Ultrasound applications in drying of fruits from a sustainable development goals perspective.

This review focuses on the many contributions of ultrasound technologies for fruit drying toward the United Nations Sustainable Development Goals (SDG). Along this review, several aspects attained from the application of ultrasound technologies are correlated with the SDGs. The main ultrasonic technologies applied for fruit drying, such as ultrasonic bath, probe ultrasound, air-borne ultrasound air-drying, and ultrasound-assisted contact air-drying, are presented. An in-depth discussion on ultrasound contributions, its advantages, disadvantages, and limitations are made. The effects of ultrasound on water diffusivity in several fruits are presented by correlating this effect with drying time and cost of energy. Ultrasound-assisted fruit drying, like other food processing technologies, directly impacts Zero Hunger, but ultrasound technologies contribute to much more than delivering long shelf-life food. This technology can be used to produce healthy foods and provide well-being, which will be discussed by correlating the effects of ultrasound-assisted air-drying with the concentration of nutritional compounds. Ultrasound-assisted fruit drying reduces wastewater toxicity and energy consumption and improves productivity, potentially improving workplaces and salaries. A walk through the technology is presented from Zero Hunger to No Poverty.

Cold plasma as a pre-treatment for processing improvement in food: A review.

Thermal processes can be very damaging to the nutritional and sensory quality of foods. Non-thermal technologies have been applied to reduce the impact of heat on food, reducing processing time and increasing its efficiency. Among many non-thermal technologies, cold plasma is an emerging technology with several potential applications in food processing. This technique can be used to preserve and sanitize food products, and act as a pre-treatment for drying, extraction, cooking, curing, and hydrogenation of foods. Furthermore, the reacting plasma species formed during the plasma application can change positively the sensory and nutritional aspects of foods. The aim of this review is to analyze the main findings on the application of cold plasma as a pre-treatment technology to improve food processing. In its current maturity stage, the cold plasma technology is suitable for reducing drying time, increasing extraction efficiency, as well as curing meats. This technology can convert unsaturated into saturated fats, without forming trans isomers, which can be an alternative to healthier foods. Although many advantages come from cold plasma applications, this technology still has several challenges, such as the scaling up, especially in increasing productivity and treating foods with large formats. Optimization and control of the effects of plasma on nutritional and sensory quality are still under investigation. Further improvement of the technology will come with a higher knowledge of the effects of plasma on the different chemical groups present in foods, and with the development of bigger or more powerful plasma systems.

Production of tung oil epoxy resin using low frequency high power ultrasound.

Epoxy resins made from vegetable oils are an alternative to synthesize epoxy resins from renewable sources. Tung oil is rich in α -eleostearic fatty acid, which contains three double bonds producing epoxy resins with up to three epoxy groups per fatty acid. This work studied the production of tung oil epoxy resin using hydrogen peroxide as an oxidizing agent and acetic and formic acid as percarboxylic acid precursors, applying low frequency high power ultrasound. This study evaluated the effects of ultrasound power density, hydrogen peroxide concentration, acetic acid concentration, and formic acid concentration on the yield into epoxy resin, selectivity, and by-products formation. Application of ultrasound was carried out using a 19 kHz probe ultrasound (horn ultrasound) with a 1.3 cm diameter titanium probe, 500 W nominal power, 2940 W L-1 maximum effective power density applied to the reaction mixture. Ultrasound technology yielded up to 85% of epoxy resin in 3 h of reaction. The use of formic acid resulted in a slightly lower oil conversion than acetic acid but with a much higher selectivity towards epoxidized tung oil. However, using acetic acid resulted in the production of high-value by-products, such as 2-heptenal and 2,4-nonadienal. The ultrasound-assisted epoxidation showed to be particularly efficient when applied to oils containing conjugated double-bonds.

Cold plasma technique as a pretreatment for drying fruits: Evaluation of the excitation frequency on drying process and bioactive compounds.

The present work aims to evaluate the effect of different excitation frequency (200, 500 and 800 Hz) of cold plasma technique as a pretreatment for drying tucumã. SEM images showed changes on the pretreated tucumã's surface, favoring the drying rate and diffusivity of water as well as reducing the drying time. Marginal variation of color and reduced drying time were observed in the samples treated using 200 and 800 Hz. The pretreatment improved the concentration of phenolic (45.3 mg GAE g-1) and antioxidant compounds (799.8 µM ET) (p-value < 0.05). Carotenoids were more sensitive to the drying time, presenting significant degradation at 500 Hz. For this reason, the propose pretreatment based on the application of cold plasma technique for drying foods can preserve/improve their nutritional quality.

Atmospheric cold plasma frequency imparts changes on cashew apple juice composition and improves vitamin C bioaccessibility.

This study evaluated the atmospheric cold plasma (ACP) effect on cashew apple juice composition at different frequencies (200 and 700 Hz). The impact of this non-thermal technology on the organic juice compounds after the processing and along with the in vitro digestion carried out in a simulated digestion system at 37 °C/6 h was evaluated. The changes in the juice composition were determined by NMR spectroscopy and chemometric analyses. Vitamin C and total phenolic compounds were also quantified in processed and non-processed (control) juices and after each digestion phase. The results showed decreased glucose and fructose in samples treated by ACP and an increment in malic acid concentration for ACP700. ACP increased the amount of vitamin C in the juices and did not affect the total phenolic content. The gastric digestion highlighted the pronounced effect of plasma on the juice composition, increasing all of the components detected by NMR. Cashew apple juice processed by ACP700 presented a higher concentration of malic acid and phenylalanine. An increased bioaccessibility of vitamin C was also found for ACP700. Although ACP processing has decreased some compounds' concentration, this technology improved the bioaccessibility of vitamin C - the main bioactive compound of cashew apple juice.

Thermal and non-thermal processing effect on açai juice composition.

This study evaluated the effects of High-Temperature Short Time (HTST), Ultra High Temperature (UHT), and the non-thermal processes High Power Ultrasound (US), UV-pulsed-light and Low Pressure Plasma (LPP) on the composition, stability, and bioactive compounds bioaccessibility of açai juice. 1H NMR based approach, coupled to chemometrics, was applied to evaluate the changes in the juice composition. All the non-thermal processes increased the sugars content (glucose and fructose), and the amino acid betaine, except the combined processing of ultrasound followed by low-pressure plasma (US.LPP). HTST and UHT increased the fatty acids and phenolic compounds content in the açai juice. The bioaccessibility of phenolic compounds decreased due to the processing. After thermal sterilization (UHT), the anthocyanin bioaccessibility was 2-fold higher. The combined non-thermal treatment reduced the biocompounds bioaccessibility to 40% of the non-processed juice. However, the combined US.LPP improved the bioaccessibility of vitamin C by 8%. UHT increased the anthocyanin's bioaccessibility but sharply decreased vitamin C bioaccessibility. Higher impact of thermal processing on vitamin C, anthocyanins, total phenolics, PPO, POD, DPPH, ABTS, and FRAP was verified after 45 and 60 days of storage compared to the non-thermally processed samples.

Effect of dielectric barrier discharge plasma excitation frequency on the enzymatic activity, antioxidant capacity and phenolic content of apple cubes and apple juice.

Cold plasma is a potential alternative to traditional thermal conservation methods because of its high efficiency in the preservation and retention of quality parameters. The objective of this study was to evaluate the application of atmospheric cold plasma on some qualitative aspects of apple cubes and apple juice. The research used dielectric barrier discharge plasma and studied different excitation frequencies of plasma: 50, 200, 400, 600, and 900 Hz. The effects of plasma application were evaluated on enzymatic activity (PPO and POD), total phenolic compounds, antioxidant capacity, and colorimetry. Plasma treatment partially inactivated the polyphenol oxidase enzyme in apples cubes and juice. Inactivation of peroxidase occurred only in apple juice. Total phenolic content and antioxidant capacity presented no significant difference between the treated and control samples of apple cubes, while significant changes were observed in apple juice. The changes in color parameters were slight and did not compromise the product quality. Plasma application was able to partially inactivate the enzymes responsible for browning while maintaining the quality and sensory properties of apple cubes and juice.

Ultrasound-assisted extraction of anthocyanins and phenolics from jabuticaba (Myrciaria cauliflora) peel: kinetics and mathematical modeling.

Jabuticaba (Myrciaria cauliflora) is a dark berry, endemic to the south and central regions of South America, rich in anthocyanins and polyphenols. This study evaluated the ultrasound-assisted extraction of bioactive compounds from jabuticaba peel, developed a new mathematical model for the process, and estimated the model parameters. Extraction was carried out using water as solvent aiming its direct use in food formulations. The main anthocyanin (cyanidin-3-O-glucoside) and the main polyphenol (ellagic acid) from jabuticaba peel were extracted and quantified by LC-MS and HPLC. The results indicate that lowering the pH increased the extraction of the anthocyanin and had only slight effect on the extraction of ellagic acid. The application of ultrasound at 25 kHz favored the extraction of both compounds. Processing time of 20 min increased the yield of both compounds, while over processing (> 20 min) let to the sonochemical-induced hydrolysis of cyanidin-3-O-glucoside and ellagic acid. The highest yield of bioactive compounds was attained at 25 kHz, 20 min of extraction and pH 1.5 (8.9 mg/g dry peel of gallic acid equivalent, 0.9 mg/g dry peel of ellagic acid, and 7.9 mg/g dry peel of cyanidin-3-O-glucoside). The new mathematical model considered the mass transfer between the powder and the liquid media, and the sonochemical-induced hydrolysis of the compound. The model was able to predict satisfactorily the extraction process and the hydrolysis effect.

Ozone and plasma processing effect on green coconut water.

In this study, the effect of plasma and ozone processing on the quality of coconut water was evaluated. For ozone processing, the samples were submitted to different ozone loads and temperatures. For atmospheric cold plasma processing (ACP), samples were exposed to plasma under different frequencies and voltages. The coconut water pH, soluble solids, titratable acidity, color, total phenolic content, and enzymatic activity were determined before and after treatments. The main compounds were also determined by NMR spectroscopy and chemometric analysis. Both processes did not change the pH values, total soluble solids, titratable acidity, and color. Chemometrics analysis of 1H NMR dataset showed no relevant changes after the processing. All ozone treatments promoted complete inactivation of POD activity and did not affect the content of phenolic compounds. After ACP, the smallest POD residual activity was observed when higher frequencies were applied, and slight changes in phenolic compounds content were observed.

Dielectric barrier atmospheric cold plasma applied on camu-camu juice processing: Effect of the excitation frequency.

The aim of this paper was to evaluate the effect of cold plasma excitation frequency on camu-camu juice processing. Different levels of frequency (200, 420, 583, 698 and 960 Hz) were applied on camu-camu juice to measure the contents of ascorbic acid and anthocyanins, as well as to evaluate the antioxidant compounds (DPPH, ABTS, FRAP and phenolic compounds), peroxidase and polyphenol oxidase enzymatic activity and color. Furthermore, the juice bioaccessibility was evaluated after simulated digestion. The ascorbic acid concentration was increased when higher excitation frequencies were employed, increasing their bioavailability. Anthocyanins, peroxidase and polyphenol oxidase presented considerable degradation with increasing the plasma excitation frequency. For this reason, the juice processing proposed herein represents an alternative to enhance its nutritional quality. Moreover, the use of cold plasma reduced the activity concentration of endogenous enzymes, presenting considerable degradation for higher excitation frequency.

Green ultrasound-assisted extraction of chlorogenic acids from sweet potato peels and sonochemical hydrolysis of caffeoylquinic acids derivatives.

Sweet potato peels are rich in chlorogenic acids. In this work, we applied ultrasound technology to extract the main compounds from sweet potato peel and used multivariate analysis and principal component analysis (PCA) to evaluate the effects of different extraction conditions on the extraction of chlorogenic acids. The extraction was studied varying ultrasonic power density (20, 35 and 50 W/L) and processing time (5, 10, 20 and 40 min) using an ultrasonic bath operating at 25 kHz. The chemical analysis was carried out by UPLC-qTOF-MS, and the results were evaluated by PCA and PLS-DA chemometric analysis. Results show that both ultrasonic power density and processing time influences in the extraction of different chlorogenic acid, and that different extraction conditions can be used to selectively extract specific caffeoylquinic acids and feruloylquinic acids in higher amounts. Ultrasound promoted the hydrolysis of tricaffeoylquinic acid when subjected to ultrasonic waves (20-50 W/L), and of 3,4-caffeyolquinic acid at high ultrasonic power density (50 W/L).

Cold plasma processing effect on cashew nuts composition and allergenicity.

The study investigated the influence of atmospheric plasma processing on cashew nut composition as well as on its allergenicity. The cashew nuts were processed by low-pressure plasma, using glow discharge plasma (80 W and 50 kHz power supply). Anacardic acids and allergens were quantified by HPLC and immunoassay, respectively. Additionally, the overall composition was evaluated by 1H qNMR. Increases in amounts of anacardic acids (15:1, 15:2, and 15:3) and fatty acids (oleic, linoleic, palmitic and stearic) were detected after all process conditions, with 70.92% of total variance captured using 2 LVs. The total amount of anacardic acids increased from 0.7 to 1.2 µg·mg-1 of nut. The major change was observed for anacardic acid (C15:3) with an increase from 0.2 to 0.55 µg/mg of nut for the samples treated with a flow of 10 mL·min-1 and 30 min of processing. On the other hand, the amount of sucrose decreased, from 33 to 18 mg·g-1 of nut, after all processing conditions. Plasma processing of cashew nuts did not affect binding of either the rabbit anti-cashew or human cashew allergic IgE binding. Among the treatments, 10 min of plasma processing at flow rate of 30 mL·min-1 of synthetic air followed by 20 min at flow rate 5.8 mL·min-1 had the least effect on nut composition as a whole.

Use of ultrasound for dehydration of mangoes (Mangifera indica L.): kinetic modeling of ultrasound-assisted osmotic dehydration and convective air-drying.

This work evaluated the production of dehydrated mangoes (Mangifera indica L.) and the effectiveness of ultrasonic-assisted osmotic dehydration on the drying kinetics of mangoes. Cube shaped mango samples were pretreated using ultrasound-assisted osmotic dehydration (UAOD) and dried in a circulating drying oven. An experimental design was created to evaluate the effect of pretreatment time and osmotic solution concentration on the water loss and sugar gain in the osmotic dehydration and on the drying time. The ultrasonic pretreatment was carried out in a bath ultrasound operating at 25 kHz and outputting 55 W/m3 of power. Osmotic solution ranging from 0 to 500 kg sucrose/m3 was applied in the treatments, and air drying was carried out at 60 °C. A mathematical model was developed for the osmotic pretreatment, and Fick's law was used to model the air-drying process. The mass transfer coefficients were estimated for the ultrasonic-assisted osmotic dehydration, and the apparent water diffusivity was estimated for the air-drying process. The mass transfer coefficient ranged from 0.017 to 0.109 m2/s and the resistance to mass transfer at the surface ranged from 0.26 × 10-6 to 1.22 × 10-6 m2/s on the UAOD, while the apparent water diffusivity during air drying ranged from 5.94 × 10-9 to 8.41 × 10-9 m2/s. Mangoes presented a different behavior when compared to other fruits. The ultrasonic pretreatment was effective only when associated with an osmotic solution at 500 kg sucrose/m3.

Guava flavored whey-beverage processed by cold plasma: Physical characteristics, thermal behavior and microstructure.

The present study aimed to compare the physicochemical (pH), physical (rheology parameters and particle size), microstructure (optical microscopy) and thermal properties (differential scanning calorimetry) of guava flavored whey-beverages submitted to cold plama technology in different processing time (5, 10, and 15 min) and gas flow (10, 20, and 30 mL min-1) conditions with a conventional pasteurized product. Whey beverages treated by cold plasma presented higher pH values, lower consistency and lower viscosity, and a flow behavior index similar to Newtonian fluids. Milder cold plasma conditions resulted in whey beverages with higher pH, lower viscosity and consistency, and similar particle distribution and microstructure compared to the pasteurized product. In contrast, more severe processing conditions resulted in a higher particle surface area ([D 3,2]) and smaller particles (~10 µM), due to the decrease in the number of larger particles (1000 µM), cell rupture, the formation of cell fragments, and higher viscosity and consistency. The treatments did not affect the thermal properties (enthalpy and bound water) of any sample.

Guava-flavored whey beverage processed by cold plasma technology: Bioactive compounds, fatty acid profile and volatile compounds.

The effect of cold plasma processing time and gas flow on bioactive compounds such as vitamin C, carotenoids and phenolic compounds, DPPH, angiotensin-converting-enzyme (ACE) inhibitory activity, fatty acids profile, and volatile compounds of guava-flavored whey beverage was investigated. For comparative purposes, a pasteurized beverage was also manufactured. Cold plasma increased the concentration of bioactive and volatile compounds, and proportionated changes in the fatty acids profile. The milder conditions like lower flow rate and processing time, resulted in higher vitamin C and volatile compounds levels, and higher antioxidant activity, but with a lower carotenoids content and a less favorable fatty acids profile. More drastic conditions like higher flow rate and processing time resulted in products with lower vitamin C and volatile compounds levels, but with higher carotenoids content and ACE inhibitory activity. It can be concluded that the cold plasma processing can improve the properties of the guava-flavored whey beverages (increased concentration of bioactive and volatile compounds), while the effect on the fatty acid profile and ACE inhibitory activity is dependent on the process parameters (processing time and flow rate).

Effects of glow plasma technology on some bioactive compounds of acerola juice.

This work examines the influence of glow plasma technology on vitamins, carotenoids, phenolic content, antioxidant capacity, and color of acerola juice. The effects of nitrogen plasma treatment were observed at different operation conditions: flowrates (from 10 to 20 mL/min) and processing times (5 to 15 min). The study explored the suitability of glow plasma on 40 mL samples, which is considered a large sample of current plasma technology studies. Nitrogen glow plasma increased the content of vitamin A and carotenoids in acerola juice under specific processing conditions. The highest increase of vitamin A and carotenoids was found at gas flow rate of 10 mL/min and 10 min of treatment time. The effect of glow plasma on vitamin C (main vitamin in acerola juice) was not significant, maintaining the retention of vitamin C above 95% under all operating conditions that were studied. The phenolics content reduced by 30% due to reaction with reactive nitrogen species when the juice was treated at the most severe condition (gas flow rate of 20 mL/min and 15 min of treatment time). The antioxidant capacity was little affected by the reactive nitrogen species formed by N2 glow plasma, which remained relatively constant at high plasma flow rate (20 mL/min) but reduced when lower gas flow rates were used (10 mL/min). The typical orange color of the juice improved due to the increase in free carotenoid content. In summary, this study showed that the operating conditions of glow plasma treatment could be adjusted to have a positive influence on vitamin A, carotenoids and color of acerola juice.

Processing chocolate milk drink by low-pressure cold plasma technology.

This study aimed to evaluate the effect of the process time (5, 10, and 15 min) and flow rate (10, 20, and 30 mL/min) of cold plasma technology on physio-chemical characteristics (pH), bioactive compounds (DPPD, Total Phenolic Compounds, ACE-inhibitory activity values), fatty acid composition, and volatile compounds profile of chocolate milk drink. The mild (lower flow rate and process time) and more severe (higher flow rate and process time) conditions led to a reduction of the bioactive compounds (total phenolic compounds and ACE-inhibitory activity), changes in fatty acid composition (increased saturated fatty acid and decreased monounsaturated fatty acid and polyunsaturated fatty acid), less favorable health indices (higher atherogenic, thrombogenic and hypercholesterolemic saturated fatty acids and lower desired fatty acids), and lower number of volatile compounds. In contrast, in intermediate cold plasma conditions, an adequate concentration of bioactive compounds, fatty acid composition, and health indices, and increased number of volatile compounds (ketones, esters, and lactones) were observed. Overall, cold plasma technology has proven to be an interesting alternative to chocolate milk drinks, being of paramount importance the study of the cold plasma process parameters.

Evaluation of thermal and non-thermal processing effect on non-prebiotic and prebiotic acerola juices using 1H qNMR and GC-MS coupled to chemometrics.

The effects of thermal (pasteurization and sterilization) and non-thermal (ultrasound and plasma) processing on the composition of prebiotic and non-prebiotic acerola juices were evaluated using NMR and GC-MS coupled to chemometrics. The increase in the amount of Vitamin C was the main feature observed after thermal processing, followed by malic acid, choline, trigonelline, and acetaldehyde. On the other hand, thermal processing increased the amount of 2-furoic acid, a degradation product from ascorbic acid, as well as influenced the decrease in the amount of esters and alcohols. In general, the non-thermal processing did not present relevant effect on juices composition. The addition of prebiotics (inulin and gluco-oligosaccharides) decreased the effect of processing on juices composition, which suggested a protective effect by microencapsulation. Therefore, chemometric evaluation of the 1H qNMR and GC-MS dataset was suitable to follow changes in acerola juice under different processing.

Improvements on the Stability and Vitamin Content of Acerola Juice Obtained by Ultrasonic Processing.

This work has examined the influence of ultrasonic processing on acerola juice and its influence in the stability of the juice and in the availability of vitamins B, C, E, and pro-vitamin A. The study has evaluated the changes in these quality parameters resulting from changes on ultrasonic power density, processing time and temperature. Ultrasound application increased the availability of pro-vitamin A and vitamins B3, B5, C and E in the juice by releasing them from the apoenzymes to which they are bound and by improving the homogeneity of the juice. The retention of the major vitamins in acerola juice (vitamins A and C) was higher when lower temperatures (10 to 20 °C) and mild ultrasound power density (2000 to 3000 W/L) were applied.