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.
Ultrasound is non-thermal food processing technique that has been used in food processing very extensively for the last 10 years. The objective of this study was to investigate the effect of high power ultrasound and pasteurization on rheological properties (n and k) of apple, cranberry and blueberry juice and nectar. Samples were treated according the experimental design, with high power sonicator at ultrasound frequency of 20 kHz under various conditions (treatment time, temperature of sample and amplitude). Thermosonication and sonicaton of juice and nectar samples have been performed. It was found that all samples of untreated, pasteurized and ultrasonically treated apple, cranberry and blueberry juices and nectars shows non-Newtonian dilatant fluid characteristics (n>1). The interaction of treatment time and temperature of sample (BC) and temperature (C) of sample of apple juice had statistically significant effect on flow behavior index (n) for ultrasound treated apple juice. Interaction of treatment time and temperature of sample (BC) has statistically significant effect on the flow behavior index (n) for blueberry nectar. Also, there is statistically significant effect of temperature (C) of sample on consistency coefficient (k) for ultrasound treated apple juice.
High power ultrasound (US) and cold gas-phase plasma (CP) are non-thermal processing technologies that maybe used in food processing industry. The main objective of this research was to study the effect of both treatments on selected yeasts (Rhodotorula spp. 74 and Candida spp. 86) in pure culture. Samples were treated by ultrasound with 57.50-, 86.25-or 115-μm amplitude, for 3, 6 or 9 min at 20°C, and 40 or 60°C in the case of thermosonication. For cold gas-phase plasma treatments, samples were treated at a gas flow of 0.75, 1 or 1.25 L min −1 , treatment time of 3, 4 or 5 min, and sample volume of 2, 3 or 4 mL. Each technology has its own advantages and is able to give the best effect on the desired target product. The experiment was designed using central composite design (CCD), and results were analysed and presented using response surface methodology (RSM). The greatest reduction of yeasts was observed after ultrasound treatments at 60°C (thermosonication) and after plasma treatments, after the longest treatment time (5 min) and the lowest sample volume (2 mL). For high power ultrasound treatment, reduction in the number of yeast cells (N) can be attributed to elevated temperature (60°C), cavitation and free radical formation. For plasma treatment, the inactivation can be attributed to UV radiation and plasma reactive oxygen species (ROS).
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