Potato Type Research Articles

Prediction of Sorptional Equilibrium Data for Starch‐Containing Foodstuffs

ABSTRACTWater accounting in a foodstuff can be done using water chemical potential to describe the equilibrium. Inspection of the structure of typical potato tissue leads to recognition of its intervening phases. Considering the chemical potential of water at each phase the corresponding amount of water can be predicted. Using these expressions and typical composition, the equilibrium water content of the foodstuff can be predicted with good agreement with experimental data. A number of correlations have been studied, concluding that the approach presented is the only one providing a good representation in the entire range of moisture contents. The method is extended to beans, white rice, peas and corn.

Potato freezing injury and survival, and their relationships to other stress

Breeding and selection for frost resistant potatoes with high yield and good quality is very promising. This has been demonstrated in a frost resistance breeding program conducted at the International Potato Center, Lima, Peru. Yield trials were conducted using selected frost resistant clones at various Andean locations at elevations from 3,200 to 3,900 meters (14). During the growth season, several hail storms and frosts occurred at these locations. These freezes (−3°C to −4°C) were very useful in elimination of the undesirable clones under natural conditions. Clones with yield from 1 to 2 kg/plant have been selected. A yield of 1 to 2 kg/plant was superior to most common cultivars grown in the Andes. The difference in frost resistance between a resistant and sensitive type of potato is about 3 to 4°C.Solanum tuberosum is a sensitive type which, in most cases, can survive at about −2.0°C. Evidence indicates that the difference in resistance to freezing injury is due to the genotype’s capability to tolerate freeze-induced dehydration and to withstand the aggregation of proteins under freezing stress. It is likely that freezing injury is caused primarily by the loss of membrane integrity and, therefore, that membrane thermal stability is paramount in the tolerance to freezing stress.

A comparison of DNA base compositions among anastomosis groups in Rhizoctonia solani Kuehn.

Base composition of DNAs of 30 isolates of Rhizoctonia solani Kuhn was compared. The relationships between the base composition of DNA and each anastomosis group or cultural type were investigated. The range of guanine plus cytosine (GC) content of R. solani DNA was 40.9 to 49.3 mole%, and its average was 45.3 mole%. The GC contents of the isolates within each anastomosis group were almost same. Little difference of GC content was observed between the sasakii type (IA) and the web-blight type (IB) in AG-1. Furthermore GC contents of the rush type (IIIB) and the root rot type (IV) in AG-2-2, were quite similar. While a significant difference was observed between the potato type (IV) in AG-3 and the root rot type (IV). AG-1 showed the highest GC content (avg. 48.8 mole%) among all of the anastomosis groups, followed by AG-4 (avg. 47.3 mole%), AG-3 (avg. 47.1 mole%), AG-5 (avg. 45.2mole%), AG-2-2 (avg. 44.6 mole%), AG-2-1 (avg. 43.7 mole%), AG-6 (avg. 41.8 mole%) and AG-BI (avg. 41.4 mole%). These results suggest that each anastomosis group must be regarded as a genetically independent unit.

Specificity in vitamin requirement among anastomosis groups of Rhizoctonia solani Kuehn.

The influence of vitamins on the growth of hyphal anastomosis groups of Rhizoctonia solani Kuhn, AG-1 (IA, sasakii type), AG-1 (IB, web-blight type), AG-2-1 (winter crop type), AG-2-2 (IIIB, rush type), AG-2-2 (IV, root rot type), AG-3 (potato type), AG-4 (praticola type), and AG-5, were studied. All isolates of AG-2-2 (IIIB), AG-2-2 (IV), and AG-5 barely grew in the medium without thiamine hydrochloride, and showed 10∼20-fold growth at 10-5M thiamine, i.e. these groups are thiamine auxotrophic. The stimulating effect of thiamine was slight at 10-10M and obvious at 10-9M, and the mycelial dry weights at 10-8 or 10-7M were almost the same at 10-5M. The need for thiamine is a specific character of the group, not of the isolate. Most of AG-2-1, AG-2-2 (IIIB), AG-2-2 (IV) and AG-5 isolates had their growth somewhat stimulated with 10-5M of calcium pantothenate, but were not auxotrophic. There were two isolates of AG-2-1 that might be Ca-pantothenate auxotrophic. Some isolates had stimulated their growth with biotin, folic acid, p-aminobenzoic acid, inositol, nicotinic acid, pyridoxine hydrochloride, and riboflavin, but were not auxotrophic. The need for these vitamins is a character of the isolate, not of the group.

Potato processing in the central highlands of Peru

The processing of food products is an important economic activity of rural households in the Andean Highlands of Perú. Potatoes are processed into several dehydrated products the most common of which are chuño and papa seca. Chuño is a freezedried product made principally from bitter types of potatoes (Solarium juzepczukii and S. curtilobum) while papa seca is made from common varieties. This article describes how these and other products are made and their role within the Peruvian diet.

Freezing Injury in Potato Leaves

Time-temperature profiles of freezing leaves from frost-resistant (Solanum acaule Bitt.) and frost-susceptible (Solanum tuberosum L. subsp. tuberosum Hawkes) types of potatoes did not reveal any major differences. The pattern of change in resistance of leaves to low voltage, low frequency current during freezing was different in the frost-resistant and susceptible leaves. In tissue sections from both types of leaves, cells freeze extracellularly at cooling velocities lower than 5 C per minute. Cells from leaves of resistant plants showed a higher osmotic pressure but not a higher water permeability than those from susceptible plants. The extent of injury caused by even very slow freezing was greater than that caused by equivalent isopiestic desiccation, particularly in susceptible leaves. The higher osmotic pressure in cells of leaves from resistant plants can account for the greater desiccation resistance but not for the frost resistance observed.

Resistance in wild species of potato to populations ofHeterodera rostochiensis Woll. from West Germany

Ten different types of wild potatoes from South America were tested for resistance against 3 populations ofHeterodera rostochiensis from West Germany. The results of the pot trials showed that 2 species were completely resistant to all three populations. A varying degree of resistance was observed in other wild potatoes. Differences in the activity of root diffusates from South American wild potatoes were observed. There was no correlation between the degree of resistance and the activity of root diffusates. A high activity was observed for the first time in root diffusates fromS. vernei. The South American wild potatoes suitable for breeding for resistance have been discussed.

CADMIUM POLLUTION OF SOME VEGETAL PRODUCTS FROM BRASOV AND DAMBOVITA COUNTY

Contamination with heavy metals is an important aspect in the continuous effort to maintain food safety. One of the metals with great toxicity is cadmium. Cadmium is a potential environmental hazard. Cadmium is considered as being a carcinogenetic compound and its chronically ingestion can modify the structure and function of kidneys, of the reproductive system and of bones. In the present paper, as part of a wider study regarding cadmium pollution in Romania, we followed the level of cadmium in vegetal origin foods from Brasov and Dambovita counties. We analyzed the content of cadmium using the atomic absorption spectrometry, in samples randomly collected from shops, markets, or individual households. We analyzed 9 types of fruit and vegetables (3 types of leafs, 3 types of fruitvegetables, potatoes, carrots and fruits cherries, apricots, peaches, prunes). We considered the European Committee regulation number 466/2001 for the maximum allowed limit (MAL) of cadmium in foods. From all, the following products had the medium level over the maximum admitted values: lettuce, spinach, eggplants, green beans, peppers, carrots, fresh fruits. The number of samples having a greater level of cadmium, compared with the maximum admitted values, among all the analyzed samples for every type of food, was situated between 10 and 99%. The highest level of cadmium load was found in lettuce, spinach and carrots, for the samples of both counties. The chemical pollution with cadmium of foods is a real fact in our country and has different ways of manifestations and different degrees of intensity, in relation with the group of aliments, the cultivation method, the geographical area, the harvesting period, the processing methods, the storage, etc. Measures to lower the cadmium level in foods have to be taken, because of the high toxicity of the contaminant.

A Seasonal Potato Market: Area of Competitive Behavior

POTATOES are not a homogeneous product. On the production side, grower groups tend to select products with characteristics that give consumers an acceptable range of choices. On the demand side, discriminating housewives interested in getting better foods select types of potatoes best suited for various purposes and food likes. It is postulated that consumers regard different types of potatoes as differentiated products, and regard each as possible substitutes.' If product differentiation in potatoes satisfies consumers' range of tastes and preferences and encourages premium prices for preferred products, the industry gains by supplying the choices that consumers like best. Various aspects of competitive behavior and substitution in demand can be analyzed by considering a seasonal potato market that involves merchandising of two or more different types of potatoes. What is the competitive behavior and substitutability between early seasonal potatoes and fall (storage) potatoes? Do competitive relationships between early seasonal and storage potatoes support an assumption of product differentiation? This study discusses these questions and analyzes statistically a relevant measure of substitution in demand.

Field experiments on the magnesium requirement of potatoes in Great Britain

1. During the years 1954–57 thirty field experiments were carried out on the magnesium requirement of main crop potatoes; eighteen covered a range of typical potato soils while the remainder were sited on sands and loams. In nine of the experiments the effect of heavy applications of potash on magnesium requirements was also investigated.2. Magnesium application to the seed-bed as kieserite raised yield in four of the experiments; the largest yield increase was 2·15 ton/acre of tubers from 45·lb./acre of MgO. Apart from these four experiments there was also a small mean increase in yield over all the remaining sites.3. Application of a very high rate of potash depressed yield compared with a normal rate, but only in one experiment could this be attributed to induced magnesium deficiency, and there was no indication of such an effect in the average results.

Studies on the physiological specialization of Phytophthora infestans on tomatoes

1. The isolates of Phytophthora infestans, twenty-seven from potatoes and forty-one from tomatoes, were obtained from different localities of eleven prefectures in Japan. These isolates were used for inoculation upon the seedlings of Irish Cobbler (Danshaku) potato and Ponderosa tomato. All isolates caused severe infection on potato seedings but on tomato caused different severities of infection. According to the relative strength of pathogenicity to tomato seedlings, these isolates were classified into three different groups. ‘Potato-type’ was lowp athogenic, ‘intermediate-type’ was moderately pathogenic and ‘tomato-type’ was highly pathogenic on tomato seedlings.2. Of the potato isolates, seventeen isolates (60.0%) belonged to potato-type, five (18.5%) to intermediate type and four (14.8%) to tomato-type. Among the tomato isolates twenty-eight (68.3%) were tomato-type and eight (19.5%) were intermediate type.3. Many potato isolates were collected from Shizuoka and Shimizu cities, in May and June from the year 1959 to 1961. The frequency of three types in these isolates were examined. All of fifty-one isolates collected in 1959 were potato type and thirty isolates in 1960 were identified as intermediate-type (4 isolates) and potato-type (26 isolates). Among one hundred and fifty-two isolates collected in 1961, five were tomato-type, six were intermediate-type and others were potato-type.4. In serial passage experiments of the potato-type and intermediate-type through tomato foliage, it was found that the intermediate-type had acquired the virulence equivalent to the tomato-type after ten passages, but the potato-type had declined after four passages.

Microscopia electrônica de estirpes do vírus Y da batatinha que ocorrem em São Paulo

Sete estirpes do vírus Y da batatinha que ocorrem no Estado de São Paulo, assim, consideradas em vista de suas características, além da estirpe típica, foram examinadas ao microscópio electrônico, preparadas pelo método do exsudato ou do "dipping"'. Em tôdas as preparações foram encontradas partículas alongadas e flexíveis, cujos comprimentos normais não variavam significantemente entre si, correspondendo ao CN já descrito para êste vírus. Entretanto, notou-se tendência de uma das estirpes ser preferencialmente mais curta e duas outras serem mais longas que o valor médio, que talvez possa ter correlação com seus comportamentos biológicos. Esta semelhança morfológica é considerada mais uma evidência em favor da hipótese de que essas estirpes possuem realmente relações de parentesco.

Veränderungen bei der Stärke und anderen Kohlenhydraten durch thermische Einflüsse

ZusammenfassungDie vorliegende Arbeit berichtet über die Veränderungen der Kohlenhydrate von Kartoffeln bei der Herstellung von Trockenprodukten. Bei allen untersuchten deutschen Kartoffelsorten und auch bei den aus ihnen hergestellten Trockenprodukten konnten Saccharose, Glucose und Fructose nachgewiesen werden. Xylose, die eine schnelle Verfärbung der Trockenprodukte bewirken soll, war nicht vorhanden. Der Gehalt an reduzierenden Zuckern schwankt in Frischkartoffeln zwischen 1,0% und 4,7% i. Tr und in Trockenprodukten zwischen 1,7 % und 2,9% i.Tr. Nach Untersuchungen amerikanischer Forscher sollen Kartoffeltrocknungserzeugnisse mit einem Wassergehalt von 6% nicht mehr als 2,7% reduzierende Zucker enthalten. Diese Voraussetzung ist mit Ausnahme einer Probe bei allen untersuchten Trockenprodukten erfüllt. Eine elektrophoretische Auftrennung der Stärke in ihre Bestandteile Amylose und Amylopektin war mit Boratpuffer (pH = 10) und bei einer Spannung von 1900 V nur bei der Verwendung von löslicher Stärke möglich, da weder Kartoffelstärke noch Weizenstärke in Boratpuffer in Lösung zu bringen war. Auch durch Herstellung eines Stärkeglykolats konnte keine Auftrennung in Amylose‐ und Amylopektinglykolat erreicht werden. Bei der Auftrennung der Stärkebestandteile an einer sauren‐basischen Aluminiumoxydsäule konnte bei der Untersuchung von thermisch behandelter Stärke aus Kartoffelpulver eine Aufspaltung der höhermolekularen Amylopektinbestandteile festgestellt werden. Diese Aufspaltung setzt bei der Herstellung der Trockenprodukte schon beim Dämpfprozeß ein. Der Durchschnittspolymerisationsgrad von Kartoffeltrocknungsprodukten liegt zwischen 138 und 170 Anhydroglucose‐Einheiten. Für reine Amylopektinstärke wurden 2000, für eine Maisstärke mit 50% Amylose 214 und für eine selbst hergestellte Kartoffelstärke 1250 Anhydroglucose‐Einheiten ermittelt. Die Veränderung der Stärke und der anderen höhermolekularen Kohlenhydratbestandteile bei der Herstellung von Trockenprodukten findet nicht durch Hitzeeinwirkung beim Trocknungsprozeß, sondern schon beim Dämpfprozeß statt. Der niedrige Polymerisationsgrad ist nicht nur auf Abbauvorgänge im Stärkemolekül (Depolymerisation der Amylopektinmoleküle) sondern in geringem Umfang auch auf die Miterfassung von niedermolekularen Polysacchariden, die als Bestandteile des Kartoffelfruchtfleisches vorkommen, zurückzuführen. Der Amylosegehalt der untersuchten Trockenprodukte schwankt zwischen 23,0% und 29,5%. Der unterschiedliche Amylosegehalt ist in erster Linie durch die Verwendung verschiedener Kartoffelsorten bedingt. Nach dem Dämpfen unter einem Druck von ½ atü und einem Druck von 1 atü ist eine geringfügige Abnahme des Amylosegehaltes zu beobachten. Eine Depolymerisation des Amylopektins läßt sich mit dieser Methode nicht nachweisen.

The potato industry in Denmark

Denmark grows a considerale amount of potatoes. The potatoes are grown on medium sized or small dairy farms in the sandy parts of Denmark where potato growing is more profitable than growing of most other crops. The Danish climate is, generally speaking, well adapted to potato growing. Two distinct types of potatoes are grown, namely table potatoes and industrial potatoes. Denmark usually exports large amounts of seed and table potatoes. One disadvantage is a thin coating on the tubers of a fine dark humus which is hard to get off. Large amounts of potatoes are used for processing, mainly starch, but also for alcohol, potato granules, chips and sticks.

A simple method for the preparation of crystalline potato phosphorylase and Q-enzyme.

IN the purification of potato phosphorylase1 by ethanol precipitation2, it has been found that conditions established for a particular variety of potato, harvested at a particular time of the year, are not generally applicable to other potatoes, even though these may contain as much enzyme. This is because the solubility of the enzyme is affected by its association with other constituents, the nature and quantity of which vary with the type of potato and the season. Since, in spite of this association, the enzyme is always able to react with its substrate, it was thought that the formation of the enzyme substrate complex might be utilized to free the enzyme from these other complexing molecules. Preliminary experiments in which the precipitation of phosphorylase was carried out in the presence of glucose-1-phosphate did not, however, show any appreciable change in the solubility of the enzyme. These experiments were not pursued further after it had been found that the presence of the co-substrate, amylose, results in a strong and selective precipitation of phosphorylase at a concentration of ethanol at which the enzyme is otherwise soluble2, and in at least a thousandfold purification of the enzyme with respect to protein. The phosphorylase is accompanied in the precipitate by the Q-enzyme of the potato3. The enzymes are readily extracted from the precipitate and can then be precipitated from solution with ammonium sulphate in crystalline form.

Spotted wilt of potato. I. The field disease and studies of the causal virus

The symptoms of spotted wilt on potato (variety Up to Date) are described in detail. The strain content of the field virus is analysed by inoculation to differential hosts, and by comparison with the symptoms produced by five purified virus strains. Potato is a selective host for the Ringspot strain. The virus affecting potato in the field lacks the Tip Blight strain and so differs in strain composition from the type commonly occurring in tomatoes. It is shown that the Tip Blight strain is unable to become systemic in potato, but that it is not a filtering action by potato that gives rise to the abbreviated complex lacking the Tip Blight strain. There is evidence of a synergism of strains of spotted-wilt virus since although the Mild and Very Mild strains are present in the naturally occurring potato virus together with the dominant Ringspot strain, they are unable to invade potato when in pure form. It is suggested that the virus affecting potato in the field be designated "potato type spotted wilt" to differentiate it from the type containing Tip Blight strain.

Disinfection of a new stationary-type seed-potato cutter to control the spread of ring rot

The tension blade, an improved type of the stationary double-edged potato cutting knife, is described.

On the potato wilt disease

The Fusarium wilt disease of potatoes is prevalent in certain districts of Hokkaido and causes severe damage on the crop in recent years. The author described the symptoms in full and isolated 3 species of Fusaria from the affected potato plants, namely Fusarium oxysporum SCHLECHT. f. 1 WR., a variety of Fusarium Solani APP. et WR., and Fusarium avenaceum SACC. Among these Fusaria, Fusarium oxysporum SBHL. f. 1 WR. and a variety of Fusarium solani APP. et WR. were pathogenic and they caused typical potato wilt in infection experiments. The variety of F. solani was markedly virulent. The toxicity of fungus filtrates was proved to cause the wilting of the cuttings of potato shoots by experiments. Fusarium avenaceum, however, seems to cause only the rottings of stored potatoes and not the wilting in the field. (Jan., 1948)