ISOLATION AND IDENTIFICATION OF ASPERGILLUS SPECIES FROM YOGHURT SOLD IN LAFIA METROPOLIS

ISOLATION AND IDENTIFICATION OF ASPERGILLUS SPECIES FROM YOGHURT SOLD IN LAFIA METROPOLIS

CHAPTER ONE

1.0 Introduction

In addition to their role as nutritious food for humans, milk and its derivatives create an ideal environment for the proliferation of various microorganisms. Yeasts and molds can thrive in milk and its derivatives, especially under specific conditions of temperature and moisture (Barrois et al 2017). Contamination of these dairy products can originate from the raw materials or may occur during the various stages of production, storage, and distribution (Kure et al, 2018). These microorganisms exert an influence on the biochemical characteristics, flavor, and appearance of these products, making them commercially undesirable. Consequently, this often leads to a decline in the grading and market appeal of dairy items, as discussed by Demarigny et al. in 1997 and Muir & Banks (2020)."

Yogurt contains high concentrations of LAB and the smaller yeast have several potential health benefits and probiotic potential; it can increase lactose tolerance, balance the intestinal microflora, act as an antimicrobial, stimulate the immune system, induce anti-tumor effects, and induce anti-cholesterolemic effects. Various species of the genus Aspergillus are commonly isolated from stored foods. Aflatoxins are mycotoxins produced by the species of the genus Aspergillus, subgenus Circumdati section Flavi (also referred to as the Aspergillus flavus group) mainly by the species Aspergillus flavus, Aspergillus parasiticus, and Aspergillus nomius.

Therefore, identification and characterization of Aspergillus spp. contaminated yoghurt are important as it will give clues or indication of mycotoxin produced. Several Aspergillus spp. such as A. niger, A. flavus, A. fumigatus, and A. terreus produced different types of mycotoxin. For example, A. flavus produced aflatoxins which are major problem globally. The most common method used for identification of Aspergillus isolates is based on morphological characteristics. The genus Aspergillus is easily distinguished based on the spore bearing structures or the conidiophores, an erect hyphal with a swollen tip called vesicle, which bear conidia (Klich, 2002). The vesicle shape, and also the conidia colour, arrangement and size are among the important morphological characteristics for identification of Aspergillus to species level (Bennett, 2010). However, identification solely based on morphological characteristics is not sufficient, particularly to differentiate species within the same section or closely related species, which may showed phenotypic variation and overlapping features.

1.1 Statement of the problem

Yogurt is a widely consumed dairy product known for its nutritional benefits and probiotic properties. However, the presence of Aspergillus species, typically associated with molds, in yogurt is a concerning issue. These molds can affect the safety, quality, and shelf-life of yogurt, rendering it unsuitable for consumption. Despite the potential health risks and product spoilage associated with Aspergillus contamination in yogurt, there is a lack of comprehensive research and established protocols for the isolation and precise identification of Aspergillus species in yogurt samples.

The primary problems related to this issue include:

1. Lack of Standardized Protocols: Currently, there is no universally accepted and standardized method for isolating and identifying Aspergillus species in yogurt samples. This hinders the accurate detection and quantification of contamination.

2. Food Safety Concerns: Aspergillus species are known to produce mycotoxins, which can pose health risks when ingested through contaminated food products. The absence of effective detection methods raises concerns about yogurt’s safety and suitability for consumption.

3. Quality Control: The presence of Aspergillus species can adversely affect the taste, texture, and appearance of yogurt, leading to decreased consumer satisfaction and potential economic losses for dairy producers.

4. Shelf-life and Storage: Aspergillus contamination can contribute to a shortened shelf-life of yogurt and challenges in storage and distribution, impacting the dairy industry’s efficiency and profitability.

5. Consumer Confidence: Aspergillus contamination incidents can erode consumer trust in yogurt products, affecting market demand and brand reputation.

To address these problems, it is imperative to develop robust and standardized methods for the isolation and identification of Aspergillus species in yogurt. This research aims to contribute to food safety, quality control, and the overall improvement of yogurt production and consumption by establishing reliable procedures for the detection and management of Aspergillus contamination in yogurt.

1.2 Justification of the study

This study is justified by its potential to enhance food safety, improve product quality, extend shelf-life, boost market competitiveness, build consumer confidence, contribute to scientific knowledge, and ensure regulatory compliance in the yogurt industry. It addresses critical issues with far-reaching implications for both public health and the dairy sector.

1.3 Objective of the study

1.3.1 General objectives

The general objective of the study is to isolate and identify aspergillus species from yoghurt sold in Lafia metropolis

1.3.2 Specific objectives

i. To isolate and identify aspergillus species from yoghurt in Lafia metropolis

ii. To conduct microscopic examinations of isolated fungal colonies

iii. To identify morphological characteristics consistent with Aspergillus species.

iv. To assess the prevalence and distribution of different Aspergillus species in yogurt products within Lafia metropolis.