This work evaluated the effectiveness of 1 and 2% acetic and lactic acid, 3% hydrogen peroxide, 200 mg/L sodium hypochlorite and 200 mg/L sodium dichloroisocyanurate to reducing natural contaminants as well as Salmonella enterica Enteritidis inoculated on the surface of strawberries, cucumbers, and rocket leaves. The reduction of aerobic mesophilic and molds and yeasts was between 1.67-2.73 and 0.61-1.46 log CFU/g in strawberries, 1.48-2.19 and 1.02-2.01 log CFU/g on rocket leaves, and 1.10-2.08 and 0.88-1.58 log CFU/g in cucumbers, respectively. The most effective sanitizers for reducing Salmonella enterica Enteritidis in strawberries were 1% and 2% lactic acid, while in cucumbers and rocket leaves was the 2% lactic acid as well as the 3% hydrogen peroxide, for both samples. The results of this study clearly show the potential of the proposed strategies to replace chlorinated compounds in the sanitization step of fresh produce.

This study aimed to evaluate the effects of different sanitization solutions on the physicochemical characteristics of strawberries, cucumbers, and rocket leaves. In each procedure, 200 g of the sample was immersed in 1 L of sanitizing solution for 5 minutes. Strawberries, cucumbers and rocket leaves were sanitized with acetic, and lactic acid (1% and 2%), hydrogen peroxide (3%), sodium hypochlorite and sodium dichloroisocyanurate (200 mg/L). Samples not submitted to sanitization were used as controls. The values of pH, total titratable acidity, total soluble solids, vitamin C content, total phenolic compounds, and antioxidant capacity were directly analyzed, and chlorophyll (SPAD Index) was indirectly analyzed. Sanitized strawberries and cucumbers presented no significant difference (p > 0.05) in pH values, total titratable acidity, and total soluble solids/total titratable acidity ratio compared with un-sanitized samples. Vitamin C content was preserved in samples treated with sodium hypochlorite. All vegetables maintained their total phenolic compounds after sanitization treatments. The proposed treatments did not alter the physicochemical characteristics of the samples.

The effects of ultrasound (US) application conditions on microbiological, physicochemical, microscopic, and sensory features of strawberry juice were evaluated. Conditions comprised US (40 kHz) for 5, 10, or 15 min at 25, 40, or 50°C. All US treatments reduced the microbial count in juice. US treatment (40°C/10 min; 50°C/15 min) reduced the °Brix value. All treatments maintained the pH, total titratable acidity, phenolic compounds, and antioxidant capacity of the samples. The thermal treatment sample presented a higher decrease in bioactive compounds. Hue angle values and changes in optical microscopy have increased as treatment temperature and time increased. The sample sonicated at 50°C for 15 min presented lower sensory acceptance indices for all the evaluated attributes. Ultrasound application at 50°C for 5 min presented effective juice properties' conservation, a good sensory acceptance, and is a promising alternative to help preserve strawberries. Efectos del baño de ultrasonido de alta intensidad en la calidad del jugo [zumo] de fresaEn el presente estudio se evaluaron los efectos de las condiciones de aplicación de ultrasonidos (US) en las características microbiológicas, fisicoquímicas, microscópicas y sensoriales del jugo de fresa. Las condiciones comprendieron la aplicación de ultrasonido (40 kHz) durante 5, 10 o 15 minutos a 25, 40 o 50°C. Se pudo constatar que todos los tratamientos de US redujeron el recuento microbiano en el jugo. Además, se observó que el tratamiento de US (40°C/10 min; 50°C/15 min) redujo el valor °Brix. Por otra parte, se constató que todos los tratamientos aplicados mantuvieron el pH, la acidez total valorable, los compuestos fenólicos y la capacidad antioxidante de las muestras. La muestra sometida a tratamiento térmico mostró una mayor disminución de los compuestos bioactivos. Los valores del ángulo de tonalidad y los cambios en la microscopía óptica aumentaron a medida que se incrementaban la temperatura y el tiempo de tratamiento. La muestra sometida a prueba sónica a 50°C durante 15 minutos registró menores índices de aceptación sensorial para todos los atributos evaluados. La aplicación de ultrasonido a 50°C durante 5 minutos dio lugar a una efectiva conservación de las propiedades del jugo, una buena aceptación sensorial, por lo que es una alternativa prometedora para ayudar a conservar la fresa.

The effect of ultrasound treatments (40 kHz; 40, 50, or 60°C; 5 or 10 min) and thermal treatment (90°C; 30 s) on the stability parameters of orange-carrot juice were evaluated. Microscopic structure, particle size distribution and turbidity were analyzed on the first day. Sedimentation and cloudiness were evaluated over 22 days of storage at 7 and 25°C. Changes in microstructure and disruption of the cell wall were evidenced after treatment at 60°C/10 min. The particle size distribution was heterogeneous with an increase of small particles after ultrasonication. Ultrasonicated and thermal treated samples did not show any differences in turbidity. Cloudiness increased after sonication and decreased over the storage in all samples. Sedimentation process at 7°C was homogeneous among samples while it was delayed in samples treated with ultrasounds at 60°C for 10 min. Ultrasound processing improved the quality of juices and can be proposed as a potential novel processing technique for blended vegetable-fruit juices.

Ultrasound combined with high temperatures (thermosonication) is an alternative to thermal treatments applied for juice preservation purposes. Blend juices, such as orange-carrot juice, are an interesting option for consumers due to their diversity of unique flavors. The main aim of the present study is to investigate thermosonication’s impact on the overall quality of an orange-carrot juice blend over 22-day storage at 7 °C, in comparison to thermal treatment. Sensory acceptance was assessed on the first storage day. The juice blend was prepared based on using 700 mL of orange juice and 300 g of carrot. The effect of ultrasound treatment at 40, 50, and 60 °C for 5 and 10 min, as well as of thermal treatment at 90 °C for 30 s, on the physicochemical, nutritional, and microbiological quality of the investigated orange-carrot juice blend was tested. Both the ultrasound and the thermal treatment could maintain pH, °Brix, total titratable acidity, total carotenoid content, total phenolic compounds, and the antioxidant capacity of untreated juice samples. All ultrasound treatments improved samples’ brightness and hue value, and made the juice brighter and redder. Only ultrasound treatments at 50 °C/10 min and at 60 °C/10 min have significantly reduced total coliform counts at 35 °C. Thus, they were selected along with untreated juice for sensory analysis, whereas thermal treatment was used for comparison purposes. Thermosonication at 60 °C for 10 min recorded the lowest scores for juice flavor, taste, overall acceptance, and purchase intention. Thermal treatment and ultrasound at 60 °C for 5 min recorded similar scores. Minimal variations in quality parameters were observed over 22-day storage in all treatments. Thermosonication at 60 °C for 5 min has improved samples’ microbiological safety and resulted in good sensorial acceptance. Although thermosonication has the potential to be used in orange-carrot juice processing, further investigations are necessary to enhance its microbial effect on this product.