Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
Browse
2 results
Search Results
Book Part Citation - Scopus: 8Uv Processing and Storage of Liquid and Solid Foods: Quality, Microbial, Enzymatic, Nutritional, Organoleptic, Composition and Properties Effects(Elsevier, 2021) Hakgüder Taze, Bengi; Pelvan Akgün, Merve; Hakgüder Taze, Bengi; Kaya, Zehra; Ünlütürk, Sevcan; 01. Izmir Institute of Technology; 03.08. Department of Food Engineering; 03. Faculty of EngineeringNon-thermal food processing technologies have been explored extensively in recent years in order to develop food products with extended shelf life as well as preserved nutritional and organoleptic characteristics in accordance with the changing consumer demands (Falguera et al., 2011a; Sanchez-Moreno et al., 2009). Ultraviolet (UV) irradiation is one of the non-thermal processes that can be applied to reduce the microbial load in liquid foods and surfaces, and to sterilize food packages and packaging materials, and environments involved in food processes (Jimenez-Sanchez et al., 2017a; Bintsis et al., 2000). UV light is subdivided into three regions as short-wave UV (UV-C, 200 and 280 nm), medium-wave UV (UV-B, 280 to 315 nm), and long wave UV (UV-A, 315 to 400 nm). The different types of effects on microorganisms can be caused by UV light of different wavelengths. The effectiveness of UV light on microorganisms results primarily from the fact that DNA molecules absorb UV photons between 200 and 300 nm, with peak absorption around 260–265 nm. This causes DNA damage by altering the nucleotide base pairing, thereby creating new linkages between adjacent nucleotides, particularly between pyrimidine bases, on the same DNA strand and ultimately results in cell death (Zimmer and Slawson, 2002). Peak et al. (1984) proposed that the dimer formation is not the only requirement to damage the DNA. Absorption of different wavelength photons by different molecular groups in the long DNA molecule can damage or destroy these bond groups. Thus, different bonds in the DNA can be affected with photons of different energy (Neister, 2014).Article Citation - WoS: 82Citation - Scopus: 103Effect of Uv-C Irradiation and Heat Treatment on the Shelf Life Stability of a Lemon-Melon Juice Blend: Multivariate Statistical Approach(Elsevier Ltd., 2015) Kaya, Zehra; Yıldız, Semanur; Ünlütürk, Sevcan; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyHeat treatment and UV-C irradiation of lemon and melon juice (LMJ) blends were comparatively evaluated by examining their impact on E. coli K12 (ATCC 25253) and their physicochemical properties, i.e., total soluble solids (TSS), pH, titratable acidity (TA), color, turbidity and absorbance coefficient, both immediately after processing and during 30 days of refrigerated storage. The newly formulated LMJ blend containing 12% (v/v) lemon juice (pH 3.92 ± 0.01) scored the highest in the consumer acceptance test. Upon UV-C irradiation (2.461 J/mL) and heat treatment (72 °C, 71 s), the E. coli K12 population in LMJ blend was reduced by > 6 log10 CFU/mL. Principal component analysis (PCA) and hierarchical cluster analyses (HCA) showed a clear discrimination among the physicochemical properties of the control and the UV-C and heat-treated LMJ blends during storage, suggesting that UV-C irradiation has a comparable effect on microbial stability at 4 °C and better quality preservation performance than heat treatment. Industrial relevance Melon juice has many beneficial health effects. It has high sugar content, pH (5.6-6.0) and a fairly short shelf life. Therefore, pasteurization is required. But the thermal pasteurization has some undesired effects on the juice quality. Consumer demands for high quality fruit juice with fresh-like characteristics has markedly expanded in recent years. In this study, an alternative lemon-melon juice (LMJ) blend formulation was developed, and pasteurized using both UV-C irradiation and mild heat treatment. The shelf life stability of pasteurized LMJ blends was assessed by means of principal component analysis and hierarchical cluster analysis. The shelf life of LMJ blends treated by both methods was increased from 2 days to 30 days. The multivariate data analysis was successfully applied as a tool for an overall evaluation of the shelf-life of the product. UV-C irradiation has a comparable effect on microbial stability at 4 °C and better quality preservation performance than heat treatment for obtaining both shelf-stable and fresh-like LMJ blends. This would be a major advantage in processing of nutritious juice products.