Browsing by Author "Akalin, AS"

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    A rapid high performance liquid chromatographic detection of furosine (ε-N-2-furoylmethyl-L-lysine) in pasteurized and UHT milks
    Tokusoglu, Ö; Akalin, AS; Unal, MK
    Furosine, generated from the acid hydrolysis of the amadori compound during the early Maillard reaction, is a suitable indicator of the effect of heating treatments on milk quality. Furosine content in pasteurized and UHT milks marketed in Turkey was detected using ion-pair reversed-phase liquid chromatography (RP-HPLC). Calibration study (R-2=0.9999), analytical method validation and recovery studies (y = 5.315 x + 0.043 (R-2 = 0.9998)) gave satisfactory results A wide range of furosine content was found in UHT milks (49.68 +/- 0.10 to 213.38 +/- 0.07 mg 100 g(-1) protein) depending on the heat-treatment intensity. Pasteurized milks had lower content of furosine (3.79 +/- 0.01 and 5.88 +/- 0.02 mg 100 g(-1) protein). The method provides rapid, reproducible and accurate determination of this amadori compound in milk and dairy products and can be utilized as one of the most commonly used quality marker in dairy industry.
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    Rapid high performance liquid chromatographic detection of furosine (ε-N-2-furoylmethyl-L-lysine) in yogurt and cheese marketed in Turkey
    Tokusoglu, Ö; Akalin, AS; Unal, K
    Furosine (epsilon-N-2-furoylmethyl-L-lysine) content determination in the yogurt and different cheese types (pickled white, kasar, processed, canned tulum, blue-veined and mozzarella cheeses) marketed in Turkey was performed using ion-pair reversed-phase high performance liquid chromatography (RP-HPLC). Calibration study (R-2 = 0.9999), analytical method validation and recovery studies gave satisfactory results. The lowest furosine values were observed in pickled white cheeses (5.35 +/- 0.01 to 7.28 +/- 0.02 mg/100 g protein). All cheeses except pickled white showed furosine values between 182.16 +/- 0.12 (canned tulum) and 261.32 +/- 0.10 mg/100 g protein (ripened kasar). The highest content of furosine was observed in whole yogurt (316.47 +/- 0.17 mg/100 g protein) which could be because of severe heat treatment and the addition of milk powder during the manufacturing process. The method provides a rapid, reproducible and accurate determination of this Amadori compound (epsilon-deoxy-fructosyl-lysine) in yogurt and cheese samples.
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    Determination of Conjugated Linoleic Acid (CLA, c9, t11 and t10, c12 18:2) and -Tocopherol in a Dairy Dessert Hosmerim
    Akalin, AS; Tokusoglu, O
    In this research, conjugated linoleic acid (CLA) as the total of cis-9, trans-11, and trans-10, cis-12 isomers of conjugated linoleic acid and -tocopherol contents of traditional Turkish dessert oHosmerimo were determined by Gas-liquid chromatography (GC) with a flame ionization detector (FID) and reversed phase high performance liquid chromatography (RP-HPLC) with UV detection respectively, during 7 days of storage. Processing of lor cheese into hosmerim resulted in 1.5-fold increase in CLA concentration. The contents of CLA and -tocopherol were found as 7.13 +/- 0.06 mg/g lipid and 0.73 +/- 0.03 mg/100 g, respectively, after manufacturing of the product. Hosmerim was evaulated as a good source of CLA and -tocopherol though both nutraceutical compound decreased during 7 days of storage (p 0.01).
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    Detection of biologically active isomers of conjugated linoleic acid in kaymak
    Akalin, AS; Tokusoglu, Ö; Gönç, S; Ökten, S
    Numerous physiological effects are attributed to conjugated linoleic acids (CLA). Biologically active isomers of CLA (cis-9, trans-11 (C 1 8 : 2) and trans-10, cis-1 2 (C 1 8 : 2)) have been reported to have anticarcinogenic, antioxidative and antiatherosclerotic properties. Relatively rich sources of CLA include milk fat-containing foods such as kaymak. Kaymak is a kind of concentrated cream which is traditionally manufactured from buffalo or cow's milk mainly in Turkey,. The objective of this study was to determine CLA concentrations during kaymak production. Kaymak was manufactured from cow's milk which was enriched with unfermented cream. Biologically active isomers of CLA in raw milk, cream and kaymak were analyzed using gas chromatography. The method was quick, repeatable and sensitive for the CLA determination of samples. Significant differences were found among the concentrations of both isomer and total CLA during the production process (p < 0.01). The total GLA contents of raw milk, cream and kaymak were determined as 0.08 +/- 0.02, 0.234 +/- 0.04 and 0.091 +/- 0.08 g/ 100 g lipid, respectively.
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    Liquid chromatographic detection of α-, γ-, δ-tocopherols in infant formulas
    Akalin, AS; Tokusoglu, Ö
    Simultaneous determination of alpha-tocopherol, gamma-tocopherol and delta-tocopherol by reversed-phase liquid chromatography (RP-HPLC) with UV detection in various infant milk formulas sold in Turkey was performed. Analytical method parameters confirmed the quality of the method. Tocopherol isomers in 15 infant formulas ranged from 8.73+/-0.09 to 27.02+/-0.06 mg alpha-tocopherol in 100 g(-1), from 1.67+/-0.04 to 7.28+/-0.10 mg gamma-tocopherol in 100 g(-1); from 0.87+/-0.05 to 1.81+/-0.03 mg delta-tocopherol in 100 g(-1).
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    Fatty acid and, conjugated linoleic acid profiles of infant formulas through direct transesterification of acyl lipids
    Tokusoglu, Ö; Durucasu, I; Akalin, AS; 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%.
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    Occurrence of conjugated linoleic acid in probiotic yoghurts supplemented with fructooligosaccharide
    Akalin, AS; Tokusoglu, Ö; Gönc, S; Aycan, S
    A gas chromatographic procedure was used for the analysis of conjugated linoleic acid (CLA) isomers, c9t11-CLA and t10c12-CLA, in yoghurts containing Lactobacillus acidophilus or Bifidobacterium animalis and/or 2% fructooligosaccharide (FOS). Two groups of set yoghurts containing no supplement or 2% FOS were manufactured using three different starter cultures to determine the effect of processing, starter culture type, FOS supplementation and storage on CLA content. Processing of milk into yoghurt, the addition of FOS alone and storage for 28 d did not significantly affect CLA isomer formation in yoghurts (P > 0.05). However, significant increases in both isomer formation were obtained by using L. acidophilus or B. animalis in yoghurt manufacture (P < 0.05). The highest increases in c9t11-CLA isomer and total CLA content were found in yoghurts manufactured with L. acidophilus and FOS (2.71-fold increase in total CLA), and B. animalis and FOS (2.90-fold increase in total CLA) (P < 0.05). (c) 2007 Elsevier Ltd. All rights reserved.