1.1 BACKGROUND OF THE STUDY
Diary foods provide and ideal food system for the delivery of beneficial bacteria to the human gut. Given the suitable environment that milk and certain dairy products including yoghurt and cheese) provided, it promotes growth and support viability of these cultures. Diary products such as yoghurt contain ‘probiotic” cultures, e.g Lactobacilli and which are currently among the best known examples of functional food”. Their associated health claims range from alleviation of symptoms of lactose intolerance, treatment of diarrhea, cancer suppression and reduction of blood cholesterol (McDonagh et al, 2007).
Yoghurt is a cultured diary product produced by lactic acid fermentation of milk and is also a means of preserving the nutrients in milk (Hui, 2002; Chandan, 2009). It is generally known as cultured milk, as it is derived from the action of bacterial on all or part of the lactose to produce lactic acid, carbon dioxide, acetic acid, diacetyl, acetaldehyde and several other components that gives the product its characteristic fresh taste (Tamine and Robinson, 2004). It is produced by the lactic fermentation of milk using a combination of bacteria such Lactobacillus bulgaricus and Streptococcus thermophilus (Hui, 2002) and is consumed as a food and thirst quenching beverage (Alfa-Lawal, 2004).