Elif Dagdemir

Mycotoxin production capability of Penicillium roqueforti in strains isolated from mould-ripened traditional Turkish civil cheese

Mould-ripened civil is a traditional cheese produced mainly in eastern Turkey. The cheese is produced with a mixture of civil and whey curd cheeses (lor). This mixture is pressed into goat skins or plastic bags and is ripened for more than three months. Naturally occurring moulds grow on the surface and inside of the cheese during ripening. In this research, 140 Penicillium roqueforti strains were isolated from 41 samples of mould-ripened civil cheese collected from Erzurum and around towns in eastern Turkey. All strains were capable of mycotoxin production and were analysed using an HPLC method. It was established that all the strains (albeit at very low levels) produced roquefortine C, penicillic acid, mycophenolic acid and patulin. The amounts of toxins were in the ranges 0.4–47.0, 0.2–43.6, 0.1–23.1 and 0.1–2.3 mg kg−1, respectively. Patulin levels of the samples were lower than the others. The lowest level and highest total mycotoxin levels were determined as 1.2 and 70.1 mg kg−1 respectively. The results of this preliminary study may help in the choice of secondary cultures for mould-ripened civil cheese and other mould-ripened cheeses.

Morphological, molecular, and mycotoxigenic identification of dominant filamentous fungi from moldy civil cheese.

Moldy Civil is a mold-ripened variety of cheese produced mainly in eastern Turkey. This cheese is produced with Civil cheese and whey curd cheese (Lor). Civil cheese has had a geographical presence since 2009 and is manufactured with skim milk. In the production of Moldy Civil cheese, Civil cheese or a mixture of Civil and Lor cheese is pressed into goat skins or plastic bags and ripened for 3 months or longer. During the ripening period, natural contaminating molds grow on the surface of and inside the cheese. In this study, 186 mold strains were isolated from 41 samples of Moldy Civil cheese, and 165 of these strains were identified as Penicillium roqueforti. Identification and mycotoxicologic analyses were conducted using morphotypic and molecular methods. PCR amplicons of the ITS1-5.8S-ITS4 region were subjected to sequence analysis. This research is the first using molecular methods on Moldy Civil cheese. Mycotoxicologic analyses were conducted using thin-layer chromatography, and random amplified polymorphic DNA genotypes were determined using the ari1 primer. Of 165 isolates, only 28 produced no penicillic acid, P. roqueforti toxin, or roquefortine.

Effect of Penicillium roqueforti and incorporation of whey cheese on volatile profiles and sensory characteristics of mould‐ripened Civil cheese

In this study, four different types of mould-ripened Civil cheese were manufactured. A defined (nontoxigenic) strain of a Penicillium roqueforti (SC 509) was used as secondary starter for the manufacture of mould-ripened Civil cheese with and without addition of the whey cheese Lor; in parallel, secondary starter-free counterparts were manufactured. A total of 83 compounds were identified. Ketones, alcohols and esters were the principal classes of volatile components. Principal component analysis of the headspace volatiles grouped cheeses by age and type. P. roqueforti inoculated cheese was clearly separated from the other cheeses at 180 days of ripening, and these cheeses were characterised with high levels of ketones (e.g., 2-butanone, 2-heptanone). Differences in the panel scores between the cheese samples were not significant during the first stage of ripening (up to 60 days); as ripening proceeded, these differences were become evident and P. roqueforti inoculated cheeses received higher scores than others. Addition of Lor in the manufacture of mould-ripened Civil cheese caused lower points by the sensory panel, and the cheese inoculated with P. roqueforti and Lor-free was the best type of mould-ripened Civil cheese. The results showed that the use of P. roqueforti in the manufacture of mould-ripened Civil cheese has significant impact on the volatile profiles and sensory attributes.

A preliminary study on functionality of Gundelia tournefortii L. as a new stabiliser in ice cream production

The aim of this study was to investigate the effect of Gundelia tournefortii L. leaves and G. tournefortii L. milk as a new natural stabiliser on the quality characteristics of ice cream. For this aim, G. tournefortii L. leaves were added to an ice cream mix at three different concentrations (0.6, 1.0 and 3.0% w/w), and also, its milk was used as a stabiliser at 0.6% w/w concentration for ice cream production. Certain physical and sensorial characteristics of ice creams were compared with those of some commercial food gums such as guar gum, carrageenan and salep. Also, the chemical structure of G. tournefortii L. milk was determined using infrared spectra and elemental analyses. In comparison with commercial stabilisers, G. tournefortii L. did not display a notable effect on quality characteristics (viscosity, overrun, first dripping times and complete melting times). However, when considering these quality characteristics, the values for G. tournefortii L. milk were close to the values obtained for the commercial gums. In terms of sensorial characteristics, all the concentrations of G. tournefortii L. leaves were given low scores by panellists compared to the commercial stabiliser. However, G. tournefortii L. milk was given scores similar to the commercial stabiliser.