Potato tuber slices

A general survey of the scope of the reaction between alcohols and dihydropyran to form tetrahydropyranyl ethers may be of value in devising syntheses requiring the protecting of hydroxy-groups. The glycosylation of 3/ -hydroxy-steroids by potato-tuber slices has been systematically investigated. 

Thus it has been shown that addition of sodium [ C2]acetate to potato tuber slices, which have been inoculated with Monilinia fructicola or Glomeralla cingulata, provides rishitin (549), lubimin (550), hydroxylubimin (551), 15-dihydrolubimin (552), solavetivone (553), isolubimin (554), 10-epilubimin (555),... 

The action of hydrolases released on physical damage has been discussed earlier. The results of such action may be rapid and extensive, as shown with bean leaves and potato tubers (see above). To illustrate this, it can be calculated that, if all the endogenous substrates (membrane phospholipids and ga-lactolipids) in potato tuber were available to the acyl hydrolase enzyme, then at pH 6 all the lipid could be deacylated within 1 s at 25°C. Hence the need for care in the isolation of lipids or of subcellular fractions from such tissues. Free fatty acids may be respiratory substrates in storage tissue slices the liberation of free fatty acids by acyl hydrolase activity on cutting the tissue can provide the substrate, as shown by Hasson and Laties (1976a) in potato tuber slices. 

Acetate is frequently used to label the fatty acyl moieties of phospholipids. Galliard (1972) employed this property in preparing radioactive phospholipids in potato tuber slices PC and neutral lipids were the major fractions labeled, and the fatty acids labeled in PC were 16 0 (22.5%), 18 0 (11.4%), 18 1 (30.4%), and 18 2 (32.6%) after a 2-h incubation at 25°C. 

Wen J.-Q., Huang F., Liang W.-S., Liang H.-G. Increase of HCN and fi-cyanoalanine synthase activity during ageing of potato tuber slices. Plant Science, 125 147-149 (1997). 

M. A. Hartmann and P. Benvenlste, Effects of ageing on sterol metabolism in potato tuber slices. Phytochemistry, 13 2667 (1974) A.M. Atallah, R.T. Axel, R.B. Ramsey and H.J. Nicholas, Biosynthesis of sterols and triterpenes in Pelargonium hortorum. Phytochemistry 14 1529 (1975)... 

In suberizing potato tuber disks, labeled oleic acid was incorporated into co-hy-droxyoleic acid and the corresponding dicarboxylic acid, the two major aliphatic components of potato suberin [73]. Exogenous labeled acetate was also incorporated into all of the aliphatic components of suberin, including the very long chain acids and alcohols in the wound-healing potato slices. The time-course of incorporation of the labeled precursors into the suberin components was consistent with the time-course of suberization. The biosynthetic pathway for the major aliphatic components of suberin is shown in Fig. 8a. 

The detailed procedure of starch isolation from potato tubers is as follows. Potato tubers (10 kg) are washed, peeled, sliced into 2-3 cm cubes, and soaked in distilled water containing 20 mM sodium bisulfite and 10 mM citric acid for 2 hours to prevent darkening. The cubes are then disintegrated using a centrifugal juice extractor, the pulp is suspended in 6 L of distilled water and passed through the extractor again, and starch milk is collected. The milk is allowed to sediment for 30 minutes the supernatant and the suspended solids are removed by decantation, and the... 

There had been good evidence for the existence of a cell division hormone (Figure 2d) since 1895 when Haberlandt first showed that slices of kohlrabi or potato tubers would, within a few days, form a new corky layer on the cut surface which was preceded by active cell division of several cell layers below the damaged cells. However, if the slices were well washed after the initial cutting, so that all traces of the damaged cells were removed, the divisions and corky layer failed to form—but would do so if crushed cells were re-applied (for summary see Haberlandt, 1921). This was not one of the properties of auxin. 

Using a scalpel (see Note 1), remove approx 0.8 g of tissue from the heel-end of each potato tuber, in thin slices (see Note 2). 

Two tomatidenol glycosides a- and )8-solamarine have been isolated as major glyco-alkaloids from the leaves and aged tuber slices of S. tuberosum L. var. Kennebec in addition to the alkaloids a-solanine and a-chaconine, usually found as major components of potatoes. ... 

It is proposed that NAD is required for the oxidation of DAMP to a diketone intermediate. The latter compound than undergoes a phosphate elimination yielding a product that undergoes a NADH-dependent reduction to form a dideoxy diketone. This intermediate cyclizes to yield dehydroquinate (Sprinson et al., 1%2 Aldersberg and Sprinson, 1964). Recently, 5-dehydro-3-deoxy-D-arabino-heptulosonic acid 7-phosphate was shown to be an intermediate in the reaction (Maitra and Sprinson, 1978). Sliced sweet potato root and potato tuber tissue show increased DHQ syntlfase activity reminiscent of the injury-stimulated increases in those tissues of phenylalanine ammonia lyase and other enzymes of phenolic biosynthesis (Saijo and Kosuge, 1978). 

The pH profile and requirement for Mg-ATP were similar to those for choline kinase however, activities could be clearly resolved by electrophoresis which revealed a single peak of ethanolamine kinase and two peaks of choline kinase activity. Phosphorylation of ethanolamine was less in the presence of monomethyl- and dimethylethanolamine, but it was not clear whether these compounds were phosphorylated by the.enzyme. Choline had no effect on the phosphorylation of ethanolamine. Waring and Laties (1977) supplied dimethylethanolamine to aging slices of potato tuber and found marked synthesis of phosphatidyldimethylethanolamine (PDME), while the accumulation of PC and PE was inhibited. It appeared that dimethylethanolamine was phosphorylated and metabolized as an analogue of choline and/or ethanolamine. 

Addition of radiolabeled [l,2- C]choline to plant tissue rather specifically labels PC. Marshall and Kates (1974) found 10% of the labeled lipid as lyso-phosphatidylcholine. (LPC). Tang and Castelfranco (1968) have published chromatograms of lipids from potato (Solanum tuberosum L.) tuber slices labeled by choline. In addition to PC there were minor spots which could correspond to LPC. Moore (1977) used [l,2- C]choline to label PC in soybean suspension cultures. The only lipid labeled was PC, and its degradation was followed after a 2-h pulse of radioactivity. The cells grew exponentially and then entered stationary phase turnover half-times in these two phases were 36 and 96 h. 

Glucosyl- and diglucosylsolanidine are synthetized by potato tuber tissue slices or cell suspension cultures that have been incubated with solanidine (355). Enzyme preparations from sprouts and dormant tubers of the potato, SoUmum tuberosum, are able to hydrolyze a-solanine, a-, /Jj-, JS2-, and y chaconine to solanidine and the respective sugars. The enzymes of tubers, unlike those of sprouts, hydrolyze a-chaconine in a stepwise, but a-solanine in a nonstepwise manner. Contrary to the literature (3), not only the enzymes of tubers but those of sprouts are capable of hydrolyzing y-chaconine (J65 cf. 166,167). 

Kolattukudy P E, Dean B B 1974 Structure, gas chromatographic measurement, and function of suberin synthesized by potato tuber tissue slices. Plant Physiol 54 116-121... 

In recent years a number of in vitro experiments have been reported on a variety of plant materials—segments of oat coleoptiles, segments of barley root, cut-up spinach leaves, discs of rhubarb leaves, slices of potato tubers —which demonstrate the utilization of di-and tricarboxylic acids by respiring cells and an increased rate of oxidation on addition of these substances they demonstrate further that malonate inhibits plant respiration. The stimulating effect of the substrates is often absent in fresh material, which is saturated with oxidizable substrates, but it is marked after storage, which depletes the tissue of substrates. The malonate inhibition is usually found only when the medium is acid (pH 5 or below) and when the concentration of malonate is relatively high (0.01 M and above). To obtain the same effects as in animal tissues ten- to a hundredfold concentrations of malonate are required. 

Gamble, M. H., Rice, P., and Selman, J. D. (1987). Relationship between oil uptake and moisture loss during frying of potato slices from c.v. Record U.K. tubers. Int. J. Food Sci. Technol. 22, 233-241. 

A high-speed slicer, where the tubers are sliced to desired thickness for the product. Water is added into the slicer along with potatoes (see Figure 11). 

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