Citrus pectin preparation

Since the x-ray fiber diffraction measurements based on citrus pectin (32) were consistent with the TEM measurements of tobacco pectin, we prepared a gel from citrus pectin similar to the previous x-ray sample. This gel was then examined by TEM. Air-dried samples of this gel, shown in Figure 5, demonstrated long stretches of helix in the molecules lying on the surface. (In the freeze-dried gels—not shown—only short stretches of helix were visible.) The average filament width in the air-dried gel was found to be 14.2A. After correcting for the added size due to the Pt/C coating... 

Figure 5. Air-dried, Pt/C replicated gel prepared from citrus pectin. This image features two pectin filaments with left-handed surface striations having 13A spacings (Each bar = 25A.)...

An experiment was conducted in which the pH of SAG jellies was varied. The objective was to determine the effect pH has on SAG grade. Jellies were prepared at pH s between 2.3 and 3.1. The pH was varied by changing the amount of tartaric acid used. Pectin dosage was held constant at. 433g. For comparative purposes two different pectins were used, one which is known to be a pure lime peel citrus pectin, and another citrus pectin with mixed peel... 

Standard apple jellies were prepared having a soluble solids of 65% and a pH of 3.15. Five commercial citrus pectins standardized to 150° SAG were used in the study. Pectin dosage was varied between 0.1% and 0.5%. The resulting jellies were tested for Breaking Strength or internal strength on the Voland Stevens Tester. The results are shown in Figure 6. 

Carrot fiber, prepared as an alcohol-acetone insoluble residue of cell wall material, binds deoxycholate and chenodeoxycholate under physiological conditions with the release of protons. Removal of calcium pectate from this material by extraction with ammonium oxalate reduces the capacity of carrot fiber to bind bile acids. Calcium carboxymethyl cellulose exhibits similar binding activity, whereas free carboxymethyl cellulose shows no binding. Calcium pectate prepared from citrus pectin and dissolved in water was found to bind bile acids under conditions used with carrot fiber. These results suggest that binding occurs through formation of salt linkage between calcium pectate in the cell wall residue and a bile acid. 

Pectin— This material is extracted from citrus peel and apple pomace (the residue after extraction of juice). It is available in pure form, or in mixtures that contain added sugar and acid and are used to prepare jams and jellies. Although pure citrus pectin has been given orally in the powdered form (1 or 2 tsp [5 or 10 ml per day) to counteract the effects of dietary cholesterol, a more desirable use for it is in low-calorie recipes such as imitation or eggless mayonnaise, tomato aspic, fruit desserts, and pie filling. It is also used in antidiarrheal preparations. 

Table 3 Specific activities of dry enzyme preparations PC-PEB-9 and PC-HOST (as a control) toward different substrates—CMC (Na-salt of carboxymethyl cellulose), xylan (birch wood xylan), PNPG (p-nitrophenyl-p-D-glucopyranoside), and citrus pectin...

The composition of multienzyme preparation PC-PEB-9 and enzyme preparation PC-HOST based on P. canescens PCXlnR host strain was determined using Fast Protein Liquid Chromatography (FPLQ and data of enzymatic activities of BGL, PEL, xylanase, and EG2 toward PNPG, citrus pectin, birch wood xylan, and CMC, respectively (Table 3). Enzyme preparatirMi PC-HOST contained 30 % of xylanases. Enzyme preparation PC-PEB-9 consisted of 15 % xylanase, 11 % PEL, 18 % EG2, and 12 % BGL (Bushina et al. 2012). 

Small proportions of acetyl groups (o.i-i.o%) are often found in the digests of purifted apple and citrus pectins. The rest of the preparation in the case of most pectins is made up by 2-8% arabinose, o. 1-6.0 galactose, and a variety of other minor constituents. 

Pectin is a long chain of pectic acid and pectinic acid molecules. Because these acids are sugars, pectin is categorized as a polysaccharide. It is prepared from citrus peels and the remains of apples after they are squeezed for juice. In the plant, pectin is the material that joins the plant cells together. When fungus enzymes break down the pectin in fruit, the fruit gets soft and mushy. 

Also he speculated that citrus juices contain two cloud-coagulating enzymes of different thermostabilities. One enzyme, most active at low pH and temperature, appeared to be destroyed by heating the juice at 65 to 70°C (149 to 158°F). The second enzyme, most active at pH 3.0 to 3.3 and about 35°C (95°F), appeared to require heating to 888C (191°F) for inactivation (12). Stevens (13) described a rapid test for pectic enzymes in citrus juice. It involved adding pectin under controlled conditions of temperature and sample preparation, and measuring the time required for flocculation. Stevens, and coworkers (14) further elaborated on the patent work (12, 13). They produced a trend curve of the... 

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