Lemon pectin

Some properties of Penicillium fellutanum pectinesterase were studied. The optimum of pectinesterase action was detected at pH 5 and 45 °C. The enzyme was stable at pH 4 — 5 and 40 °C (pH 5) for 240 min. and was specific towards lemon pectin. An enzyme preparation composed mainly of pectinesterase was partially purified by gel filtration. Pectinesterase activity was accumulated in one of the obtained fractions. Molecular weights of fraction determined were found to be 46,000 and 1,200. Disk electrophoresis in polyacrilamide gel of the purified preparation revealed two protein bonds with one active component. The partially purified enzyme had the kinetic characteristics =... 

For study of substrate specificity pectin with various degrees of metoxilation (expressed as a percentage) were used beet substrate —37.8, apple substrate — 70, lemon—82. Specificity of pectinesterase action was analyzed under optimum temperature and acidity of the medium using beet, apple and lemon pectin according to the speed of methanol formation (M 10 min. ). 

Degree of pectin metoxylation is the main factor that determines the pectinesterase action. Lemon pectin was hydrolyzed most easily among all pectin studies the speed of methanol release was 2.02 M 10 min.. This is accounted by the fact, that the degree of the lemon pectin metoxylation is higher than in case of beet and apple pectin. All above mentioned shows, that pectinesterase from P. fellutanum possesses specificity towards lemon pectin (Figure 3). 

The molecular weight distribution curves for apple and lemon pectins were obtained similarly by Owens, Miers and Maclay.79 These workers were not satisfied that the preparation of the nitrate involved no degrada-... 

Aspinall, G.O., Craig, J.W.T., and Whyte, J.L. (1968) Lemon-peel pectin. Part I. Fractionation and partial hydrolysis of water-soluble pectin. CarbohydrJies. 1 442-452. 

Qualitatively, the results observed with ferric chloride and lead acetate were highly variable. It was first noted with ferric chloride that gels were forming within the reaction vessel We observed the formation of translucent gels in the reaction vessel with calcium chloride, spermidine and ferric chloride. In the case of lead acetate, a feathery type precipitate formed in the reaction vessel. Macdonald et al. (14) observed formation of a clear gel and flocculated precipitate in high ester pectin treated with lemon endocarp and peel PE isozymes, respectively. They hypothesized that the different gel structures were due to unique mechanism of deesterification by the PE isozymes. Our results with different cations and formation of different gel structure or precipitate seems to be similar to that reported by Macdonald et al. (14). If there is a different mechanism of de-esterification for plant PEs,... 

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. 

Chemical classification of polysaccharides is the least ambiguous system of grouping these macromolecules. Polysaccharides of different origins can have similar structures, as Kravtchenko et al. (1992) discovered in lemon and apple pectin. Likewise, polysaccharides of the same origin can have different structures, as for example, the concentration of pyruvate and acetyl substituents in xanthan, depending on incubation conditions (Pettitt, 1982). 

Aspinall, G. O., and Cottrell, I. W. (1970). Lemon-peel pectin. II. Isolation of homogeneous pectins and examination of some associated polysaccharides. Can. J. Chem. 48 1283-1289. 

Pectin, citrus flavonoids Rutaceae Citrus lemon L. Carper (1988) Potter (1995) Bmneton (1995)... 

Endogenous pectin esterases play an important role in citrus processing they have therefore been studied intensively. They cause cloud loss in citrus juices, which is due to the calcium precipitation of enzymatically de-esterified pectin. This is desirable in the production of lemon and lime juices but undesirable in the production of orange juice. In orange juice concentrates strong calcium pectate gels may form which cannot be reconstituted... 

Cloud stability in citrus juices Pectin manufacture from citrus pomace Distillates from fermented fruit pulps Enzymatic maceration of fruits and vegetables Self-clarification of lemon/lime and apple juices Pressing characteristics of citrus pomace Ca2 -firming of fruits and vegetables... 

Fungal pectin esterases have lower pH optima (ca 4.5) than plant pectin esterases (7,8) and are less heat stable (3 5,26 ). A commercially available fungal PE preparation has been introduced for industrial application in cider and lemon juice clarification (52,60). A process for the manufacture of low-ester pectins with a lower sensitivity for calcium has been patented by Ishii et al. 

Pectin can also be added in the form of a solution. The required amount of pectin is dissolved in a small amount of hot water (about 80°C) and added to the fruit mixture. In this case the pectin is not added until after the sugar. Citric acid or lemon juice is also added in order to speed up the gelling process and improve the taste. The amount of pectin to be added depends on the original pectin content of the fruit and on the size of the container. Less pectin is needed for small containers than for bigger containers. 

Cutler et al. (1983) extended the experimental techniques used by Morris et al. (1983) to fluid foods syrups, chocolate spread, condensed milk, strawberry dessert sauce, lemon curd, tomato ketchup, rosehip syrup, milk, and sieved chicken soup. Again, the 2.77 w/v % pectin solution (log jo (poise) = 1.64 and log yo.i = 2.30)... 

Commercial pectins are partially esterified (methyl ester) polymers composed primarily of a-D-galacturonopyranosyl units linked (1— 4) [51,52,53,54,55,56,57,58,59]. The native molecules present in the ceU walls and intercellular layers of all land plants (O Chap. 6.1), from which commercial pectins are obtained, are more complex molecules that are converted into the partially methyl esterified poly(a-D-galactopyranosyluronic acids) during extraction with acid. Commercial pectin is obtained from citms peel and apple pomace. Generally, the highest quality pectin is obtained from lemon and lime peel. 

Ralet, M.-C. and Thibault, J.-F. 1994. Effect of extrusion-cooking on plant cell-walls from lemon. I. Characterisation of the water soluble pectins and comparison with acid-extracted pectins, Carbohydr. Res., 260 283-296. 

The results from the GPC and the size exclusion chromatography studies together with a number of intrinsic viscosities that were measured in our laboratories have clearly demonstrated that on a constant and consistent basis citrus pectins derived only from lime peels have a molecular weight superior to citrus pectins of normal mixed peel origin. A citrus pectin of mixed peel origin can consist of any proportion of peels from orange, grape fruit, lemon, and lime. 

Pectin is extracted commercially from citrus peel (lemon, lime and grapefruit) and apple pomace.1,2 The food industry is the most important field of application of extracted pectin. Pectins from different sources are widely used to stabilize food emulsions and dispersions in products such as fruit drinks, and fruit and tomato pastes.3 Pectin can form gels under certain circumstances and it... 

Studies on lemon peel pectin illustrate the value of combining data from chemical and enzymic studies. Partial acid hydrolysis and acetolysis... 

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