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High Performance Liquid Chromatographic Assay for Potato Tuber 3′-Nucleotidase
COLOUR STABILITY OF BLUEBERRY, RASPBERRY AND STRAWBERRY JUICE. R.A. Speers' and M.A. Tung, Department of Food Science, University of British Columbia, Vancouver, British Columbia V6T 2A2 and R.L. Jackman, Department of Food Science, University of Guelph, Guelph, Ontario NIG 2WI. The influence of temperature, package type and glucose oxidase treatment on the colour stability of blueberry, raspberry and strawberry juice was examined over 8 weeks. Colour stability was monitored by measuring absorbance at 420 nm, 700 nm and at the maximum wavelength. Also, the proportion of monomeric to polymeric anthocyanin colour was determined. In most cases, absorbance data could be modeled using first order reaction theory. Generally, absorbance maxima declined with time for all juices. At 420 nm, absorbance decreased with storage time for blueberry and raspberry juice. Strawberry juice brown colour increased with time. Absorbance at 700 nm was found to increase over time for all the juices and treatments. These data exhibited low variability and seem to reflect juice stability.
HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC ASSAY FOR POTATO TUBER 3'-NUCLEOTIDASE. T.T. Nguyen', M.M. Palcic and D. Hadziyev, Department of Food Science, University of Alberta, Edmonton, Alberta T6G 2P5. A rapid and reproducible HPLC method is presented for assaying the activity of 3'-nucleotidase isolated from potato tubers. Nucleotide substrates were incubated with the enzyme and the activity determined by measuring the concentration of nucleosides as reaction products. The relative rate of substrate hydrolysis was 3'-AMP > 3'-UMP > 3'-GMP > 3'-CMP > 3'-dAMP. The enzyme temperature optimum was 75°C and pH optimum 6.5 when 3'-AMP was used as a substrate. Enzyme inhibition was observed in the presence of EDTA, phosphate anion, zinc chloride and the flavorenhancing nucleotide 5'-GMP. This assay could also be used for the simultaneous determination of amino- or keto nucleotides and deoxynucleotides as substrates.
APPLICATION OF CATALASEMETER AS A RAPID METHOD OF ASSESSING CLEANLINESS OF MEAT WORK SURFACES. L. Jacques", J.P. Smith, F.R. van de Voort and S. Kermasha, Department of Food Science and Agricultural Chemistry, Macdonald College of McGill University, Ste. Anne de Bellevue, Quebec H9X ICO. The catalasemeter, an instrument which determines catalase activity based on the measurement of disc flotation time (DFT), was used to assess the cleanliness of meat work surfaces. The catalasemeter was able to detect low concentrations (10- 5 uL/50 cm 2) of residual blood on meat surfaces compared to 10-3 uL/50 cm 2 by enzymatic and non-enzymatic visual detection methods. However, the limit of detection of residual microorganisms on meat work surfaces by the catalasemeter method was 1()4 CFU/50 cm 2 • Used in conjunction with the conventional plate count method, which does not detect residual blood, the catalasemeter technique could be a useful ancillary method to assess the cleanliness of meat work surfaces.
PURIFICATION OF AVIDIN BY CATION EXCHANGE, GEL FILTRATION, MCIC, AND HYDROPHOBIC INTERACTION CHROMATOGRAPHY. T. Durance' and S. Nakai, Department of Food Science, University of British Columbia, Vancouver, British Columbia V6T 2A2. Avidin is a commercially valuable glycoprotein which has a high affinity for the vitamin biotin, and which is present in small amounts in hen egg albumen (e.g. 50 mg/L). Avidin containing extracts of egg white may be prepared by selective solvent precipitation or by treatment with ion exchange resins. In this study cation exchange, gel filtration, metal chelate interaction chromatography (MCle), and two types of hydrophobic interaction chromatography were evaluated for avidin purification. Although all five methods substantially improved avidin purity, cation exchange chromatography was superior in terms of avidin purity, 1110 recovery, and column capacity. 318 / Abstract
DETERMINATION OF SPAN 60 IN DRY YEAST BY GAS CHROMATOGRAPHY. B. Kamel' and H.J. Dawson, Atkemix Inc., Brantford, Ontario, and J. McNeill and Y. Kakuda, Department of Food Science, University of Guelph, Guelph, Ontario NIG 2WI. Span 60 is added to dry yeast to extend its shelf life and improve its dispersibility when mixed with water. Approval for use of Span 60 has been granted and an analytical procedure to monitor levels has been developed. Span 60 is extracted from yeast with chloroform on a Soxhlet extraction apparatus for a minimum of 5 hr. The chloroform is removed and the residue saponified with alcoholic potassium hydroxide. Fatty acids are removed by acidification with HCI and extraction with hexane. The solution containing Span 60 polyol is a complex mixture of hexitols, hexitans and hexides and is analyzed by gas chromatography for the principal hexide constituent isosorbide. The separation was preformed on 25% Carbowax 20 M using an internal standard for quantification.
MOISTURE DETERMINATION OF FOOD PRODUCTS USING MID-IR TRANSMISSION SPECTROSCOPY. M. Laureano and F.R. van de Voort, Department of Food Science and Agricultural Chemistry, Macdonald College of McGill University, Ste. Anne de Bellevue, Quebec H9X ICO. A new method based on the use of mid-infrared (IR) transmission spectroscopy had been developed to measure moisture content in foods such as skim milk powder, bread crumbs, and flour. Using a research IR spectrophotometer, and a dual wavelength approach, 6.02 micron was chosen as the sample wavelength and 5.56 micron as a reference wavelength. Water methanol standards were assessed for linearity and accuracy. Moisture was extracted from samples using dry methanol, shaken for 15 minutes at 45°C, centrifuged at 150xg and then assessed in the Spectroprocessor IV. The results obtained using the Spectroprocessor were compared to the AOAC Karl Fischer and near IR methods and found to be comparable. The data obtained indicates that filter based IF anaJysers such as the Multispec or Foss could be used to accurately determine moisture if they were equipped with a 6.02/5.56 miCron filter.
DEVELOPMENT. OF LOW CALORIE CAKES UTILIZING EMULSIFIERS, SORBITOL AND POLYDEXTROSE. B.S. Kamel' and V.F. Rasper, Atkemix Inc., P.O. Box 1085, Brantford, Ontario and Department of Food Science, University of Guelph, Guelph, Ontario NIG 2WI. As nutritional and health awareness increases, consumers are more diet conscious. The Calorie Control Council estimates that 68 million U.S. citizens aged 18 and older now use low calorie products. An increase of more than 601110 since 1978. The present work was undertaken to produce light cake formula acceptable to consumers by reducing or eliminating sugar, egg, shortening and the addition of crystalline sorbitol, polydextrose, crystalline cellulose, CMC and emulsifiers. Sensory attributes, textural properties, specific volume, density, proximate analysis and caloric value were used to monitor the cake quality. The emulsifier levels used were 1.5 to 7.5%. The sorbitol was used at 30% level and polydextrose was tried at 20-50% replacement of sucrose. Cellulose levels varied from 0-6%. The caloric value of the different combination was reduced by at least 20% without sacrificing taste, texture or acceptability.
MICROSTRUCTURE OF REDUCED SALT MEAT EMULSIONS WITH POL YPHOSPHATES. S. Barbut, Department of Food Science, University of Guelph, Guelph, Ontario NIG 2WI. The effects of salt reduction, polyphosphate addition, and chopping time (short vs. long) on the microstructure of meat emulsios was studied. Salt reduction significantly decreased emulsion stability in the long chopping setting but not in the short setting. Average fat globule size decreased as chopping time increased and/or salt level decreased. SEM revealed fat globules which lost fat during cooking due to insufficient salt levels. Hexametaphosphate and sodium acid pyrophosphate significantly improved the low salt emulsion stability as well as fat globules morphology, however, tripolyphosphate was not as effective. 1. InSl. Call. Sci. Techno/. Alil/lelll. Vol. 20, No. 5.
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HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC ASSAY FOR POTATO TUBER 3'-NUCLEOTIDASE. T.T. Nguyen', M.M. Palcic and D. Hadziyev, Department of Food Science, University of Alberta, Edmonton, Alberta T6G 2P5. A rapid and reproducible HPLC method is presented for assaying the activity of 3'-nucleotidase isolated from potato tubers. Nucleotide substrates were incubated with the enzyme and the activity determined by measuring the concentration of nucleosides as reaction products. The relative rate of substrate hydrolysis was 3'-AMP > 3'-UMP > 3'-GMP > 3'-CMP > 3'-dAMP. The enzyme temperature optimum was 75°C and pH optimum 6.5 when 3'-AMP was used as a substrate. Enzyme inhibition was observed in the presence of EDTA, phosphate anion, zinc chloride and the flavorenhancing nucleotide 5'-GMP. This assay could also be used for the simultaneous determination of amino- or keto nucleotides and deoxynucleotides as substrates.
APPLICATION OF CATALASEMETER AS A RAPID METHOD OF ASSESSING CLEANLINESS OF MEAT WORK SURFACES. L. Jacques", J.P. Smith, F.R. van de Voort and S. Kermasha, Department of Food Science and Agricultural Chemistry, Macdonald College of McGill University, Ste. Anne de Bellevue, Quebec H9X ICO. The catalasemeter, an instrument which determines catalase activity based on the measurement of disc flotation time (DFT), was used to assess the cleanliness of meat work surfaces. The catalasemeter was able to detect low concentrations (10- 5 uL/50 cm 2) of residual blood on meat surfaces compared to 10-3 uL/50 cm 2 by enzymatic and non-enzymatic visual detection methods. However, the limit of detection of residual microorganisms on meat work surfaces by the catalasemeter method was 1()4 CFU/50 cm 2 • Used in conjunction with the conventional plate count method, which does not detect residual blood, the catalasemeter technique could be a useful ancillary method to assess the cleanliness of meat work surfaces.
PURIFICATION OF AVIDIN BY CATION EXCHANGE, GEL FILTRATION, MCIC, AND HYDROPHOBIC INTERACTION CHROMATOGRAPHY. T. Durance' and S. Nakai, Department of Food Science, University of British Columbia, Vancouver, British Columbia V6T 2A2. Avidin is a commercially valuable glycoprotein which has a high affinity for the vitamin biotin, and which is present in small amounts in hen egg albumen (e.g. 50 mg/L). Avidin containing extracts of egg white may be prepared by selective solvent precipitation or by treatment with ion exchange resins. In this study cation exchange, gel filtration, metal chelate interaction chromatography (MCle), and two types of hydrophobic interaction chromatography were evaluated for avidin purification. Although all five methods substantially improved avidin purity, cation exchange chromatography was superior in terms of avidin purity, 1110 recovery, and column capacity. 318 / Abstract
DETERMINATION OF SPAN 60 IN DRY YEAST BY GAS CHROMATOGRAPHY. B. Kamel' and H.J. Dawson, Atkemix Inc., Brantford, Ontario, and J. McNeill and Y. Kakuda, Department of Food Science, University of Guelph, Guelph, Ontario NIG 2WI. Span 60 is added to dry yeast to extend its shelf life and improve its dispersibility when mixed with water. Approval for use of Span 60 has been granted and an analytical procedure to monitor levels has been developed. Span 60 is extracted from yeast with chloroform on a Soxhlet extraction apparatus for a minimum of 5 hr. The chloroform is removed and the residue saponified with alcoholic potassium hydroxide. Fatty acids are removed by acidification with HCI and extraction with hexane. The solution containing Span 60 polyol is a complex mixture of hexitols, hexitans and hexides and is analyzed by gas chromatography for the principal hexide constituent isosorbide. The separation was preformed on 25% Carbowax 20 M using an internal standard for quantification.
MOISTURE DETERMINATION OF FOOD PRODUCTS USING MID-IR TRANSMISSION SPECTROSCOPY. M. Laureano and F.R. van de Voort, Department of Food Science and Agricultural Chemistry, Macdonald College of McGill University, Ste. Anne de Bellevue, Quebec H9X ICO. A new method based on the use of mid-infrared (IR) transmission spectroscopy had been developed to measure moisture content in foods such as skim milk powder, bread crumbs, and flour. Using a research IR spectrophotometer, and a dual wavelength approach, 6.02 micron was chosen as the sample wavelength and 5.56 micron as a reference wavelength. Water methanol standards were assessed for linearity and accuracy. Moisture was extracted from samples using dry methanol, shaken for 15 minutes at 45°C, centrifuged at 150xg and then assessed in the Spectroprocessor IV. The results obtained using the Spectroprocessor were compared to the AOAC Karl Fischer and near IR methods and found to be comparable. The data obtained indicates that filter based IF anaJysers such as the Multispec or Foss could be used to accurately determine moisture if they were equipped with a 6.02/5.56 miCron filter.
DEVELOPMENT. OF LOW CALORIE CAKES UTILIZING EMULSIFIERS, SORBITOL AND POLYDEXTROSE. B.S. Kamel' and V.F. Rasper, Atkemix Inc., P.O. Box 1085, Brantford, Ontario and Department of Food Science, University of Guelph, Guelph, Ontario NIG 2WI. As nutritional and health awareness increases, consumers are more diet conscious. The Calorie Control Council estimates that 68 million U.S. citizens aged 18 and older now use low calorie products. An increase of more than 601110 since 1978. The present work was undertaken to produce light cake formula acceptable to consumers by reducing or eliminating sugar, egg, shortening and the addition of crystalline sorbitol, polydextrose, crystalline cellulose, CMC and emulsifiers. Sensory attributes, textural properties, specific volume, density, proximate analysis and caloric value were used to monitor the cake quality. The emulsifier levels used were 1.5 to 7.5%. The sorbitol was used at 30% level and polydextrose was tried at 20-50% replacement of sucrose. Cellulose levels varied from 0-6%. The caloric value of the different combination was reduced by at least 20% without sacrificing taste, texture or acceptability.
MICROSTRUCTURE OF REDUCED SALT MEAT EMULSIONS WITH POL YPHOSPHATES. S. Barbut, Department of Food Science, University of Guelph, Guelph, Ontario NIG 2WI. The effects of salt reduction, polyphosphate addition, and chopping time (short vs. long) on the microstructure of meat emulsios was studied. Salt reduction significantly decreased emulsion stability in the long chopping setting but not in the short setting. Average fat globule size decreased as chopping time increased and/or salt level decreased. SEM revealed fat globules which lost fat during cooking due to insufficient salt levels. Hexametaphosphate and sodium acid pyrophosphate significantly improved the low salt emulsion stability as well as fat globules morphology, however, tripolyphosphate was not as effective. 1. InSl. Call. Sci. Techno/. Alil/lelll. Vol. 20, No. 5.
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