Commercial Yogurt Production: Types, Ingredients, and Processing Techniques

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

Beer production and processing

Beer is an alcoholic beverage made by brewing and fermentation from cereals, usually malted barley, as well as maize and flavoured with hops and the like for a slightly bitter taste. Beer is the most consumed alcoholic beverage in the world and the third most popular beverage after water and tea.

The manufacturing processes of beer essentially involves treatment of grains, malting or germination, mashing or extraction with water, filtration and fermentation. However, the advanced techniques have allowed brewers to produce beer in a more sophisticated and efficient way.

The raw materials for beer production generally include cereal (barley malt, rice or maize), hops, water, and yeast. Malted barley is the main ingredient, which, when milled and heated in water to extract its nutrients, provides a nourishing sugar and protein-rich solution named wort (pronounced as wert). It is an ideal medium in which yeast may grow and ferment. The malting process converts the starch in the cereal into fermentable sugar which is extracted from the malt during mashing.

Hops is added to the boiling wort as it was discovered that hops had anti -bacterial properties which preserved the wort and fermented beer, giving the beer a refreshing bitter taste.

Germination process is halted at desired malt quality, green brown malt is converted to stable, storable product, colour and flavour are also developed, enzymes are stabilized and preserved, and unwanted flavours are removed.

The mixture of milled malt, gelatinized adjunct and water is called mash. Mashing consists of mixing and heating the mash in the mash tun, and takes place through infusion, decoction or a combination of the two.

The objectives of mashing are solubilization and dissolution of grain components, breakdown of grain cell wall structure extraction and hydrolysis of starch, sugars, proteins and non-starch polysaccharides and fermentable sugar profile is established. This process producing a liquor called sweet wort.

Once the wort is cooled, it is oxygenated and blended with yeast on its way to the fermentor. The wort is then put in a fermentation vessel. Fermentation of the wort carried for 5-6 days at controlled temperature of 16ᵒC with the help of glycol.

During the fermentation, alcohol level is established, flavour profile of beer is established and carbonation level is established. At the end of fermentation, yeast flocculates and can be easily separated. The tanks are then rapidly cooled from 16ᵒC to - 2ᵒC with the help of glycol within 72 hrs.

Beer aging or conditioning is the final step in producing beer. Cold maturation temperatures will influence beer clarity.

The filtration takes place in a kieselguhr (diatomaceous earth) filter using frame, candle, or mesh filters. Spent kieselguhr can be used in farming, reprocessed, or as building material. Following filtration beer is stored in “bright beer tanks” and is ready for packaging in the bottling section.

Beer production and processing

Plant sanitation: Piping and pumps

Piping, fittings and connections should be of ample diameter to permit easy cleaning; the design should provide for total drainage.

Piping and pumps should have no threaded joint where foods can accumulate. Sanitary design for such equipment calls for flush joints held together by clams, allowing thorough cleaning and sanitizing.

For product likely to solidify if pumping stops, such as liquid chocolate, the throughput pipe can be equipped with a hot water jacket. Hot water jackets also prevent an accumulation of fat inside the pipe when pumping certain types of sausage meat emulsion.

Pipes that carry food materials should have no dead ends that cannot be cleaned and where food material can accumulated and decompose.

With such construction, surges in the line cause decomposed material to enter the mainstream of the food material passing through the pipes.

Any permanently installed piping system must be provided with a return cleaning line to allow complete recirculation of detergent and sanitizer solutions during cleanup.

Pipe should not be joined to tanks and hoppers, so that the pipe end extended into the tank itself. In some cases when the liquid falls below the level of the pipe, some food remains in the pipe end where it may decompose and eventually contaminate new material entering the tank.

Pipes or chutes using gravity flow should be readily demountable for cleaning and inspection. When possible, easily removed covers should be used.

Pumps, valves and pipe fittings, including those used to insert thermometers and pressure gauge bulbs, should be the sanitary take-apart type and are readily accessible or removable. Pumps must have no internal bypasses in the head that are not self-draining. The pump head itself should be self-draining.

Tanks, flumes, thermometer wells, pots and pans should have only curve corners and junctions of side and bottom in order to facilitate cleaning.
Plant sanitation: Piping and pumps