Browsing by Author "Panaro, Eleonora"
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- Enhancing the safety and quality of blueberry juice by thermosonicationPublication . Panaro, Eleonora; Silva, Cristina L. M.; Miller, Fátima A.According to consumers' newest preferences, the juice segment is expanding in the market, especially using novel high technologies for processing. Ultrasound is an up-and-coming technology increasingly being applied in the food field since it can minimize the undesirable effects of thermal processing. This study aimed to evaluate the influence of thermosonication on the inactivation kinetics of L. innocua 2030c, a non-pathogenic surrogate of L. monocytogenes, in blueberry juice. Thermal treatments were conducted as controls, and both processes' impact was assessed on some physicochemical attributes of the juice. Blueberry fruit was chosen since it is recognized as a superfruit due to its high content of health-promoting compounds. Juice samples were prepared by defrosting frozen blueberries and using a domestic centrifuge. Freshly prepared juices were inoculated with L. innocua subculture (~109 CFU/mL). Thermosonication at two amplitude levels (60 and 100%) with a pulse duration of 10 sec on and 5 sec off was applied using a sonicator probe (700 W, 20 kHz). Thermosonication and thermal treatments were performed at 45 and 55 °C until a 5-log reduction was achieved. Physicochemical parameters of the juice (pH, total soluble solids, water activity, and color) were analyzed in fresh and treated samples. All treatments/analyses were performed in triplicate. The Weibull model was successfully applied to fit L. innocua inactivation kinetic by regression analysis. The processing times needed to achieve a 5-log reduction were, in the case of thermosonicated samples, much shorter (1 and 25 min) than the heated ones (10 and 60 min), showing the effectiveness of the synergistic effect of ultrasound and mild heating compared to heat treatment alone. For thermosonication treatments, the first decimal reduction time () obtained at 55 °C was 5.13 ± 0.83 and 4.26 ± 0.36 min, respectively, for 100 and 60% amplitudes. At 45 °C, those values were reduced to 1.15 ± 0.49 and 0.51 ± 0.17 min. When thermal treatments were used, decreased to 1.18 ± 0.33 (55 HT) and 0.08 ± 0.09 min (45 HT), showing the dependence on temperature and process. Thermosonication processes were more effective in microbial inactivation and retaining quality parameters than thermal procedures, with thermosonication at 45 °C the best treatment for blueberry juice.
- Enhancing the safety and quality of blueberry juice by thermosonicationPublication . Panaro, Eleonora; Silva, Cristina L. M.; Miller, Fátima A.
- The power of thermosonication on quality preservation and listeria control of blueberry juicePublication . Panaro, Eleonora; Brandão, Teresa R. S.; Silva, Cristina L. M.; Miller, Fátima A.Due to the increasing consumer demand for healthy, beneficial foods, natural fruit juices have gained popularity for their rich nutritional value and appealing flavor. However, traditional thermal processing can compromise these quality attributes. This study investigates using pulsed thermosonication, a novel mild thermal processing method, on Listeria innocua inactivation in blueberry juice, chosen for its high phenolic and anthocyanin content. Ultrasonication was applied at 60% and 100% amplitudes combined with heat treatments at 45 °C and 55 °C and compared to control heat treatments. The Weibull model effectively described the inactivation kinetics, showing that the thermosonicated samples required significantly shorter times (1 and 25 min) for a 5-log reduction compared to the heated samples (10 and 60 min). While pH, total soluble solids, and water activity remained unaffected, color parameters improved, and the best retention of phenolics and anthocyanins was observed at 100% amplitude and 45 °C. Rheological properties were unchanged. The findings demonstrate that thermosonication at milder temperatures is more effective than conventional heat treatment for microbial inactivation and quality retention in blueberry juice, suggesting it is a superior processing method for preserving fruit juices’ nutritional and sensory attributes.
- Thermosonication impact on blueberry juice quality preservationPublication . Panaro, Eleonora; Silva, Cristina L. M.; Brandão, Teresa R. S.; Miller, Fátima A.The FIVE A DAY rule promotes fruit juice consumption for its flavor and nutritional benefits, aiming to fulfill daily nutrient requirements. However, thermal processing challenges food products' nutritional quality, prompting a rise in non-thermal methods within the beverage market to promote healthier choices. This study explores the application of ultrasound, an emerging, cost effective, energy-efficient, and eco-friendly technology. Blueberries, recognized as superfruits for their high content of health-promoting compounds, were chosen for their phenolic and anthocyanin amounts. To develop a high-quality blueberry juice through the application of thermosonication treatments. • Safety indicator - Listeria innocua, a non-pathogenic surrogate of Listeria monocytogenes. • Quality indicators – Total phenolics, anthocyanins and rheological properties (shear rate and shear stress).