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93-404: Quavers were launched in 1968 with the advertising slogan "you get a lovely lot of Quavers in a bag", described as "curly potato puffs". The brand was originally sold in cheese and smoky bacon flavours, but over the years flavours like Spicy Beef, Sweet and Sour, Prawn Cocktail, and Ketchup were also part of the range. In 1993, a Salt and Vinegar flavour was added to the range, and by this time,

186-506: A Brønsted–Lowry acid , or forming a covalent bond with an electron pair , known as a Lewis acid . The first category of acids are the proton donors, or Brønsted–Lowry acids . In the special case of aqueous solutions , proton donors form the hydronium ion H 3 O and are known as Arrhenius acids . Brønsted and Lowry generalized the Arrhenius theory to include non-aqueous solvents . A Brønsted or Arrhenius acid usually contains

279-437: A pH less than 7 and is colloquially also referred to as "acid" (as in "dissolved in acid"), while the strict definition refers only to the solute . A lower pH means a higher acidity , and thus a higher concentration of positive hydrogen ions in the solution. Chemicals or substances having the property of an acid are said to be acidic . Common aqueous acids include hydrochloric acid (a solution of hydrogen chloride that

372-414: A spans many orders of magnitude, a more manageable constant, p K a is more frequently used, where p K a = −log 10 K a . Stronger acids have a smaller p K a than weaker acids. Experimentally determined p K a at 25 °C in aqueous solution are often quoted in textbooks and reference material. Arrhenius acids are named according to their anions . In the classical naming system,

465-450: A values are small, but K a1 > K a2 . A triprotic acid (H 3 A) can undergo one, two, or three dissociations and has three dissociation constants, where K a1 > K a2 > K a3 . An inorganic example of a triprotic acid is orthophosphoric acid (H 3 PO 4 ), usually just called phosphoric acid . All three protons can be successively lost to yield H 2 PO 4 , then HPO 4 , and finally PO 4 ,

558-465: A "99 Calories or Less" range with a consumers' focus on “New Year New Me”. The Cheese flavour was reduced to 87 Calories for a standard pack. In February 2011, Quavers packaging updated to a brighter bag colour with the Walkers logo on the packets again. After a while, the brand was sold in simply Cheese flavour. In July 2013, the six-packs were reduced in size removing 30% of the wrapping but keeping

651-436: A Lewis acid explicitly as such. Modern definitions are concerned with the fundamental chemical reactions common to all acids. Most acids encountered in everyday life are aqueous solutions , or can be dissolved in water, so the Arrhenius and Brønsted–Lowry definitions are the most relevant. The Brønsted–Lowry definition is the most widely used definition; unless otherwise specified, acid–base reactions are assumed to involve

744-447: A Lewis acid, H , but at the same time, they also yield an equal amount of a Lewis base (acetate, citrate, or oxalate, respectively, for the acids mentioned). This article deals mostly with Brønsted acids rather than Lewis acids. Reactions of acids are often generalized in the form HA ⇌ H + A , where HA represents the acid and A is the conjugate base . This reaction is referred to as protolysis . The protonated form (HA) of an acid

837-638: A Lewis base and transfers a lone pair of electrons to form a bond with a hydrogen ion. The species that gains the electron pair is the Lewis acid; for example, the oxygen atom in H 3 O gains a pair of electrons when one of the H—O bonds is broken and the electrons shared in the bond become localized on oxygen. Depending on the context, a Lewis acid may also be described as an oxidizer or an electrophile . Organic Brønsted acids, such as acetic, citric, or oxalic acid, are not Lewis acids. They dissociate in water to produce

930-580: A benzene solvent and in the third gaseous HCl and NH 3 combine to form the solid. A third, only marginally related concept was proposed in 1923 by Gilbert N. Lewis , which includes reactions with acid–base characteristics that do not involve a proton transfer. A Lewis acid is a species that accepts a pair of electrons from another species; in other words, it is an electron pair acceptor. Brønsted acid–base reactions are proton transfer reactions while Lewis acid–base reactions are electron pair transfers. Many Lewis acids are not Brønsted–Lowry acids. Contrast how

1023-477: A blue cheese such as Stilton (hard: cow's milk), Roquefort (medium: ewe's milk) or Bleu d'Auvergne (medium-soft cow's milk); and a soft/medium-soft goat's cheese (e.g. Sainte-Maure de Touraine , Pantysgawn , Crottin de Chavignol ). A cheeseboard 70 feet (21 m) long was used to feature the variety of cheeses manufactured in Wisconsin , where the state legislature recognizes a " cheesehead " hat as

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1116-433: A class of strong acids. A common example is toluenesulfonic acid (tosylic acid). Unlike sulfuric acid itself, sulfonic acids can be solids. In fact, polystyrene functionalized into polystyrene sulfonate is a solid strongly acidic plastic that is filterable. Superacids are acids stronger than 100% sulfuric acid. Examples of superacids are fluoroantimonic acid , magic acid and perchloric acid . The strongest known acid

1209-511: A covalent bond with an electron pair. An example is boron trifluoride (BF 3 ), whose boron atom has a vacant orbital that can form a covalent bond by sharing a lone pair of electrons on an atom in a base, for example the nitrogen atom in ammonia (NH 3 ). Lewis considered this as a generalization of the Brønsted definition, so that an acid is a chemical species that accepts electron pairs either directly or by releasing protons (H ) into

1302-755: A crumbly, flavorful Greek cheese. Cheese produced in Europe, where climates are cooler than the Middle East, required less salt for preservation. With less salt and acidity, the cheese became a suitable environment for useful microbes and molds, giving aged cheeses their respective flavors. The earliest ever discovered preserved cheese was found in the Taklamakan Desert in Xinjiang , China, dating back as early as 1615 BCE (3600 years before present). Ancient Greek mythology credited Aristaeus with

1395-469: A dairy farmer from Rome , New York, who in 1851 started making cheese in an assembly-line fashion using the milk from neighboring farms; this made cheddar cheese one of the first US industrial foods . Within decades, hundreds of such commercial dairy associations existed. The 1860s saw the beginnings of mass-produced rennet, and by the turn of the century scientists were producing pure microbial cultures. Before then, bacteria in cheesemaking had come from

1488-521: A hydrogen atom bonded to a chemical structure that is still energetically favorable after loss of H . Aqueous Arrhenius acids have characteristic properties that provide a practical description of an acid. Acids form aqueous solutions with a sour taste, can turn blue litmus red, and react with bases and certain metals (like calcium ) to form salts . The word acid is derived from the Latin acidus , meaning 'sour'. An aqueous solution of an acid has

1581-407: A limited time only and are no longer available. In January 2021, Quavers returned two long-lost flavours (prawn cocktail and salt & vinegar) by popular demand. A one pack (16.4 g) serving of regular Quavers contains 88 calories , of which 44 are from fat. Quavers contain a mixture of fats (4.9g): saturated fat 0.4g, polyunsaturated fat 0.6g and monounsaturated fat 3.8g. The sodium content

1674-662: A new word started to be used: formaticum , from caseus formatus , or "cheese shaped in a mold". It is from this word that the French fromage , standard Italian formaggio , Catalan formatge , Breton fourmaj , and Occitan fromatge (or formatge ) are derived. Of the Romance languages, Spanish, Portuguese , Romanian , Tuscan and some Southern Italian dialects use words derived from caseus ( queso , queijo , caș , cacio and caso for example). The word cheese

1767-538: A pH of less than 7. While the Arrhenius concept is useful for describing many reactions, it is also quite limited in its scope. In 1923, chemists Johannes Nicolaus Brønsted and Thomas Martin Lowry independently recognized that acid–base reactions involve the transfer of a proton. A Brønsted–Lowry acid (or simply Brønsted acid) is a species that donates a proton to a Brønsted–Lowry base. Brønsted–Lowry acid–base theory has several advantages over Arrhenius theory. Consider

1860-590: A proton to ammonia (NH 3 ), but does not relate to the Arrhenius definition of an acid because the reaction does not produce hydronium. Nevertheless, CH 3 COOH is both an Arrhenius and a Brønsted–Lowry acid. Brønsted–Lowry theory can be used to describe reactions of molecular compounds in nonaqueous solution or the gas phase. Hydrogen chloride (HCl) and ammonia combine under several different conditions to form ammonium chloride , NH 4 Cl. In aqueous solution HCl behaves as hydrochloric acid and exists as hydronium and chloride ions. The following reactions illustrate

1953-441: A range of foodstuffs since ancient times, it is probable that the process of cheese making was discovered accidentally by storing milk in a container made from the stomach of an animal, resulting in the milk being turned to curd and whey by the rennet from the stomach. There is a legend —with variations—about the discovery of cheese by an Arab trader who used this method of storing milk. The earliest evidence of cheesemaking in

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2046-505: A separation of their fats. Many of these can be coaxed into melting smoothly in the presence of acids or starch . Fondue , with wine providing the acidity, is a good example of a smoothly melted cheese dish. Elastic stringiness is a quality that is sometimes enjoyed, in dishes including pizza and Welsh rarebit . Even a melted cheese eventually turns solid again, after enough moisture is cooked off. The saying "you can't melt cheese twice" (meaning "some things can only be done once") refers to

2139-555: A similar texture to krupuk (prawn crackers), but have a different flavour and are smaller with a curled-up rectangle shape (similar in cross-section to a quaver ). Quavers are currently available in Cheese, Prawn Cocktail and Salt and Vinegar, but have had many other varieties over the years. The product line went on to introduce two other flavours, prawn cocktail and salt and vinegar . These were discontinued in 2012. Ketchup and sweet and sour flavours were also introduced, but for

2232-464: A simple solution of an acid compound in water is determined by the dilution of the compound and the compound's K a . Lewis acids have been classified in the ECW model and it has been shown that there is no one order of acid strengths. The relative acceptor strength of Lewis acids toward a series of bases, versus other Lewis acids, can be illustrated by C-B plots . It has been shown that to define

2325-498: A solution with pH 7.0, which is only the case with similar acid and base strengths during a reaction. Neutralization with a base weaker than the acid results in a weakly acidic salt. An example is the weakly acidic ammonium chloride , which is produced from the strong acid hydrogen chloride and the weak base ammonia . Conversely, neutralizing a weak acid with a strong base gives a weakly basic salt (e.g., sodium fluoride from hydrogen fluoride and sodium hydroxide ). In order for

2418-594: A state symbol. The nutritional value of cheese varies widely. Cottage cheese may consist of 4% fat and 11% protein while some whey cheeses are 15% fat and 11% protein, and triple cream cheeses can contain 36% fat and 7% protein. In general, cheese is a rich source (20% or more of the Daily Value , DV) of calcium , protein , phosphorus , sodium and saturated fat . A 28-gram (one ounce ) serving of cheddar cheese contains about 7 grams (0.25 oz) of protein and 202 milligrams of calcium. Nutritionally, cheese

2511-444: A substance that increases the concentration of hydronium ions when added to water. Examples include molecular substances such as hydrogen chloride and acetic acid. An Arrhenius base , on the other hand, is a substance that increases the concentration of hydroxide (OH ) ions when dissolved in water. This decreases the concentration of hydronium because the ions react to form H 2 O molecules: Due to this equilibrium, any increase in

2604-455: A very large number of acidic protons. A diprotic acid (here symbolized by H 2 A) can undergo one or two dissociations depending on the pH. Each dissociation has its own dissociation constant, K a1 and K a2 . The first dissociation constant is typically greater than the second (i.e., K a1 > K a2 ). For example, sulfuric acid (H 2 SO 4 ) can donate one proton to form the bisulfate anion (HSO 4 ), for which K a1

2697-418: Is helium hydride ion , with a proton affinity of 177.8kJ/mol. Superacids can permanently protonate water to give ionic, crystalline hydronium "salts". They can also quantitatively stabilize carbocations . While K a measures the strength of an acid compound, the strength of an aqueous acid solution is measured by pH, which is an indication of the concentration of hydronium in the solution. The pH of

2790-420: Is 170mg. Quavers have 86 calories in their Cheese flavour and 83 in the salt and vinegar variety. Cheese Cheese is a type of dairy product produced in a range of flavors, textures , and forms by coagulation of the milk protein casein . It comprises proteins and fat from milk (usually the milk of cows , buffalo , goats or sheep ). During production, milk is usually acidified and either

2883-410: Is a different French cheese for every day of the year, and Charles de Gaulle once asked "how can you govern a country in which there are 246 kinds of cheese?"). At refrigerator temperatures, the fat in a piece of cheese is as hard as unsoftened butter, and its protein structure is stiff as well. Flavor and odor compounds are less easily liberated when cold. For improvements in flavor and texture, it

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2976-408: Is a substance that, when added to water, increases the concentration of H ions in the water. Chemists often write H ( aq ) and refer to the hydrogen ion when describing acid–base reactions but the free hydrogen nucleus, a proton , does not exist alone in water, it exists as the hydronium ion (H 3 O ) or other forms (H 5 O 2 , H 9 O 4 ). Thus, an Arrhenius acid can also be described as

3069-426: Is also sometimes referred to as the free acid . Acid–base conjugate pairs differ by one proton, and can be interconverted by the addition or removal of a proton ( protonation and deprotonation , respectively). The acid can be the charged species and the conjugate base can be neutral in which case the generalized reaction scheme could be written as HA ⇌ H + A . In solution there exists an equilibrium between

3162-621: Is based on moisture content, which is then further discriminated by fat content and curing or ripening methods. Some attempts have been made to rationalise the classification of cheese—a scheme was proposed by Pieter Walstra which uses the primary and secondary starter combined with moisture content, and Walter and Hargrove suggested classifying by production methods which produces 18 types, which are then further grouped by moisture content. The British Cheese Board once claimed that Britain has approximately 700 distinct local cheeses; France and Italy have perhaps 400 each (a French proverb holds there

3255-412: Is essentially concentrated milk, but altered by the culturing and aging processes: it takes about 200 grams (7.1 oz) of milk to provide that much protein, and 150 grams (5.3 oz) to equal the calcium, though values for water-soluble vitamins and minerals can vary widely. Acid An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen ion, H ), known as

3348-605: Is found in gastric acid in the stomach and activates digestive enzymes ), acetic acid (vinegar is a dilute aqueous solution of this liquid), sulfuric acid (used in car batteries ), and citric acid (found in citrus fruits). As these examples show, acids (in the colloquial sense) can be solutions or pure substances, and can be derived from acids (in the strict sense) that are solids, liquids, or gases. Strong acids and some concentrated weak acids are corrosive , but there are exceptions such as carboranes and boric acid . The second category of acids are Lewis acids , which form

3441-492: Is largely a result of the breakdown of casein proteins and milkfat into a complex mix of amino acids , amines , and fatty acids . Some cheeses have additional bacteria or molds intentionally introduced before or during aging. In traditional cheesemaking, these microbes might be already present in the aging room; they are allowed to settle and grow on the stored cheeses. More often today, prepared cultures are used, giving more consistent results and putting fewer constraints on

3534-476: Is more compact and has a longer shelf life than milk. Hard cheeses , such as Parmesan , last longer than soft cheeses, such as Brie or goat's milk cheese . The long storage life of some cheeses, especially when encased in a protective rind, allows selling when markets are favorable. Vacuum packaging of block-shaped cheeses and gas-flushing of plastic bags with mixtures of carbon dioxide and nitrogen are used for storage and mass distribution of cheeses in

3627-649: Is occasionally employed, as in Head cheese , to mean "shaped in a mold". Cheese is an ancient food whose origins predate recorded history . There is no conclusive evidence indicating where cheesemaking originated, whether in Europe , Central Asia or the Middle East . The earliest proposed dates for the origin of cheesemaking range from around 8000 BCE, when sheep were first domesticated . Because animal skins and inflated internal organs have provided storage vessels for

3720-476: Is simply added to the name of the ionic compound. Thus, for hydrogen chloride, as an acid solution, the IUPAC name is aqueous hydrogen chloride. The strength of an acid refers to its ability or tendency to lose a proton. A strong acid is one that completely dissociates in water; in other words, one mole of a strong acid HA dissolves in water yielding one mole of H and one mole of the conjugate base, A , and none of

3813-422: Is very large; then it can donate a second proton to form the sulfate anion (SO 4 ), wherein the K a2 is intermediate strength. The large K a1 for the first dissociation makes sulfuric a strong acid. In a similar manner, the weak unstable carbonic acid (H 2 CO 3 ) can lose one proton to form bicarbonate anion (HCO 3 ) and lose a second to form carbonate anion (CO 3 ). Both K

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3906-406: Is widely advised that cheeses be allowed to warm up to room temperature before eating. If the cheese is further warmed, to 26–32 °C (79–90 °F), the fats will begin to "sweat out" as they go beyond soft to fully liquid. Above room temperatures, most hard cheeses melt. Rennet-curdled cheeses have a gel -like protein matrix that is broken down by heat. When enough protein bonds are broken,

3999-629: The Helvetii . Cheese was an everyday food and cheesemaking a mature art in the Roman empire. Pliny's Natural History (77  CE) devotes a chapter (XI, 97) to describing the diversity of cheeses enjoyed by Romans of the early Empire. He stated that the best cheeses came from the villages near Nîmes , but did not keep long and had to be eaten fresh. Cheeses of the Alps and Apennines were as remarkable for their variety then as now. A Ligurian cheese

4092-613: The River Thames Ceswican , meaning "Cheese farm". In 1022, it is mentioned that Vlach ( Aromanian ) shepherds from Thessaly and the Pindus mountains, in modern Greece , provided cheese for Constantinople . Many cheeses popular today were first recorded in the late Middle Ages or after. Cheeses such as Cheddar around 1500, Parmesan in 1597, Gouda in 1697, and Camembert in 1791 show post-Middle Ages dates. In 1546, The Proverbs of John Heywood claimed "

4185-425: The citrate ion. Although the subsequent loss of each hydrogen ion is less favorable, all of the conjugate bases are present in solution. The fractional concentration, α (alpha), for each species can be calculated. For example, a generic diprotic acid will generate 3 species in solution: H 2 A, HA , and A . The fractional concentrations can be calculated as below when given either the pH (which can be converted to

4278-561: The enzymes they produce) also play a large role in the eventual flavor of aged cheeses. Most cheeses are made with starter bacteria from the Lactococcus , Lactobacillus , or Streptococcus genera. Swiss starter cultures include Propionibacterium freudenreichii , which produces propionic acid and carbon dioxide gas bubbles during aging, giving Emmental cheese its holes or eyes . Some fresh cheeses are curdled only by acidity, but most cheeses also use rennet. Rennet sets

4371-628: The 21st century. The word cheese comes from Latin caseus , from which the modern word casein is derived. The earliest source is from the proto-Indo-European root *kwat- , which means "to ferment , become sour". That gave rise to cīese or cēse (in Old English ) and chese (in Middle English ). Similar words are shared by other West Germanic languages — West Frisian tsiis , Dutch kaas , German Käse , Old High German chāsi —all from

4464-629: The Middle East, the Indian subcontinent , and areas influenced by those cultures. But with the spread, first of European imperialism, and later of Euro-American culture and food, cheese has gradually become known and increasingly popular worldwide. The first factory for the industrial production of cheese opened in Switzerland in 1815, but large-scale production first found real success in the United States. Credit usually goes to Jesse Williams,

4557-406: The [H ]) or the concentrations of the acid with all its conjugate bases: A plot of these fractional concentrations against pH, for given K 1 and K 2 , is known as a Bjerrum plot . A pattern is observed in the above equations and can be expanded to the general n -protic acid that has been deprotonated i -times: where K 0 = 1 and the other K-terms are the dissociation constants for

4650-424: The acid and its conjugate base. The equilibrium constant K is an expression of the equilibrium concentrations of the molecules or the ions in solution. Brackets indicate concentration, such that [H 2 O] means the concentration of H 2 O . The acid dissociation constant K a is generally used in the context of acid–base reactions. The numerical value of K a is equal to the product (multiplication) of

4743-435: The acid. Neutralization is the reaction between an acid and a base, producing a salt and neutralized base; for example, hydrochloric acid and sodium hydroxide form sodium chloride and water: Neutralization is the basis of titration , where a pH indicator shows equivalence point when the equivalent number of moles of a base have been added to an acid. It is often wrongly assumed that neutralization should result in

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4836-445: The addition of rennet completes the curdling. Vegetarian varieties of rennet are available; most are produced through fermentation by the fungus Mucor miehei , but others have been extracted from Cynara thistles. For a few cheeses, the milk is curdled by adding acids such as vinegar or lemon juice . Cheese is valued for its portability, long shelf life , and high content of fat, protein, calcium , and phosphorus . Cheese

4929-551: The archaeological record dates back to 5500 BCE and is found in what is now Kuyavia , Poland, where strainers coated with milk-fat molecules have been found. The earliest evidence of cheesemaking in the Mediterranean dates back to 5200 BCE, on the coast of the Dalmatia region of Croatia . Cheesemaking may have begun independently of this by the pressing and salting of curdled milk to preserve it. Observation that

5022-405: The cheese has set into a very moist gel. Some soft cheeses are now essentially complete: they are drained, salted, and packaged. For most of the rest, the curd is cut into small cubes. This allows water to drain from the individual pieces of curd. Some hard cheeses are then heated to temperatures in the range of 35–55 °C (95–131 °F). This forces more whey from the cut curd. It also changes

5115-400: The cheese into a strong and rubbery gel compared to the fragile curds produced by acidic coagulation alone. It also allows curdling at a lower acidity—important because flavor-making bacteria are inhibited in high-acidity environments. In general, softer, smaller, fresher cheeses are curdled with a greater proportion of acid to rennet than harder, larger, longer-aged varieties. While rennet

5208-577: The cheese itself turns from a solid to a viscous liquid. Soft, high-moisture cheeses will melt at around 55 °C (131 °F), while hard, low-moisture cheeses such as Parmesan remain solid until they reach about 82 °C (180 °F). Acid-set cheeses, including halloumi , paneer , some whey cheeses and many varieties of fresh goat cheese , have a protein structure that remains intact at high temperatures. When cooked, these cheeses just get firmer as water evaporates. Some cheeses, like raclette , melt smoothly; many tend to become stringy or suffer from

5301-438: The concentration of hydronium is accompanied by a decrease in the concentration of hydroxide. Thus, an Arrhenius acid could also be said to be one that decreases hydroxide concentration, while an Arrhenius base increases it. In an acidic solution, the concentration of hydronium ions is greater than 10 moles per liter. Since pH is defined as the negative logarithm of the concentration of hydronium ions, acidic solutions thus have

5394-423: The concentrations of the products divided by the concentration of the reactants, where the reactant is the acid (HA) and the products are the conjugate base and H . The stronger of two acids will have a higher K a than the weaker acid; the ratio of hydrogen ions to acid will be higher for the stronger acid as the stronger acid has a greater tendency to lose its proton. Because the range of possible values for K

5487-494: The curds into a single solid body. A newborn cheese is usually salty yet bland in flavor and, for harder varieties, rubbery in texture. These qualities are sometimes enjoyed— cheese curds are eaten on their own—but normally cheeses are left to rest under controlled conditions. This aging period (also called ripening, or, from the French, affinage ) lasts from a few days to several years. As a cheese ages, microbes and enzymes transform texture and intensify flavor. This transformation

5580-547: The discovery of cheese. Homer 's Odyssey (8th century BCE) describes the monstrous Cyclops making and storing sheep's and goats' milk cheese (translation by Samuel Butler ): We soon reached his cave, but he was out shepherding, so we went inside and took stock of all that we could see. His cheese-racks were loaded with cheeses, and he had more lambs and kids than his pens could hold... When he had so done he sat down and milked his ewes and goats, all in due course, and then let each of them have her own young. He curdled half

5673-795: The effect of making cheese in an animal stomach gave more solid and better-textured curds may have led to the deliberate addition of rennet. Early archeological evidence of Egyptian cheese has been found in Egyptian tomb murals, dating to about 2000 BCE. A 2018 scientific paper stated that the world's oldest cheese, dating to approximately 1200 BCE (3200 years before present), was found in ancient Egyptian tombs. In 2024, even older preserved remnants of cheese were identified on mummies in Xiaohe Cemetery in present-day Xinjiang . The earliest cheeses were likely quite sour and salty, similar in texture to rustic cottage cheese or feta ,

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5766-542: The end of a meal before or following dessert, or replacing the last course. The British tradition is to have cheese after dessert, accompanied by sweet wines like Port . In France, cheese is consumed before dessert, with robust red wine. A cheeseboard typically has contrasting cheeses with accompaniments, such as crackers, biscuits, grapes, nuts, celery or chutney . A cheeseboard typically contains four to six cheeses, for example: mature Cheddar or Comté (hard: cow's milk cheeses); Brie or Camembert (soft: cow's milk);

5859-555: The environment or from recycling an earlier batch's whey; the pure cultures meant a more standardized cheese could be produced. Factory-made cheese overtook traditional cheesemaking in the World War II era, and factories have been the source of most cheese in America and Europe ever since. By 2012, cheese was one of the most shoplifted items from supermarkets worldwide. In 2021, world production of cheese from whole cow milk

5952-902: The environment where the cheese ages. These cheeses include soft ripened cheeses such as Brie and Camembert , blue cheeses such as Roquefort , Stilton , Gorgonzola , and rind-washed cheeses such as Limburger . There are many types of cheese, with around 500 different varieties recognized by the International Dairy Federation, more than 400 identified by Walter and Hargrove, more than 500 by Burkhalter, and more than 1,000 by Sandine and Elliker. The varieties may be grouped or classified into types according to criteria such as length of ageing, texture, methods of making, fat content, animal milk, country or region of origin, etc.—with these criteria either being used singly or in combination, but with no single method being universally used. The method most commonly and traditionally used

6045-404: The enzymes of rennet or bacterial enzymes with similar activity are added to cause the casein to coagulate. The solid curds are then separated from the liquid whey and pressed into finished cheese. Some cheeses have aromatic molds on the rind, the outer layer, or throughout. Over a thousand types of cheese exist, produced in various countries. Their styles, textures and flavors depend on

6138-403: The fact that oils leach out during the first melting and are gone, leaving the non-meltable solids behind. As its temperature continues to rise, cheese will brown and eventually burn. Browned, partially burned cheese has a particular distinct flavor of its own and is frequently used in cooking (e.g., sprinkling atop items before baking them). A cheeseboard (or cheese course) may be served at

6231-413: The fluoride nucleus than they are in the lone fluoride ion. BF 3 is a Lewis acid because it accepts the electron pair from fluoride. This reaction cannot be described in terms of Brønsted theory because there is no proton transfer. The second reaction can be described using either theory. A proton is transferred from an unspecified Brønsted acid to ammonia, a Brønsted base; alternatively, ammonia acts as

6324-449: The following reactions are described in terms of acid–base chemistry: In the first reaction a fluoride ion , F , gives up an electron pair to boron trifluoride to form the product tetrafluoroborate . Fluoride "loses" a pair of valence electrons because the electrons shared in the B—F bond are located in the region of space between the two atomic nuclei and are therefore more distant from

6417-427: The following reactions of acetic acid (CH 3 COOH), the organic acid that gives vinegar its characteristic taste: Both theories easily describe the first reaction: CH 3 COOH acts as an Arrhenius acid because it acts as a source of H 3 O when dissolved in water, and it acts as a Brønsted acid by donating a proton to water. In the second example CH 3 COOH undergoes the same transformation, in this case donating

6510-530: The highest consumers of cheese in 2014, averaging 25 kg (55 lb) per person per annum. A required step in cheesemaking is to separate the milk into solid curds and liquid whey . Usually this is done by acidifying ( souring ) the milk and adding rennet . The acidification can be accomplished directly by the addition of an acid, such as vinegar, in a few cases ( paneer , queso fresco ). More commonly starter bacteria are employed instead which convert milk sugars into lactic acid . The same bacteria (and

6603-454: The ionic suffix is dropped and replaced with a new suffix, according to the table following. The prefix "hydro-" is used when the acid is made up of just hydrogen and one other element. For example, HCl has chloride as its anion, so the hydro- prefix is used, and the -ide suffix makes the name take the form hydrochloric acid . Classical naming system: In the IUPAC naming system, "aqueous"

6696-467: The limitations of Arrhenius's definition: As with the acetic acid reactions, both definitions work for the first example, where water is the solvent and hydronium ion is formed by the HCl solute. The next two reactions do not involve the formation of ions but are still proton-transfer reactions. In the second reaction hydrogen chloride and ammonia (dissolved in benzene ) react to form solid ammonium chloride in

6789-546: The milk and set it aside in wicker strainers. Columella 's De Re Rustica (c. 65 CE) details a cheesemaking process involving rennet coagulation, pressing of the curd, salting, and aging. According to Pliny the Elder , it had become a sophisticated enterprise by the time the Roman Empire came into being. Pliny the Elder also mentions in his writings Caseus Helveticus , a hard Sbrinz -like cheese produced by

6882-509: The moon is made of a green cheese " ( Greene may refer here not to the color, as many now think, but to being new or unaged). Variations on this sentiment were long repeated and NASA exploited this myth for an April Fools' Day spoof announcement in 2006. Until its modern spread along with European culture, cheese was nearly unheard of in east Asian cultures and in the pre-Columbian Americas and had only limited use in sub-Mediterranean Africa, mainly being widespread and popular only in Europe,

6975-503: The more easily it loses a proton, H . Two key factors that contribute to the ease of deprotonation are the polarity of the H—A bond and the size of atom A, which determines the strength of the H—A bond. Acid strengths are also often discussed in terms of the stability of the conjugate base. Stronger acids have a larger acid dissociation constant , K a and a lower p K a than weaker acids. Sulfonic acids , which are organic oxyacids, are

7068-600: The order of Lewis acid strength at least two properties must be considered. For Pearson's qualitative HSAB theory the two properties are hardness and strength while for Drago's quantitative ECW model the two properties are electrostatic and covalent. Monoprotic acids, also known as monobasic acids, are those acids that are able to donate one proton per molecule during the process of dissociation (sometimes called ionization) as shown below (symbolized by HA): Common examples of monoprotic acids in mineral acids include hydrochloric acid (HCl) and nitric acid (HNO 3 ). On

7161-644: The origin of the milk (including the animal's diet), whether they have been pasteurised , the butterfat content, the bacteria and mold , the processing, and how long they have been aged . Herbs, spices, or wood smoke may be used as flavoring agents . The yellow-to-red color of many cheeses is produced by adding annatto . Other added ingredients may include black pepper , garlic, chives or cranberries . A cheesemonger, or specialist seller of cheeses, may have expertise with selecting, purchasing, receiving, storing and ripening cheeses. Most cheeses are acidified by bacteria, which turn milk sugars into lactic acid ;

7254-423: The orthophosphate ion, usually just called phosphate . Even though the positions of the three protons on the original phosphoric acid molecule are equivalent, the successive K a values differ since it is energetically less favorable to lose a proton if the conjugate base is more negatively charged. An organic example of a triprotic acid is citric acid , which can successively lose three protons to finally form

7347-740: The other hand, for organic acids the term mainly indicates the presence of one carboxylic acid group and sometimes these acids are known as monocarboxylic acid. Examples in organic acids include formic acid (HCOOH), acetic acid (CH 3 COOH) and benzoic acid (C 6 H 5 COOH). Polyprotic acids, also known as polybasic acids, are able to donate more than one proton per acid molecule, in contrast to monoprotic acids that only donate one proton per molecule. Specific types of polyprotic acids have more specific names, such as diprotic (or dibasic) acid (two potential protons to donate), and triprotic (or tribasic) acid (three potential protons to donate). Some macromolecules such as proteins and nucleic acids can have

7440-414: The outside with dry salt or brine washes. Most cheeses have the salt mixed directly into the curds. Other techniques influence a cheese's texture and flavor. Some examples are: Most cheeses achieve their final shape when the curds are pressed into a mold or form. The harder the cheese, the more pressure is applied. The pressure drives out moisture—the molds are designed to allow water to escape—and unifies

7533-482: The packaging for Quavers, Wotsits , Squares, French Fries and Monster Munch . This packaging reflected the usage of sunseed oil , which was used in all products. The Multipack bags were in a different layout, being in Landscape style. Quavers' logo was changed slightly, and the flavours remained the same. In December 2009, Quavers, Wotsits, Squares, and French Fries all changed their packaging again to coincide with

7626-715: The packaging transitioned to the Walkers brand name. Walkers, owned by PepsiCo , purchased the Quavers brand in July 1995, when it became one of the Frito Lay International brand names. In 1996, a Tangy Tomato flavour was added to the range. By 1997, the brand was part of Walkers' short-lived "Snackshack" range, and was relaunched twice in April 1998 and in March 1999. In October 1998, the first relaunch coincided with

7719-423: The protonated acid HA. In contrast, a weak acid only partially dissociates and at equilibrium both the acid and the conjugate base are in solution. Examples of strong acids are hydrochloric acid (HCl), hydroiodic acid (HI), hydrobromic acid (HBr), perchloric acid (HClO 4 ), nitric acid (HNO 3 ) and sulfuric acid (H 2 SO 4 ). In water each of these essentially ionizes 100%. The stronger an acid is,

7812-575: The reconstructed West-Germanic form *kāsī , which in turn is an early borrowing from Latin. The Online Etymological Dictionary states that "cheese" derives from: Old English cyse (West Saxon), cese (Anglian) ... from West Germanic *kasjus (source also of Old Saxon kasi , Old High German chasi , German Käse , Middle Dutch case , Dutch kaas ), from Latin caseus [for] "cheese" (source of Italian cacio , Spanish queso , Irish caise , Welsh caws ). The Online Etymological Dictionary states that

7905-560: The return of Prawn Cocktail with a new recipe (as such, was branded as "New") replacing Tangy Tomato, while the second relaunch coincided with a newly refreshed Cheese flavour. Another packaging refresh took place in July 2000. In August 2002, a "Streaky Bacon" flavour was added to the range, which contained pink and brown pieces, that resembled bacon. In September 2004, Ghost-shaped Cheese Quavers were released for Halloween, and returned in September 2005. In February 2007, Walkers changed

7998-462: The same amount of bags inside. In August 2019, the packaging was updated alongside other Walkers Snacks, to inform about a reduction in plastic used on the packet. In December 2020, Walkers announced that Prawn Cocktail and Salt and Vinegar would return to shelves in January 2021 due to popular demand. The primary ingredient in Quavers is potato starch . They are deep fried to give a snack with

8091-406: The solution, which then accept electron pairs. Hydrogen chloride, acetic acid, and most other Brønsted–Lowry acids cannot form a covalent bond with an electron pair, however, and are therefore not Lewis acids. Conversely, many Lewis acids are not Arrhenius or Brønsted–Lowry acids. In modern terminology, an acid is implicitly a Brønsted acid and not a Lewis acid, since chemists almost always refer to

8184-485: The taste of the finished cheese, affecting both the bacterial culture and the milk chemistry. Cheeses that are heated to the higher temperatures are usually made with thermophilic starter bacteria that survive this step—either Lactobacilli or Streptococci . Salt has roles in cheese besides adding a salty flavor. It preserves cheese from spoiling, draws moisture from the curd, and firms cheese's texture in an interaction with its proteins . Some cheeses are salted from

8277-439: The transfer of a proton (H ) from an acid to a base. Hydronium ions are acids according to all three definitions. Although alcohols and amines can be Brønsted–Lowry acids, they can also function as Lewis bases due to the lone pairs of electrons on their oxygen and nitrogen atoms. In 1884, Svante Arrhenius attributed the properties of acidity to hydrogen ions (H ), later described as protons or hydrons . An Arrhenius acid

8370-480: The word is of: unknown origin; perhaps from a PIE root *kwat- "to ferment, become sour" (source also of Prakrit chasi "buttermilk;" Old Church Slavonic kvasu "leaven; fermented drink ," kyselu "sour," - kyseti "to turn sour;" Czech kysati "to turn sour, rot;" Sanskrit kvathati "boils, seethes;" Gothic hwaþjan "foam"). When the Romans began to make hard cheeses for their legionaries ' supplies,

8463-517: Was 22.2 million tonnes , with the United States accounting for 28% of the total, followed by Germany, France, Italy and the Netherlands as secondary producers (table). As of 2021, the carbon footprint of a kilogram of cheese ranged from 6 to 12 kg of CO 2 eq , depending on the amount of milk used; accordingly, it is generally lower than beef or lamb, but higher than other foods. France , Iceland, Finland, Denmark and Germany were

8556-569: Was noted for being made mostly from sheep's milk, and some cheeses produced nearby were stated to weigh as much as a thousand pounds each. Goats' milk cheese was a recent taste in Rome, improved over the "medicinal taste" of Gaul 's similar cheeses by smoking . Of cheeses from overseas, Pliny preferred those of Bithynia in Asia Minor. c. 1000, Anglo-Saxons in England named a village by

8649-433: Was traditionally produced via extraction from the inner mucosa of the fourth stomach chamber of slaughtered young, unweaned calves, most rennet used today in cheesemaking is produced recombinantly . The majority of the applied chymosin is retained in the whey and, at most, may be present in cheese in trace quantities. In ripe cheese, the type and provenance of chymosin used in production cannot be determined. At this point,

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