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    CATECHINS AND METHYLXANTHINES IN TWENTY-THREE BLACK TEA INFUSIONS BY HPLC: CORRELATIONS WITH ASTRINGENCY
    (Chiriotti Editori, 2008) Tokusoglu, Oe.; Uenal, M. K.; Balaban, M. Oe.
    Simultaneous detection of flavanols [catechin (C), epicatechin (EC), epigallocatechin (EGC), epicatechingallat (ECG), epigallocatechingallate (EGCG)], gallic acid (GA), theogalline, methylxanthines (caffeine, theobromine, theophylline) were performed on 23 black tea infusions. A hypersil-ODS column (4.6 mm I.D. x 250 mm) with methanol: distilled water: formic acid (19.5:80.2:0.3, v:v:v) as a mobile phase was used for optimizing the RP-HPLC separation (R(2)=0.9997). Total flavanols varied from 1.423 to 12.051 mg 100 mg(-1) whereas EGCG was the major catechin in all of the infusions (0.356-5.972 mg 100 mg(-1)) (p<0.01). Caffeine levels were high (4.002-8.657 mg 100 mg(-1)) followed by theobromine and theophylline (p<0.01). Black tea contained 0.134-1.392 mg/100 mg of GA, and 0.156-1.241 mg 100 mg(-1) of its ester theogalline. An 8-member trained sensory panel judged black tea infusions for astringency. The correlations between the total catechins and astringency (y=1.675+6.631 In X) (R(2)=0.9551) were extremely high at the 95 percent confidence level (X=total catechin, y=astringency) and total interactions on astringency were obtained.
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    Fatty acid and, conjugated linoleic acid profiles of infant formulas through direct transesterification of acyl lipids
    (Chiriotti Editori, 2007) Tokusoglu, Oe.; Durucasu, I.; Akalin, A. S.; Serin, E.; Aksit, S.
    Fatty acid (FA) values, including C8:0, C10:0, C12:0, C13:0, C14:0, C16:0, C18:0, C18:1t, C18:1c, C18:2, C18:2 CLA, C20:0, C18:3 and C22:0, in sixteen infant formulas were determined through direct transesterification of acyl lipids with sodium methoxide by capillary gas chromatography. Total FA values ranged from 250.25-256.06 mg/g sample and the conjugated linoleic acid (CLA) (cis-9, trans-11 octadecadienoic acid) values were 1.41-2.02 mg/g sample (p < 0.01) in the infant formulas. The total saturated fatty acid, monounsaturated fatty acid and polyunsaturated fatty acid values were also obtained. The C18:3 (linolenic acid (n-3)) values were 0.63-0.88 mg/g sample, whereas the C18:2 (linoleic acid (n-6)) values ranged from 35.64-35.82 mg/g sample. FA standard mix including CLA had linear calibration curves through the origin (R-2 = 0.9999). The precision of the analytical method was (using C13:0, methyl tri-decanoate, as internal standard) within the 95% confidence limits and the mean recoveries determined for individual fatty acids in infant formulas varied from 99.8 to 100%.