ZIB

1

Digitale Medien

ENZYMATIC BROWNING OF PEACHES: EFFECT OF GIBBERELLIC ACID AND ETHEPHON ON PHENOLIC COMPOUNDS AND POLYPHENOLOXIDASE ACTIVITY (1980)

PAULSON, A. T. ; VANDERSTOEP, J. ; PORRITT, S. W.

Oxford, UK : Blackwell Publishing Ltd

Journal of food science 45 (1980), S. 0

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ISSN: 1750-3841

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Foliar sprays of gibberellic acid and ethephon applied to Redhaven peach trees at 21 and 46 days after bloom caused a reduction of enzymatic browning in mature fruit tissue. A replicate from each treatment was analyzed by two-dimensional thin-layer chromatography and polyacrylamide disc gel electrophoresis. Twenty-one polyphenolic compounds were separated. Eight were oxidized by PPO, and were tentatively identified as four chlorogenic acid isomers, three leucoanthocyanidins, and catechin. No differences in qualitative distributions of phenolic compounds were observed which would account for the inhibition of browning in peach tissue. Polyacrylamide disc gel electrophoresis of peach PPO preparations showed the presence of up to 11 multiple forms displaying activity toward catechol. The bands had different substrate specificities and were present in different amounts, but PPO from peaches treated 21 days after bloom appeared to have a catechol reactive band not present in untreated peaches or peaches treated 46 days after bloom. One band from peaches treated 46 days after bloom with 150 ppm ethephon appeared to have decreased substrate specificity toward pyrogallol. Crude PPO preparations from untreated fruit and fruit receiving the 46-day treatments oxidized o-dihydroxyphenols only, and the relative PPO activities varied with treatment. These PPO preparations exhibited two pH optima; pH 4.4 and 6.2 for untreated and GA-treated peaches (46-day treatment), and pH 4.4 and 6.6 for peaches treated with ethephon (75 or 1.50 ppm, 46-day treatment). PPO from the treated peaches had a lower proportion of total activity at pH 4.4 than PPO from untreated peaches.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2621.1980.tb02610.x

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2

Digitale Medien

Characterization of the Residual Pink Color in Cooked Turkey Breast and Pork Loin (1990)

GIRARD, B. ; VANDERSTOEP, J. ; RICHARDS, J.F.

Oxford, UK : Blackwell Publishing Ltd

Journal of food science 55 (1990), S. 0

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ISSN: 1750-3841

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: The residual redness was characterized in well cooked meat from turkey breast and pork loin. A simple method of scanning thin slices by transmission spectrophotometry was used to evaluate the meat pigments in situ. Absorption bands at 414, 520, and 550 nm of the spectra obtained from cooked meat led to the conclusion that residual pink color was caused by cytochrome c. The method was further modified to study the effect of air contact on meat color after cooking. Other pigments were spontaneously oxidized as soon as meat surface was exposed to air. The concentrations of hemoproteins in turkey and pork were determined and found to be related to cooked meat color.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2621.1990.tb03908.x

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3

Digitale Medien

FOLATE LEVELS IN FOOD—A COMPARISON OF MICROBIOLOGICAL ASSAY AND RADIOASSAY METHODS FOR MEASURING FOLATE (1978)

RUDDICK, J. E. ; VANDERSTOEP, J. ; RICHARDS, J. F.

Oxford, UK : Blackwell Publishing Ltd

Journal of food science 43 (1978), S. 0

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ISSN: 1750-3841

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Concentrations of N5-methyltetrahydrofolic acid (N5 MTHFA) were determined by the radioassay and the L. casei microbiological assay methods. The correlation coefficient for samples analyzed by both methods was 0.93. The radioassay method was found to be faster, simpler and more accurate than the microbiological method. The milk folate binder and L. casei were found to react differently to pteroylglutamic acid compared to N5-MTHFA acid. The two methods are suitable only for measuring the form of folate used to construct the standard curve for the assay. Therefore, neither method can be used to accurately quantitate folate levels in foods.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2621.1978.tb15277.x

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4

Digitale Medien

Effect of Germination Environment on Nutrient Composition of Alfalfa Sprouts (1984)

HARRISON, J. E. ; VANDERSTOEP, J.

Oxford, UK : Blackwell Publishing Ltd

Journal of food science 49 (1984), S. 0

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ISSN: 1750-3841

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Alfalfa seeds were germinated for 120 hr utilizing solutions of 0.05M (NH4SO4, 0.05M urea, 0.05M KNO3, 0.1M KNO3 or distilled water for rinsing. One of the water rinsed samples was flushed with CO2 after each rinse. Proximate analysis, NPN, amino acids and reduced ascorbic acid contents were measured to determine the effect of germination environment on the nutrient composition. The sprouts had significantly increased crude protein values but reduced fat and carbohydrate concentrations as compared to the seeds. True protein content increased significantly in the sprouts rinsed with 0.05M (NH4SO4 or 0.1M KNO3. The essential amino acid patterns of these were not significantly affected. Although the treatments used did not appear to affect adversely the composition of the sprouts, visually the sprouts did suffer somewhat.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2621.1984.tb13659.x

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5

Digitale Medien

KINETICS OF THERMAL DEGRADATION OF METHYLTETRAHYDROFOLIC ACID (1980)

RUDDICK, J. E. ; VANDERSTOEP, J. ; RICHARDS, J. F.

Oxford, UK : Blackwell Publishing Ltd

Journal of food science 45 (1980), S. 0

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ISSN: 1750-3841

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Thermal degradation of N5 methyltetrahydrofolic acid (N5 MTHFA) under various conditions was studied, using a radioassay method to measure N5 MTHFA concentrations. In the presence of an unlimited oxygen supply, the degradation reaction could be described as pseudo first order. Reaction rate constants were found to increase with increasing reaction temperature. Conformity with the Arrhenius equation enabled calculation of the activation energy (7.10 Kcal mole−1). The overall reaction appeared to be second order in the presence of a limited oxygen supply. The presence of mercaptoethanol or ascorbic acid in the assay system delayed the beginning of the N5 MTHFA degradation reaction but did not alter the reaction rate constants.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2621.1980.tb07502.x

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6

Digitale Medien

GERMINATION AND NUTRIENT COMPOSITION OF ALFALFA SEEDS (1979)

HAMILTON, M. J. ; VANDERSTOEP, J.

Oxford, UK : Blackwell Publishing Ltd

Journal of food science 44 (1979), S. 0

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ISSN: 1750-3841

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Alfalfa seeds were germinated for 72 and 120 hr in the absence and presence of light. Reduced ascorbic acid, riboflavin, iron, amino acid and proximate analysis of ungerminated alfalfa seeds and sprouted alfalfa seeds were conducted to determine the effect of germination conditions on the nutrient composition. Sprouts were found to have slightly smaller concentrations of protein and ash than seeds, whereas fat content was significantly reduced in sprouts as compared to seeds. Moisture content was found to increase consistently with increased sprouting time. Reduced ascorbic acid content was greater in the sprouts grown in the light for either growth period and during germination and sprouting increased to 3-4 times the concentration found in the seeds. Riboflavin concentration increased by as much as 3 times. Essential amino acid content was significantly higher in 72 hr sprouts than in the seeds. Although claims for the superb nutritional worth of alfalfa sprouts appear to be unfounded, they could serve as a good dietary source of several nutrients.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2621.1979.tb03807.x

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7

Digitale Medien

A Radiation Hybrid Map of the BRCA1 Region of Chromosome 17q12-q21

Abel, K.J. ; Boehnke, M. ; Prahalad, M. ; [weitere]

Amsterdam : Elsevier

Genomics 17 (1993), S. 632-641

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ISSN: 0888-7543

Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Thema: Biologie , Medizin

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1006/geno.1993.1383

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