Food Spoilage in Dairy Product

FOOD SPOILAGE IN DAIRY PRODUCT

ABSTRACT

Food spoilage is a complex process and excessive amounts of foods are lost due to microbial spoilage even with modern day preservation techniques. Despite the heterogeneity in raw materials and processing conditions, the micro flora that develops during storage and in spoiling foods can be predicted based on knowledge of the origin of the food, the substrate base and a few central preservation parameters such as temperature, atmosphere, a(w) and pH. Based on such knowledge, more detailed sensory, chemical and microbiological analysis can be carried out on the individual products to determine the actual specific spoilage organism. Whilst the chemical and physical parameters are the main determining factors for selection of spoilage microorganisms, a level of refinement may be found in some products in which the interactive behaviour of microorganisms may contribute to their growth and/or spoilage activity. Milk and milk products are promising sources of energy to meet the global increase in food demand. Lactic acid bacteria are the key organisms in starter culture for milk fermentation. Lactobacillus bulgaricus and Streptococcus themophillus from “kindirmo” have been isolated using the Man, Rogosa and Sharpe (MRS) a selective medium for lactic acid bacteria. Kindirmo is a kind of local yoghurt dominantly consumed in sub Saharan Africa and sold by Hausa-Fulani women in Nigeria. The starter culture was obtained from Fulani women hawking kindirmo in Federal University of Technology, Yola and fresh milk from local herdsman. The strains were identified according to their morphological, cultural, physicochemical and biochemical characteristics. Two isolates were able to grow on MRS medium. The isolate that was able to grow at 30oC, pH 5.4 and 6.3 was Lactobacillus bulgaricus, while the one identified as Streptococcus themophillus does not show any growth at pH 5.4 and temperature of 42oC. The colonies revealed big sized, circular, irregular, creamy grey colonies indicative of Lactobacillus bulgaricus and Streptococcus themophillus bacteria. There is need to exploit the potential in using the Fulani starter culture for increased yoghurt production using biotechnological techniques such as rational design using site-directed mutagenesis. Key words: Kindirmo; Lactobacillus bulgaricus; mixed cultures; Streptococcus themophillus; starter culturers. ORDER HERE NOW

CHAPTER ONE

1.0   INTRODUCTION

THE MICROORGANISM

The tiniest life forms are bacteria, yeasts, molds, and viruses, termed “microorganisms” because of their size (micro meaning small and organism meaning living being).

BACTERIA

Bacteria are the most important microorganisms to the food processor. Most are harmless, many are highly beneficial, some indicate the probable presence of filth, disease organisms, spoilage and a few cause disease. There are thousands of species of bacteria, but all are single-celled and fall into three basic shapes: spherical, straight rods, and spiral rods. To see them, you need a microscope that magnifies about 1000-fold. All bacteria reproduce by….Show More Content….

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