Yogurt is a widely consumed dairy product, with commercial varieties broadly classified into three main categories: plain (or natural), fruit, and flavored yogurts. These varieties are typically manufactured in one of three forms: set, stirred, or drinking yogurt. Drinking yogurt, characterized by its smooth, thin consistency, has become particularly popular in recent years, especially among consumers seeking a convenient and portable product.
The type of milk used in yogurt production significantly affects the final product's flavor, texture, and nutritional content. Manufacturers may use whole milk or skimmed milk, depending on the type of yogurt being produced and the desired fat content. For example, whole milk is typically preferred for creamier, richer yogurts, while skimmed milk is used to produce low-fat or fat-free yogurts.
Before fermentation, the milk undergoes heat treatment, which serves multiple purposes. Heating the milk to a high temperature denatures its proteins, which helps create a thicker and more stable yogurt. Additionally, this process reduces oxygen levels in the milk and eliminates bacterial contaminants, creating an ideal environment for controlled bacterial fermentation. In general, milk intended for drinking or natural set yogurt is concentrated to a total solid content of 18-35 grams per 100 grams. The concentrated milk is then diluted with an equal volume of boiling water, allowed to cool, and fermented at the incubation temperature. Although this processing method results in a lower-fat yogurt, homogenization is recommended to improve consistency.
To ensure proper fermentation, yogurt milk is typically heated to 85°C for 20 minutes and then incubated at 42°C for approximately three hours. During incubation, the milk is stored in either large tanks or individual retail containers, depending on the desired packaging. The addition of flavorings, such as fruit or other ingredients, can easily be integrated into the process using a dosing pump just before the yogurt is dispensed into distribution containers.
The fermentation process, essential for yogurt production, relies on bacteria known as Bacillus lactis (commonly known as Lactobacillus species). When added as a bacterial culture to the milk, these bacteria multiply, producing lactic acid as they digest lactose. The lactic acid not only thickens the milk but also imparts the characteristic tart flavor associated with yogurt. By the end of fermentation, the yogurt’s pH level reaches around 4-4.2, with lactic acid content ranging between 0.7-1.1%. To halt fermentation and preserve the yogurt, it is rapidly cooled to 5°C and stored at that temperature.
The addition of fruits, fruit pastes, or sweeteners to yogurt further diversifies the range of available products. These ingredients create unique flavors and textures, catering to a wide range of consumer preferences. Fruit yogurts, for instance, are especially popular for their sweetness and added nutrients from fruit pulp or puree.
Top-quality yogurt is defined by its smooth consistency, free from grittiness or granules. It should have a stable, uniform texture without any signs of effervescence or off-flavors. Through precise control over ingredients and processing conditions, manufacturers strive to produce yogurt that meets high standards for both taste and texture, appealing to a broad consumer base.Commercial Yogurt Production: Types, Ingredients, and Processing Techniques
