Preparation of the Fruit

Separation of the juice is achieved using continuous or discontinuous presses or processes such as vacuum filtration or extraction. 

Before pressing, the fruit tissue is digested with pectinolytic and cellulolytic enzymes at 50 °C to increase the yield. In this way, especially fruit 

The juice treatment step involves fining and clarification, i. e. removal of turbidity, and stabilization to prevent additional turbidity. The former step commonly involves treatment with enzymes, mostly pectinolytic, and, if necessary, removal of starch and poljfphenols using gelatin, alone or together with colloidal silicic acid or tannin, or polyvinylpjnrolidone. Finally, proteins are removed by adsorption on bentonite. 

Clarification of juice is achieved by filtration through porous pads or layers of cellulose, asbestos or kieselguhr, or by centrifugation. 

Since juice production provides juices which are well-saturated with air oxygen-sensitive products are deaerated. This is achieved by an evacuation step or by purging the juice with an inert gas such asN2 orC02. 

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Many factors affect the volatile composition of fruit and vegetables, e.g. genetics, maturity, growing conditions and postharvest handling. Furthermore, preparation of the fruits and vegetables for consumption and the method for isolation of volatile compounds may change the volatile profile and key aroma compounds compared to non-processed fruits and vegetables. 

Determination of the Sugars.—The principal sugar present is saccharose, but invert sugar is also found—mostly due to inversion of the saccharose during the preparation of the fruits—as well as glucose, which is added directly. The method of determination is as follows ... 

Preparation of the fruit. Since the early research of Webb et al. (33) several workers have recognized the problem of artefact formation during work-up of grapes. Accordingly, these investigators have employed additives such as NaF and ascorbic acid or SO. and sorbic acid to minimize microbial and oxidative degradation of the juice (2,10,34). 

We can compare the incomplete formation of a chemical product with the process of harvesting. When a farmer harvests a fruit crop, some of the fruit is left on the trees. Some may spill off the truck on the way to market. Some of the fruit may be unsuitable for sale. The result is that less than 100% of the potential crop eventually finds its way to market. Likewise, a synthetic chemist loses some of the potential product of a reaction at each step in the preparation. 

Figure 3 gives an example of a typical force profile. The force is increased continuously and reaches the point - at the end of the first part of the force profile - where the pectin preparations start to flow. The so-called yield point is reached. The further increase leads to the continuous destruction of the internal structure and the proceeding shear thinning. The applied stress in part 3 of the stress profile destroys the structure of the fruit preparations completely. Now the stress is reduced linearly, see part 4 and 5, down to zero stress. The resulting flow curves 2, 3 and 4 and the enclosed calculated area from the hysteresis loop give important evidence about the time-dependent decrease of viscosity and a relative measure of its thixotropy. 

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. 

The authors are grateful to Dr. M.S. Nechaev and Dr. V.N. Khrustalev for help in the preparation of the text, to Professors R. West, C. Eaborn, D.J. Smith, J. Barrau, K. Izod, S. Berger, M. Veith, E. Vedejs, E. Nifant ev, and O. Kolodyazhnyi and to Dr. D. Laikov for fruitful discussions. This work was financially supported by the Russian Foundation for Basic Research (Project Nos. 96-03-33188 and 00-03-32889). 

ACS isozymes differ from each other in their sensitivity to inhibitors. For example, the eight catalytically active ACS isozymes from Arabidopsis have Ki values for AVG and sinefungin ranging from 0.019 to 0.8 and 0.15 to 12pmol, whereas those from the crude extract preparation of tomato fruit have 1) values for the same inhibitors ranging from 0.2 to 10 and 1.0 to 25 pmol, respectively. ... 

Phagocytosis rate increase. Polysaccharide fraction of the fruit, administered to adults at a concentration of 10 pg/mL, was active on polymorphonuclear leukocytes k Pharmacokinetics. Hexane extract of the fruit, administered rectally to 12 healthy male adults at a dose of 640 mg, produced bioavailability similar to that observed for the oral formulations. Extract, administered orally to healthy males at a dose of 320 mg (1 X 320 mg capsule, new formulation or 2 X 160 mg, reference preparation) for 1 month, produced a rapid absorption with a peak time (T J of 1.5-1.58 hour and peak plasma level (C J of 2.54-2.67 pg/mL. The area under the curve value ranged from 7.99 to 8.42 pg/hour/mL. The plasma concentration-time profile of both preparation was nearly identical. Both preparations can be considered as bioequivalenp Hexane ex-... 

Photocycloaddition of thiones to alkenes is the most popular and fruitful method for the preparation of the thietane system. In analogy to the formation of the oxetanes by cycloaddition of the electronic excited ( ,tc ) carbonyls, thietanes can be expected to arise photochemically from aromatic thioketones and substituted olefins as well as 1,2- and 1,3-dienes. ° Thiobenzophenone serves as a source of a sulfur atom and, because of its blue color, which disappears on photocycloaddition, permits exact control over the reaction time. A mixture of thiobenzophenone and a-phellandrene must be irradiated for 70 hr before the blue color disappears (Eq. 2) and... 

Methionine can be obtained from enzymatic protein hydrolysates or from petrochemical sources. To a lesser extent than cysteine, it is a raw material in Maillard reactions for the preparation of process flavours and it can also be utilised as a precursor for the chemical preparation of the sulfide methional, which is an important flavour constituent for potato, malt, seafood and many other flavours. Methional can be reduced to methionol, which can be esterified with organic acids to, for instance, methionyl acetate and methionyl butyrate, which are useful compounds for pineapple and other fruit flavours (Scheme 13.16). 

I should like to thank my coworkers at the Universities of Bochum and Kiel who have contributed to the progress in the chemistry and biology of sialic acid over the past 14 years, and also the many colleagues, all over the world, who have given me advice, and participated in fruitful collaboration. Thanks are also due A. P. Corfield, G. Reuter (University of Kiel), and H. Rahmann (University of Stuttgart-Hohenheim) for assistance and criticism during the preparation of the manuscript. 

BERGAMOT OIL. An essential oil, Brownish-yellow to green liquid, agreeable odor, bitter taste, produced from the nnd of the fruit of Citrus aurantium or C. bergamia, relatives of the orange and lemon, The small trees are cultivated in southern Europe. The oil is expressed from the skin of the small yellow fruits and sometimes is used as a scent for cosmetics. The oil also is used sometimes as a clearing agent in the preparation of material for microscopic examination. 

A simplified flow diagram for the preparation of dehydrated fruits and vegetables is given in Fig. ft. 

To ascertain the quantity of sugar (saccharose) used in the preparation of the preserved fruit, from the total sugar (invert sugar x 0 95 plus saccharose) contained in the sample must be deducted the natural sugar (also calculated as saccharose) due to the quantity of fruit in the sample. For this purpose it is, of course, necessary to know the saccharine contents of different fruits, so that an analysis of fruit of the same quality preserved in water in the same conditions as in the syrup must be made. 

Microscopic Test.—This is carried out more especially with jams and preferably in comparison with samples of certain origin, in order to characterise the particular tissues of the fruit used and to detect any elements of different fruits, which may be present particularly in products prepared with residues from the manufacture of crystallised fruit. 

Only about 6% of the total XIV content of the fruit is present in the juice vesicles. Any step in juice preparation that increases incorporation of the other tissues into the juice or that increases the extraction of XIV from those tissues will increase the limonin content of the juice. Consequently, techniques that increase juice yield, such as hard versus soft extraction, tend to increase limonin content (34). 

Citranaxanthene 543 is found in citrus fruits and is used as a food dye like P-carotene. The same phosphonium salt synthon 505 as used for the vitamin A synthesis is monoolefinated with the polyene dialdehyde 539. The Wittig reaction of the resulting 540 with phosphorane 541 followed by aldol condensation of the obtained 542 with acetone gives citranaxanthene 54 3 255,263) (Scheme 92). In the preparation of the polyenedial 539 l,4-dibromo-2-butene 544 is reacted with trimethyl... 

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