Lactic Culture Cheese

Definition and Scope

Lactic cultures are specific strains of bacteria used in cheesemaking to initiate fermentation. These microorganisms convert lactose into lactic acid, lowering the milk’s pH. This acidification is a fundamental biochemical process in cheese production. The primary bacterial genera involved are Lactococcus, Lactobacillus, and Streptococcus.

The scope of lactic cultures extends beyond basic acidification to influencing cheese texture, moisture, and safety. They are categorized as either mesophilic, thriving at moderate temperatures, or thermophilic, requiring higher heat. The selection of a specific culture directly determines the cheese’s final classification and style.

Production and Inoculation

Lactic cultures are produced under sterile laboratory conditions to ensure purity and viability. They are typically supplied to cheesemakers in frozen or freeze-dried forms. These starter cultures are then carefully measured and added to pasteurized milk at the vat stage. The inoculation rate is precisely calculated based on the desired cheese type.

During production, the culture is allowed to ripen the milk for a specific period before rennet addition. This ripening time allows bacterial populations to multiply and begin acidification. For some fresh, high-moisture cheeses, the action of the lactic culture alone, without rennet, causes the coagulation. This method is central to creating lactic-set cheeses.

Sensory Profile Development

Lactic cultures are primary drivers of a cheese’s basic flavor profile, often described as clean, tangy, or buttery. The specific strains metabolize milk components to produce various flavor compounds. Diacetyl, for instance, is a compound created by certain cultures that imparts a distinct buttery aroma and taste. The rate of acid development profoundly impacts the final taste.

Beyond basic flavors, these cultures contribute to the development of texture, such as the smooth, spreadable consistency of fresh chèvre. They also help control moisture levels by weakening the protein matrix. In aged cheeses, the initial work of lactic cultures sets the stage for secondary microbial activity that develops more complex flavors over time.

Functional Uses in Cheesemaking

The primary function of lactic cultures is to acidify milk, which is essential for coagulation and syneresis. Acidification helps expel whey from the curds, determining the final cheese’s moisture content. This process also aids in developing the cheese’s final body and texture, making it firmer and less prone to spoilage.

Lactic cultures also play a crucial role in preserving cheese and inhibiting the growth of pathogenic bacteria. The low pH environment they create is hostile to many undesirable microorganisms. Furthermore, they contribute to the development of the cheese’s rind, especially in bloomy-rind and washed-rind varieties where surface flora interact with the acidic substrate.

Regional and Stylistic Examples

In French cheesemaking, lactic cultures are essential for producing soft-ripened cheeses like Camembert and Brie. These cheeses rely on specific mesophilic cultures to create a slightly acidic, milky base for the Penicillium candidum mold to flourish. The slow lactic fermentation is critical for their characteristic creamy texture and mild tang.

Many fresh cheeses, such as French Fromage Blanc and American Cream Cheese, are direct products of lactic fermentation. These styles often use a higher proportion of culture and a longer ripening time before draining. The technique is also fundamental in traditional quark and some types of feta, where the sharp, clean acidity defines the product’s character.

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