Osmosonication of Blackberry Juice: Impact on Selected Pathogens, Spoilage Microorganisms, and Main Quality Parameters

Comparing the antioxidant properties and volatile compounds of carrot-orange juice blend processed through varied chemical, pasteurization and ultrasound conditions

Ultrasound technique is one of the green technologies that is being utilized widely for varying food processes. Our aim in this study was to carry out ultrasonication, pasteurization and chemical preservation (Potassium metabisulfite) techniques on a carrot-orange juice blend. Additionally, the effect of these treatments on the storage period of about 21 days was also determined. The study displayed an array of results under the effect of different treatments. Throughout the storage period of 21 days' significant results were presented by the carrot juice blend subjected to the ultrasound technique (25 min) giving the highest values for total phenolic content (25.56 ± 1.29 mg GAE/100 mL), total antioxidant activity (573.48 ± 2.29 mg Trolox /100 mL), DPPH (32.32 ± 1.83 %) and reducing power (45.45 ± 1.92 mg AAE/100 mL) with least deterioration, followed by the blends treated with potassium metabisulfite (KMS) and pasteurization. The physicochemical analysis showed a non-significant effect of treatments on pH and total soluble solids (oBrix) of carrot-orange juice blends whereas, the changes in color parameters L*, a* and b* were noted to show changes in treated blends. Similarly, the results for the GC-MS quantification of volatile compounds displayed the highest concentrations in the ultrasonicated blends as compared to other techniques. The peak quantity was obtained for the hexanal (9903.43 ± 7.61 μg.kg-1) followed by 3-Methylbutanal (2638.7 ± 5.44 μg.kg-1), terpinolene (2337.16 ± 5.28 μg.kg-1), elemicin (2198.28 ± 5.28 μg.kg-1), myristicin (1936.62 ± 6.72 μg.kg-1). The use of sonication can effectively enhance the nutritional qualities of juice, as perceived by consumers.

Thermosonication of Orange-Carrot Juice Blend: Overall Quality during Refrigerated Storage, and Sensory Acceptance

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.

Effect of Multi-Mode Thermosonication on the Microbial Inhibition and Quality Retention of Strawberry Clear Juice during Storage at Varied Temperatures

Strawberry juice, which is rich in nutrients and charming flavor, is favored by consumers. To explore whether multi-mode thermosonication (MTS) can ensure the quality stability of strawberry clear juice (SCJ) during storage, the effects of microbial inhibition, enzyme activity, and physicochemical properties of SCJ pretreated by MTS were evaluated during storage at 4, 25, and 37 °C in comparison with thermal pretreatment (TP) at 90 °C for 1 min. The MTS, including dual-frequency energy-gathered ultrasound pretreatment (DEUP) and flat sweep-frequency dispersive ultrasound pretreatment (FSDUP), were conducted at 60 °C for 5 and 15 min, respectively. Results showed that the total phenols, flavonoids, anthocyanins, ascorbic acid, and DPPH free radical scavenging ability of SCJ decreased during the storage period. The control sample of SCJ was able to sage for only 7 days at 4 °C based on the microbiological quality, while the FSDUP and DEUP group extended the storage period up to 21 and 14 days, respectively. The polyphenol oxidase in SCJ pretreated by MTS did not reactivate during the storage period. The MTS remarkably (p < 0.05) reduced the color deterioration, browning degree, and nutrient degradation during the storage period. Moreover, the FSDUP group exhibited the maximum shelf life with a minimum loss of quality, demonstrating that it was the most suitable processing method for obtaining high-quality SCJ. It can be concluded that the MTS has the potential to inhibit enzymatic browning, inactivating microorganisms, preserve original quality attributes, and prolong the shelf life of SCJ.

Effect of high intensity ultrasound on main bioactive compounds, antioxidant capacity and color in orange juice

Ultrasound is a useful alternative to thermal processing that can be applied to many food products and juices to aid with enzymes and microorganism inactivation and to improve the efficiency of unit operations generally applied in the food industry. The aim of this study was to evaluate the effect of a high-intensity sonication treatment (frequency 20 kHz; intensity 39.4 W/cm²) applied for treatment times from 0 to 105 min on the content of polyphenols, vitamin C, organic acids, and carotenoids, and on the hydrophilic and lipophilic antioxidant capacity and color of orange juice. Treatments were performed in triplicate and data was statistically analyzed. Sonication time did not have a significant effect (P > 0.05) on total polyphenols, total vitamin C, organic acid, and carotenoid contents, lipophilic antioxidant capacity, or juice color. The hydrophilic antioxidant activity and the lutein content increased significantly (P < 0.05) with increased sonication time. These results may be useful as a baseline for the development of sonication treatments that could be used in combination with other traditional and emerging processing approaches to protect the most important bioactive compounds and quality properties of orange juice.

Effects of ultrasound on the enzymatic degradation of pectin

Ultrasound-assisted enzymatic maceration (UAEM) has gained considerable interest in the fruit juice industry, owing to its potential to increase juice yield and content of polyphenols while simultaneously saving time and energy. In this study, the effects of UAEM (ultrasonic probe, 20 kHz, 21 W*cm^-2 and 33 W*cm^-2) on pectin degradation in a continuous circulation system were investigated over 60 and 90 min. Main pectinolytic enzymes activities of (polygalacturonase, pectin lyase and pectin methylesterase) of a commercial enzyme preparation were examined for individual synergistic effects with US. Pectin hydrolysis by UAEM differed significantly compared to treatment with ultrasound or enzymes alone regarding the profile of degradation products compared to treatment with ultrasound or enzymes alone. Ultrasound fragmented pectin to less branched oligomers of medium molecular weight (Mp approx. 150 kDa), which were further degraded by pectinolytic activities. The low molecular weight fraction (<30 kDa), which is known to be beneficial for juice-quality by adding nutritional value and stabilizing polyphenols, was enriched in small oligomers of homogalacturonan-derived, rhamnogalacturonan I-derived, and rhamnogalacturonan II-derived residues. Synergistic effects of ultrasound application enhanced the effective activities of polygalacturonase and pectin lyase and even prolonged their performance over 90 min, whereas the effective activity of pectin methylesterase was not affected. Final marker concentrations determined by each enzyme assay revealed a considerable higher total process output after UAEM treatment at reduced temperature (30 °C) comparable to the output after conventional batch maceration at 50 °C. The obtained results demonstrate the high potential of UAEM to produce high-quality juice by controlling pectin degradation while reducing process temperature and equally highlight the matrix and enzyme specific effects of a simultaneous US treatment.

Influence of high power ultrasound on selected moulds, yeasts and Alicyclobacillus acidoterrestris in apple, cranberry and blueberry juice and nectar

The purpose of this study was to investigate the effect of non-thermal technology, high power ultrasound (HPU) on inactivation of Aspergillus ochraceus 318, Penicillium expansum 565, Rhodotorula sp. 74, Saccharomyces cerevisiae 5 and Alicyclobacillus acidoterrestris DSM 3922 in clear juices and nectars from apple, blueberry and cranberry juice concentrate. Inoculated juice and nectars were treated by high power ultrasound (20kHz) according to procedure set by central composite design (CCD). Three operational parameters, amplitude (60, 90 and 120μm), temperature (20, 40 and 60°C), and treatment time (3, 6 or 9min) were varied in order to observe the influence of ultrasound and combination of ultrasound and slight heating (thermosonication) on growth and inactivation of selected microorganisms. Number of vegetative cells of A. acidoterrestris DSM 3922 were not significantly reduced by high power ultrasound (p>0.05), except in apple juice, where statistical significant (p<0.05) influence of quadratic interaction of amplitude on bacteria reduction were observed. In all samples of fruit juices and nectars in terms of ultrasonic treatment at 60°C and times of 3, 6 and 9min, regardless of the value of the amplitude, complete inactivation of the growth of yeasts and moulds were achieved, while at 20 and 40°C it is not observed. The value of reduction of cells of selected yeasts and moulds for ultrasound treatments at 60°C and the duration of the 3, 6 and 9min ranged from 3.556 to 5.934 log units, depending on the initial number of selected yeasts and moulds before treatment.

Influence of fruit juice processing on anthocyanin stability

Anthocyanins are quality determining compounds in red fruits and their corresponding juices. The fate of anthocyanins during production of juices is determined by countless factors and all of these need to be taken into consideration to optimize juice processes. Storage and pre-press procedures like freezing and thawing may influence the fruit's integrity and accordingly affects the extraction of valuable components during the subsequent mashing and pressing. Conventional thermal or novel non-thermal treatments to ensure microbial safety have both positive and negative effects on the anthocyanins. By inactivation of oxidizing enzymes, profiles and quantities of anthocyanins may be maintained, but more severe conditions may have adverse effects. To improve juice extraction and to increase yield, enzyme-assisted degradation of the cell walls is conducted. The applied enzyme preparations contain numerous side activities which also may degrade anthocyanins. Clarification and concentration will further reduce the final anthocyanin concentrations. Many studies have been published regarding evaluating individual fruits or single processing steps but, obviously, these results are not necessarily transferable. Accordingly, this review aims to summarize all relating studies comprehensively to the fate of anthocyanins during juice processing giving an overview of underlying mechanisms as well as the chemical and analytical background.

Hybrid Drying of Carrot Preliminary Processed with Ultrasonically Assisted Osmotic Dehydration

In this paper the kinetics of osmotic dehydration of carrot and the influence of this pretreatment on the post-drying processes and the quality of obtained products are analysed. Osmotic dehydration was carried out in the aqueous fructose solution in two different ways: with and without ultrasound assistance. In the first part of the research, the kinetics of osmotic dehydration was analysed on the basis of osmotic dewatering rate, water loss and solid gain. Next, the effective time of dehydration was determined and in the second part of research samples were initially dehydrated for 30 min and dried. Five different procedures of drying were established on the grounds of convective method enhanced with microwave and infrared radiation. The influence of osmotic dehydration on the drying kinetics and final product quality was analysed. It was found that it did not influence the drying kinetics significantly but positively affected the final product quality. Negligible influence on the drying kinetics was attributed to solid uptake, which may block the pores, hindering heat and mass transfer. It was also concluded that the application of microwave and/or infrared radiation during convective drying significantly influenced the kinetics of the final stage of drying. A proper combination of aforementioned techniques of hybrid drying allows reducing the drying time. Differences between the particular dehydration methods and drying schedules were discussed.

Enzymatic inactivation and antioxidant properties of blackberry juice after thermoultrasound: Optimization using response surface methodology

The purpose of this research was to optimize the thermoultrasound conditions for blackberry juice using the response surface methodology and considering juice quality parameters and antioxidant capacity. With the exception of microbial growth, the response variables showed high correlation coefficients with the mathematical model (R²adj>0.91). Thermoultrasound treatment inactivated all the evaluated microorganisms, and at the optimum conditions (50±1°C at 17±1min) it increased enzyme inactivation and antioxidant activity in comparison to pasteurized juice. The results demonstrated that thermoultrasound can be an alternative to pasteurization for the production of safe and high-quality juices with the added value of higher concentration of bioactive compounds and antioxidant capacity.

Design, development and evaluation of an automatic fruit-juice pasteurization system using microwave - ultrasonic waves

Conventional pasteurization treatments often lead to substantial decrease in fruits juice quality. Due to these issues, the objective of this research was to compare the combined effect of a novel thermal (microwave) and non-thermal (ultrasonic) treatments with conventional thermal pasteurization on some qualitative characteristics of sour cherry juice (vitamins, phenolics, anthocyanins, etc.). For this purpose, an automatic control system comprising of ultrasonic generator, ultrasonic transducer, horn, pump, circulator, microwave oven, container, pipe interface, temperature sensor, float, data acquisition card, microwave power control circuit, and reactor was designed and developed. Moreover, in order to optimize the effect of ultrasonic waves on the existing micro-organisms in the sour cherry juice, some preliminary experiments were carried out to optimize the ultrasonic probe and reactor design. The results of evaluations showed that using the combined automatic system, the qualitative properties of sour cherry (vitamin C content 14 %, total phenolics content 1 %, total anthocyanins content 6 %) can be better maintained compared with the conventional thermal method. Based on the results obtained in this study, the following processing conditions: microwave power of 541.7 W, temperature of 41 °C, ultrasonic power of 799.57 W and ultrasonic exposure time of 6 min were recommended for optimum processing of sour cherry juice.

Study on combined effects of blanching and sonication on different quality parameters of carrot juice

This study was conducted to evaluate the combined effects of blanching and sonication on carrot juice quality. Carrots were blanched at 100 °C for 4 min in normal and acidified water. Juice was extracted and sonicated at 15 °C for 2 min keeping pulse duration 5 s on and 5 s off (70% amplitude level and 20 kHz frequency). No significant effect of blanching and sonication was observed on Brix, pH and titratable acidity except acidified blanching that decreased pH and increased acidity significantly. Peroxidase was inactivated after blanching that also significantly decreased total phenol, flavonoids, tannins, free radical scavenging activity, antioxidant capacity and ascorbic acid and increased cloud and color values. Sonication could improve all these parameters significantly. The present results suggest that combination of blanching and sonication may be employed in food industry to produce high-quality carrot juice with reduced enzyme activity and improved nutrition.