Citrus clarified

GA is used as an emulsifier in beverages such as citrus juices, beer, and cola drinks. GA ability to stabilize foams is used in the manufacture of beer and soft drinks. Besides, it can be used for clarifying wines. 

Dilute citrus juice (5 ml) with dimethylformamide (DMF, 10 ml) and 50 mM ammonium oxalate (10 ml), and then steam-bath for 10 min at 90°C. Cooling, adjust the volume to 50 ml with water, centrifuge (10 min at 2500 g), and then filter (Acrodisc, 5 and 0.45 /nm) the clarified juice. For standard preparation, prepare hesperidin (20 ppm) in DMF-water (2 1) solution and other flavanone glycosides (neohesperidin, eriocitrin, neoeriocitrin, naringin, and narirutin, 10 ppm) in the mobile phase. 

If steps are not taken to stabilize cloud, most citrus juices will clarify when allowed to stand. Clarification occurs when native PE lowers the ester content of juice soluble pectin until it becomes susceptible to precipitation as insoluble pectates (23). If pectin levels are high enough, as in concentrates, these pectates may form a gel. 

Clarified Juice. Some citrus juices, notably lime and lemon, are in demand as clarified products. Natural clarification, in combination with filtration, is often used to achieve a sparkling clear serum. However, native PE action is slowed by the high acidity of these juices, and may not give satisfactory cloud removal. In this instance, modified pectins can serve to enhance juice quality by removing cloud. 

The quality of extracted citrus juices depends on enzyme reactions that occur not only in the fruit during the development period, but also in the juice during processing. When juice is extracted from citrus fruit, enzymes are released from their normal restraint in the cell. Several of these enzymes catalyze reactions that adversely affect taste and appearance of the juice. Unless the reactions are controlled, the juice products will not meet the standards of quality set up by the USDA Food Safety and Quality Service. The two reactions of commercial importance are the hydrolysis of pectin to pectic acid, which clarifies juice, and the lactonization of limonoic acid A-ring lactone to the bitter compound, limonin. Research efforts to identify and characterize the reactions, to isolate and purify the enzymes, and to develop methods to control the reactions are described in this review. 

Okada et at 189) reported an unknown enzyme from Aspergillus niger which was not a polygalacturonase nor a pectinesterase but which was a potent clarifier of citrus juices. This factor had no effect by itself, but it strongly accelerated juice clarification when added with polygalacturonase. In subsequent papers 190, 191) the enzyme was reported purified and found to be a hemicellulase. 

Tidd has clarified the role of pyrophosphates in terpene biogenesis by measuring the hydrolysis rate of isopentenyl pyrophosphate and related pyrophosphates over the physiological pH range. Potty and Bruemmer, continuing their search for enzymes causing transformations of terpenes in citrus fruits, have discovered a system that reduces ( + )-limonene [but not (— )-limonene] in the orange. 

Ultrafiltration has also been used for the production of citrus juices with a natural unprocessed taste (BERTUZZl) (4) [15]. The fresh juice is split by ultrafiltrafion into a clarified and a cloudy part. The cloudy retentate contains the pulp, other cloudy substances and microorganisms. This retentate is pasteurised at 85°C - 98°C and. 

The spined citrus bug (Biprorulus bibax) is a pest of citrus in southern Australia. The major component (74, Figure 4.5) of the male-produced pheromone of B. bibax was isolated and identified by the joint work of James in Australia and Oliver et al. in the USA. Oliver found by chiral GC analysis that the insect produces a single enantiomer of 74. In 1992 I became interested in clarifying the absolute configuration of this pheromone, because Dr. Oliver requested me to do so. 

Citral is well-known as the most characteristic component of lemon flavor. The value of citrus drinks containing lemon flavor is dependent on the stability of citral (/). However, citral is deteriorated through acid-catalyzed or oxidation mechanisms (2-7). The potent off-flavor components formed from citral under acidic and heated conditions have been clarified by aroma extract dilution analysis (AEDA) (8). In recent years, longer storage times and displays using transparent containers under fluorescent lamps in stores have significantly increased and citral is easily deteriorated by UV light from fluorescent lamps. 

A one-stage procedure involving sodium catalysed transesterification between raffinose undeca-acetate and methyl esters of long-chain fatty acids (derived, for example, from salad oil) has been employed to produce raffinose fatty acid polyesters in excellent yields (>96%) their physical properties are described as similar to those of analogous sucrose polyesters." Certain carbohydrate esters of fatty acids, e.a.. sucrose mono-laurate, -palmitate, and -stearate, have been found to enhance the activity of thiabendazole, a fungicide used against Penicillium dioitatum infections of citrus fruit. The mechanism of this action remains to be clarified. ... 

Citrus fruit, juice - 382, 615, 788 Citrus pectin liquor - 840, 861 Clarifier liquid - 679 Clay - 615... 

After an investigation of the formation of honeydew by insects growing on citrus plants. Wolf and Ewart found that the melezitose-containing honeydew of the cottony-cushion scale, Icerya purchasi Mask, contains an enz)une capable of forming melezitose from sucrose. Bacon and Dickinson clarified the relation ip between the insects and the mother plants and... 

---