The aroma, body and flavor of yogurt and other cultured dairy products can vary depending on the type of culture and milk, amount of milk fat and non-fat milk solids, fermentation process and temperature used. These foods are made by adding specific cultures to fluid dairy products in order to convert some lactose (milk's sugar) into lactic acid. The word "acidified" in the product name means acidifiers were added to produce the lactic acid.
What is Yogurt?
Yogurt is a mixture of milk (whole, reduced-fat, low-fat or non-fat) and cream fermented by a culture of lactic acid-producing bacteria, Lactobacillus bulgaricus and Streptococcus thermophilus. Other bacteria (e.g., acidophilus) and other strains of the above bacteria may be added to the culture. Sweeteners (e.g., sugar, honey, aspartame), flavorings (e.g., vanilla, coffee) and other ingredients (e.g., fruits, preserves, stabilizers such as gelatin) may also be added. Yogurt contains at least 3.25% milk fat and 8.25% solids-not-fat. The mixture of dairy products and optional ingredients, except bulky flavorings, must be pasteurized or ultra-pasteurized. The milk in most yogurts is also homogenized. Some yogurts also contain beneficial live, active cultures which are indicated on the label.
- Low-fat Yogurt contains either 0.5%, 1%, 1.5% or 2% milk fat.
- Non-fat Yogurt contains less than 0.5% milk fat.
- Greek Yogurt contains about twice the protein of regular yogurt. It is available in a variety of flavors and in single-serve and larger containers.
- Yogurt Beverages are available in a variety of flavors and in single-serve and larger containers.
- Frozen Yogurt is available in fat-free, low-fat and no sugar added and in a variety of flavors and sizes.
Other Cultured Dairy Foods
- Buttermilk is made by adding lactic acid-producing bacteria, usually Streptococcus lactis, to pasteurized or ultra-pasteurized milk (whole, reduced-fat, low-fat, non-fat) with non-fat dry milk solids under controlled conditions. The product is heated until the desired acidity is achieved, then cooled to stop fermentation. Buttermilk flakes or liquid butter may be added to give cold milk the appearance of churned buttermilk. Salt, citric acid or sodium citrate may be added to enhance flavor. Today, depending on the level of milk fat in the product, buttermilk may be called cultured buttermilk, cultured low-fat buttermilk or cultured skim (non-fat) buttermilk. Originally, buttermilk was the low-fat liquid remaining after churning cream into butter.
- Acidophilus Milk is typically a low-fat or non-fat milk to which active cultures of Lactobacillus acidophilus have been added. The mixture is heated until a curd forms and the desired acidity is reached. The milk is then refrigerated. Adding Lactobacillus acidophilus cultures to cold, low-fat or non-fat milk and then refrigerating the product to prevent further growth of the harmless bacteria produces sweet acidophilus milk. Unlike fermented acidophilus milk, which has a slightly tart taste, this product has a sweet taste.
- Kefir is a tart and tangy cultured milk smoothie beverage containing live and active cultures that is high in protein, calcium and vitamin D. It is available in a variety of flavors. Most kefir contains probiotics. The benefits of these good bacteria may include supporting immunity and a healthy digestive system.
The nutritional and caloric contents of yogurt, buttermilk and acidophilus milk are similar to those of the fluid milks from which they are made. Each is an important source of calcium, riboflavin (B2) and protein. Check the Nutrition Facts panel on product labels for the nutritional content of specific products.
Storing and Handling
Yogurt, buttermilk and acidophilus milk should be stored in closed containers in the refrigerator at 40°F to maintain their quality. Yogurt will keep for about a week and buttermilk and acidophilus milk will keep for about 2 weeks in the refrigerator. Freezing is not recommended for any of these cultured dairy foods.
Commonly Asked Questions About Yogurt and Other Cultured Dairy Products
- Does Yogurt Have Unique Health Benefits?
Yogurt provides protein, calcium, vitamins and minerals. Numerous health benefits beyond its nutritional value have been associated with consuming yogurt. Scientists have found that intake of yogurt with live and active cultures may aid digestion, ease diarrhea, boost immunity, fight infection and protect against cancer. These specific health benefits depend on the strain and viability of the culture in yogurt. This is why it is important to choose yogurt with a seal indicating that it contains live, active cultures.
- Why is Yogurt Beneficial for Indivduals with Lactose Intolerance?
Many yogurts contain lower amounts of lactose than milk. As yogurt ferments, some of the lactose (a natural source of sugar in milk) changes to lactic acid. Importantly, starter cultures in yogurt may produce the enzyme lactase, which digests lactose. Yogurt's semi-solid state also contributes to improved tolerance to lactose.
- Is Yogurt Fortified with Vitamin D?
Fortification of milk products with Vitamin D is optional. If vitamin D is added to yogurt, it must be indicated on the product label.
- Is Sweet Acidophilus Milk Advantageous for Lactose Intolerant Individuals?
The lactose in sweet acidophilus milk is tolerated about the same as that in regular milk. Sweet acidophilus milk, cultured buttermilk or yogurt without live, active cultures all have about the same amount of lactose as regular milk. Consuming these milk products with meals improves lactose digestion.
- What is a/B Milk?
This is a low-fat or non-fat milk to which acidophilus and bifidobacteria cultures have been added. Some cottage cheeses and light ice creams have a/B cultures added. Nutritionally, these products are similar to the milk from which they are made. There is some evidence that these cultures have unique health benefits such as improving lactose digestion, lowering blood pressure and promoting healthy bacteria in the gastrointestinal tract.