Alfred A. Bushway

High-performance liquid chromatographic separation of potato glycoalkaloids

Separations of three glycoalkaloids (a-chaconine, β-chaconine, and a-solanine) have been achieved by using three different columns: μBondapak C18, μBondapak NH2, and a carbohydrate analysis column. These methods have been employed to examine the purity of the potato glycoalkaloids isolated by thin-layer and column chromatographic separations. Also, samples of tubers, peels, blossoms, and sprouts have been analyzed to determine their content of a-chaconine, β-chaconine, and a-solanine by using the carbohydrate and μBondapak NH2 columns.

The nutrient composition of an insect flour sample from Lake Victoria, Uganda☆

Abstract The nutrient composition of a flour prepared from three genera of dried aquatic insects (Chironomidae, Chaoborus, and Povilla) harvested from the islands and shores of Lake Victoria, Uganda, was determined. The insect flour contained 67 g/100 g crude protein, 6.7 g/100 g crude fiber, 9.8 g/100 g moisture, 4.2 g/100 g fat and 11.6 g/100 g ash. This flour was an excellent source of phosphorus (1.1 g/100 g), zinc (13.1 mg/100 g), iron (1.3 g/100 g), and magnesium (169 mg/100 g) and had a potassium (997 mg/100 g) to sodium (390 mg/100 g) ratio of 2.6:1.0. A 100-g portion of the insect flour would provide over 100% of the FAO recommended intake of nutrients for niacin (26 mg), thiamin (1.6 mg), and riboflavin (8.0 mg) based on a 65 kg moderately active adult male. An amino acid profile revealed cysteine to be the limiting amino acid. The estimated in vitro digestibility of the protein from the insect flour was 91% with a discriminant computed protein efficiency ratio (DC-PER) of 2.1.

Determination of total glycoalkaloids in potato tubers using a modified titration method

A new method for determining total glycoalkaloid content of potatoes (TGA) was developed by extensively modifying the comprehensive titration procedure of Fitzpatrick and Osman (1). This modified titration method eliminates the need to hydrolyze the glycoalkaloids and to purify the resulting aglycones by partitioning them into an organic solvent such as benzene or methylene chloride. Instead the glycoalkaloids are precipitated using ammonium hydroxide with the precipitate being dissolved in a tetrahydrofuran-water-acetonitrile (50:30:20) mixture. An aliquot is evaporated and quantitated using the nonaqueous titration procedure developed by Fitzpatrick and Osman (1). A comparison between this modified method and a high-performance liquid Chromatographic (HPLC) procedure was made using three commercial potato varieties and five experimental selections. Results from the two methods compared favorably.ResumenUn nuevo método para determinar contendo total de glicoalcaloides en papas (TGA) fué desarrollado modificando extensamente el procedimiento de titulación de Fitzpatrick y Osman. Este método modificado elimina la necesidad de hidrolizar los glicoalcaloides y de purificar los aglicones resultantes separándolos en un solvente orgánico como benceno o cloruro de metileno. En su lugar, los glicoalcaloides fueron precipitados usando hidróxido de amino, siendo el precipitado disuelto en una mexcla 50:30:20 de tetrahidrofuran — agua y acetonitrilo. Una alicuota fué evaporada, y cuantificada usando el procedimiento de titulación orgánica desarrollado por Fitzpatrick y Osman (1). Un comparativo entre este método modificado y un procedimiento de Cromatografía Líquida de Alta Eficacia (HPLC) fué hecho, utilizando tres variedades comerciales de papa y 5 selecciones experimentales. Los resultados de los métodos compararon favorablemente.

Effects of Alternative Postharvest Treatments on the Microbiological Quality of Lowbush Blueberries

Abstract The applicability of commonly used postharvest treatments to control produce decay is often limited by toxicity regulations and residual by-product accumulation. Chlorine is the most widely used sanitizer in the produce industry for improving microbial quality and extending shelf-life of most minimally processed fruits and vegetables. Although effective, recent environmental and public health concerns associated with the use of chlorine have stimulated the produce industry to identify alternative treatments equivalent to chlorine in antimicrobial effectiveness. This study compared the effectiveness of alternative post-harvest treatments, hydrogen peroxide and citric acid, to the current industry standard, chlorine, in improving the microbiological quality of lowbush blueberries. Significant differences (p < 0.05) in antimicrobial effectiveness existed among treatments allowed the same contact time. Samples treated with 100 ppm chlorine resulted in the greatest microbial reduction in total aerobes, yeast, and mold counts compared to samples treated with 0.5% hydrogen peroxide, 0.5% citric acid, or distilled water; however, chlorine was second in antimicrobial effectiveness when a 1% hydrogen peroxide treatment was administered. Overall, samples treated with 1% hydrogen peroxide for 120 seconds resulted in population reductions two times greater than reductions observed on samples treated with 100 ppm chlorine. Results indicate postharvest treatments of 1% hydrogen peroxide are an effective alternative to chlorine for improving the microbiological quality and safety of lowbush blueberries during processing without compromising blueberry color.

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.ResumenSe desarrolló un nuevo procedimiento para extraer cantidades gramo de glicoalcaloides a partir de flores liofilizadas de papa. El porcentaje de recuperación es de 65–70%, lo que produce un producto mezclado de glicoalcaloide que contiene más de 90% de glicoalcaloides. Este método es muy simple y rápido y se termina en sólo dos días. Este nuevo método será muy útil en la investigación entomológica y toxológica en que se utilizan grandes cantidades de estos glicoalcaloides.

Comparison of Sodium Acid Sulfate to Citric Acid to Inhibit Browning of Fresh‐Cut Potatoes

Sodium acid sulfate (SAS) dip treatments were evaluated against a distilled water control and citric acid (CA) to compare its effectiveness in reducing enzymatic browning of raw, French-fry cut potatoes. Two separate studies were conducted with dip concentrations ranging from 0%, 1%, and 3% in experiment 1 to 0%, 2%, and 2.5% in experiment 2 to determine optimal dip concentrations. Russet Burbank potatoes were peeled, sliced, and dipped for 1 min and stored at 3 °C. Color, texture, fry surface pH, and microbiological analyses were conducted on days 0, 7, and 14. The 3% SAS- and CA-treated samples had significantly (p<0.0001) lower pH levels on fry surfaces than all other treatments. Both acidulants had significantly (p≤0.05) lower aerobic plate counts compared to controls in both studies by day 7. However, SAS appeared to be the most effective at the 3% level in maintaining a light fry color up to day 14 and had the highest L-values than all other treatments. The 3% SAS-treated fry slices appeared to have the least change in textural properties over storage time, having a significantly (p=0.0002) higher force value (kg force [kgf]) than the other treatments during experiment 1, without any signs of case-hardening that appeared in the control and CA-treated samples. SAS was just as comparable to CA in reducing surface fry pH and also lowering microbial counts over storage time. According to the results, SAS may be another viable acidulant to be utilized in the fresh-cut fruit and vegetable industry.

Isolaton, partial purification and characterization of a potato peel glycoalkaloid glycosidase

The enzymes involved in the hydrolysis of the rhamnose moieties fromα-chaconine were isolated and partially purified by ammonium sulfate precipitation from the peels of Kennebec and Wauseon potatoes. Enzyme activity was found to be present in the 60 to 80% ammonium sulfate precipitate. Enzyme activity was increased by the use of non-ionic detergents with a mixture of Triton X-100:Triton CF-54 providing the greatest increase in activity. The pH and temperature optimums for the enzymes from both varieties were found to be 6.0 and 42 C, respectively. The route ofα-chaconine metabolism (either through B1-or B2-chaconine) was dependent upon incubation temperature. The effect of substrate concentration on enzyme activity was determined for both varieties and the Kms calculated from Lineweaver-Burke double reciprocal plots. The Km values for the Kennebec and Wauseon rhamnosidases were found to be 9.2×10−4 and 1.7×10−5M, respectively.CompendioLas enzimas que intervienen en la hidrólisis de las fracciones de ramnosa de laα-chaconina fueron aisladas y parcialmente purificadas por precipitación con sufato de amonio, a partir de cáscaras de papa de las variedades Kennebec y Wauseon. Se encontró presencia de actividad enzimática en la fracción saturada (0,6 a 0,8) de sulfato de amonio. La actividad enzimática se incrementó usando detergentes no iónicos con una mezcla de Triton X-100: Triton CF-54, que proporciona, el mayor incremento de la actividad. El óptimo de pH y temperatura para las enzimas de ambas variedades fué de 6,0 y 42 C respectivamente. La ruta del metabolismo de laα-chaconina (sea ésta a través de chaconina B1 ó B2) dependió de la temperatura de incubación. Se determinó) el efecto de la concentración del substrato sobre la actividad enzimática para ambas variedades y el Kms se calculó por la función recíproca doble Lineweaver-Burke. Se encontró que los valores Km para las ramnosidasas de Kennebec y Wauseon fueron de 9,2×10−4 y l,7×10−5M, respectivamente.

Isolation, partial purification and characterization of a potato peel ∞-solanine cleaving glycosidase

An enzyme which hydrolyzes the rhamnose from ∞-solanine was isolated and partially purified by ammonium sulfate precipitation from the peels of Kennebec and Wauseon potatoes. Enzyme activity was found to be present in the 60 to 80% ammonium sulfate fraction. Enzyme activity was increased by the use of non-ionic detergents with a mixture of Triton X-100:Triton CF-54 (2:1, w/w) providing the greatest increase in activity. The pH optimum for the rhamnosidase for both varieties was found to be 6.0 while of the temperatures evaluated 42 °C was the optimum temperature. The effect of substrate concentration on enzyme activity was determined for both varieties and the Vmax and Km were calculated from Lineweaver-Burke double reciprocal plots. The Vmax and Km for the Kennebec and Wauseon rhamnosidases were found to be 0.27 mg/ml and 5.4 x 10-4 M and 0.48 mg/ml and 8.2 x 10-4 M, respectively.CompendioSe aisló de la cáscara de papas Kennebec y Wauseon una enzima que hidroliza la ramnosa de laα-solanina y se le purificó parcialmente por precipitación con sulfato de amonio. Se encontró acrividad enzimática en la porción de 60 a 80% de sulfato de amonio. La actividad de la enzima se incrementó utilizando detergentes no iónicos; con una mezcla de Triton X-100: Triton CF-54 (2:1, w/w) se obtuvo el mayor incremento en la actividad. El pH óptimo para la ramnosidasa, para ambas variedades, fue 6.0, mientras que 42°C fue la temperatura óptima de todas las temperatures evaluadas. El efecto de la concentratión del sustrato en la actividad de la enzima fue determinado para ambas variedades y la Vmax y Km fueron calculadas de las parcelas Lineweaver-Burke de doble reciprocidad. La Vmax y Km para las ramnosidasas de Kennebec y Wauseon fueron 0.27 mg/cm3 y 5.4 x 10-4M, y 0.48 mg/cm3 y 8.2 x 10-4M, respectivamente.

A comparison of chemical and physical methods for treating French fries to produce an acceptable microwaved product

Frozen par-fries were processed in January and February using BelRus and Russet Burbank potatoes which were obtained from the same source and held under the same storage conditions. Prior to par-frying the raw potato slices were treated chemically or physically in order to increase the amount of bound water, or to remove water. At each processing date total solids of the raw and treated tissue were determined. Par-fries were analyzed for fat content. Treated samples were microwave heated and evaluated for sensory qualities as compared to frozen par-fries heated in a conventional oven.In no cases were the microwaved fries superior to the oven-heated fries in color, flavor, or texture. Drying the blanched fries in an oven for 10 min. prior to par-frying produced a microwaved product that was quite similar to the oven-heated fries, particularly in the case of the BelRus potatoes. In all cases BelRus potatoes absorbed less fat on par-frying than did Russet Burbank potatoes.ResumenEn enero y febrero se procesó papa prefrita y congelada utilizando las variedades BelRus y Russet Burbank provenientes de las mismas fuentes y conservadas en las mismas condiciones de almacenamiento. Antes de hacerse la fritura partial, los trozos de papa cruda fueron tratados química o físicamente para incrementar la cantidad de agua ligada o para extraer el agua. En cada fecha de procesamiento, se determinaron los sólidos totales del tejido crudo y del tratado. La papa prefrita fue analizada por su contenido de grasa. Las muestras de la papa tratada fueron calentadas por micro-ondas y evaluadas por sus calidades sensoriales en comparación con la papa prefrita y congelada calentada en un horno convencional.En ningún caso, la capa frita a la francesa expuesta a las micro-ondas estuvo superior a la que fue calentada en un horno convencional. Al secar los trozos de papa escaldada en un horno durante 10 minutos antes de someterlos a la fritura parcial, se obtuvo un producto que, cuando fue calentado por micro-ondas, era muy similar a la papa frita calentada en el horno, particularmente en el caso de BelRus. En todos los casos, BelRus absorbía menos grasa por la fritura parcial que Russet Burbank.

The proximate composition and glycoalkaloid content of three potato meals.

The proximate composition and glycoalkaloid content of a dried potato by-product meal (tater meal) and two dried potato pulp meals (potato meal and potato meal plus 10% molasses) were determined. All three feeds demonstrated variable compositions: the tater meal averaged 8.7% moisture, 9.1% crude protein, 5.4% ether extract, 5.0% crude fiber, 4.1% ash and 56.8% nitrogen-free extract; the potato meal averaged 14.5% moisture, 6.0% crude protein, 0.5% ether extract, 9.5% crude fiber, 2.2% ash and 57.1% nitrogen-free extract; the potato meal plus 10% molasses averaged 15.3% moisture, 6.4% crude protein, 0.3% ether extract, 8.0% crude fiber, 2.6% ash and 57.8% nitrogen-free extract. The phosphorus concentration was determined to be approximately 0.2% for the three samples. Other minerals were found in lesser concentrations. The riboflavin and thiamine concentrations of the three potato meals were less than 10% of the values reported for raw potato pulp and peel. The niacin concentration was approximately 40% of the values reported for raw potato pulp and peel.Tater meal contained 11.5 mg a-chaconine and 6.5 mg α-solanine per 100g meal. Analysis of potato meal gave 15.8 mg α-chaconine and 7.8 mg α-solanine per 100g meal while the potato meal plus 10% molasses was found to contain 13.2 mg α-chaconine and 7.3 mg α-solanine per l00g meal.ResumenSe determinó la compositión proximal y el contenido de glicoalcaloide de un subproducto de harina de papa seca (tater meal) y dos de pulpa de harina de papa seca (harina de papa y harina de papa más 10% de melaza). Los tres alimentos para ganado demostraron composiciones variables: “tater meal” dio como promedio 8.7% de humedad, 9.1% de proteína cruda; 5.4% extracto etéreo, 5.0% fibra cruda, 4.1% cenizas y 56.8% extracto libre de nitrógeno; tuvo como término medio 14.5% de humedad, 6.0% de proteína cruda, 0.5% de extracto etéreo, 9.5% de fibra cruda, 2.2% cenizay 57. l%de extracto libre de nitrógeno, la harina de papa más 10% de melaza dio como promedio 15.3% de humedad, 6.4% proteína cruda, 0.3% extracto etéreo, 8.0% fibra cruda, 2.6% cenizas y 57.8% extracto libre de nitrógeno. Se determiné que la concentratión de fósforo fue de aproximadamente 0.2% para las tres muestras. De otros minerales se encontraron concentraciones menores. La concentratión de riboflavina y tiamina de las tres harinas de papa fueron menos de 10% de los valores indicados para la pulpa cruda y cáscara. La concentración de niacina fue de aproximadamente 40% de los valores indicados para la pulpa de papa cruda y cáscara.La harina “tater” contuvo 11.5 mg de α-chaconina y 6.5 mg de α-solanina por 100 g de harina. Los análisis de la harina de papa dieron 15.8 mg de α-chaconina y 7.8 mg de α-solaninapor 100 g de harina, mientras que la harina de papa más 10% de melaza présentó un contenido de 13.2 mg de α-chaconina y 7.3 mg de α-solanina por 100 g de harina.