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    The effect of inulin as a fat replacer on the quality of set-type low-fat yogurt manufacture
    (Wiley, 2005) Guven, M; Yasar, K; Karaca, OB; Hayaloglu, AA
    The influence of different levels of inulin on the quality of fat-free yogurt production was investigated. Inulin was added to milk containing 0.1% of milk fat to give inulin levels of 1, 2 and 3%. The experimental yogurts were compared with control yogurt produced from whole milk. The total solids content of milk was standardized to 14% by adding skim milk powder to the experimental yogurt. The chemical composition, pH, titratable acidity, whey separation, consistency, acetaldehyde and volatile fatty acidity contents were determined in the experimental yogurts after 1, 7 and 15 days. Sensory properties of the yogurts were evaluated during storage. The addition of inulin at more than 1% increased whey separation and consistency. Acetaldehyde, pH and titratable acidity were not influenced by addition of inulin. Tyrosine and volatile fatty acidity levels were negatively affected by inulin addition. With respect to the organoleptic quality of yogurt, inulin addition caused a decrease in organoleptic scores: the control yogurt had the highest score, and the lowest score was obtained in yogurt samples containing 3% of inulin. Overall, the yogurt containing 1% of inulin was similar in quality characteristics to control yogurt made with whole milk.
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    Influence of salt concentration on the characteristics of Beyaz cheese, a Turkish white-brined cheese
    (Edp Sciences S A, 2006) Guven, M; Yerlikaya, S; Hayaloglu, AA
    Beyaz cheese (Turkish white-brined cheese) was ripened in four different brines with 12, 14, 16 or 18 g NaCl center dot 100 g(-1) water (w/w) at 7 +/- 1 degrees C for 9 weeks. The effect of NaCl concentration on gross composition, proteolysis, sensory characteristics and hardness of the cheeses were investigated during ripening. The cheeses ripened in varying concentrations of NaCl differed in pH values, dry matter, total protein, hardness (mm/5 s), 12% (w/v) trichloroacetic acid-soluble nitrogen fraction and hydrolysis of beta-casein, but they did not differ in water-soluble nitrogen or hydrolysis of alpha(s1)-casein. The cheeses ripened in a 12 g NaCl center dot 100 g(-1) brine had the best flavour score and overall acceptability by the panellists. The results obtained from this study indicated that increase in NaCl concentration in brine (more than 14 g center dot 100 g(-1)) is correlated with lower levels of proteolysis and overall acceptability in Beyaz cheese.
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    Influence of starters on chemical, biochemical, and sensory changes in Turkish White-brined cheese during ripening
    (Elsevier Science Inc, 2005) Hayaloglu, AA; Guven, M; Fox, PF; McCweeney, PLH
    Turkish White-brined cheese was manufactured using Lactococcus strains ( Lactococcus lactis ssp. lactis NCDO763 plus L. lactis ssp. cremoris SK11 and L. lactis ssp. lactis UC317 plus L. lactis ssp. cremoris HP) or without a starter culture, and ripened for 90 d. It was found that the use of starters significantly influenced the physical, chemical, biochemical, and sensory properties of the cheeses. Chemical composition, pH, and sensory properties of cheeses made with starter were not affected by the different starter bacteria. The levels of soluble nitrogen fractions and urea-PAGE of the pH 4.6-insoluble fractions were found to be significantly different at various stages of ripening. Urea-PAGE patterns of the pH 4.6-insoluble fractions of the cheeses showed that considerable degradation of alpha(s1)-casein occurred and that beta-casein was more resistant to hydrolysis. The use of a starter culture significantly influenced the levels of 12% trichloroacetic acid-soluble nitrogen, 5% phosphotungstic acid-soluble nitrogen, free amino acids, total free fatty acids, and the peptide profiles ( reverse phase-HPLC) of 70% (vol/vol) ethanol-soluble and insoluble fractions of the pH 4.6-soluble fraction of the cheeses. The levels of peptides in the cheeses increased during the ripening period. Principal component and hierarchical cluster analyses of electrophoretic and chromatographic results indicated that the cheeses were significantly different in terms of their peptide profiles and they were grouped based on the use and type of starter and stage of ripening. Levels of free amino acid in the cheeses differed; Leu, Glu, Phe, Lys, and Val were the most abundant amino acids. Nitrogen fractions, total free amino acids, total free fatty acids, and the levels of peptides resolved by reverse phase-HPLC increased during ripening. No significant differences were found between the sensory properties of cheeses made using a starter, but the cheese made without starter received lower scores than the cheeses made using a starter. It was found that the cheese made with strains NCDO763 plus SK11 had the best quality during ripening. It was concluded that the use of different starter bacteria caused significant differences in the quality of the cheese, and that each starter culture contributed to proteolysis to a different degree.
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    Proteolysis in Turkish White-brined cheese made with defined strains of Lactococcus
    (Elsevier Sci Ltd, 2004) Hayaloglu, AA; Guven, M; Fox, PF; Hannon, JA; McSweeney, PLH
    The effects of defined lactococcal starter strains (UC317, NCDO763, HP or SK11) on proteolysis in Turkish White-brined cheese were studied throughout ripening (1, 15, 30, 60 or 90 days). No significant differences were found in the gross compositions of the cheeses made with different strains, although the pH values were slightly different. Proteolysis was assessed at each ripening time by urea-polyacrylamide gel electrophoresis (urea-PAGE) of the pH 4.6-insoluble fractions and by reversed-phase high performance liquid chromatography (RP-HPLC) of the pH 4.6-soluble, the 70% (v/v) ethanol-soluble or 70% (v/v) ethanol-insoluble fractions of the cheese samples. Only minor differences were apparent during early ripening (at 1 or 15 days) but considerable differences were found in the urea-PAGE patterns after 60 days of ripening. Urea-PAGE of the pH 4.6-insoluble fraction of the cheeses showed that alpha(s1)-casein was hydrolysed more rapidly than beta-casein. The use of single strains of Lactococcus markedly influenced the peptide profiles obtained by RP-HPLC of the pH 4.6-soluble or 70% (v/v) ethanol-soluble or 70% (v/v) ethanol-insoluble fractions of the cheeses. Significant differences in the level of free amino acids were also observed between the cheeses; the cheeses made with NCDO763 or SK11 had the highest concentrations of free amino acids. The use of different lactococcal strains in the manufacture of Turkish White-brined cheese affected the degradation of alpha(s1)-casein, the formation of peptides detectable by RP-HPLC and the level of free amino acids. (C) 2004 Elsevier Ltd. All rights reserved.