Background
Frozen yoghurt is a refreshing, tangy dessert that combines the flavours and textures of ice cream and sorbet. Frozen yoghurt is a relatively new entrant in the dessert market. The history of frozen desserts dates back thousands of years to Asia, where water ices were first created.
Roman literature describes how Emperor Nero was treated to exotic fruit juices and wines chilled with mountain snow. However, it was not until the 13th century that Marco Polo introduced Asian-style water ices to Italy. Their popularity spread throughout Europe, and within a few centuries, European colonists introduced ice cream to the United States.
Technological improvements throughout the 1800s simplified the process of making frozen desserts. The first hand freezer was patented in 1848, and shortly thereafter, Jacob Fussell of Baltimore established the first wholesale ice cream manufacturing company in the United States. By the turn of the century, pasteurisation machines and homogenisers had been developed, improving both the hygiene and texture of ice cream.
Further advancements followed with the invention of the direct expansion freezer and continuous freezing process. Low-temperature refrigeration systems, developed in the 1940s, expanded the frozen dessert industry into new markets, leading to the creation of take-home products. By the late 1960s and 1970s, high-tech, high-volume processing machinery allowed large-scale production to flourish.
Dessert makers had long experimented with different ice cream flavours and styles. When frozen yoghurt first entered the market in the 1970s, it was initially unsuccessful—consumers complained that it tasted too much like yoghurt. However, manufacturers refined their recipes, and with the health-conscious trend of the 1980s, frozen yoghurt gained widespread popularity as a lower-calorie dessert alternative.
Soon available in a range of flavours, frozen yoghurt became as versatile as ice cream—served in cones and cups, with toppings, or alongside crepes, waffles, and banana splits. It offered a tangier flavour than ice cream and a creamier texture than sherbet.
By the mid-1980s, the frozen yoghurt market achieved sales of $25 million, experiencing triple-digit growth. Major ice cream producers quickly entered the market, recognising the long-term potential of this healthier dessert. By the early 1990s, frozen yoghurt accounted for around 10% of the total frozen dessert market, generating $330 million from 135 million gallons produced annually.
Raw Materials
Frozen yoghurt derives its distinctive flavour from cultures of Lactobacillus bulgaricus and Streptococcus thermophilus. The yoghurt culture, which makes up about 1% of the ingredients, contributes to its tangy taste.
Frozen yoghurt is made similarly to ice cream and, aside from the yoghurt culture, uses comparable ingredients. Two of the most important elements are water and air. Air is incorporated into the mix to add volume, while water forms the continuous phase that transitions from liquid to partially solid. Frozen yoghurt is never completely frozen; it contains small ice crystals that give it a smooth, semi-solid texture.
The primary ingredient is milk and milk products. Milk fat typically constitutes between 0.5–6% of the mix, depending on whether the product is non-fat, low-fat, or regular. Milk fat adds richness and enhances flavour.
Milk solids-not-fat (MSNF) account for 8–14% of frozen yoghurt. MSNF is balanced inversely with fat to achieve the desired texture. It contains roughly 55% milk sugar (lactose), 37% protein, and 8% minerals. Protein contributes to smoothness, viscosity, and resistance to melting.
Sugar makes up 15–17% of the ingredients. Sucrose, derived from cane or beet sugar, is the most common sweetener, though alternatives may be used. Sugar enhances sweetness, improves texture and viscosity, and increases the concentration of total solids (TS), which add body and nutritional value by replacing water in the mix. Egg solids may also be used to improve structure and reduce freezing time.
Stabilisers, such as animal or vegetable gelatins, ensure a smooth texture and prevent crystallisation during temperature fluctuations at retail outlets. They also help control melting and improve handling. Emulsifiers, typically fatty acids, promote even air distribution and enhance firmness. Together, stabilisers and emulsifiers account for only 0.5–0.6% of the total mix.
Other minor ingredients include egg solids, colourings, mineral salts, and caseinate derivatives (such as citrates and phosphates). Additional flavourings may include fruits, extracts, nuts, cocoa, vanilla, sugars, and spices such as allspice, cinnamon, nutmeg, and ginger.
The Manufacturing Process
Processing the Mix
The ingredients are selected for freshness and quality, measured precisely, and separated into liquid and dry components.
Liquids are poured into a vat, mixed, and heated before dry ingredients are gradually added. The batch is stirred continuously as the temperature rises. Most ingredients are incorporated before heating reaches 120°F (49°C) to prevent lumping. The mixture is heated further to ensure thorough blending.
Pasteurising the Mix
Pasteurisation destroys pathogenic bacteria and preserves product quality. It is legally required in most regions. The mix is rapidly heated to a high temperature, held for a short time, and then cooled to below 40°F (4°C).
Industry practice generally involves heating to 175°F (79°C) for 25–40 seconds, though some processes reach 210°F (99°C) to 220°F (104°C) for improved flavour and ingredient integration.
Homogenising the Mix
Homogenisation smooths the mixture by reducing fat globule size to below two micrometres. Without this process, fat would rise to the surface and form a cream layer. The mixture is pumped at high velocity (around 30,000 fpm) through a valve and impact ring, where shear, impact, and cavitation forces break down fat droplets for an even, creamy consistency.
Inoculating with Yoghurt Culture
When the mix reaches around 90°F (32°C), it is inoculated with 1% yoghurt culture. The mix remains at this temperature until it sets and is ready for cooling.
Cooling and Ageing
After homogenisation, the mixture is cooled gradually from 90°F (32°C) to 40°F (4°C). Slow cooling increases viscosity. The batch is then stored in ageing tanks for up to four hours.
Flavouring, Colouring, and Freezing
Sweeteners, flavourings, and colourings are added in a flavour vat before being combined with the rest of the mixture, maintained between 20°F (-6°C) and 28°F (-2°C).
As the mix freezes, it is agitated to incorporate air and achieve “overrun” (added volume). Air gives the product its light texture and creaminess. In about three minutes, the mix begins to freeze, and within a few more minutes, the desired 50% overrun is achieved. Roughly one- to two-thirds of the water freezes at this stage.
Packaging and Hardening
Once the desired texture is reached, the mixture is packaged and placed in freezers, rapidly cooled to at least 0°F (-17°C), ideally -15°F (-26°C). Fast freezing prevents large ice crystal formation, resulting in a smoother texture. The final hardening process can take from 30 minutes to 12 hours depending on freezer type and packaging.
Shipping
Frozen yoghurt containers are packed closely in refrigerated trucks maintained at -15°F (-26°C) to preserve product integrity. Dry ice may be used, though excessive cold can cause heat shock, damaging the texture. The frozen yoghurt is distributed to retail outlets, foodservice establishments, or other manufacturers for further processing.
Quality Control
All production, packaging, and distribution stages must maintain strict hygiene standards to prevent contamination. Automated Clean-in-Place (CIP) systems efficiently sanitise pumps and tanks to ensure maximum protection against bacteria.
Manufacturers must adhere to pasteurisation standards as set by public health authorities. Regular testing for bacterial count, coliform, mould, and yeast contamination is essential. Care is also taken to prevent fermentation, which can cause excessive acidity, discolouration, and curdling.
Finally, frozen yoghurt producers are required by law to provide accurate information about ingredients and caloric composition on packaging.