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    Influence of exopolysaccharide-producing cultures on the volatile profile and sensory quality of low-fat Tulum cheese during ripening
    (Wiley, 2014) Oluk, Aylin C.; Guven, Mehmet; Hayaloglu, Ali Adnan
    The objective of this investigation was to compare the composition and changes in the concentration of volatiles in low-fat and full-fat Tulum cheeses during ripening. Tulum cheese was manufactured from low- or full-fat milk using exopolysaccharide (EPS)-producing or non-EPS-producing starter cultures. A total of 82 volatile compounds were identified belonging to the following chemical groups: acids (seven), esters (21), ketones (14), aldehydes (six), alcohols (14) and miscellaneous compounds (20). The relative amounts of acids, alcohols and aldehydes increased in the cheeses made with EPS-producing cultures during 90days of ripening. Differences were found in the volatile profile of full-fat Tulum cheese compared with the low-fat variant, especially after 90days of ripening. Exopolysaccharide-producing cultures changed the volatile profile, and the EPS-producing cultures including Streptococcus thermophilus+Lactobacillus delbrueckii subsp. bulgaricus+Lactobacillushelveticus (LF-EPS2) produced cheese with higher levels of methyl ketones and aldehydes than the non-EPS cultures. In the sensory analysis, full-fat Tulum cheeses and the cheese produced with the EPS-producing culture containing Lb.helveticus (LF-EPS2) were preferred by the expert panel. It was concluded that the use of EPS-producing starter cultures in the manufacture of low-fat Tulum cheese had the potential to improve the flavour.
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    Proteolysis texture and microstructure of low-fat Tulum cheese affected by exopolysaccharide-producing cultures during ripening
    (Wiley, 2014) Oluk, Aylin C.; Guven, Mehmet; Hayaloglu, Ali A.
    The objective of the study was to determine the effects of exopolysaccharide (EPS)-producing or non-EPS-producing starters on proteolysis, physical and microstructural characteristics of full-fat or low-fat Tulum cheeses during ripening. For this purpose, Tulum cheese was manufactured using full- or low-fat milk with EPS-producing and non-EPS-producing starter cultures. Chemical composition, proteolysis, texture profiles and microstructure of the cheeses were studied during 90days of ripening. Urea-PAGE of water-insoluble and RP-HPLC peptide profiles of water-soluble fractions of the cheeses showed that the use of starters resulted in different degradation patterns in all cheeses during ripening. Although -casein exhibited similar degradation patterns in all cheeses, small differences are present in (s1)-casein degradation during ripening. Reducing fat in Tulum cheese changed the RP-HPLC peptide profile of the cheeses. The use of EPS-producing cultures improved the textural characteristics and changed the microstructure and proteolysis of low-fat Tulum cheese.