Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
Browse
2 results
Search Results
Article Citation - WoS: 59Citation - Scopus: 71Microbial Safety and Shelf Life of Uv-C Treated Freshly Squeezed White Grape Juice(John Wiley and Sons Inc., 2015) Ünlütürk, Sevcan; Atılgan, Mehmet ReşatThe effects of UV-C irradiation on the inactivation of Escherichia coli K-12 (ATCC 25253), a surrogate of E. coli O157:H7, and on the shelf life of freshly squeezed turbid white grape juice (FSWGJ) were investigated. FSWGJ samples were processed at 0.90 mL/s for 32 min by circulating 8 times in an annular flow UV system. The UV exposure time was 244 s per cycle. The population of E. coli K-12 was reduced by 5.34 log cycles after exposure to a total UV dosage of 9.92 J/cm2 (1.24 J/cm2 per cycle) at 0.90 mL/s flow rate. The microbial shelf life of UV-C treated FSWGJ was extended up to 14 d at 4 °C. UV exposure was not found to alter pH, total soluble solid, and titratable acidity of juice. There was a significant effect (P < 0.05) on turbidity, absorbance coefficient, color, and ascorbic acid content. Furthermore, all physicochemical properties were altered during refrigerated storage. The microbial shelf life of FSWGJ was doubled after UV-C treatment, whereas the quality of juice was adversely affected similarly observed in the control samples. Practical Applications: UV-C irradiation is a non-thermal method used for processing of fruit juices with a minimal or no changes in flavor, essential nutrients, and vitamins. Fresh grape juice is a popular drink, usually consumed at summer time due to many beneficial health effects. Although thermal pasteurization is widely used for extending the shelf life of fruit juices, it causes a "cook taste" in grape juice. The applicability of UV-C irradiation as an alternative to thermal pasteurization was investigated. It is concluded that UV-C treatment can be used for extending the shelf life of fresh grape juice.Article Citation - WoS: 8Citation - Scopus: 8Differential Scanning Calorimetry as a Tool To Detect Antibiotic Residues in Ultra High Temperature Whole Milk(John Wiley and Sons Inc., 2009) Yıldız, Özge; Ünlütürk, SevcanDetection of penicillin G, ampicillin and tetracycline in ultra high temperature whole milk was studied by differential scanning calorimetry (DSC). Thermal parameters including the heat of fusion, the evaporation temperature, the heat of evaporation and the melting temperature obtained from DSC analysis were used to characterise thermal behaviour of antibiotic free milk samples and milk samples fortified with Penicillin G, Ampicillin and Tetracycline. DSC curves of these antibiotics at selected concentrations (0, 2, 4, 8 ppb for Penicillin G and Ampicillin; 0, 100, 250, 500 ppb for Tetracycline) show big endothermic peaks in the temperature range of -30 °C and 200 °C. It was concluded that the antibiotic concentration had a significant effect on the thermal parameters at a 95% confidence level. The differences between the melting temperatures and the peak areas in heat flow curves provided a basis for detection of antibiotic residues in UHT whole milk.