Microbiology of Yogurt (Fermented Milk Product)

Outlines

1. What is yogurt? (Pande, 2010: 1)

2. Yogurt manufacturing process. (El Bashiti, 2010: 56)

3. The benefits of yogurt. (Lourens, 2001: 7)

Microbiology of Yogurt (Fermented Milk Product)

1. What is yogurt?

Yogurt is made by the fermentation of lactose (milk sugar) by bacterial enzymes. This process is anaerobic, meaning that it occurs in the absence of oxygen. Lactose is a compound sugar, made up of the two simple sugars glucose and galactose. During the making of yogurt, the lactose is broken down by the lactase enzyme (provided by bacteria) into these two components. Further processing of glucose and galactose results in the end products of lactic acid and acetaldehyde. The production of lactic acid and acetaldehyde lowers the pH of the milk, causing it to have a sour, tart taste. The lower pH also affects the casein (milk protein), causing it to coagulate and precipitate, forming the solid curd that makes up yogurt. The leftover watery liquid is the whey. The two bacteria most commonly used to make yogurt are Lactobacillus bulgaricus and Streptococcus thermophilus. (Pande, 2010: 1)

2. Yogurt Manufacturing Process

The main processing steps involved in these two types of yogurt manufacture include the standardization of milk (fat and protein content), homogenization, milk heat treatment, incubation / fermentation, cooling, and storage. (El Bashiti, 2010: 56)

3. The Benefits of Yogurt

The benefit of eating yogurt is improved health. Yogurt contains healthy bacteria, known as probiotics, that help keep your digestive and immune systems functioning well. It is also a good source of protein and nutrients important for bone health. Additionally, some studies suggest yogurt may aid weight loss. In fact, the health benefits of yogurt are so impressive that many health-conscious people make it a daily habit.  Here are five possible health benefits of having a yogurt a day: yogurt may help prevent osteoporosis, yogurt may reduce the risk of high blood pressure, yogurt with active cultures helps the gut, yogurt with active cultures may discourage vaginal infections, and yogurt may help you feel fuller. (Lourens, 2001:7)

Microbiology of Yogurt (Fermented Milk Product)

According to the Code of Federal Regulations of the FDA, yogurt is defined as the “food produced by cultur­ing one or more of the optional dairy ingredients (cream, milk, partially skimmed milk, and skim milk) with a characterizing bacteria culture that contains the lactic acid-producing bacteria, Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus”. (Pande, 2010: 1)

Yogurt is made by the fermentation of lactose (milk sugar) by bacterial enzymes. This process is anaerobic, meaning that it occurs in the absence of oxygen. Lactose is a compound sugar, made up of the two simple sugars glucose and galactose. During the making of yogurt, the lactose is broken down by the lactase enzyme (provided by bacteria) into these two components. Further processing of glucose and galactose results in the end products of lactic acid and acetaldehyde. The production of lactic acid and acetaldehyde lowers the pH of the milk, causing it to have a sour, tart taste. The lower pH also affects the casein (milk protein), causing it to coagulate and precipitate, forming the solid curd that makes up yogurt. The leftover watery liquid is the whey. The two bacteria most commonly used to make yogurt are Lactobacillus bulgaricus and Streptococcus thermophilus.(Pande, 2010: 1)

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