopting a hygienic layout for buildings and facilities. This includes segregating post-baking areas (cooling and packing) from the breadmaking processing area, thereby reducing the influx of spores from raw materials that may contaminate freshly baked bread slices (Shephard, 2018). Additionally, minimizing the time of cooling and packaging can positively impact shelf life. By reducing the exposure of bread to contaminated air, the chance of spore deposition on the product surface is diminished, leading to an extended shelf life.

Conclusion

Our study findings revealed that bread samples distributed in the Wudil local government area of Kano state exhibited contamination with a diverse array of bacterial and fungal species. This contamination poses a significant safety risk to human health, potentially exposing the population to food-borne diseases. Bread is abundant in carbohydrates, serving as a primary energy source for the body. Moreover, it acts as a crucial fuel for essential organs such as the brain, kidneys, heart muscles, and central nervous system. Additionally, the presence of such contaminants indicates inadequate hygienic practices carried out by the handlers involved in the bread’s production and distribution.”

Recommendations

By addressing the issues related to handwashing, promoting hygienic handling practices, and embracing GHP and HACCP principles, the risk of contamination in bread can be significantly reduced, leading to safer food consumption and improved public health. Based on the finding of this study the following recommendations were made;

Frequent and sufficient handwashing, this suggests that the hands of individuals involved in food handling, such as vendors and consumers, may carry harmful microorganisms that can contaminate the food, including bread.
To mitigate the risk of contamination, both bread vendors and consumers are strongly advised to follow hygienic practices while handling bread. This includes maintaining cleanliness during storage, distribution, and consumption.
It is recommended to buy bread from reputable and approved sources that adhere to proper processing and packaging practices.
Bread and other foods producers should implement Good Hygienic Practice (GHP) and Hazard Analysis and Critical Control Point (HACCP) principles

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