CHAPTERONE
INTRODUCTION
1.1 Background of the study
Yoghurt is a product of bacterialfermentation of milk, through the action of Streptococcus salivarius subsp. Thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (FAO/WHO, 1977). The bacteria used to make yoghurt are known as yoghurt cultures. The fermentation of lactose by these bacteria produces lacticacid, which acts on milk protein to give yoghurt its texture and characteristic tart flavor.Cow milk is commonly available worldwide and, as such, is the milk most commonly used to make yoghurt. Milk from water buffalo, goats, ewes, mares, camels, and yaks is also used to produce yoghurt where available locally. In addition, other lactobacilli and bifidobacteria are sometimes added during or after culturing yoghurt. Some countries require yoghurt to contain a certain amount of colony-forming units (CFU) of bacteria. In China, for example, the requirement for the number of lactobacillus bacteria is at least 1 million CFU per milliliter (Lee et al., 2012).
The probiotic yoghurt, having probiotic effect is a fermented milk product with adjuvant microorganisms. There are numerous advantages of consuming fermented dairy products containing probiotic bacteria. A high population of probiotic organisms in the colon contributes to good intestinal health. Consequently, consumption of products such as yoghurt containing viable probiotic organisms adds benefit to human gut health. Moreover, yoghurt supplies good quality proteins, also an excellent source of calcium, phosphorus, potassium and contains significant quantities of general vitamins. Yoghurt could be used for feeding, owing to its higher Ca/Na ratio (Demott, 1985). Yoghurts vary in appearance, flavor and ingredients. Yoghurt is a functional food. The functional food includes probiotics, prebiotics and synbiotics. Probiotics can be defined as “live microbial feed supplements that beneficially affect the host animal by improving its intestinal microbial balance” (Champagne et al., 2005)
Yoghurt (plain yoghurt from whole milk) is 81% water, 9% protein, 5% fat, and 4% carbohydrates, including 4% sugars. A 100g amount provides 406 kilojoules (97 kcal) of dietary energy. As a proportion of the DailyValue (DV), a serving of yoghurt is a rich source of vitaminB12 (31% DV) and riboflavin (23% DV), with moderate content of protein, phosphorus, and selenium (14 to 19% DV)
1.3. AIM AND OBJECTIVE OF THE STUDY
There is an increasing demand for taste, quality, stability and shelf life of the yoghurt from customers’ side. Hence the research in the field of quality assessment of yoghurt marketed is the basic need to create awareness among common people.
