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TOPIC: What is in an orange?

 
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June 10, 2011 4:53 AM
Thought I would post this as a separate item....

There used to be an old Monsanto ad from the 70's.
It was a picture of an orange and the list of ingredients was right next to it.
This was not a man made orange, or a frankenstein orange.... just a natural orange.
(course this is kind of ironic since Monsanto was the number one producer of one of the most toxic agents ever... the generic dioxiin called "agent orange"; along with their current reputation of onerous seed monopolies, GM foods, and debatable food supply controls)

Nonetheless, there is an important chemical lesson here.
Hundreds of chemical components make up all foods.
Natural? Organic? That is a great way to MARKET toxic cigarettes and all sorts of other things, including food.

I am certainly not against understanding how food is produced, and minimizing unnecessary exposure to any "cidal" agent.. I just think that often the views are not balanced by epidemiological and scientific evidence.

So just what is in an orange?
Get ready....

Carbohydrates represent most of soluble solids in citrus fruits; they are present both as simple sugars and as polysaccharides. Citrus soluble solids are on the average made by a 70% of sugars, whilst pulp solids are made by a 40% of sugars and by a 50% of polysaccharides. Citrus flavor is due to the blend of sugars, acids and specific flavor compounds, some of which are sugar-containing substances known as glycosides. Contribution to fruit color may be made by sugar-containing anthocyanidins while texture is controlled by the structural carbohydrate polymers.

Between monosaccharides, major components are glucose and fructose.
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Galactose is present just in some phenolic glycosides and in polysaccharides. There are no free
pentose sugars; the aforementioned are only present in hemicelluloses and arabinans.
Among other constituents of citrus pectic substances, one finds 6-deoxyaldohexoses in the form of fuctose and rhamnose.

Saccharose is the main naturally occurring oligosaccharide in citrus fruits.
Polysaccharides are mainly represented by pectic substances (galacturonans) (1-4) linked D-galactopiranuronic acid units in extended chains; their carboxyl group is partially or completely neutralized with one or more cations and some may be esterified by methanol to form esters (carbometoxy gropus).
Pectic substances can be classified as follows
Protopectin: the term is applied to the water insoluble parent pectic substance which occurs in plants and which upon restricted hydrolysis yields pectin or pectinic acids.

Pectinic Acids: the term is used for colloidal polygalacturonic acids containing more than a negligible portion of methyl ester groups. Pectinic acids, under suitable conditions, are capable of forming gels with sugars and acids or, if suitably low in methoxyl content, with certain metallic ions.

Pectin: the term designates those water soluble pectinic acids of varying methyl ester content and degree of neutralization which are capable of forming gels with sugars and acids, under suitable conditions.

Peptic Acids: the term is applied to pectic substances mostly composed of colloidal polygalacturonic acids and essentialy free form methyl ester groups.
Peptinic acids, the most useful of the pectic substances because of their jellying power, are divided into two groups of pectins for commercial gel making.

1) High-methoxyl (above 7% methoxyl) will form jams and jellies with the proper proportion of sugar and acids.
2) Low-methoxyl pectins (3 to 7% methoxyl) will form stable gels with small quantities of polyvalent cations such as calcium without the additional soluble solids and acids.
Pectin changes during maturation, as the fruits ripen, the insoluble protopectin of mersitematic and parenchymatous tissue changes into water-soluble pectin and pectinates; as the fruits continue to ripen and become over-ripe these products are converted into low-grade pectin and insoluble pectates. Furthermore, juices and other by-products of the fruit processing need to be kept under control to prevent anomalous changes due to lack of control over processing parameters.
Pectin changes may be enzymatic or chemical. Because enzymes are an important factor in the pectic changes that occur in citrus, only two pectic enzymes will be considered:
Pectinestarase (PE) is an enzyme capable of demethylating pectin and 2) Polygalacturonase (PG) is a pectic depolymerizing enzyme. Only PE occurs naturally in citrus.
Let's consider now organic acids. Organic acids are: 1) Citric Acid; 2) L-Malic Acid. 3) D-Isocitric Acid (found in small concentration, but determining quality and purity). Oxalic Acid, Succinic Acid, Malonic Acid, Quinic Acid, Tartaric Acid, Adipic Acid, 2-ketogluratic Acid are found only in small traces. Total acidity range has an extremely wide range between different species and different locations of the orchards.
The isocitrico acid is contained in small succinico, malonico, chinico, tartarico, adipic, 2-chetoglutarico and benzoic concentration while they are present ossalico acid traces.

The nitrogenous compound in citrus are contained in rather low concentration but are important for assessing purity of the juices. Within of the nitrogenous substances without doubt more important ones are free amminoacids, representing approximately 70 % of the total nitrogenous substances. Citrus juices contain almost all important amminoacids, the most abundant are praline, asparagines, aspartic acid, serine, glutamic acid and arginine. Citrus contains small amounts of proteins which are basically enzymes (oxidoreductases, transferases, hydrolases and lyases, isomerases and ligases). Nitrogen bases and nucleic acids contents are extremely low.

There are three classes of Citrus lipids: non-polar, polar not ionic and polar ionic. Between non-polar lipids there are aldehydes, ketones and alcohols with long chain, carotins and their esters and some triglycerides. Non-ionic polar lipids usually contain sugars like glucosilglucerides. Polar ionic lipids contain reactive functional groups like aminic, carboxylic or phosphoric; free fatty acids and phosphatidic acid belong to this group. Despite their small content, lipids are important because they are involved in “off-flavors” development during juices storage.

Carotenoids derive their name from the main representative of their group, beta-carotene and pigments widely spread in nature responsible for bright shades ranging from yellow to deep red. Carotenoids are tetraterpenes formed by joining together of eight C5 isoprene units; the units are linked in a regular head to tail manner, except in the center of the molecule where the order is inverted tail to tail, thus making the molecule symmetrical.

A group of complex chemically related substances, triterpene derivatives, have been named limonoids; all components have a furan ring attached to the D-ring at C-17.
Between limonoids, the most important is limonin, known as citrus constituent since 1841.
Limonin is not directly present in fruit tissues, it is contained in the aslimonoic acid A-ring lactone, that is not bitter. When the fruit is macerated, during juicing, the combined action of fruit acids and an enzyme converts the aslimonoic acid info limonin, which is extremely bitter. In citrus products this is usually known as “delayed bitterness”. The absence of bitterness in the intact fruit and the delay in the onset of bitterness after juicing differentiate limonin bitterness from that due to the flavone neohesperidosides, such as naringin of grapefruit or bitter orange. In the latter case, the intact fruit is bitter and so is the fresh squeezed juice from it. Flavone neohesperidosides do not occur in many citrus species like sweet oranges (Citrus Sinensis), lemons (Citrus Lemon), limes (Citrus Aurantifolia) and in mandarins and tangerines (Citrus Reticulata); limonin, on the other end, is ubiquitous in all citrus species, although it may not be present in sufficient quantity at maturity to cause delayed bitterness of the juice. Delayed bitterness is most noticeable in the juice of the Navel orange and the Shamouti orange. There is no way, after juicing, to stop the reation. There is a direct relationship between limonin concentration and bitterness; generally speaking less than 6 ppm = not bitter; more than 9 ppm = bitter; 24 to 30 ppm = extremely bitter. Obviously, variations in acidity amd sweetness influence subjective responses to bitterness. In fact, a 1 ppm solution of limonin in water is considered bitter.
Flavenoids
Flavonoids are very abundant in Citrus and have a very complex pattern. Three types of flavonoids occur in Citrus: flavones (including 3-hydroxyflavanones), flavones (including 3-dydroxyflavones) and anthocyanins. Depending upon whether or not a glucosyl residue is present, the flavanones and flavones are further divided in O-glycosyl, aglycones and C-glycosylflavones. Anthocyanins are only known as constituents of blood oranges. The most important flavanones are hesperidin, naringin, poncirin, neoheriocitrin and neohesperidin. Between flavones, the most important are rhoifolin, rutin and diosmin. Between aglycones, of mention are sinensetin, auranetin, tangeritin. Without taking into account anthocyanins, there are 56 flavonoids in citrus. Some are bitter. Some, like diosmin, hesperidin and rutin, show pharmacological activity. In fact, Vitamin P, a very effective factor for reducing capillary permeability was discovered in 1937 by Szent and Gyorgyi while working on lemon peels. Pharmacological use is important in vascular and trombotic diseases like varicose veins. Diosmin, in particular, reduces capillary damage induced by histamine. Recent research shows that some flavonoids act as regulators in 1) prostaglandins synthesis (prostaglandins are a class of natural compounds physiologically very active at the level of muscles and involved in the inflammatory processes), 2) platelets aggregation, as well as other processes. Some flavonoids act as inhibitors and others as enhancers of enzymatic biosynthesis. Some flavonoids, like hydroxyethylrutinosideres are anti-inflammatory, others are immunosuppressive and other show antiallergenic properties. New research points to anticancerous properties of tangeritin by delaying metastasis of a primary cancer to a secondary or tertiary stage. Hesperidin, naringin and nobiletin have lower therapeutic potential. Dihydrochalcones derivatives of flavonoids are low calorie sweetners. Flavonoids are found mainly in the albedo and their concentration in juices depends upon the juicing technology. Due to their bitterness, it is desirable to remove flavonoids (such as limonin) through a process known as absorber resins.
With respect to anthocyanins, the most abundant is cyanidin-3-glucoside, then cyanidina-3.5-diglucoside, peonidin-5-glucoside, delphinidin-3-glucoside and petunidin-3-glucoside.
Coloring agents, generally anthocyanin (cianidyn-3-glucoside, cianidyn-3,5-diglucoside, peonidina-5-glucoside, delfinidina-3-glucoside and the petunidina-3-glucoside) Vitamin C (Ascorbic Acid). Pholacine, Vitamin B6, Thiamine, Riboflavin, Biotin, Pantotenic acid, Vitamin A
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June 10, 2011 4:57 AM
Great information, but you forgot the most important thing...

They taste super YUMMY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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