Orange juice

Orange juice is a primarily liquid extract of the orange tree fruit, produced by squeezing or reaming oranges. It comes in several different varieties, including blood orange, navel oranges, valencia orange, clementine, and tangerine. As well as variations in oranges used, some varieties include differing amounts of juice vesicles, known as "pulp" in American English, and "(juicy) bits" in British English. These vesicles contain the juice of the orange and can be left in or removed during the manufacturing process. How juicy these vesicles are depend upon many factors, such as species, variety, and season. In American English, the beverage name is often abbreviated as OJ.

Commercial orange juice with a long shelf life is made by pasteurizing the juice and removing the oxygen from it. This removes much of the taste, necessitating the later addition of a flavor pack, generally made from orange products. Additionally, some juice is further processed by drying and later rehydrating the juice, or by concentrating the juice and later adding water to the concentrate.

The health value of orange juice is debatable: it has a high concentration of vitamin C, but also a very high concentration of simple sugars, comparable to soft drinks. As a result, some government nutritional advice has been adjusted to encourage substitution of orange juice with raw fruit, which is digested more slowly, and limit daily consumption.

History

During World War II, American soldiers often rejected the vitamin C-packed lemon-flavored drink powder found in K-rations because of its unappetizing taste. Thus, the government searched for a better alternative that would fulfill the nutritional needs of the soldiers and prevent diseases such as scurvy while still having a desirable taste. The government and the Florida Department of Citrus worked with a group of scientists to develop a product superior to the canned orange juice available in the 1940s. The result was frozen, concentrated orange juice; this was not until three years after the war had ended.

By 1949, orange juice processing plants in Florida were producing over 10 million gallons of concentrated orange juice. Consumers liked concentrated canned orange juice as it was high in vitamin C, and they regarded it as affordable, tasty and convenient. The preparation was simple: empty the container of frozen concentrate into a measured volume of water and stir. However, by the 1980s, food scientists developed a fresher-tasting juice known as reconstituted ready-to-serve juice. Eventually in the 1990s, "not from concentrate" (NFC) orange juice was developed.

Due to the importance of oranges to the economy of Florida, "the juice obtained from mature oranges of the species Citrus sinensis and hybrids thereof" was adopted as the official beverage of Florida in 1967.

Nutrition

thumb|left|190x190px|A glass of orange juice with pulp

A cup serving (250 mL or 8 fluid ounces) of fresh orange juice is 88% water and contains 26 grams of carbohydrates (including 21 grams of sugar), two grams of protein, and 0.5 grams each of dietary fiber and fat (table). One cup supplies 112 calories and 149% of the Daily Value (DV) of vitamin C, with moderate amounts (11-19% DV) of potassium, thiamin, and folate (table).

Because of its citric acid content, orange juice is acidic, with a typical pH of around 3.5.

As of 2020, consumption of orange juice was under preliminary research for the potential to improve nutrition and affect cardiovascular diseases.

Commercial orange juice and concentrate

===Frozen concentrated orange juice===

Commercial squeezed orange juice is pasteurized and filtered before being evaporated under vacuum and heat. After removal of most of the water, this concentrate, about 65% sugar by weight, is then stored at about . Essences, Vitamin C, and oils extracted during the vacuum concentration process may be added back to restore flavor and nutrition (see below).

When water is added to freshly thawed concentrated orange juice, it is said to be reconstituted.

The product was developed in 1948 at the University of Florida's Citrus Research and Education Center. Since, it has emerged as a soft commodity, and futures contracts have traded in New York since 1966. Options on FCOJ were introduced in 1985. From the late 1950s to the mid-1980s, the product had the greatest orange juice market share, but not-from-concentrate juices surpassed FCOJ in the 1980s.

Not from concentrate

Orange juice that is pasteurized and then sold to consumers without having been concentrated is labeled as "not from concentrate". Just as "from concentrate" processing, most "not from concentrate" processing reduces the natural flavor from the juice. The largest producers of "not from concentrate" use a production process where the juice is placed in aseptic storage, with the oxygen stripped from it, for up to a year.

Removing the oxygen also strips out flavor-providing compounds, and so manufacturers add a flavor pack in the final step, which Cook's Illustrated magazine describes as containing "highly engineered additives." Flavor pack formulas vary by region, because consumers in different parts of the world have different preferences related to sweetness, freshness and acidity. According to the citrus industry, the Food and Drug Administration does not require the contents of flavor packs to be detailed on a product's packaging.

One common component of flavor packs is ethyl butyrate, a natural aroma that people associate with freshness, and which is removed from juice during pasteurization and storage. Cook's Illustrated sent juice samples to independent laboratories, and found that while fresh-squeezed juice naturally contained about 1.19 milligrams of ethyl butyrate per liter, juice that had been commercially processed had levels as high as 8.53 milligrams per liter. The canned product loses flavor, however, when stored at room temperature for more than 12 weeks. In the early years of canned orange juice, the acidity of the juice caused the juice to have a metallic taste. In 1931, Dr. Philip Phillips developed a flash pasteurization process that eliminated this problem and significantly increased the market for canned orange juice.

Freshly squeezed, unpasteurized juice

thumb|upright|Mexico City merchant with his freshly squeezed orange juice, March 2010

Fresh-squeezed, the unpasteurized juice is the closest to consuming the orange itself. This version of the juice consists of oranges that are squeezed and then bottled without having any additives or flavor packs inserted. The juice is not subjected to pasteurization. Depending on storage temperature, freshly squeezed, unpasteurized orange juice can have a shelf life of 5 to 23 days.

Major orange juice brands

In the U.S., the major orange juice brand is Tropicana Products (owned by PAI Partners and PepsiCo Inc.), which possesses nearly 65% of the market share. Tropicana also has a large presence in Latin America, Europe, and Central Asia. Competing products include Minute Maid (of The Coca-Cola Company) and Florida's Natural Growers (a Floridian agricultural cooperative that differentiates itself from the competition by being locally owned and using only Florida grown oranges; Tropicana and Simply Orange use a mixture of domestic and foreign stock).

In Australia, Daily Juice (owned by National Foods) is a major brand of partially fresh, partially preserved, orange juice.

In the United Kingdom, major orange juice brands include Del Monte and Princes.

Additives

Some producers add citric acid or ascorbic acid to juice beyond what is naturally found in the orange. Some also include other nutrients. Often, additional vitamin C is added to replace that destroyed in pasteurization. Additional calcium may be added. Vitamin D, not found naturally in oranges, may be added as well. Sometimes omega-3 fatty acids from fish oils are added to orange juice. Low-acid varieties of orange juice also are available.

FCOJ producers generally use evaporators to remove much of the water from the juice in order to decrease its weight and decrease transportation costs. Other juice producers generally deaerate the juice so that it can be sold much later in the year.

Because such processes remove the distinct aroma compounds that give orange juice a fresh-squeezed taste, producers later add back these compounds in a proprietary mixture, called a "flavor pack", in order to improve the taste and to ensure a consistent year-round taste. The compounds in the flavor packs are derived from orange peels by squeezing the oil out of them.

The concentrated juice is held in a cold wall tank and is stored at or below 35 °F to prevent browning and development of undesired flavors. Next, a small amount of fresh juice is added to the concentrated juice to restore natural and fresh flavors of orange juice that have been lost through the concentration process. Specific cold-pressed orange oils are used to restore the lost aroma and volatile flavors. After the addition of fresh juice, the brix content is reduced to 42 °F. The fresh juice is referred to as "cut-back" in the industry and attributes to 7-10% of the total juice. Orange peel oil is also added if the oil content is below the required level. The concentrate is then further cooled in a continuous cooler or cold wall tank to 20 to 25 °F. The concentrate is canned using steam injection methods to sterilize the lid and develop a vacuum in the can. The cans then undergo final freezing where they are conveyed on a perforated belt in an air blast at -40 °F. After freezing, the product is stored at 0 °F in a refrigerated warehouse.

The oranges then go through roller conveyors, which expose all sides of the fruit. The roller conveyors are efficiently built as they are well lighted, installed at a convenient height, and width to ensure all inspectors can reach the fruit to determine inadequacies. Some reasons why fruit may be rejected include indication of mold, rot, and ruptured peels. Afterwards, the oranges are separated based on size through machines prior to juice extraction. There are a number of different ways orange juice industry leaders extract their oranges. Some common methods include halving the fruit and pressing/reaming the orange to extract juice from the orange. One instrument inserts a tube through the orange peel and forces the juice out through the tube by squeezing the entire orange. Despite the variety of machines used to extract juices, all machines have commonalities in that they are rugged, fast, easy to clean and have the ability to reduce peel extractives into the juice. The extracted juice product does not contain the orange peel, but it may contain pulp and seeds, which are removed by finishers. Additional ingredients into the mixture may include fresh/frozen/pasteurized orange juice from mature oranges, orange oil, and orange pulp.

Regulations in the United Kingdom

In the United Kingdom, orange juice from concentrate is a product of concentrated fruit juice with the addition of water. Any lost flavour or pulp of the orange juice during the initial concentration process may be restored in the final product to be equivalent to an average type of orange juice of the same kind. Any restored flavour or pulp must come from the same species of orange. Sugar may be added to the orange juice for regulating the acidic taste or sweetening, but must not exceed 150g per litre of orange juice. Vitamins and minerals may be added to the orange juice in accordance with Regulation (EC) 1925/2006.

Physical and chemical properties

Molecular composition

thumb|right|UV 280 nm chromatogram after UHPLC separation of commercial orange juice, showing, amongst other peaks, [[narirutin and hesperidin.]]

On a molecular level, orange juice is composed of organic acids, sugars, and phenolic compounds. The main organic acids found in orange juice are citric, malic, and ascorbic acid. The major sugars found in orange juice are sucrose, glucose, and fructose. There are approximately 13 phenolic compounds in orange juice including hydroxycinnamic acids, flavanones, hydroxybenzoic acids, hesperidin, narirutin, and ferulic acid.

Composition of the cloud

The cloud is the portion of suspended particles that range in size from 0.05 micrometers to a few hundred micrometers in orange juice. The cloud is responsible for several sensory attributes in orange juice including color, aroma, texture, and taste. The continuous medium of the cloud consists of a solution of sugars, pectin, and organic acids while the dispersed matter is formed through cellular tissue comminuted in fruit processing. Specifically, the cloudiness of the juice is caused by pectin, protein, lipid, hemicellulose, cellulose, hesperidin, chromoplastids, amorphous particles, and oil globules. In particular the chemical composition of the cloud consists of 4.5-32% pectin, 34-52% protein, 25% lipids, 5.7% nitrogen, 2% hemicellulose, 2% ash, and less than 2% cellulose.

The suspension is unstable when the zeta potential is less than 25 mv in magnitude. Zeta potential is a measure of the magnitude of electrostatic forces between particles, which affect repulsion, and attraction between particles. A low zeta value signifies that the repulsive forces will not be able to overcome Van der Waals attractions between cloud particles and thus begin to agglomerate. Agglomeration of cloud particles will prevent free flow characteristics, which is essential in the juice. A high zeta potential will inhibit particle-particle agglomeration and maintain the free flowing nature as well as uniform dispersion in orange juice.

Hydrocolloids

Hydrocolloids are long-chain polymers that form viscous dispersions and gels if dispersed in water. They have a number of functional properties in food products including emulsifying, thickening, coating, gelling, and stabilization. The main reason hydrocolloids are used in foods is their capability to modify the rheology of food systems. Hydrocolloids impact viscosity through flow behavior and mechanical solid properties like texture. Some common hydrocolloids that are used to stabilize juice products include gellan gum, sodium carboxymethylcellulose, xanthan, guar gum, and gum Arabic. The aforementioned hydrocolloids are generally used in the production of imitation orange juices and are often referred to as synthetic hydrocolloids. Pectin is the hydrocolloid found in natural orange juices.

There is a specific interaction between pectin and hesperidin through the sugar moieties in the hesperidin molecule. Through acid hydrolysis, the rhamnose and glucose sugar moieties are removed from hesperidin, which breaks the interaction between hesperidin and pectin. Hydrogen bonding plays a role in the specific interaction of neutral sugars of pectin and the sugar moiety of hesperidin. A polymer that has a high structural content of neutral sugar branches interacts with hesperidin more tightly and strongly than that of a low content of neutral sugar branches. The interaction between pectin and hesperidin is one of the factors that enable the colloidal suspension in orange juice to be stable.

References

External links

Orange juice production Production process and distinction between juice products
Brief film clip of orange juice processing from 1968. From the State Library & Archives of Florida
Natural orange juice processing Industrial processing of natural orange juice