Mary V. Zaehringer

Potato extractives: Sloughing as related to replacement of anions or cations

All anions or cations were removed from potato extract and were replaced by a single, naturally occurring anion or cation in an effort to determine the relative effect of each on the sloughing of potato tissue. The treated extracts were used in cooking soaked potato tissue slices. In the anion series, citrate caused the greatest amount of sloughing. Other cooking media and treatments in decreasing order of effectiveness were untreated extract, malate, oxalate, chloride, and distilled water. In the cation series, sodium and potassium caused significantly more sloughing than the untreated extract. Magnesium and calcium firmed the potato tissue, resulting in less sloughing than that obtained with distilled water.

Potato extractives and the sloughing of potato tissue

SummaryPotato tissue extracts differed in their ability to cause sloughing of soaked potato tissue slices. Extracts from the bud half of the tuber caused greater sloughing than those from the stem half. Extracts from inner and outer tissue of the tuber were equally effective. Extracts from potatoes stored at 38 F generally caused more sloughing than extracts from potatoes stored at 38 F and conditioned for 1 week at 70–75 F, or from potatoes stored at 45 F or 52 F.Freshly prepared extracts were most effective in causing sloughing. When held at 0 F, their stability was maintained for extended periods. The extractives responsible for sloughing were readily soluble in water, slightly less soluble in alcohol, and insoluble in acetone. Steaming, blanching, or boiling potato tissue slices increased the sloughing properties of the extracts prepared from them.Potato tissue extracts passed through anion-cation exchange resins lost their ability to cause sloughing, showing that the components associated with sloughing are ionized compounds.ResumenExtractos de tejido de papa tenían diferente habilidad de producir la disgregación de rebanadas de papa inmersas en ellos. Extractos obtenidos de la mitad brotadora del tubérculo produjeron mayor disgregación que los obtenidos de la mitad tallar. Extractos de tejidos internos y externos fueron efectivos de igual manera. Extractos obtenidos de papas almacenadas a 38 F generalmente produjeron más disgregación que los obtenidos de papas almacenadas a 38 F y acondicionadas por una semana a 70–75 F o de papas almacenadas a 45 F o 52 F.Extractos recién preparados fueron más efectivos en la producción de disgregación. Cuando se mantuvieron a 0 F, su estabilidad se mantuvo por mucho tiempo. Extractos que causan disgregación se disuelven facilmente en agua, son un poco menos solubles en alcohol e insolubles en acetona. Poniendo, blanqueando o hierviendo cortes de tejidos de papa incrementó las propiedades disgregadoras de los extractos preparados de ellos.Extractos de papa pasados por resinas de cambio de anion-cation perdieron la habilidad de producir disgregación, dando así a entender que los componentes causantes de disgregación son compuestos ionizados.

Sugar content and color of Russet Burbank potatoes as related to storage temperature and sprout inhibitors

SummaryReducing and total sugar assays and cooked flesh color measurements were made on Idaho-grown Russet Burbank potatoes at monthly intervals during 12 months of storage. The six storage treatments included untreated tubers stored at 38 F, 45 F, and 52 F; untreated tubers stored at 38 F followed by one week of conditioning at room temperature; tubers treated with MH-30 stored at 45 F; and tubers treated with CIPC stored at 45 F.The tubers stored at 45 F contained significantly less reducing and total sugars and were significantly lighter in color than those stored at 38 F. Tubers stored at 45 F were comparable to those stored at 52 F in sugar content and color and had a longer storage life. Treatment with MH-30 or CIPC had no effect on sugar accumulation and no important effect on color.Conditioning potatoes from storage at 38 F for one week at room temperature significantly decreased the contents of total and reducing sugars, although they remained significantly higher than those of tubers stored at 45 F. Conditioning did not reverse the yellow color which had developed during 38 F storage.ResumenSe efectuaron determinaciones de azucares totales y reductores así como estimaciones de color de pulpa cocida a intervalos mensuales, durante un período de 12 meses de almacenaje, en tubérculos de papa de la variedad Russet Burbank, cosechados en Idaho.Los six tratamientos de almacenaje incluian tubérculos sin tratar almacenados a 38, 45 y 52 F; tubérculos sin tratar almacenados a 38 F seguido por una semana de acondicionamiento a temperatura ambiente; tubérculos tratados con MH-30 almacenados a 45 F; y tubérculos tratados con CIPC almacenados a 45 F.Los tubérculos almacenados a 45 F contuvieron menos azucares totales y reductores y eran de un color mas ligero que aquellos almacenados a 38 F. Las diferencias fueron significativas en ambos casos.Los tubérculos almacenados a 45 F tuvieron un contenido de azucares y color comparable a aquellos almacenados a 55 F, además exibieron una capacidad de almacenaje mas larga.Los tratamientos con MH-30 o CIPC no tuvieron efecto sobre la acumulación de azucares o en la coloración de los tubérculos.Acondicionando los tubérculos por una semana a temperatura ambiente después de estar almacenados a 38 F, disminuyó significativamente el contenido de azucares totales y reductores. El contenido de estos azucares, sin embargo, se mantuvo significativamente mas alto que en aquellos tubérculos almacenados a 45 F.Tubérculos almacenados a 38 F exibieron un color amarillo el cual no fue trastrocado por medio del acondicionamiento a temperatura ambiente.

Observations on the decrease in sloughing of potato tissue slices on soaking in distilled water

SummaryThin slices of potato tissue were soaked in distilled water under various conditions of time, temperature, and volume of water. In one group of studies, the potato slices were drained and cooked in distilled water. In a second group of studies, the soak water from the potato tissue slices obtained under the various conditions was used as part of the water for cooking soaked and unsoaked potato tissue slices. The amount of tissue which did not disintegrate was weighed directly and was reported as the cooked potato weight (CPW). The CPW is inversely related to the amount of sloughing.The sloughing of soaked potatoes cooked in distilled water decreased directly with length of soak period, temperature during soaking, and volume of water used in soaking.Using soak water as part of the cooking water increased sloughing in both soaked and unsoaked potato tissue slices. The effectiveness of the soak water in causing sloughing increased with increase in length of soak period, in temperature during soaking, in amount of surface area exposed during soaking, and with increase in the ratio of soak water to distilled water for cooking. The increase in sloughing was greater for soaked potato tissue than for unsoaked tissue.Soak water prepared from potatoes of high specific gravity was more effective than soak water from potatoes of low specific gravity in causing sloughing.

Evaluation of Methods for Measuring Texture Using Fresh Apples as the Test Material

Abstract Two laboratories used three varieties of apples as materials for standardizing and correlating various physical, chemical and sensory evaluations of texture. The criteria used to evaluate the appropriateness of the objective methods were: Sensitivity to differences in texture. Relationship to sensory assessments. Agreement between laboratories. The effectiveness of the methods in detecting differences in texture due to the variety and storage conditions was remarkably similar in the two laboratories. For most of the methods, the relative standard deviation was 11% or less. Correlations among the various pairs of methods differed with variety and with the basis used to calculate the correlation coefficients. The two laboratories agreed substantially on the presence or absence of significance with respect to relationships between pairs of methods. The most appropriate objective measurement for evaluating texture appeared to be maximum force. The possibility of using specific gravity as a non-destructive method of measuring texture is suggested.

Leaching of solutes and sloughing of potato tuber tissue

Thin slices of tissue from low (1.075–1.078 and high (1.092–1.094) specific gravity tubers were soaked in distilled water (100g/250ml) for 0, 1, 2, 3, 4, and 6 hours. Following the soak periods, the soak water and remaining tissues were separated and analyzed. Analyses of the soak water included pH, electrical conductivity, total solids, K, P and citric acid. The tissue analyses included total ash, alkalinity of ash, Ca, Mg, total N and phytate P. Other tissue samples were soaked the same periods of time and used to evaluate the amount of sloughing that occurred during cooking.All constituents studied diffused into the water during the soak periods. The greatest loss from the slices occurred in the first 2 to 3 hours and were similar for both specific gravity groups. After 6 hours the average amounts of material in the soak water were: total solids — 23%, P — 68%, phytate P —55%, K — 71%, total ash — 62%, total nitrogen — 56%, Ca — 35% and Mg —50%. Citric acid diffused into the soak water during the first 3 hours and the amount in the water then decreased. This apparent change may be due to metabolism of the acid. The sloughing of tissue decreased with the length of the soak period. The decrease in sloughing was highly correlated (P<1 %) with the length of the soak period, increases in electrical conductivity of the soak water, and with the leaching of all constituents measured.

Measurement of color in potatoes

Reproducible, objective methods which conformed closely to visual appraisal were developed for measuring color differences in either cooked or raw potatoes. Experimental samples, selected from lots stored at various temperatures for different periods of time, differed in extent of graying and yellowing.Ricing was found to be preferable to mashing as a method of cooked sample preparation. A comparison of methods of sample presentation using the Gardner Color Difference Meter showed thin-layer measurement was most successful in separating cooked samples differing in amount of yellow pigment; deep-layer measurement was most successful in separating grayed samples. A simple method for measurement of color differences in raw tubers successfully separated the samples. All three methods of sample presentation were significantly correlated with visual ranking.ResumenMátodos objectivos y reproducibles, que concordaron estrechamente con la evaluación visual, se desarrollaron para medir diferencias de color en paapas y crudas. Muestras experimentales, seleccionadas de lotes almacenados a varias temperaturas y a diferentes periodos de tiempo, mostraron diferentes grados de coloración gris y amarillo.Se encontró que “ricing” as preferible en lugar de amasado como método de preparación de muestras cocidas. La comparación de métodos dep resentación de muestras usando el “Gardner Color Difference Meter” mostró que el método de medición de capas finas fue el mas satisfactorio en la preparacion de muestras cocidas que difieren en cantidad de pigmento amarillo; la medición de capas profundas fue la mas satisfactoria en la separación de muestras grises. Un método sencillo para medir las diferencias de color en tubérculos crudos separó satisfactoriamente las muestras. Los tres métodos de presentación de muestras fueron significativamente correlacionados con la clasificación visual.

Storage temperature for maintenance of internal quality in Idaho Russet Burbank potatoes

Idaho-grown Russet Burbank potatoes treated with a sprout inhibitor were stored at 42 F, 45 F, and 48 F for 11 months. Monthly quality evaluations showed that tubers stored at 42 F were less mealy, contained more reducing sugars, and were yellower in color than those stored at 45 F or 48 F. The latter two treatments were not significantly different in mealiness and were generally similar in yellowness of color. Tubers stored at 48 F had less reducing sugars than those stored at 45 F. Although all treatments resulted in a gradual darkening of the potatoes during storage, differences in grayness among the three storage treatments were minor from a practical standpoint. It is suggested that a storage temperature no lower than 45 F be used to maintain the internal quality of Russet Burbank potatoes.

Internal quality of Russet Burbank potatoes following chilling

Russet Burbank potatoes were chilled at 25 F (−3.8 C), 27.5 F (−2.5 C), or 30 F (−1.1 C) for various periods of time and were then held at 45 F (7.2 C) for one or four weeks before testing. Susceptibility to injury was quite variable between the two crops and among tubers of the same lot exposed to the same treatment. The greatest amount of low temperature breakdown occurred in tubers chilled at 27.5 F (−2.5 C) for 10 hours. Flesh color, reducing sugar content, mealiness, and amount of sloughing in tubers that survived chilling were not markedly different from those in control samples although certain trends were observed indicating that the quality of chilled tubers was beginning to deteriorate. Chilling increased yellowness of flesh color in most treatments and darkness in several. Chilled tubers had a reducing sugar content slightly to moderately higher than the controls. They sloughed less than the controls and tended to be less mealyResumenPlantas de papa de la variedad Russet Burbank fueron congelados a temperaturas de 25°F (−3.8°C), 27.5°F (−2.5°C) o 30°F (−1.1°C) por varios períodos y luego mantenidos a 45°F (7.2°C) por una a cuatro semanas antes de analizarlas. La suseptibilidad del daño fue bastante variable entre los dos cultivos y entre tubérculos del mismo lote expuestos al mismo tratamiento. La mayor descomposición debida a bajas temperaturas ocurrió en tubérculos sometidos a congelamiento de 27.5°F (−2.5°C) por 10 horas. El color del tubérculo, el contenido de azúcares reductores, harinosidad y la abertura de la capa superficial de tejido en tubérculos que sobrevivieron al congelamiento no fueron marcadamente diferentes de aquellos: de las muestras de control si bien ciertas tendencias fueron observadas indicando que la calidad de los tubérculos congelados estaba empezando a deteriorarse. El congelamiento incrementó el color amarillento del tubérculo en la mayoría de los tratamientos y la oscuridad en varios de ellos. Los tubérculos congelados tuvieron un contenido de azúcares reductores ligera a moderadamente más alto que los controles, la capa superficial se abrió menos y tendieron a ser menos harinosas

Quality of baked potatoes as influenced by baking and holding methods

Russet Burbank potatoes baked with and without wrapping were held at different temperatures to determine the effect of the procedures on cooking quality. Unwrapped and foil-wrapped tubers did not differ in mealiness, color, and extent of off-flavor devlopment when judged at the time of doneness.A holding period of 1 hr for both treatments resulted in a marked deterioration of quality that progressed during a second hour of holding. Unwrapped potatoes showed greater textural impairment after holding and were significantly cooler than foil-wrapped potatoes treated in the same manner. Although foil-wrapped potatoes remained hot during the holding period, low mealiness scores, off-flavors, and discoloration showed they were substandard in quality.Quality deterioration was minimized when pierced foil or a paper bag was used as wrapping during baking and holding, but the serving temperature was low for the paper-wrapped tubers. If baked potatoes must be held before serving, it is recommended that they be wrapped in pierced foil prior to baking and that they be held at 200 F for as short a time as possible.