82.

83.

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des A.C. ils ont muri normalement, sans qu'on puisse detecter dedifferences significatives de taux de murissement entre les traite­ments.

EFFET DE DlFFERENTES CONCENTRATIONS D'02 ET DEC02 SUR LES MITOCHONDRIES DU CHOU-FLEUR. L.Ramo-Parada, C. Willemot, L.P. Vezina et F. Castaigne,Departement de sciences et technologie des aliments, UniversiteLaval, Quebec, P.Q. GIK 7P4; et Centre de recherche alimentairesde St-Hyacinthe, Agriculture Canada, St- Hyacinthe, P.Q. 12S8E3.

L 'entreposage du chou-fIeur (Brassica oleracea L.) enatmospheres controlees (A.C.). entrai'ne une alteration de larespiration, principalement une accumulation de I'acide succini­que. L'objectif de ce projet a ete d'etablir l'effet in vitro et in vivode ces A.C. sur.les mitochondries du chou-f1eur. Les effets de cesatmospheres (070 d'02 et de C02: 21-0; 3-0; 3-15; 21-15) surl'activite mitochondriale ont ete evalues par la mesure du contr6lerespiratoire, le rapport ADP/a, le dosage de la succinate deshy­drogenase et de la cytochrome c oxydase, ainsi que I'observationde la structure des mitochondries par microscopie electronique.

SUGAR CONTENT OF PARSNIP ROOT TISSUES DURINGLOW TEMPERATURE STORAGE. R.Y. Yada* I, V.I. Shatluck2

a~d Y. Kakuda', 'Department of Food Science; and 2Departmentof Horticultural Science, University of Guelph, Guelph, ant. NI G2WI.

Changes in the sugar content in the cortex (phloem) and cone(xylem) tissues of two parsnip (Pastinaca sativa) cultivars duringlow temperature storage (O°C and 95070 humidity) was investigated.Five major sugars were identified in both root tissues and includedsucrose, fructose, glucose, maltose and an unidentified oligosac­charide. The sucrose concentration increased over three fold at asteady and equivalent rate in both the cortex and core tissues.Glucose, fructose, maltose and the unidentified oligosaccharidewere also observed to accumulate in root tissues during the monthlong study. Cultivar differences for sugar levels in root tissues werenoted.

THE IDENTIFICATION OF PYRAZINE COMPOUNDS INMAPLE SYRUP. I. Alii, J. Bourque and R. Metussin*, Depart­ment of Food Science and Agriculture Chemistry, MacdonaldCollege of McGiII University, Ste. Anne de Bellevue, P.Q. H9XICO.

Commercial samples of maple syrup (dark, amber) were ex­tracted with diethyl ether and the ether phase was separated anddiscarded. The aqueous phase was adjusted to pH 8.5 then ex­tracted with dichloromethane. Capillary gas chromatographicanalysis of the concentrated dichloromethane extract suggested thepresence of 2-methylpyrazine, 2,3-dimethylpyrazine, 2,6-dimethyl­pyrazine aoo trimethylpyrazine in the amber maple syrup andpyrazine, 2-methylpyrazine, 2,6-dimethylpyrazine and ethylpyra­zine in the dark maple syrup. Mass spectrometric analysis con­firmed the presence of these pyrazine compounds. In all like­lihood, the pyrazines are formed by reactions of amino acids andsugars during heating of maple sap for processing into maplesyrup.

POSSIBLE INFLUENCE OF STARCH GRANULE COMPOSI·TION ON LOW TEMPERATURE SWEETENING. V. Barichel·10*, D.W. Stanley, R.Y. Yada and R.H. Coffin, Department ofFood Science, University of Guelph, Guelph, ant. NIG 2WI.

Differential scanning calorimetry (DSC), alpha -amylolysis,scanning electron (SEM) and light microscopy (LM) were used toinvestigate differences in starch granule properties between maturepotato tubers of a potato cutivar susceptible to low-temperaturesweetening (Norchip) and one resistant to low-temperture sweeten­ing (ND 860-2). Tubers were stored 4 weeks at either 4 or 12C(90-95070 RH). Over the entire storage period, starch isolated fromND 860-2 displayed significantly (p<O.OI) greater resistancc toenzyme attack and significantly (p<O.OI) higher gelatinizationtemperatures (DSC) than that from Norchip. Examination ofstarch granules using brightfield LM indicated crystalline con­centric rings in ND 860-2 while not in Norchip. In addition,examination of SEM micrographs of granules incubated with

Can. Inst. Food Sci. Technol. J. Vol. 22. No. 4. 1989

alpha-amylase indicated more ND 860-2 starch granules were intactcompared to Norchip. These data suggest that starch granulecomposition may be a factor differentiating low-temperaturesweetening sensitive from resistant potato cultivars.

86. ISOLATION OF CYSTATlN FROM EGG WHITE. T.D.Durance*, Department of Food Science, University of BritishColumbia, Vancouver, B.C. V6T IW5.

Cystatin (also known as ficin inhibitor), a protein found in lowconcentrations in many animal tissues, is a specific inhibitor ofcysteine proteinases. Affinity chromatography was the most ap­propriate purification procedure for this protein because of its verylow concentration in egg white (Le. 40 mg/L). Ficin was inac­tivated with L-trans-epoxysuccinyl-Ieucylamido (4-guanidino)butane (E-64) or sodium tetrathionate and immobilized on ac­tivated agarose (Affigel-IO). Papain was also inactivated withiodoacetic acid and immobilized. Ovomucin was precipitated fromegg white to reduce viscosity and the supernatant was applied tothe affinity columns. Cystatin activity was monitored as inhibitionof papain under standard conditions. SDS-PAGE indicated highpurity in the eluted cystatin fractions.

87. PHYTATE DETERMINATION IN PROTEINS USINGPOLYACRYLAMIDE·DlSC GEL ELECTROPHORESIS. A.B.Di Lollo*, I. Alii and S. Kermasha, Department of Food Scienceand Agricultural Chemistry, Macdonald College of McGiII Univer­sitY,Ste. Anne de Bellevue, P.Q. H9X ICO.

Protein-phytate interaction is common in cereal grains andoilseeds. The identification of complexes on polyacrylamide gelswill help to provide an understanding of the nature of theseinteractions. A technique for identification of protein-phytatecomplexes on polyacrylamide gels, precipitates the phytate as awhite band of ferric-phytate. A colorimetric reaction believed tobe specific for iron was investigated to improve the visualizationof the ferric phytate on the gels. The results indicate that whitebands which are formed when protein-phytate complexes onpolyacrylamide gels treated with iron solution, could be the resultof protein-iron interaction in addition to phytate-iron interaction.This was confirmed by the use of proteins which contained nophytate. The effect of phytate addition to proteins was alsostudied. Electrophoretic analysis followed by staining of the gelsfor iron confirmed the complexation of proteins with iron duringthe phytate visualization procedure.

88. STANDARDIZATION OF A METHOD TO DETERMINE THEEMULSIFYING CAPACITY OF PROTEINS. J.C. Vuillemard*,S. Gauthier, P. Paquin and J.P. Richard, Groupe STELA,Departement de sciences et technologie des aliments, UniversiteLaval, Quebec, P.Q. GIK 7P4.

The method of emulsion preparation influences the determina­tion of emulsion capacity (E.C.) of food proteins. Hence, there isa need for standard method for quantifying E.C. The equipment,speed of stirring, rate of oil addition and protein concentration arethe most important parameters in the determination of E.C.Protein concentration should be previously determined. The otherparameters should be controlled in order to obtain an emulsionwith fat globules of mean diameter 2.0 /Lm. According to ourresults, the E.C. should be defined as the amount of oil emulsifiedminus a blank divided by the amount of protein.

89. APPLICATION OF RESPONSE SURFACE METHODOLOGYIN PROTEIN EXTRACTION STUDIES FROM BREWER'SSPENT GRAIN. R. Diptee, J.P. Smith and I. Alii, Departmentof Food Science and Agricultural Chemistry; and S. Khanizadeh,Department of Plant Science, Macdonald College of McGilIUniversity, Ste. Anne de Bellevue, P.Q. H9X ICO.

Effects of temperature of extraction, time of extraction, con­centration of sodium dodecly sulphate and Na2HP04 in the ex­tractant solution, particle size of grain and BSG: extractant ratioon the yield of protein solubilized from dried brewer's spent grain(DBSG) and pressed brewer's spent grain (PBSG) were studiedsimultaneously using a process optimization technique termedResponse Surface Methodology (RSM). The initial fractional fac­torial screening design indicated that time, temperature and par­ticle size of grain were significant variables with concentration of

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