Effects of Penicillium roqueforti and whey cheese on gross composition,microbiology and proteolysis of mould‐ripened Civil cheese during ripening

Four different types of mould‐ripened Civil cheese were manufactured. A defined (nontoxigenic) strain of a Penicillium roqueforti (SC 509) was used as the secondary starter with and without addition of the whey cheese (Lor); in parallel, secondary starter‐free counterparts were manufactured. Chemical composition, microbiology and proteolysis were studied during the ripening. The incorporation of whey cheese in the manufacture of mould‐ripened Civil cheese altered the gross composition and adversely affected proteolysis in the cheeses. The inoculated P. roqueforti moulds appeared to grow slowly on those cheeses, and little proteolysis was evident in all cheese treatments during the first 90 days of ripening. However, sharp increases in the soluble nitrogen fractions were observed in all cheeses after 90 days. Microbiological analysis showed that the microbial counts in the cheeses were at high levels at the beginning of ripening, while their counts decreased approximately 1–2 log cfu/g towards the end of ripening.     

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.     

Comparative Study of Bioactive Constituents in Turkish Olive Oils by LC-ESI/MS/MS

The purpose of this research was to evaluate and compare the differences in the phenolic composition, antioxidant properties, and fatty acids of virgin olive oils from the Ayvalik, Gemlik, and Memecik olive varieties cultivated in their respective growing areas over two harvest years. The phenolic composition of olive oils was carried out by liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry analysis and the fatty acid composition was determined by gas chromatography analysis. Fourteen phenolic compounds were identified and, among these, the most dominant were elenolic acid, tyrosol, and hydroxytyrosol. For olives from both years, the highest total phenolic content was determined in Memecik followed by Ayvalik and Gemlik. 2,2-diphenyl-1-picryl hydrazyl and 2,2′-azino-bis- (3-ethyl-benzothiazoline-6-sulphonic acid) methods were used to determine the antioxidant capacity of the olive oil extracts. In both methods, the antioxidant capacity values were higher for oil from cv. Ayvalik. Thirteen fatty acids were identified and quantified in all samples. Oleic acid was the highest concentration and this acid was more dominant in Gemlik oils.     

Comparison of aroma,aroma-active,and phenolic compounds of crude and refined hazelnut oils

Hazelnut (Corylus avellana L.) is an important shelled nut with its pleasant aroma. The refining process causes significant changes in the quality attributes of hazelnut oil. The aim of this study was to assess the aroma, aroma-active, and phenolic compounds of the crude and refined hazelnut oils by using gas chromatography–mass spectrometry (GC–MS), GC–MS-olfactometry (GC–MS-O), and liquid chromatography–mass spectrometry (LC–MS/MS). The antioxidant capacities were also determined by DPPH and ABTS methods. Results showed that terpenes and aldehydes constituted a significant portion of the aroma profile. Refining process dramatically reduced the numbers (from 63 to 25) and amounts of aroma compounds (from 36,769 to 4461 μg/kg). Similarly, the numbers of aroma-active compounds were reduced from 22 to 8 by the refining process. Their flavor dilution factors ranged from 2 to 1024 for crude oil and from 2 to 32 in the refined oil. As of the phenolics, five and two compounds were quantified in the crude and refined oil samples, respectively. In sum, the refining process had a considerable adverse effect on the aroma, aroma-active, and phenolic constituents of the hazelnut oil; hence, the refining process has to be planned with minimal negative effect on its organoleptic properties.     

Polythiophene/SiO2 nanocomposites prepared in the presence of surfactants and their application to glucose biosensing

Conducting polythiophene/SiO₂ (PT/SiO₂) nanocomposites were prepared in the presence of three different surfactants (anionic, cationic and non-ionic) via chemical oxidative polymerization in an anhydrous medium to create an enzyme-immobilized polymeric amperometric biosensor. An anionic surfactant, sodium dodecylbenzenesulfonate (DBSNa), a cationic surfactant, tetradecyltrimethylammonium bromide (TTAB), and a non-ionic surfactant, poly(ethylene oxide) (20) sorbitan monolaurate (Tween 20), were used as additives. The properties of the nanocomposites were investigated, as a function of surfactant type and the amount of PT contained, by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The SEM results reveal that all PT/SiO₂ samples form nanometer-dimensioned globular structures. The highest conductivity obtained was 2.7 × 10⁻² S cm⁻¹ for a PT/SiO₂-Tween 20 nanocomposite. Thermogravimetric analysis (TGA) shows that the residue decreases with increasing amount of PT. Glucose oxidase (GOX) was immobilized by crosslinking to the conducting PT/SiO₂ composites and was used for amperometric detection of glucose.     

Significance of Biogenic Amines in Foods and Their Reduction Methods

The term ＂biogenic amines＂ defines decarboxylation products such as histamine, putrescine, serotonin, tyramine, phenylethylamine, tryptamine and also aliphatic polyamines. They can be detected in both raw and processed foods. In the recent years, there is a great interest in biogenic amines as they are associated with quality, safety and freshness of some foods, particularly fermented foods. The presence of biogenic amines in foods can also be used as an indicator of hygienic quality. Biogenic amines also cause health hazards due to their toxic effects especially in sensitive individuals. It is therefore important to control and reduce the biogenic amines. The reduction can be brought about by the use of high pressure, irradiation, packaging, additives, starter cultures and by reduction of decarboxylase activity and temperature. This review summarizes the significance, function, occurrence and formation of biogenic amines in different foods and their reduction by different methods.