Newswise — CHICAGO—Ancient people called yogurt the “food of the gods,” and today yogurt continues to have an outstanding reputation and a promising future as a healthy processed food product. In the December issue of Food Technology magazine published by the Institute of Food Technologists (IFT), contributing editor Tara McHugh, PhD explains how yogurt goes from fermented milk to creamy delight.
Step 1Modification of Milk CompositionYogurt processing begins with reducing the fat content and increasing the total solids in the milk. A clarifier or separator is used to separate fat from milk and reduce the fat content; alternatively milk fat can be added to skim milk to obtain the desired level. Depending on the type of yogurt being created fat content ranges from one to 10 percent, and the final fat content affects the yogurts consistency and viscosity. After going through the separator the yogurt is places in a storage tank and tested for fats and solids, and then water is evaporated off of the milk to increases the solids. More recently, ultrafiltration and reverse osmosis technologies have been used.
Step 2Pasteurization and Homogenization Pasteurization destroys the microorganisms in milk that may interfere with the fermentation process, improves the texture and body of the final result, and helps release compounds in the milk, and removes dissolved oxygen both of which stimulate growth of starter cultures. Homogenization subjects the milk fat globules to several conditions that disrupt the membrane surrounding globules, breaking them into smaller, more consistently dispersed particles, thus producing a smoother and creamier product with greater stability.
Step 3FermentationAfter the milk is pasteurized and homogenized, it is cooled to 40-44 degrees Celsius and inserted with a lactic acid-producing culture. During this stage the curd is formed and the yogurt’s textural characteristics and taste are developed. For a fermented product to be labeled yogurt it needs to contain two live bacterial strains: Lactobacillus bulgaricus and Streptococcus thermophiles. The yogurt is then held at this temperature for three to four hours while the incubation time takes place. Depending on the type of yogurt, the milk is either stored in a hygienically sealed stainless steel, stirred vessel, or consumer-sized sterile packages to incubate in a temperature controlled environment. Different types of yogurts then go through final processing stages in order to form them into their finished product. For example, Greek yogurt is strained through a filter to separate out some of the whey, resulting in a thicker, higher-protein yogurt.
Yogurt Fun Facts• Evidence has shown that around 5000 BC domesticated goat and sheep milk was stored in gourds in warm climates and formed a curd, which was the first form of yogurt.• Yogurt has only become popular in the United States in the last 30-40 years.• France and Turkey are the countries with the highest yogurt consumption, with 57 percent and 52 percent eating yogurt every day.• Twenty percent of Americans eat yogurt every day.• An average American eats 13 pounds of yogurt each year. Europeans eat 40 pounds annually.• Americans typically eat yogurt for breakfast which differs from Europeans who typically eat it mid-day or in the evening.• The majority of people in China drink their yogurt, with only 11 percent eating it with a spoon. Fun facts sourced from DSM Food Specialties
Read the article in Food Technology here
About IFTFounded in 1939, the Institute of Food Technologists is committed to advancing the science of food. Our non-profit scientific society—more than 17,000 members from more than 95 countries—brings together food scientists, technologists and related professionals from academia, government and industry. For more information, please visit ift.org.
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