Production of potato starch with low waste

The use of fine grinding and air classification of dehydrated potatoes with sieving and minimum washing to produce potato starch is described. A substantial reduction in the amount of waste water over that required by conventional wet milling procedures was obtained. The procedure proposed would reduce wastes by 90%.     

Changes in potato starch quality during growth

Summary Potato starch quality parameters (amylose concentration, glucose-6-phosphate content and granule size) were analyzed in relation to the harvesting date and tuber size of four cultivars. A significant increase in the glucose-6-phosphate content and granule size of starch was observed during tuber growth, whereas the amylose concentration was constant. Granule size increased markedly, whereas glucose-6-phosphate content showed slightly increasing values with increasing tuber size. Amylose concentration showed no correlation with tuber size. We conclude that the changes in the granule size, glucose-6-phosphate and amylose content of potato starch during growth are independent of each other.     

Resistance toErwinia spp. in diploid potato with a high starch content

Summary Tubers of diploid interspecific hybrids, hexaploid somatic hybrids ofSolanum tuberosum andSolanum brevidens, a fusion parental line (S. tuberosum) and several Polish and American commercial cultivars were screened for resistance toErwinia carotovora subsp.atroseptica andErwinia chrysanthemi, in laboratory tests. Both groups of hybrids showed a high level of resistance to soft rot and gave a similar type of resistant reaction, which distinguished them from the cultivars and fusion parent. Tubers of the diploid interspecific hybrids had a high starch content. Our results indicate the possibility of obtaining breeding material with a high starch content and resistance to bacterial soft rot.     

Tuber and starch quality of wild and cultivated potato species and cultivars

Summary Between 1993 and 1998 205 different potato cultivars and 1220 accessions/genotypes of wild and cultivated potato species from the IPK Genebank Gatersleben were evaluated. Parameters interesting for starch isolation and especially for the use of starch were determined. Altogether, there was a higher variability in wild potato species than in cultivated potatoes for all characteristics investigated: dry matter content, starch content, protein content, amylose content and mean particle diameter of starch granules.     

Rapid detection of potato viruses by dot-ELISA

Summary The dot-ELISA, an immunosorbent assay on nitrocellulose (NC) membranes, was applied to potato viruses. The sensitivity of the test, as determined by visual assessment of the colour reactions in serial dilutions, allowed a reliable detection of the potato viruses M, S, X, Y, A and of potato leafroll virus in leaves of non-potato hosts and potato plants. Tuber extracts taken from the rose end resulted in higher dilution end points than those from the heel end. The test can be performed within two to three hours by using stored NC-membranes precoated with specific γ-globulin. The possibility of storing antigen treated NC-membranes for some days allows the assay to be quickly applied to samples taken in the field.     

Effect of temperature on the starch content of potato callus tissue

Starch content was determined in Lemhi Russet callus grown on MS medium for 2 and 4 weeks at 25, 15, and 5°C with 50 μM 2,4-D or 10 μM picloram as the only plant growth regulator. A treatment of 5°C for 4 weeks followed by 25°C for 2 and 4 weeks was included to simulate reconditioning. Callus starch content ranged from 0.01 to 0.08% on a wet weight basis and 0.5 to 4.0% on a dry weight basis. Starch content was highest after 2 weeks at 25 and 15°C and decreased with time in a similar manner at both 25 and 15°C. Starch content decreased at 5°C, then increased significantly during simulated reconditioning at 25°C. Starch content was higher in callus grown with 50 μM 2,4-D than in callus grown with 10 μM picloram. After staining the callus with I₂-KI solution, starch granule formation was observed in the callus grown with 50 μM 2,4-D, while little granule formation was observed in the callus grown with 10 μM picloram.     

Sap extraction device for sampling potato leaves and tubers

An adaptation of a metal shop crimping machine with knurled rollers and driven with a foot-switch activated, geared-down electric motor was used to express sap from potato foliage or tuber pieces placed in triangular polythylene envelopes. Approximately 150–180 leaf samples/hour were processed by one operator. This sap extraction system eliminated the need for washing the rollers between samples and prevented contamination between samples. It worked equally well with oat or sorghum foliage.     

The mass extraction of potato glycoalkaloids from blossoms

A new procedure has been developed to extract gram quantities of glycoalkaloids from freeze-dried potato blossoms. The per cent recovery is 65–70%, yielding a mixed glycoalkaloid product that is greater than 90% glycoalkaloids. This method is very simple and rapid with completion in only two days. This new methodology will be very useful in entomological and toxicological research where large amounts of these glycoalkaloids are utilized.     

Methods to increase the starch content of potato tuber callus tissue

Summary Attempts were made to increase the starch content of callus tissue from tubers of cvs Lemhi Russet and Russet Burbank by varying growth regulator concentration, sugar source, sugar concentration, temperature and callus shape. Starch content was always higher in media containing no growth regulators. Callus spread over the media contained more starch than unbroken rectangular or cube-shaped callus. Sucrose was superior to glucose and fructose for starch formation. A sucrose concentration of 20 % produced more starch than lower concentrations. Callus growth decreased as the sucrose concentration increased. ‘Lemhi Russet’ callus incubated with 8 % sucrose at 20, 25 and 30 °C contained 1.2, 0.4 and 0.8 % starch respectively, which was much higher than in ‘Russet Burbank’ callus. With varying amounts of mannitol as an osmoticum in 8 % sucrose, the most starch was found in the medium containing 5 % mannitol. Research Paper 92B2 of the Idaho Agricultural Experiment Station     

Rapid determination of host receptivity in potato blight forecasting

Summary The degree of host receptivity (disease potentia) of the potato to the late blight fungus can be measured by the C_p/R₈-ratio (see text). In blight forecasting this ratio can be used to reveal the duration of a period of non-receptivity (the physiological barrier phase, C_p/R_s · 1,0) in early mid-growth. Periods of weather suitable for the fungus that occur during this phase are non-valid but the first weather period to occur after the C_pR_s-ratio of the host has risen above 1,0is the valid one. It is, therefore, important to be able to determine the C_p/R_s-ratio quickly. Good correlations have been found between C_p and the fresh weight of all underground parts less the mother tuber, and between R_s and the fresh weight of the shoot. A table of estimated values is given, and a suitable field kit is described. Results from its use fit well with those obtained by analysis during the period of non-receptivity of the host, but are less precise for other stages of growth. Bright sun can delay or arrest the early stages of a blight epidemic, whilst the fungusBotrytis cinerea can combine with the blight fungus to accentuate an epidemic.

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Zusammenfassung Der Empf?nglichkeitsgrad der Kartoffel als Wirtspflanze (Krankheitspotential) für den Krautf?ulepilz kann durch das C_p/R_s-Verh?ltnis gemessen werden (C_p — Gewicht des gesamten Kohlehydrates in der ganzen Pflanze. R_s=übriges (kohlehydratfreies) Trockengewicht der Triebe). Im Krautf?ule-Warndienst kann dieses Verh?ltnis benützt werden, um Aufschluss zu erhalten über die Dauer der Nichtempf?nglichkeits-period (physiologische Grenzphase, C_p/R_s · 1,0) im frühen Entwicklungsstadium (abb. 1). Für den Pilz günstige Wetterperioden, die in dieses Stadium fallen, sind nicht gültig; gültig ist die erste Wetterperiode, nachdem das C_p/R_s-Verh?ltnis der Wirtspflanze 1,0 übersteigt (abb, 3). Es ist deshalb wichtig, das Verh?ltnis C_p/R_s rasch bestimmen zu k?nnen. Gute Korrelationen wurden festgestellt zwischen C_p und dem Frischgewicht aller unterirdischen Teile ohne die Mutterknolle und zwischen R_s und dem Frischgewicht der Triebe. Es wird eine Zusammenstellung der berechneten Werte gegeben (Tabelle) und eine günstige Feldausrüstung beschrieben (Abb. 2). Die damit erhaltenen Ergebnisse stimmen gut überein mit jenen, die durch Analysen w?hrend der Nichtempf?nglichkeitsperiode des Wirtes erzielt wurden, aber sie sind weniger genau in andern Wachstumsstadien. Starker Sonnenschein kann die frühen Stadien einer Krautf?ulepidemie verz?gern oder aufhalten, w?hrend der PilzBotrytis cinerea sich mit dem Krautf?ulepilz vereinigen kann, um eine Epidemie zu verst?rken.

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Résumé Le degré de réceptivité de l'h?te-pomme de terre (potentiel de la maladie) au mildiou peut être mesuré par le rapport C_p/R_s (C_p étant le poids de tous les hydrates de carbone dans la plante entière, R_s étant le poids sec résiduel (sans hydrate de carbone) des pousses). Pour prévoir le mildiou, le rapport peut être utilisé pour révéler la durée de la période de non réceptivité (phase de barrière physiologique: rapport C_p/R_s · 1) dans la moyenne croissance précoce (Fig. 1). Les périodes de temps favorable au champignon qui se produisent pendant cette phase ne sont pas valables mais bien la première période favorable après que le rapport C_p/R_s de l'h?te est arrivé au-dessus de 1 (Fig. 3). II est par conséquent important de déterminer rapidement le rapport C_p/R_s. De bonnes corrélations ont été trouvées entre C_p et le poids frais de toutes les parties souterraines moins le tubercule-mère, et entre R_s et le poids frais des pousses. Le tableau donne les valeurs estimées, et lafig. 2 montre une trousse d'analyse pour le champ. Les résultats de l'utilisation de cette trousse s'accordent bien avec ceux obtenus par l'analyse durant la période de non-réceptivité de l'h?te, mais sont moins précis pour les autres stades de croissance. Un soleil brillant peut retarder ou arrêter les stades précoces de l'épidémie de mildiou, tandis que le champignonBotrytis cinerea peut combiner son action avec le champignon du mildiou pour accentuer une épidémie.

     

Simplified extraction method for ELISA and PCR detection of potato leafroll luteovirus primary infection in dormant potato tubers

This report describes a simple, rapid and inexpensive procedure for sampling large numbers of dormant tubers for analysis of potato leafroll luteovirus (PLRV) infection. The procedure uses a common electric drill to simultaneously remove and macerate tuber-eye samples for detection of PLRV by the enzyme-linked immunosorbant assay (ELISA) and the polymerase chain reaction (PCR). By using these sampling and analysis approaches, 19 of 20 different PLRV isolates were detected in dormant tubers from plants with primary infections. Results from the dormant tuber analysis, were verified by planting the tubers and testing leaf tissue by ELISA and PCR. Similar sampling and testing done on healthy dormant tubers and sprouts from the tubers consistently gave negative results as expected.     

Accumulation of protein,non-protein nitrogen and starch during tuber growth of three potato cultivars

The proportion of protein and non-protein nitrogen (NPN) in tuber dry matter decreases rapidly during the initial stages of tuber growth. Protein then stabilizes but NPN increases during the final stages of tuber growth. The percentage of starch in the dry matter increases rapidly during early tuber growth and then either stabilizes or increases at a slower rate. Protein and starch are accumulated at constant rates with respect to tuber growth and the relative amount of protein or starch in the tuber is logarithmically related to tuber size. During tuber growth some protein molecular weight classes increase in concentration while others decrease. We propose a model, based on the growth of storage parenchyma, to explain the data.     

A new procedure for the mass extraction and collection of potato glycoalkaloids

A methodology for the collection of large volumes of potato glycoalkaloids from potato blossoms has been developed for use in preparative work. This new modification shortens and simplifies the laborious proceduresutilized heretofore and should prove a valuable aid for those requiring multiple gram quantities of pure glycoalkaloids for use in further research.