Hrvoje Juretić

Photodegradation of Natural Organic Matter in Water with UV Irradiation at 185 and 254 nm: Importance of Hydrodynamic Conditions on the Decomposition Rate

Abstract The kinetic investigation of photodegradation of the natural organic matter (NOM) in natural lake water was conducted using two low‐pressure mercury lamps of the same nominal power: a) with suprasil quartz envelope emitting at both wavelengths −254 nm and 185 nm (hereafter VUV); b) with standard quartz envelope emitting only at 254 nm (hereafter UV). In comparison to the UV process, the addition of 185 nm irradiation (VUV process) increased the degradation rate ten‐fold overall at lower and seventeen‐fold at higher Reynolds numbers, respectively. The hydrodynamic characteristics of the photoreactor are of crucial importance for total energy efficiency for VUV processes.

Pilot Studies of Ozonation for Inactivation of Artemia salina Nauplii in Ballast Water

A pilot-plant study was conducted in the Republic of Croatia to determine the applicability of ozonation for inactivation of non-indigenous species and to provide necessary information regarding use of ozone as a ballast water treatment option. Nauplii of the brine shrimp Artemia salina were used as model organisms to investigate the efficacy of ozonation at three different ozone dosages (2.4, 3.7 and 10.9 mg L−1). Mortality of Artemia nauplii at 98.6%, was achieved after 3 h of exposure in ozone-treated water with the highest ozone dosage. Our results indicated that ozonation is a promising treatment for controlling non-indigenous and potentially invasive species; however, to draw more general conclusions, several species with higher level of resistance to ozone are required and will be studied in the future.

Aromatic profile and sensory characterisation of ultrasound treated cranberry juice and nectar

Ultrasonication is a nonthermal food processing technology that is used in several applications (extraction, pretreatment before drying, freezing, inactivation of microorganisms etc.). The objective of this study was to investigate the effect of high power ultrasound and pasteurisation on the aroma profile and sensory properties of cranberry juice and nectar. Samples were treated according to the experimental design, with high power sonicator at ultrasound frequency of 20kHz under various conditions (treatment time 3, 6 and 9min, sample temperature: 20, 40 and 60°C and amplitude 60, 90 and 120μm). The aromatic profiles of juices showed that, compared to the untreated samples of juices and nectars, the ultrasonic treatment led to the formation of new compounds or to the disappearance of compounds that were found in the untreated samples. Samples treated at the highest amplitude (120μm) were used for evaluation and comparison with untreated and pasteurised samples using electronic tongue study. Principle component analysis (PCA) confirmed the results of electronic tongue study, which showed that the ultrasound-treated and pasteurised juices had different scores compared to the untreated samples. Sensory evaluation showed that ultrasonically treated and pasteurised juices received lower scores in comparison with the untreated samples.