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Öğe Characterizing volatile compounds and proteolysis in Gokceada artisanal goat cheese(Elsevier, 2013) Hayaloglu, A. A.; Yasar, K.; Tolu, C.; Sahingil, D.The objective of the study was to determine the gross composition, proteolysis and volatile compounds in Gokceada goat cheese and to provide initial information on its manufacturing and ripening processes. Gokceada goat cheese is traditionally manufactured from raw goat milk in Gokceada (Imbros) island, Canakkale, Turkey. In the present study, 23 commercial samples were characterized. Urea-polyacrylamide gel electrophoresis of the water-insoluble fractions showed that both alpha(s)- and beta-caseins were extensively decomposed, but beta-casein was less degraded compared to alpha(s)-casein. RP-HPLC of peptide profiles in the water-soluble fractions demonstrated qualitative and quantitative differences among the samples. Sixty volatile compounds were identified by SPME/GC-MS technique with alcohols and esters as the principal class of volatile components in the cheeses. In general, relatively large variability in gross composition and concentration of volatile aroma was found, which probably reflects lack of standardization in the production of the cheese. (C) 2013 Elsevier B.V. All rights reserved.Öğe Influence of goat breeds and starter culture systems on gross composition and proteolysis in Gokceada goat cheese during ripening(Elsevier, 2013) Hayaloglu, A. A.; Tolu, C.; Yasar, K.Milk from two different breeds (Gokceada and Turkish Saanen) and three different starter culture systems (starter-free, mesophilic and thermophilic cultures) were used in the manufacture of Gokceada goat cheeses. Milk from the two breeds differed in dry matter, protein, fat and ash contents. These differences were reflected on the yield and chemical composition of the cheese. The pH values and soluble nitrogen fractions (in water, 12% trichloroacetic acid, and 5% phosphotungstic acid) were significantly influenced by the starter culture systems, but not the types of milk. The degradation of alpha(s)-caseins and its degradation products sharply increased after 60 days of ripening, especially in the cheese made using mesophilic starters. Greater changes were observed in RP-HPLC peptide profiles of the cheeses made using mesophilic starter cultures during ripening; however, the breed has minor effect on peptide profile. In conclusions, cheeses made using mesophilic starter culture exhibited different proteolysis patterns during ripening and the milk from Gokceada breed increased the gross composition parameters and cheese yield. (C) 2013 Elsevier B.V. All rights reserved.Öğe Physical, chemical and flavour quality of non-fat yogurt as affected by a ?-glucan hydrocolloidal composite during storage(Elsevier Sci Ltd, 2008) Sahan, N.; Yasar, K.; Hayaloglu, A. A.In this study, a possible use of beta-glucan hydrocolloidal composite as a fat replacer in the manufacture of non-fat yogurts was investigated. The yogurts with added beta-glucan composite were compared with non-fat yogurt without addition of beta-glucan composite and the samples were analysed for physical, chemical and sensory attributes after 1, 7 or 15 d of storage. Fat and protein contents of the experimental yogurts were identical, while ash content differed. Addition of beta-glucan composite did not show a significant change of pH, titratable acidity, acetaldehyde, volatile fatty acids and tyrosine contents at any storage time. Titratable acidity and tyrosine content increased significantly throughout storage. Gel firmness and water-holding capacity in the yogurts were not influenced by addition of beta-glucan composite, but these variables decreased with storage time. Addition of beta-glucan composite and storage time caused a decrease in whey separation. Viscosity values in the yogurts increased by addition of beta-glucan composite and storage time. Sensory results indicated a preference for control yogurts; however, use of low levels of beta-glucan composite in the production of non-fat yogurt gave satisfactory sensory scores. Yogurts containing 0.25% or 0.50% beta-glucan hydrocolloidal composite were acceptable by expert panels and had scores similar to the control yogurt. (C) 2007 Elsevier Ltd. All rights reserved.Öğe Volatiles and sensory evaluation of goat milk cheese Gokceada as affected by goat breeds (Gokceada and Turkish Saanen) and starter culture systems during ripening(Elsevier Science Inc, 2013) Hayaloglu, A. A.; Tolu, C.; Yasar, K.; Sahingil, D.The effect of goat breed and starter culture on volatile composition and sensory scores in goat milk cheese was studied during 90 d of ripening. Milk from 2 goat breeds (Gokceada and Turkish Saanen) and different starter culture systems (no starter, mesophilic and thermophilic starters) were used in the manufacture of goat milk cheeses (called Gokceada goat cheese). Volatile composition was determined by a solid-phase microextraction gas chromatography-mass spectrometric method. Sixty compounds including esters (13), carboxylic acids (7), aldehydes (6), ketones (8), alcohols (14), and miscellaneous compounds (12) were identified. Esters, alcohols, and carboxylic acids were the main classes of volatile components in the cheeses. Both qualitatively and quantitatively, the use of different starter cultures and goat breeds significantly influenced the volatile fraction of goat milk cheese. Decanoic, hexanoic, and octanoic (commonly named capric, caproic, and caprylic) acids were indicator compounds to distinguish the goat breeds. Principal component analysis grouped the cheeses based on the use of starter culture and goat breed. Starter-free cheeses were separately located on the plot and age-related changes were present in all samples. Sensory evaluation of 90-d-old cheeses showed that the cheeses from the Gokceada breed received higher odor, flavor, and quality scores than those from the Turkish Saanen breed, and cheeses made using mesophilic starters resulted in the most satisfactory scores for flavor and quality attributes. In conclusion, goat milk cheeses made using milk from Gokceada goats and mesophilic starter culture had the best quality in terms of volatile composition and sensory attributes.
