Juice elements

Filtration. Diatomite is used as a filter aid for appHcations with difficult-to-filter soflds to improve permeabiUty of the filter cake, to prevent the blinding of filter elements, and where high clarity is required such as in the poHsh filtration of wine (qv) or beer (qv) before bottling. It is also used in sugar (qv) refining, water treatment, and in the production of fmit juices (qv) and industrial chemicals. 

Nahrungs-rohr, n., -rShre, /. alimentary canal, -sait, m. nutrient juice specif., (Med.) chyle, (Bot.) sap. -stoff, m. nutritive substance, nourishment, food. -stSrung, /. nutritional disturbance, -teilchen, n. nutritive element, -vergiftung, /. food poisoning, -wert, m. nutritive value, -zufuhr, /. food intake. 

To date there is no proof for the inevitability of lead for plant and animal organisms (including humans), whereas its toxic activity is widely known. More reported poisonings involved lead than any other elements (Philip and Gearson, 1994a,b). As early as in 1774, Lind noted that lemon juice stored in lead-enameled containers may cause poisoning. A special royal commission was appointed to study the problem four years later. 

Potassium, along with nitrogen and phosphorus, is an essential element needed for plant growth. In plants, it occurs mostly as K+ ion in cell juice. It is found in fruit or seed. Deficiency can cause curling leaves, yellow or brown coloration of leaves, weak stalk and diminished root growth. Potassium deficiency has been associated with several common animal ailments. Potassium is in extracellular fluid in animals at lower concentrations than sodium. 

He proved that the acidity of the gastric juice is due to hydrochloric acid showed that the molecular weight of any substance is equal to twice its vapor density referred to hydrogen and put forth the hypothesis that the atomic weights of all of the elements, referred to hydrogen as unity, are integers. See ref. (54),... 

Centuries before the element bromine was discovered, one of its organic compounds, Tyrian purple, was used as a rich costly dye prepared from a white juice secreted by the Mediterranean mollusk, the straight-spined Murex (M. brandaris Linne) (91,166). Strabo described the Tyrian dye works in his Geography, and the product was mentioned frequently in the Bible (Ezek. 27, 7, 16) (92). In 1909 H. Friedlander of Vienna discovered that this royal dye from Murex brandaris is identical with the 6 6 dibrom indigo which F. Sachs of Berlin and his collaborators had prepared only five years previously from p-bromo-o-nitrobenzalde-hyde (93, 94, 95). 

Isotopic distribution within an element will vary between living organisms depending on the biosynthetic pathways that lead to its formation. Furthermore, the rate at which a molecule crosses cellular membranes will depend on the molecule s isotopic distribution. Hence, detectable differences in isotopic composition can be observed in the products formed. Detection of adulterated vegetable oils, flavourings and fruit juices, as well as the study of metabolism in plants and numerous biomedical applications, use isotopic abundance as a tool. For example, the... 

This chapter will cover the analysis of the different key elements of a soft drink formulation or a juice, for example, sweetener s and pr eser vatives, and the procedures for their assessment. When both soft drinks and juices contain a particular ingredient or component, then analysis is discussed together. Where there is no overlap, soft drinks and juices are covered separately. 

As the flavour and odour of a soft drink or fruit juice are very important elements of a product they should be closely controlled. This is generally carried out by trained panellists who have been screened to ensure that they have an aptitude for this type of assessment they are often quality assurance personnel or workers from the factory. Sensory assessments should be carried out in surroundings where the panellists can concentrate without distractions. 

In a soft drink, or a fruit juice reconstituted from concentrate, the quality of the water is an essential element. Checking the water quality includes assessment to ensure that it does not contain any off-tastes or odour s. It also involves checking that any water-treatment processes have been effective and have not introduced defects into the water. The water should also be assessed to ensure that it does not contain materials that are likely to precipitate from the product on storage. Such precipitates are often called floes . 

Occurrence and Distribution. PE was found associated with structural elements of the orange. McDonnell et al. (17) reported no activity in filtered orange juice, but found 58, 44 and 28 PE units per kg wet tissue in flavedo, albedo and cell sacs respectively. Working with four varieties of Florida oranges and Dancy tangerine, Rouse (20) showed that juice sacs had the highest... 

Other mineral elements are present in citrus juices in measurable quantities. McHard et al. (34) reported on the trace element contents of Florida and Brazilian orange juice. They cited concentration ranges for 25 elements. Ting (23) reported that calcium, iron, phosphorus, magnesium, zinc, and copper are present in reconstituted FCOJ at levels equivalent to about 1% to 5% of their respective U.S. RDA s. 

Because of the important nutritive attributes of the eleven elements specifically listed above, most of the analytical effort in the past few decades has been directed toward the determination of the concentrations of some or all of these elements in foods and plants of interest. However, there can also he justifiable interest in what other elements are present. Some elements are, of course, toxic even at low concentrations. Some elements may have as yet undiscovered nutritive value. Beyond these considerations it may he important to know if there are elements whose concentration depends on, and thus may be indicative of, the geographical locale in which the plants were grown. If such elements are present and if their concentrations can he measured, this information, perhaps, could be used for "fingerprinting" or characterizing the juice as to its origin. 

An examination of these comparisons reveals that they deal mostly with the more common nutrient elements like calcium, phosphorus, potassium and nitrogen. An interesting aspect of this compilation is the wide range in concentration values for elements in juices from different locations throughout the world. Of the geographical areas studied by us, these wide variations have not been observed. A selection of references from the extensive literature is given at the end of this chapter (7-22). 

There have been only two comprehensive studies made on the elemental content of orange juices produced in the United States. The first of these was reported by Roberts and Gaddum (23) a little over Uo years ago. That study was a spectrographic analysis of the elemental contents of several varieties of Florida oranges and grapefruit which were grown during that period of time. Excerpts from their results are shown in somewhat modified form in Table III. 

Table Element i III. Elemental Seedling Orange Content of Several Blood Orange Varieties of Florida Orange (1937) Valencia Orange Juices (PPM)a Lue Gim Gong Orange Tangerine...

Table IV. Elemental Content of California Valencia and Navel Orange Juices (PPM) (l96l)a...

For a selected list of elements (26) there is another acid treatment procedure which is readily applicable to the analysis of orange juice this procedure involves hydrolysis with moderately strong nitric acid to breakdown most of the sugars and to decrease the size of the pulpy constituents. The solution is then filtered, diluted, and measured by atomic absorption. For elements that can be determined with an air-acetylene flame using a high solids (three slot) burner, this procedure offers a useful alternative. Fricke et al. (33) also mentions the utility of this method and gives comparative results on the use of this method in sample preparation. 

A few of the elements in orange juice are present in large enough concentrations and/or have chemical characteristics which permit the use of classical analysis. Phosphate and some heavy metals like zinc and iron may be measured colorimetrically. Calcium has been measured as the oxalate, but such methods are time consuming and may require prior separation from the inevitable matrix before analysis. 

Atomic Emission Spectrometry. Emission spectroscopy was the earliest developed multielement measurement technique (1 9,50,51, 52). Its widest acceptance was by the metal industry where it was particularly useful in determining a few elements repetitively in a metal (usually some form of steel) matrix which was well defined. It was also used in the food and agricultural field and was responsible for much of the early knowledge of the concentrations of a number of trace elements in orange juice (23, 2k). 

Neutron Activation Spectrometry. Another instrumental technique which has applicability to a wide range of elements is neutron activation analysis. In this method the sample (which could be orange juice without any prior sample treatment) is irradiated with a strong neutron flux. The elements of analytical interest are thus converted to unstable isotopes which decay with characteristic energies and thus measurement of the intensities results in analytical values for the elements of interest. There are some serious drawbacks to this method, however. The matrix can cause severe background effects especially when the sample contains large amounts of an element, like potassium, which is the situation with orange juice. In this event tedious chemical separations must be carried out to achieve adequate selectivity, accuracy... 

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