POTASSIUM ACID TARTRATE

CAS: 868-14-4 EMULSIFIER OR EMULSIFIER SALT, NUTRIENT SUPPLEMENT, PH CONTROL AGENT

Potassium acid tartrate is the potassium acid salt of l-(+)‑tartaric acid, commonly known as cream of tartar, used in food formulation primarily to regulate acidity and act as an emulsifier or pH control agent.

What It Is

Potassium acid tartrate is a crystalline chemical compound defined as the potassium acid salt of l‑(+)-tartaric acid, identified by the CAS number 868‑14‑4. It is also commonly called potassium bitartrate or cream of tartar, and it belongs to a class of food additives used for multiple technical functions including acting as an emulsifier and pH control agent in food formulations. As a salt derived from a naturally occurring organic acid found in grapes, it manifests as a white or colorless crystalline powder with a mildly acidic taste, and it has been utilized in food processing and culinary applications for many decades. Under regulatory systems such as the US Code of Federal Regulations, it is recognized as an affirmed generally recognized as safe (GRAS) direct food substance, subject to specifications for purity that ensure it meets food‑grade quality standards. Its diverse nomenclature reflects a range of functional and chemical descriptors used in industry and scientific literature.

How It Is Made

Potassium acid tartrate is typically obtained as a byproduct of the winemaking process, where tartaric acid and potassium ions precipitate out of fermenting grape must and wine as wine lees or argol. These potassium tartrate crystals are collected and purified through processes such as extraction with hot water, filtration, and controlled cooling to yield high‑purity potassium acid tartrate crystals that are then dried for use in food applications. Food‑grade material must meet identity and purity criteria outlined in compendia such as the Food Chemicals Codex, which specify assay and impurity limits to ensure suitability for use in food. While the core extraction process is rooted in agricultural residues, industrial producers may apply additional refinement steps to consistently meet regulatory standards for use in food products. The naturally derived origin and crystalline nature of potassium acid tartrate are central to its classification as a food additive and its functional reliability across many types of food systems.

Why It Is Used In Food

Potassium acid tartrate is used in food production because of its versatile technological functionality and compatibility with food ingredients. Its acidic nature allows it to act as a pH control agent in formulations where specific acidity levels are desired for texture, stability, or microbial control. In baked goods, it is a classic acid component of leavening systems such as baking powder, where it reacts with alkaline bicarbonates to generate carbon dioxide gas and contribute to rise and texture. Its emulsifying and stabilizing properties help maintain the consistency of products like whipped creams and egg white foams, while its buffering capacity supports the maintenance of a controlled acidity environment in confectionery and dairy systems. These combined roles support manufacturability, product consistency, and sensory qualities in a wide range of culinary applications without imparting strong sensory characteristics of its own.

Adi Example Calculation

To illustrate how an acceptable daily intake might be contextualized, consider an ADI expressed as milligrams of tartaric acid per kilogram of body weight per day. For a hypothetical adult weighing 70 kilograms, a group ADI of 240 mg per kilogram per day expressed as tartaric acid would correspond to a total estimated allowable daily intake of 16,800 mg of tartaric acid equivalents. This illustrative example is based on a regulatory standard intended as a safety threshold and does not imply a nutritional requirement or therapeutic benefit. Typical dietary exposures from food additives would be expected to be significantly lower than this threshold under authorized use conditions.

Safety And Health Research

Safety evaluations for potassium acid tartrate and related tartrate salts have been part of broader assessments of tartaric acid and tartrates as food additives by expert regulatory panels. These assessments consider toxicological data across a range of endpoints, including acute toxicity, genotoxicity, and chronic exposure, in order to characterize the safety profile of these compounds when used within regulatory limits. Regulatory science reviews by entities such as the European Food Safety Authority have re‑evaluated tartaric acid and tartrates, concluding that available data support acceptable daily intake estimates for the group when expressed as tartaric acid, reflecting a high level of tolerance relative to typical dietary exposures under authorised uses. National and international food standards bodies also define identity and purity criteria for food‑grade material to ensure that impurities do not contribute to safety concerns. These combined scientific assessments and regulatory specifications support the continued use of potassium acid tartrate in food formulations, with safety characterization rooted in structured evaluation of available data.

Regulatory Status Worldwide

In the United States, potassium acid tartrate is affirmed as a direct food substance under 21 CFR 184.1077, which lists it as an additive that is generally recognized as safe when it meets specified food‑grade purity criteria. Under this regulation, the compound is defined by its chemical identity and permitted for use in food formulations with specifications from recognized compendia incorporated by reference. In the European Union, potassium tartrates, including monopotassium forms like potassium acid tartrate, are included in the group of potassium tartrates assigned the E number E336 and are authorized for use under Regulation (EC) No 1333/2008 with conditions of use and specifications; scientific re‑evaluations have established a group acceptable daily intake for tartaric acid and tartrates expressed as tartaric acid. Other international food safety bodies such as the Joint FAO/WHO Expert Committee on Food Additives maintain specification monographs and safety evaluations for food additives, which include tartaric acid and tartrate salts, further supporting their global regulatory acceptance when used in accordance with purity and usage standards. These layers of regulatory oversight ensure that potassium acid tartrate can be included in food products with consistent safety and quality standards across jurisdictions.

Taste And Functional Properties

Potassium acid tartrate typically presents as a white or colorless crystalline powder with a mild acidic taste derived from its constituent tartaric acid. In solution, it contributes a referenced acidity that can be measured and controlled, making it a useful agent for pH adjustment and buffering in food systems. Its solubility in water increases with temperature, which is relevant when it participates in thermal processes like baking. While its intrinsic taste is mildly tart, when used at regulatory levels in formulations it does not dominate the sensory profile but rather complements the acidity balance of ingredients. Functionally, it interacts predictably with alkaline compounds, facilitating carbon dioxide release for leavening, and contributes to the stabilization of foams and emulsions by influencing the protein and fat interfaces. Its physical stability as a dry crystalline material also contributes to ease of handling and formulation, and its buffering behavior helps to maintain target pH ranges during processing.

Acceptable Daily Intake Explained

An Acceptable Daily Intake (ADI) is a regulatory public health concept used to express the amount of a substance that can be consumed daily over a lifetime without appreciable risk, based on toxicological evidence and applying conservative uncertainty factors. For potassium acid tartrate and related tartrates assessed as a group, regulatory scientific panels have established an ADI expressed in terms of tartaric acid to reflect the shared metabolic outcomes of these compounds when ingested and to provide a safety benchmark for exposure assessments. The ADI value is derived from studies that examine responses at varying exposure levels and includes safety margins to address sensitive populations and data uncertainties. It is important to note that an ADI is not a recommended intake but rather a risk assessment tool that informs regulatory standards and ensures that permitted uses in food contribute to exposures well below levels associated with adverse health effects.

Comparison With Similar Additives

Potassium acid tartrate can be compared with other food additives that serve related functional roles. For example, citric acid is another organic acid used to control pH and act as an acidity regulator in many food systems; unlike potassium acid tartrate, citric acid is often more soluble and has a sharper sour taste, which may influence its selection in beverage applications. Sodium acid pyrophosphate is commonly paired with acid salts like potassium acid tartrate in leavening systems but has a different chemical mechanism and technical function, contributing additional leavening and buffering characteristics. Tartaric acid itself, the parent acid of potassium acid tartrate, is used as a direct acidity regulator and antioxidant in certain food categories and shares metabolic processing pathways with its salts. These additives differ in their sensory contributions and technical profiles but are grouped in food formulation based on complementary roles in pH adjustment, leavening, and stabilization.

Common Food Applications Narrative

Potassium acid tartrate appears across a broad spectrum of food applications where controlled acidity and stable functionality are needed. In baked goods, it is a traditional acid component combined with sodium bicarbonate to form baking powder, providing consistent leavening performance that contributes to light, aerated textures in cakes, quick breads, and cookies. In confectionery products, its acidity helps prevent unwanted crystallization in sugar syrups and frostings, aiding in the production of smooth textures and desired mouthfeel properties. Products such as whipped creams and meringues benefit from potassium acid tartrate’s ability to stabilize protein foams, improving volume and stability during whipping and subsequent storage. In dairy and fermented products, controlled acidity is often critical for flavor balance and shelf stability, and potassium acid tartrate contributes to that regulation without introducing off‑flavors. Its role as a pH buffer also supports microbiological quality control in low‑pH products where maintaining specific acidity thresholds can limit the growth of spoilage organisms. Across these varied uses, it serves as a functional additive that enhances process reliability and product quality.

Safety & Regulations

FDA

  • Approved: True
  • Regulation: 21 CFR 184.1077

EFSA

  • Notes: Group ADI for tartaric acid and tartrates established by EFSA re evaluation.
  • Approved: True
  • E Number: E336
  • Adi Display: 240 mg/kg bw per day
  • Adi Mg Per Kg: 240

JECFA

  • Notes: Specific JECFA ADI for potassium acid tartrate not explicitly found on JECFA database deep link.

Sources

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