Citrus fruits, components

Rouseff RL and Nagy S. 1994. Health and nutritional benefits of citrus fruit components. Food Technol November 1994 125-130. 

Figure 9-3 Conversion of Beta-Carotene to Vitamin A. Source Reprinted with permission from R.R. Rouseff and S. Nagy, Health and Nutritional Benefits of Citrus Fruit Components, Food Technology, Vol. 48, No. 11, p. 125, 1994, Institute of Food Technologists.

CAS 65997-06-0 EINECS/ELINCS 266-041-3 Synonyms Rosin, hydrogenated Classification Thermoplastic acidic resin Definition Derived from hydrogenation of wood rosin Pre rerties Solid soften, pt. (R B) 68 C acid no. = 160 Uses Tackifier, modifier in adhesives and hot-melt-applied decorative, pressure-sensitive, and heat-sealable coatings prod, of rosin ester gum coatings on fresh citrus fruit component of food-contact articles fragrance in cosmetics... 

Carboxylic acids with one acid group are known as monobasic acids while those with two acid groups are dibasic acids. All acids with more than one acid group are in the class of polybasic acids. The simplest organic acid, formic acid, is responsible for the irritation of bee and ant stings. Vinegar is a 5% solution of acetic acid in water. The acetic acid is responsible for the characteristic sour taste. Citric acid, found in citrus fruits and used in soft drinks, is a tribasic acid with three carboxylic acid groups. The dibasic acid, adipic acid, is a major component of nylon. 

Rouse, A.H. 1953. Distribution of pectinesterase and pectin in component parts of citrus fruits. Food Technol. 7 360-362. 

In many instances the problem of surface contamination has been principally studied 3-5, 7-10,16,17, 19, 22). However, early in the DDT studies on citrus fruits, it became evident that appreciable amounts of this insecticide penetrated into certain components of the peel. Following this disclosure, suitable techniques were investigated and an evaluation of the penetration of DDT and later of parathion into various kinds of fruit was undertaken. 

Citrus Fruit Types. The method previously described 11) consisted essentially of scrubbing the fruits with a warm 10% trisodium phosphate solution, rinsing with distilled water, halving each fruit, and reaming the juice and pulp from each half with a power juicer. Pieces of pulp adhering to the insides of the individual hemispheres of peel were carefully scraped free and combined with the remainder of the pulp and juice. Independent analyses were then completed on the discrete peel and pulp-juice samples. Whenever desirable the flavedo and albedo components of the peel were separated with peeling tools, and each was pooled and analyzed. 

When dissection of fruits was involved in the preparation of the samples, the values reported represent the parts per million of toxicant based on fresh weight of the indicated component only and not of the weight of the whole fruit. As separated in these studies the peel of most citrus fruits constitutes approximately one sixth the weight of the whole fruits. 

Alpha hydroxy acids (AHAs) are water-soluble substances and thereby penetrate the outermost epidermal skin layers. In contrast, beta hydroxy acids (BHAs) are lipid (fat) soluble and are capable of penetrating to the underlying layers of skin (the dermis) located 1-5 mm below the surface of the skinJ2 Most AHAs are derived from plant materials and marine sources. Commonly used AHAs include malic acid (found in apples), ascorbic acid (a common ingredient in numerous fruits), glycolic acid (a constituent of sugar cane), lactic acid (a component of milk), citric acid (naturally abundant in citrus fruits), and tartatic acid (found in red wine). A common BHA is salicylic acid (an ingredient in aspirin). 

The first fully comprehensive coupling of NP and RP, where the previously described difficulties related to solvents immiscibility were overcome, was developed by Dugo et al. and applied to the analyses of oxygen heterocyclic components of lemon essential oils [22], Based on the configuration described in this work, other applications were developed for the analysis of carotenoids in citrus samples [48], citrus fruit extracts [29], pharmaceutical products [29], and triglycerides in fats and... 

Although 2,3-benzofuran is a component of coumarone-indene resin and this resin has been approved by the FDA for use as a coating on citrus fruits, as a component of food-preparation utensils, and as an adhesive in food packages (see Table 7-1), no information was located confirming that coumarone-indene resin is currently used on food in the United States. Furthermore, no data were located to indicate that 2,3-benzofuran migrates from the resin into foodstuffs. 

Humans may be exposed to 2,3-benzofuran by inhalation, ingestion, or dermal absorption. Based on the limited data available, exposure of the general population to 2,3-benzofuran does not appear to be substantial. However, since this compound has been detected at hazardous waste sites, is reported to be a component of cigarette smoke, and is one monomer in a resin which may be used as a coating on citrus fruits and in packaging materials for foods, human exposure may be possible from these sources. People in Britain who had died in fires had 2,3-benzofuran in some blood samples, but no source of exposure was identified (Anderson and Harland 1980). 2,3-Benzofuran was... 

Exceptions to the simple definition of an essential oil are, for example, garlic oil, onion oil, mustard oil, or sweet birch oils, each of which requires enzymatic release of the volatile components before steam distillation. In addition, rhe physical process of expression, applied mostly to citrus fruits such as orange, lemon, and lime, yields oils that contain from 2-15% nonvolatile material. 

Another very important development was the production of citrus comminutes. These were produced by mixing together, in appropriate proportions, the juice, peel components and essential oils of citrus fruits and comminuting the mixture in a stone mill. The resulting product delivered a more intense flavour and cloud than could be obtained from juice alone and allowed the creation of whole fruit drinks , which have dominated the concentrates market in the United Kingdom over the past 40-50 years. 

Figure 3.3 Component parts of a typical citrus fruit.

The components of the citrus fruit are separated into the principal products citrus oils, juice and residual peel and pith. After concentration of the juice, the oils and some peel and pith will be recombined with the concentrated juice. The whole mixture will then typically be finely milled and homogenised before being pasteurised. 

As citrus fruits and their products contribute substantially to the American diet and are consumed in great abundance, we believe the time is appropriate to review in detail some important nutritional and quality properties of this important fruit. Twenty-eight scientists joined with us to cover extensively subjects in the following areas nutrition and health quality as related to specific biochemical components effects of handling and processing quality control and evaluation regulatory implication and adulteration. 

The organic acids of citrus fruit include a group of carboxylic acids (23) with different acids predominant in various component parts of the fruit. Citric acid is the main acid in the juice, representing from 80 percent of the total acidity in juice from ripened oranges, about 90 percent of that of grapefruit and nearly all of that of lemon. The pH of the juice greatly affects the sourness of the product (24) and is, in turn, affected by the cations, especially potassium. The major acids in citrus peel are malic, oxalic (25), malonic (26), and quinic (27). 

Citrus fruits, especially certain of their component parts, constitute one of the richest sources of pectin. On a dry weight basis, as much as 30% of orange fruit albedo may be pectin (8). The rag, comprising the fruit core and segment membranes after juice extraction, is also a rich source. Since pectin is a cell wall component, it follows that comparatively little would be present in juice expressed from fruit. For example, concentrations ranging from 0.01 to 0.13% in orange juice have been reported (15). Much of this would be present as cell wall fragments and particulate material in juice pulp and cloud. 

Juice Cloud. Mechanical extraction of citrus fruits yields a turbid suspension of wall fragments and cellular organelles in a serum composed primarily of cell vacuolar fluids. In most citrus juice products, such a suspension of fragments and organelles is a desirable component, since it provides most of the characteristic color and flavor (28). Essence and peel oils suspended in juice contribute desirable citrus notes to flavor, and these oils are rapidly adsorbed by juice particulate material shortly after extraction (29). 

The flavonoids are found in fruits, vegetables, nuts, seeds, herbs, spices, stems, flowers, as well as in tea and red wine. They are prominent components of citrus fruits. Flavonoids are effective in ... 

Aroma components of citrus fruit juice128-132 are different from that of essential oils (see Section 4.15.4.5 for composition of the latter).133-135 Other familiar fruits like apples,136 grapes,137 strawberries,129 138 bananas,139 and pineapples140 were analyzed as well. Place of origin (e.g., grapes) and ripeness of the obtained fruit (e.g., pineapples), in many cases, bring substantial difference in its composition and enantiomeric properties (Table 14).141... 

Is a water-soluble emulsifier and solubilizing agent. It is used as a component in dyeing assistants and as a low-foaming solvent emulsifier in textile dye carriers. It acts as a stabilizer in natural and synthetic latices, and is used as a wax emulsifier in coatings for citrus fruits. 

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