The impact of ultrasound-assisted thawing on the bioactive components in juices obtained from blue honeysuckle (Lonicera caerulea L.).

Ultrasound (US) assisted thawing of blue honeysuckle berry was utilized in order to reduce the losses of bioactive components (ascorbic acid, anthocyanins, phenolic acids, iridoids, proanthocyanins) and increase the extraction efficiency during juice processing. It was analysed whether it was more beneficial to apply US (alone or with enzymatic treatment) to the frozen state, until reaching the cryoscopic temperature or thawed state. Both the US and enzymatic treatment significantly increased the extraction efficiency, extract content, acidity and the content of iridoids and chlorogenic acid in juices, especially if the US was applied to 50 °C. It was probably due to a higher extractivity by the greater damage of the tissue and detexturation. Enzymatic treatment due to long heating contributed to a higher degradation of anthocyanins, ascorbic acid and proanthocyanidins, which are more heat-sensitive. The results of the study mainly indicated the possibility of including ultrasound-assisted thawing in the fruit processing before pressing the juices. This may replace costly enzymatic treatment.

Effect of Thermal and Non-Thermal Technologies on Kinetics and the Main Quality Parameters of Red Bell Pepper Dried with Convective and Microwave-Convective Methods.

The drying process preserves the surplus of perishable food. However, to obtain a good-quality final product, different pretreatments are conducted before drying. Thus, the aim of the study was the evaluation of the effect of thermal (blanching treatments with hot water) and non-thermal technologies (pulsed electric field (PEF) and ultrasound (US)) on the kinetics of the drying process of red bell pepper. The convective and microwave-convective drying were compared based on quality parameters, such as physical (water activity, porosity, rehydration rate, and color) and chemical properties (total phenolic content, total carotenoids content, antioxidant activity, and total sugars content). The results showed that all of the investigated methods reduced drying time. However, the most effective was blanching, followed by PEF and US treatment, regardless of the drying technique. Non-thermal methods allowed for better preservation of bioactive compounds, such as vitamin C in the range of 8.2% to 22.5% or total carotenoid content in the range of 0.4% to 48%, in comparison to untreated dried material. Moreover, PEF-treated red bell peppers exhibited superior antioxidant activity (higher of about 15.2-30.8%) when compared to untreated dried samples, whereas sonication decreased the free radical scavenging potential by ca. 10%. In most cases, the pretreatment influenced the physical properties, such as porosity, color, or rehydration properties. Samples subjected to PEF and US treatment and dried by using a microwave-assisted method exhibited a significantly higher porosity of 2-4 folds in comparison to untreated material; this result was also confirmed by visual inspection of microtomography scans. Among tested methods, blanched samples had the most similar optical properties to untreated materials; however non-thermally treated bell peppers exhibited the highest saturation of the color.

The Influence of Polyols on the Process Kinetics and Bioactive Substance Content in Osmotic Dehydrated Organic Strawberries.

In recent years, an increasing interest in reducing sugar consumption has been observed and many studies are conducted on the use of polyols in the osmotic dehydration process to obtain candied or dried fruits. The studies in the literature have focused on the kinetics of the process as well as the basic physical properties. In the scientific literature, there is a lack of investigation of the influence of such polyol solutions such as sorbitol and mannitol used as osmotic substances during the osmotic dehydration process on the contents of bioactive components, including natural colourants. Thus, the aim of the study was to evaluate the impact of polyols (mannitol and sorbitol) in different concentrations on the process kinetics and on chosen physical (colour and structural changes) as well as chemical (sugars and polyol content, total anthocyanin content, total polyphenol content, vitamin C, antioxidant activity) properties of osmotic-dehydrated organic strawberries. Generally, the results showed that the best solution for osmotic dehydration is 30% or 40% sorbitol solutions, while mannitol solution is not recommended due to difficulties with preparing a high-concentration solution and its crystallization in the tissue. In the case of sorbitol, the changes of bioactive compounds, as well as colour change, were similar to the sucrose solution. However, the profile of the sugar changed significantly, in which sucrose, glucose, and fructose were reduced in organic strawberries and were partially replaced by polyols.

Effect of nonthermal treatments on selected natural food pigments and color changes in plant material.

In recent years, traditional high-temperature food processing is continuously being replaced by nonthermal processes. Nonthermal processes have a positive effect on food quality, including color and maintaining natural food pigments. Thus, this article describes the influence of nonthermal, new, and traditional treatments on natural food pigments and color changes in plant materials. Characteristics of natural pigments, such as anthocyanins, betalains, carotenoids, chlorophylls, and so forth available in the plant tissue, are shortly presented. Also, the characteristics and mechanism of nonthermal processes such as pulsed electric field, ultrasound, high hydrostatic pressure, pulsed light, cold plasma, supercritical fluid extraction, and lactic acid fermentation are described. Furthermore, the disadvantages of these processes are mentioned. Each treatment is evaluated in terms of its effects on all types of natural food pigments, and the possible applications are discussed. Analysis of the latest literature showed that the use of nonthermal technologies resulted in better preservation of pigments contained in the plant tissue and improved yield of extraction. However, it is important to select the appropriate processing parameters and to optimize this process in relation to a specific type of raw material.

Influence of Ultrasound and the Conditions of Convective Drying with Dehumidified Air on the Course of the Process and Selected Properties of Apple Tissue.

The conditions of convective drying induce a negative effect on the quality of the dried products, and thus, innovative solutions, such as the utilization of ultrasound and dehumidified air are gaining importance. Therefore, the aim of this study was to evaluate the impact of ultrasound pretreatment and variable air temperature on the kinetics of convective drying with dehumidified air and the quality of dried apples. Apples were dried with dehumidified and non-dehumidified air at 55, 70 and 85 °C. Preliminary ultrasound treatment was conducted by immersion for 60 min. The effect of both ultrasound and dehumidified air utilization was more prominent in the terms of drying time reduction, when lower drying temperatures were used. Drying of apples with dehumidified air, preceded by ultrasound pretreatment, resulted in a greater rehydration capacity of the products, and limited the browning process. Dehumidified air increased the lightness of the dried products, while sonication darkened them. The use of ultrasound before drying coupled with a drying with dehumidified medium at a temperature of 70 °C reduced the exposure of the product to a high temperature and oxygen. Products treated before dehumidified air drying with ultrasounds were characterized by high total phenolic content and the greatest antioxidant activity. This was because such technological treatment reduced exposure of the product to a high temperature and oxygen.

Selected Quality Parameters of Air-Dried Apples Pretreated by High Pressure, Ultrasounds and Pulsed Electric Field-A Comparison Study.

The aim of this work was to compare selected physicochemical properties of air dried 'Golden Delicious' apples, pretreated either by high-pressure processing (HPP), ultrasound (US) or pulsed electric field (PEF). Following parameters of pretreatment were used: HPP-400 MPa for 15 min, US-21 kHz, 180 W for 45 min, PEF-1 kV/cm, 3.5 kJ/kg. The quality of materials was evaluated by their rehydration properties, hygroscopicity, color and total phenolic content. To compare the effectiveness of the utilized methods, determined properties were expressed as relative comparison values against the reference sample obtained without any pretreatment in the same conditions. The performed research demonstrated that properties can be shaped by the application of proper pretreatment methods. For instance, PEF was shown to be the best method for improving water uptake during rehydration, whereas HPP was the most effective in decreasing hygroscopic properties in comparison with untreated dried apples. Among the investigated methods, HPP resulted in the deepest browning and thus total color difference, while the effects of US and PEF were comparable. For all pretreated dried apples, the total phenolic content was lower when compared with reference material, though the smallest drop was found in sonicated samples.

The Application of Combined Pre-treatment with Utilization of Sonication and Reduced Pressure to Accelerate the Osmotic Dehydration Process and Modify the Selected Properties of Cranberries.

The aim of this study was to investigate the effect of a pretreatment, performed by a combined method based on blanching, ultrasound, and vacuum application, on the kinetics of osmotic dehydration and selected quality properties such as water activity, color, and bioactive compound (polyphenols, flavonoids, and anthocyanins) content. The pretreatment was carried out using blanching, reduced pressure, and ultrasound (20 min, 21 kHz) in various combinations: Blanching at reduced pressure treatment conducted three times for 10 min in osmotic solution; blanching with reduced pressure for 10 min and sonicated for 20 min in osmotic solution; and blanching with 20 min of sonication and 10 min of reduced pressure. The osmotic dehydration was performed in different solutions (61.5% sucrose and 30% sucrose with the addition of 0.1% of steviol glycosides) to ensure the acceptable taste of the final product. The changes caused by the pretreatment affected the osmotic dehydration process by improving the efficiency of the process. The use of combined pretreatment led to an increase of dry matter from 9.3% to 28.4%, and soluble solids content from 21.2% to 41.5%, lightness around 17.3% to 56.9%, as well as to the reduction of bioactive compounds concentration until even 39.2% in comparison to the blanched sample not subjected to combined treatment. The osmotic dehydration caused further changes in all investigated properties.

The application of unconventional technologies as pulsed electric field, ultrasound and microwave-vacuum drying in the production of dried cranberry snacks.

A lot of effort is put to decrease the energy consumption of drying. This effect might be achieved by shift of a drying technology e.g. from a hot-air to a microwave-vacuum method. Moreover, an unconventional pre-treatment such as ultrasound or pulsed electric field may modify a cellular tissue, what influences drying kinetics of plant tissue. The aim of the study was to analyse the quality of microwave-vacuum dried, osmodehydrated (OD) cranberries processed by the means of blanching and ultrasound (US) or blanching followed by pulsed electric field and sonication (PEF + US) in comparison to traditionally treated material. Physical, chemical and sensorial properties of cranberry fruits were assessed. What is more, the impact of aforementioned unconventional treatments on the kinetics of microwave-vacuum dried cranberries was studied. Microwave-vacuum drying process was very short (25-38 min) in comparison to convective drying, which lasted several hours (13.2 h). Most of the samples subjected to US and PEF + US treatments before OD and drying were characterized by similar or a higher amount of bioactive compounds such as polyphenols, anthocyanins and flavonoids, and better colour and taste, as compared to cut osmodehydrated cranberry fruits subjected to convective drying (reference samples).

Postharvest Monitoring of Tomato Ripening Using the Dynamic Laser Speckle.

The dynamic laser speckle (biospeckle) method was tested as a potential tool for the assessment and monitoring of the maturity stage of tomatoes. Two tomato cultivars—Admiro and Starbuck—were tested. The process of climacteric maturation of tomatoes was monitored during a shelf life storage experiment. The biospeckle phenomena were captured using 640 nm and 830 nm laser light wavelength, and analysed using two activity descriptors based on biospeckle pattern decorrelation—C4 and ε. The well-established optical parameters of tomatoes skin were used as a reference method (luminosity, a*/b*, chroma). Both methods were tested with respect to their prediction capabilities of the maturity and destructive indicators of tomatoes—firmness, chlorophyll and carotenoids content. The statistical significance of the tested relationships were investigated by means of linear regression models. The climacteric maturation of tomato fruit was associated with an increase in biospckle activity. Compared to the 830 nm laser wavelength the biospeckle activity measured at 640 nm enabled more accurate predictions of firmness, chlorophyll and carotenoids content. At 640 nm laser wavelength both activity descriptors (C4 and ε) provided similar results, while at 830 nm the ε showed slightly better performance. The linear regression models showed that biospeckle activity descriptors had a higher correlation with chlorophyll and carotenoids content than the a*/b* ratio and luminosity. The results for chroma were comparable with the results for both biospeckle activity indicators. The biospeckle method showed very good results in terms of maturation monitoring and the prediction of the maturity indices of tomatoes, proving the possibility of practical implementation of this method for the determination of the maturity stage of tomatoes.

Effect of ultrasound treatment during osmotic dehydration on bioactive compounds of cranberries.

The aim of the study was to investigate the influence of ultrasound treatment applied in osmotic solution on bioactive compounds, such as vitamin C, polyphenols, anthocyanins and flavonoids content as well as antioxidant activity in cranberries (Vaccinium oxycoccus). Ultrasound treatment was performed at the frequency of 21kHz for 30 and 60min in two osmotic solutions - 61.5% sucrose and 30% sucrose with an addition of 0.1% of steviol glycosides. Before the ultrasound treatment the material was subjected to cutting or blanching. The obtained results indicated that the influence of ultrasound waves on cranberries depends on a type of bioactive component. The ultrasound treated cranberries as well as the ones subjected to cutting or blanching enhanced by ultrasound were characterized mainly by a lower content of bioactive compounds.

Selected chemical composition changes in microwave-convective dried parsley leaves affected by ultrasound and steaming pre-treatments - An optimization approach.

Parsley leaves contain a high amount of bioactive components (especially lutein), therefore it is crucial to select the most appropriate pre-treatment and drying conditions, in order to obtain high quality of dried leaves, which was the aim of this study. The optimization was done using response surface methodology (RSM) for the following factors: microwave power (100, 200, 300W), air temperature (20, 30, 40°C) and pre-treatment variant (ultrasound, steaming and dipping as a control). Total phenolic content (TPC), antioxidant activity, chlorophyll and lutein contents (using UPLC-PDA) were determined in dried leaves. The analysed responses were dependent on the applied drying parameters and the pre-treatment type. The possibility of ultrasound and steam treatment application was proven and the optimal processing conditions were selected.

Influence of power ultrasound on the main quality properties and cell viability of osmotic dehydrated cranberries.

The aim of the study was to investigate the effect of ultrasound treatment in two osmotic solutions, carried out at different time, on some physical properties, antioxidant activity and cell survival of cranberries. Ultrasound treatment was conducted at 21kHz for 30 and 60min in liquid medium: 61.5% sucrose solution and 30% sucrose solution with 0.1% steviol glycosides addition. Some samples before the ultrasound treatment were subjected to cutting or blanching. The results showed that dry matter content and concentration of the dissolved substances increased during ultrasound treatment in osmotic solution, however higher value was observed for treatment in 61.5% sucrose solution and for longer time. Water activity and volume of cranberries did not change after the ultrasonic treatment. Combined treatment led to colour and antioxidant activity alterations as well. A cell viability of whole and cut samples decreased after 60min of osmotic treatment and completely lost in the blanched samples.