Buttermilk
Buttermilk is a fermented dairy drink traditionally produced as the liquid residue remaining after churning butter from fermented cream, resulting in a tangy, slightly thickened liquid rich in lactic acid due to natural bacterial fermentation.[1] In modern commercial production, particularly in Western countries, it is typically made by inoculating pasteurized low-fat or nonfat milk with lactic acid bacteria such as Lactococcus lactis and Lactobacillus bulgaricus to achieve a pH of 4.4–4.8, imparting its characteristic sour taste and creamy consistency while extending shelf life.[2][3] This cultured form has largely replaced the traditional byproduct, though variations include sweet buttermilk from churning sweet cream, sour buttermilk from fermented cream, and whey buttermilk from cheese production.[1] Buttermilk is low in fat (typically 1–2% milkfat), high in protein (about 8 grams per cup), and provides essential nutrients such as calcium (22% of daily value per cup), riboflavin (29% DV), and vitamin B12 (39% DV).[2][4] Its unique composition, including milk fat globule membrane material with phospholipids at levels 4–7 times higher than in whole milk, contributes to its emulsifying properties in food applications.[1]Overview
Definition and Characteristics
Buttermilk is the liquid residue left after churning butter from cream, consisting primarily of water, milk proteins, lactose, and minerals, or it is produced as a cultured dairy product by fermenting milk with lactic acid bacteria such as Lactococcus lactis or Lactobacillus bulgaricus.[1][5] This process generates lactic acid, imparting a characteristic tangy, slightly sour flavor to the product.[6] Physically, buttermilk exhibits a thin, fluid consistency similar to skim milk, with a pale yellow to off-white color and a smooth texture free of lumps in its fresh form.[1][7] Its pH typically ranges from 4.5 to 4.6, reflecting its higher acidity compared to regular milk (pH around 6.6).[5] When refrigerated, buttermilk maintains its quality for 1 to 2 weeks, after which it may develop off-flavors or visible mold.[8] In comparison to whole milk, buttermilk has a notably lower fat content, usually 0.5% to 2%, making it a low-fat dairy option while retaining similar levels of proteins and lactose.[1] Cultured varieties often contain live probiotic bacteria, contributing to potential gut health benefits not typically found in unfermented milk.[5] Unlike thicker, gel-like fermented products such as yogurt or the effervescent kefir, buttermilk remains a pourable liquid due to milder fermentation and the absence of thickening agents or extended culturing.[6]Etymology
The English term "buttermilk" derives from the Middle English compound "buttermilke," formed by combining "butter" and "milk," and first appears in records from the late 14th century to denote the liquid residue left after churning butter from cream.[9] The word "butter" itself traces to Old English "butere," borrowed from Latin "butyrum" via Germanic languages, while "milk" comes from Old English "meolc," rooted in Proto-Indo-European *melg- meaning to rub or stroke, reflecting the milking process.[10] [11] This nomenclature emphasized buttermilk's origin as a byproduct of butter production in traditional dairy practices. Cognate terms appear in other Germanic languages, such as German "Buttermilch," which evolved from Middle High German "butermilch" in the 16th century, similarly denoting the churned milk remainder. In Scandinavian languages, equivalents like Danish "kærnemælk" (churn milk) and Swedish "kärnmjölk" preserve the connection to churning, though modern variants such as Swedish "filmjölk" refer to fermented milk products akin to cultured buttermilk. Beyond Europe, in South Asian languages, buttermilk is known as Hindi "chaas" (from Gujarati "chāś," implying diluted yogurt) or "mattha" (referring to churned whey), terms that highlight its role as a spiced, diluted curd drink rather than a direct butter byproduct.[12] With the rise of industrialization in the 20th century, the meaning of "buttermilk" evolved in English usage from strictly the traditional byproduct of butter churning to encompass cultured buttermilk, a fermented milk product created by adding lactic acid bacteria to whole or skim milk for commercial production.[13] This shift occurred as mechanical churning reduced the availability of the original byproduct, leading dairies to standardize cultured versions that mimic its tangy flavor and acidity for baking and drinking.[14]History
Origins and Early Use
Buttermilk emerged as a byproduct of butter production in ancient pastoral societies, where churning cream separated into butterfat and the remaining acidic liquid. In Mesopotamia, particularly among Sumerian civilizations around 3000–2000 BCE, cuneiform tablets mention dairy processing, including butter and cheese, implying the production of residual liquids like buttermilk as the residual whey-rich fluid.[15] Similarly, in the Indus Valley Civilization circa 2500 BCE, lipid residue analysis of pottery reveals limited dairy production, possibly including processing of milk into products like curd or ghee, from cattle and buffalo milk.[16][17] Early uses of buttermilk centered on its utility as a natural preservation method for milk in hot climates, where fermentation created an acidic environment that inhibited bacterial growth and extended shelf life without modern refrigeration. In regions like the ancient Near East and South Asia, this process allowed pastoralists to store and transport dairy longer during warm seasons. Ancient Ayurvedic texts, such as the Charaka Samhita (circa 300 BCE – 200 CE), describe takra—buttermilk—as a probiotic aid for digestion, praising its light, digestible qualities for alleviating abdominal disorders, edema, and anorexia, and recommending it as a daily therapeutic drink to promote gut health.[18][19] Among nomadic cultures of Central Asia, such as the Scythians from the first millennium BCE, fermented dairy products like kumis from mare's milk, produced through churning, played a vital role in extending the shelf life of milk during long migrations across arid steppes, providing a portable, nutrient-dense option without spoilage, similar in preservation role to buttermilk. In ancient Scandinavia, Viking-era communities (circa 800–1050 CE) valued buttermilk for its preservative fermentation, using it to sustain dairy supplies in cooler but variable climates where fresh milk was prone to souring. These practices underscored buttermilk's practicality for mobile herders reliant on livestock.[20][21] As a low-fat, hydrating beverage, buttermilk became seamlessly integrated into the daily diets of these pre-industrial societies, often consumed fresh after butter-making sessions to utilize the entire yield from milk processing and provide refreshment in labor-intensive pastoral routines.Modern Developments
The introduction of mechanical cream separators in the late 19th century fundamentally altered buttermilk production by enabling the efficient separation of cream from whole milk prior to churning, which significantly reduced the volume of traditional buttermilk as a byproduct compared to churning unseparated milk. Invented by Swedish engineer Carl Gustaf Patrik de Laval in 1878, this centrifugal technology allowed dairies to process only the cream, yielding far less liquid residue and making authentic churned buttermilk increasingly scarce as butter making shifted toward industrialized scales.[22][23] In the early 20th century, this scarcity prompted the development of cultured buttermilk in the United States, commercially introduced in the 1920s to replicate the tangy flavor and texture of traditional varieties using low-fat milk fermented with specific mesophilic lactic acid bacteria, such as Lactococcus lactis (formerly Streptococcus lactis). These bacterial strains, isolated and propagated for consistent fermentation, enabled scalable production without relying on butter byproducts, marking a key innovation that sustained buttermilk's availability for baking and drinking.[22][24][25] Following World War II, buttermilk production adapted further amid global dairy shortages, with cultured varieties becoming more widely commercialized as packaged beverages in Europe and Asia to promote health benefits like digestion aid. In regions such as Germany and parts of South Asia, where traditional fermented milk drinks like Buttermilch or lassi predated industrialization, post-war packaging innovations facilitated broader distribution as probiotic refreshments, aligning with rising demand for convenient, nutrient-rich options.[6][22] Since the early 2000s, buttermilk consumption has faced challenges from shifting dietary preferences, with U.S. sales declining from a peak of approximately 517 million kg in 1960 to about 234 million kg by 2012, less than half the historical high, and further to approximately 201 million kg in 2024 due to reduced fluid milk intake and competition from alternatives. Concurrently, the vegan movement has driven the rise of plant-based buttermilk substitutes, such as those made from almond or soy milk acidified with lemon juice or vinegar, and innovative commercial products like fermented grain-based dairy-free buttermilk launched in 2022 to meet demand for lactose-free, ethical options. As of 2024, U.S. fluid buttermilk sales were about 444 million pounds (201 million kg), reflecting ongoing decline amid rising popularity of plant-based substitutes.[24][26][27][28]Production Methods
Traditional Buttermilk
Traditional buttermilk is produced as a byproduct of the butter-churning process, where cream from raw or low-pasteurized milk is first allowed to undergo natural fermentation before being churned. In artisanal settings, fresh cream is collected and left at ambient temperatures to sour naturally, typically for 12-24 hours, during which ambient lactic acid bacteria, such as species of Lactobacillus, convert lactose into lactic acid, imparting a tangy flavor and thickening the cream slightly.[29][30][31] Once fermented, the cream is cooled to an optimal churning temperature of 10-15°C to facilitate the separation of butterfat globules. The cream is then vigorously agitated in a churn—traditionally a wooden barrel or dasher-style vessel operated by hand—until the fat coalesces into butter granules, leaving behind the acidic liquid known as buttermilk. This liquid constitutes approximately 50–70% of the original cream's volume, depending on the cream's fat content and churning efficiency.[32][33] This method was prevalent in rural households worldwide until the mid-20th century, serving as a resourceful way to utilize the remnants of butter production in home dairying. Artisanal techniques emphasized manual labor and reliance on environmental microbes, fostering unique regional flavors. Variations included the use of goat or sheep milk in pastoral communities, where the lower fat content of these milks required adjusted churning times but yielded similarly acidic buttermilk prized for its digestibility.[13][34][35][36] The practice declined with the rise of industrialized dairy processing in the mid-20th century, which favored pasteurized products and direct culturing methods.[13]Cultured Buttermilk
Cultured buttermilk is produced through a commercial fermentation process designed to replicate the tangy flavor of traditional buttermilk while ensuring product consistency and safety. The process starts with pasteurized skim or low-fat milk, which is cooled and inoculated with a mesophilic starter culture primarily composed of Lactococcus lactis subspecies (such as L. lactis ssp. lactis and L. lactis ssp. cremoris) and Leuconostoc mesenteroides subspecies.[37] The inoculated milk is transferred to large stainless-steel vats in dairy processing plants, where it undergoes fermentation under controlled conditions. Temperature is maintained at 20–22°C using integrated cooling and agitation systems to promote even bacterial activity, with the process lasting 12–14 hours until the pH drops to approximately 4.6, indicating optimal acidity (0.8–0.9%).[37][38][39] Once fermentation is complete, the product is cooled rapidly to 4–5°C to halt further acid development and is then homogenized and packaged.[38] This method relies on lab-cultured strains for reliable results, distinguishing it from ambient natural fermentation.[37] Unlike traditional buttermilk, which is a thinner byproduct, cultured buttermilk achieves a thicker, more viscous consistency through exopolysaccharides (EPS) produced by the starter bacteria during fermentation. These EPS form a network that enhances texture and mouthfeel, contributing to the product's stability and appeal in applications like baking and beverages.[40][41] By the 2020s, cultured buttermilk production has scaled significantly, exceeding 1 billion liters annually across Europe and North America, driven by demand in the dairy sector and supported by advanced processing infrastructure.[42][43]Acidified Buttermilk
Acidified buttermilk is a non-fermented dairy product created by directly adding food-grade acids to milk, producing a tangy, curdled liquid suitable as a quick substitute in recipes requiring buttermilk's acidity.[44] This method employs acids such as lactic acid, citric acid from lemon juice, or acetic acid from vinegar, which lower the milk's pH and cause partial coagulation without microbial activity.[45] The production process is straightforward and rapid: the acid is added to whole, low-fat, or skim milk, typically 1 tablespoon of vinegar or lemon juice per cup (approximately 240 ml) of milk, and the mixture is stirred and left to stand at room temperature for 10-30 minutes until it thickens and develops curds.[46] No heating is required, making it ideal for immediate use in home baking where the acidity reacts with leavening agents like baking soda to produce carbon dioxide for rise.[44] The target pH is 4.5-4.8, which imparts the desired tartness while ensuring the product remains fluid yet slightly viscous.[45] This approach mimics the tanginess of cultured buttermilk but lacks live probiotics, focusing instead on chemical acidification for convenience in small-scale or home settings.[45] Developed in the mid-20th century, as evidenced by patented processes from the 1960s, it became common for household use as a stand-in for naturally soured milk in recipes, especially as refrigeration reduced spontaneous souring in homes.[44][13]Regional Variations
United States
Cultured buttermilk was commercially introduced in the United States during the 1920s as dairies began producing it deliberately by adding lactic acid bacteria to milk to mimic the traditional byproduct of butter churning, filling a market gap as home butter-making declined.[13] This innovation gained popularity, particularly among immigrant communities familiar with fermented dairy, and reached peak production and consumption around 1960, with annual output at approximately 1,140 million pounds (517 million kilograms).[47] In the Southern United States, buttermilk consumption was notably high during this period, often used as a marinade for fried chicken to tenderize and flavor the meat through its acidity.[48] U.S. buttermilk production has since declined steadily due to competition from yogurt and other fermented dairy alternatives, dropping to 513 million pounds (233 million kilograms) by 2015, with the decline continuing thereafter.[47] This shift reflects broader changes in consumer preferences toward yogurt's thicker texture and perceived health benefits, reducing buttermilk's share in the cultured dairy market.[13] Under U.S. Food and Drug Administration (FDA) guidelines in the Pasteurized Milk Ordinance, buttermilk must contain at least 0.5 percent milkfat and 8.25 percent milk solids-not-fat, and when cultured, it requires the use of safe and suitable lactic acid-producing bacteria to achieve the characteristic tangy flavor and viscosity.[49] Regional consumption patterns show higher per capita use in the Southern states compared to the national average, where it remains a key ingredient in traditional baked goods like biscuits, leveraging its acidity to promote leavening and tenderness.[48]International Variations
In India, buttermilk is commonly known as chaas or incorporated into lassi variants, where it is spiced with roasted cumin powder and other herbs like ginger and mint to enhance its cooling and digestive properties as a probiotic-rich beverage consumed during hot weather.[50] Traditionally, chaas is produced by churning cultured full-cream milk, often from buffalo sources prevalent in the region, resulting in a tangy, diluted yogurt drink served salted or mildly sweetened.[51] In Scandinavia, buttermilk appears as thicker fermented milk products like filmjölk in Sweden and surmjölk in Norway, which are mesophilic cultures yielding a spoonable consistency distinct from thinner variants.[52] These are typically consumed with porridges, cereals, or crispbread, providing a tangy flavor and nutritional preservation in traditional diets. Their origins trace back to the Viking era, around the late 8th to 11th centuries, when natural fermentation extended milk's shelf life in harsh climates.[52] Across the Middle East and North Africa, buttermilk is recognized as laban in Levantine countries or ayran in Turkey, prepared by diluting yogurt with water and salting it for a refreshing, hydrating effect in arid environments.[53] This beverage is particularly popular during Ramadan, when it aids rehydration and electrolyte balance after fasting periods.[54] In Mexico, suero refers to the whey byproduct from traditional cheese-making processes, such as those for asadero or fresco varieties, which is integrated into ranching diets as a simple, nutrient-dense liquid often consumed fresh or in salsas for its protein content.[55]Nutrition and Health
Nutritional Composition
Buttermilk's nutritional profile varies slightly depending on whether it is whole, low-fat, or cultured, but it generally serves as a nutrient-dense dairy product with a high water content and balanced macronutrients. Per 100 grams of whole fluid buttermilk, the composition includes approximately 62 kcal of energy, 3.3 grams of total fat (of which 1.9 grams are saturated), 3.3 grams of protein, 4.8 grams of carbohydrates, and 88 grams of water.[56] In terms of micronutrients, whole buttermilk is notably rich in certain vitamins and minerals essential for bone health and metabolism. It provides about 115 mg of calcium, 0.15 mg of riboflavin (vitamin B2), and 0.46 µg of vitamin B12 per 100 grams, while containing a relatively low 4.8 grams of lactose compared to unfermented milk.[56]| Nutrient | Amount per 100g (Whole Buttermilk) |
|---|---|
| Energy | 62 kcal |
| Total Fat | 3.3 g |
| Saturated Fat | 1.9 g |
| Protein | 3.3 g |
| Carbohydrates | 4.8 g |
| Water | 88 g |
| Calcium | 115 mg |
| Riboflavin | 0.15 mg |
| Vitamin B12 | 0.46 µg |
| Lactose | 4.8 g |