Vitamin D formation in milk by ultraviolet treatment-Novel insights into a rediscovered process.

Vitamin D is essential for several functions in the human body and the demand is usually covered by natural reactions in skin with UV radiation delivered by the sun. But living beyond a latitude of 35° can lead to a lack of sufficient exposure to the deciding wavelength. Here, many countries fortify their milk prophylactically with artificial vitamin D.

Observation of a temperature dependent anomaly in the UV translucency of milk useful for UV-C preservation techniques.

Milk fat globules and casein micelles are the dispersed particles of milk that are responsible for its typical white turbid appearance and usually make it difficult to treat with modern ultraviolet light (UV) preservation techniques. The translucency of milk depends largely on the refractive indices of the dispersed particles, which are directly affected by temperature changes, as incorporated triglycerides can crystallize, melt or transition into other polymorphs. These structural changes have a significant effect on the scattering properties and thus on the UV light propagation in milk, especially by milk fat globules.

Uridine as a non-toxic actinometer for UV-C treatment: influence of temperature and concentration.

UV-C treatment is an effective method to inactivate microorganisms and therefore gets increasingly more attention in food industry, especially for liquid products. To test and monitor different UV-C reactor designs, a photochemical actinometer is required that gives reliable UV-C dose values and is non-toxic allowing frequent control of the production chain. Here, a variable concentrated aqueous uridine solution is tested as a photochemical actinometer.

Inactivation of E. coli and L. innocua in milk by a thin film UV-C reactor modified with flow guiding elements (FGE).

In this study the suitability of a thin-film reactor (TFR) equipped with special flow guiding elements (FGE) was examined to analyse its capability to inactivate microorganisms in milk. Experiments were carried out with UHT-milk inoculated with Escherichia coli (E. coli), DH5α and Listeria innocua (L.

Experimental setup and image processing method for automatic enumeration of bacterial colonies on agar plates.

Automated colony counting methods have long been known in Microbiology. Numerous methods for automated image analysis have been described and a wide range of commercial products exists. Known advantages are saving cost by reducing enumeration time, automatic documentation, reproducibility, and operator independence.

Actinometric and biodosimetric evaluation of UV-C dose delivery in annular, Taylor-Coutte and coiled tube continuous systems.

In this study, the evaluation of the performance of two thin-film UV-C reactors (annular and Taylor-Couette) and a coiled tube system is presented using actinometry and biodosimetry methods. The iodide/iodate actinometry method was found suitable for comparison of the efficiency of UV-C dose delivery of the UV-C continuous flow systems. Inactivation kinetics of Escherichia coli ATCC 8739 in quarter-strength Ringer's solution (absorption coefficient α ∼ 0 cm) at various flow conditions at Reynolds numbers in the range of 26 to 3000 showed a good correlation between the different reactor types.

Cyto-genotoxic and oxidative effects of a continuous UV-C treatment of liquid egg products.

UV-C treatment of food is a promising non-thermal processing technology to improve food safety and preservation. Most of the chemical constituents of food absorb UV-C light that can lead to chemical modifications and quality changes. This work investigated the effects of UV-C treatment of liquid egg products on lipid, protein oxidations and potential cyto- and genotoxic effects on intestinal epithelial cells in vitro.

Post-irradiation changes of the volatile oil constituents of Monodora myristica (Gaertn) Dunal.

Volatile oil rich spices cannot be sterilised by pasteurisation because of the presence of thermal-sensitive components. In this article, we report the effect of irradiation on the volatile constituents of Monodora myristica. The samples were irradiated at ambient conditions at dose levels of 0 and 15 kGy using a linear accelerator at a dose rate of approximately 10(7) Gy s(-1).