Search Results (1,460)

The pods from Neltuma ruscifolia (vinal), an underutilized species, are rich in bioactive functional compounds. However, the extraction procedures to obtain the highest proportion of these compounds, considering sustainability aspects, have not been optimized. This study aimed to optimize and compare three affordable extraction methods—dynamic maceration (DME), ultrasound-assisted extraction (UE), and microwave-assisted extraction (ME)—to obtain enriched extracts. The effects of temperature, ethanol-to-water ratio in the solvent, extraction time, and frequency (for ME) were evaluated using a Box–Behnken design and response surface methodology to optimize total polyphenolic content (TPC), total flavonoids (TF), and antioxidant capacity (DPPH). Energy consumption and carbon footprints were also assessed, and phenolic compounds in the optimized extracts were identified by HPLC. The ethanol-to-water ratio emerged as the most influential factor, showing synergistic effects with both time and temperature, enabling optimal yields at intermediate ethanol concentrations. Gallic acid, rutin, and theobromine were found to be the most abundant components, followed by cinnamic, caffeic, and chlorogenic acids. Although UE exhibited the lowest energy consumption (0.64 ± 0.03 Wh/mg of TPC), the simple and easily implementable DME—optimized at 40 min, 50 °C, and 42% ethanol—proved to be the most efficient method, combining high extractive performance (TPC 1432 mg GAE/100 g Dw), reduced solvent use, and intermediate energy efficiency (1.84 Wh/mg of TPC). These findings highlight the potential of vinal as a natural source of bioactive ingredients obtained through simple and cost-effective techniques adaptable to small producers while underscoring the value of experimental design in optimizing sustainable extraction technologies and elucidating the interactions between key processing factors. Full article

Due to the degradative effect of the traditional pasteurization process related to the long exposure of high temperatures to the food matrix, alternative methods of food preservation are being investigated. In the case of liquid fruit products, unconventional thermal and non-thermal methods can be used for this purpose. The aim of the study was to evaluate the effect of various preservation methods: conventional pasteurization (PT), microwave pasteurization (MP), hot bottling (HB), pulsed electric field (PEF) and pulsed light (PL) on selected quality parameters of mixed juices. In the studied samples, extract (TTS), active acidity (pH), titratable acidity (TTA), nephelometric turbidity (NT), total polyphenol content (TPC), color parameters and antioxidant activity (AA) were determined. Qualitative and quantitative chromatographic analysis of anthocyanins was also performed. The different influence of the preservation methods and the raw materials used on the individual characteristics was demonstrated. The TTS and TTA changes did not exceed 4%, while no changes in pH were observed. Thermal methods increased turbidity significantly, with HB increasing it to the greatest extent. Non-thermal methods caused greater degradation of TPC, anthocyanins, and AA, while they caused significantly less color change. The microwave pasteurization resulted in an increase in TPC in two out of three studied juice blends. Based on the obtained results, it can be concluded that thermal methods allowed for the preservation of a greater amount of bioactive compounds, which translates into a potentially greater health-promoting value of the produced juice blends. Full article

This paper proposes a non-contact heart rate long-time monitoring system based on multi-source data fusion. Microwave radar cannot associate the identity of a target with its signal, whereas rPPG can achieve this through facial recognition. Additionally, rPPG technology is unable to monitor heart rate in completely dark environments, while visible light is not a prerequisite for radar-based heart rate monitoring. Consequently, this paper proposes a method for heart rate monitoring that fuses microwave and video data. The methodology involves preprocessing both microwave and video data, extracting specific features of different types of data, and identifying the heart rate by the signal features. In the experiments, the identification accuracy for heart rates ranging from 57 to 171 bpm was 73.1%, with accuracies of 75.8% for heart rates below 60 bpm and 89.9% for heart rates above 120 bpm. Compared to single-source data, the accuracy increased by 25.4% and 28.6%, respectively. The monitoring duration is approximately 30 s and achieves model optimization through algorithm deployment. These results validate the effectiveness and timeliness of the proposed method. Full article

To address the efficiency bottlenecks of traditional full-wave simulation methods in the high-performance design and rapid optimization of microwave filters, this study proposes an efficient design method based on an improved surrogate model and a hybrid optimization algorithm. A one-dimensional dense convolutional autoencoder (1D-DenseCAE) model is constructed to enhance the model’s ability to extract key features and improve convergence speed. Additionally, the Ivy–Hiking optimization algorithm (IHOA) is introduced, combining the advantages of global search and local fine-tuning. Experiments demonstrate that this method achieves approximately a 25% improvement in convergence speed over the standard one-dimensional convolutional autoencoder (1D-CAE) in cavity filter design, and enables efficient optimization in complex structures such as interdigital filters and seventh-order cross-coupled cavity filters, meeting design requirements of return loss below −20 dB and in-band ripple under 0.5 dB. This method provides an effective technical pathway for the intelligent design of microwave filters. Full article

The milling process is a critical technological step that regulates wheat flour characteristics and ultimately determines end-product quality. This study systematically evaluated the effects of three key milling parameter adjustments in a laboratory-scale roller mill—double sifting (2S), double break milling (2BM), and increased roll gap (IRG)—on the physicochemical properties of wheat flour and the quality of microwave freeze-dried non-fried instant noodles. The results demonstrated that milling processes significantly influenced the particle size and composition of flour. The 2BM-IRG process increased the volume mean diameter of flour to 86.38 μm, while significantly improving flour extraction rate (69.80%), protein content (10.98%), and ash content (0.54%). In contrast, the 2S process significantly reduced the volume mean diameter (65.27 μm). These changes in flour properties directly affected noodle quality—noodles made from 2BM-IRG flour exhibited the highest rehydration ratio but also the greatest cooking loss, along with the lowest expected glycaemic index (eGI); noodles produced from 2S flour showed the highest hardness, while the 2BM process endowed noodles with superior elasticity. A correlation analysis revealed that the digestibility characteristics of noodles (eGI) were predominantly and significantly influenced by flour protein and ash content (p < 0.01), while also being significantly affected by particle size (p < 0.05). The study confirmed distinct quality trade-offs between different milling strategies. Therefore, by optimizing combinations of break milling and sifting processes, it is possible to develop specialized flour tailored for specific quality requirements. Full article

A microwave extraction method was developed to isolate antioxidant polysaccharides from Plantago depressa (psyllium), and the structure, free radical-scavenging ability, as well as in vivo antioxidant activity of psyllium polysaccharides were analyzed. The optimal condition for microwave extraction was as follows: duration of microwave radiation of 35 min, extraction temperature of 80 °C, and ratio of liquid to solid of 80:1 (mL/g). The yield of psyllium polysaccharides by microwave extraction was significantly higher than that by heating extraction (p < 0.05). The volumes of P. depressa samples notably increased after microwave extraction, which implied that microwave radiation might loosen the structure of cells and tissues of psyllium leaves and facilitate the exudation of target polysaccharides from leaf samples. The structure of polysaccharides was analyzed by infrared spectroscopy. The effective concentrations of psyllium polysaccharides scavenging DPPH^• and ABTS^•+ radicals by 50% (EC₅₀) were 0.20 and 0.10 mg/mL, respectively. Moreover, P. depressa polysaccharides increased activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in Drosophila melanogaster. In conclusion, microwave extraction seems to be an efficient method to isolate bioactive polysaccharides from P. depressa, which were a potential source of natural antioxidants. Full article

Three-layer polyethylene (3LPE) coated steel pipelines are currently the preferred solution for global oil and gas transmission. However, external corrosion beneath the 3LPE coating poses a serious threat to pipeline operations. The pressing concern for pipeline safety and integrity involves non-destructive evaluation techniques for the non-invasive and quantitative interrogation of such defects. This study therefore explores linear frequency-sweeping microwave near-field non-destructive testing (NDT) techniques for imaging and evaluating the pitting corrosion beneath 3LPE coating. An improved branch-cut method is proposed for the high-precision phase unwrapping of the microwave phase image sequence, and its superiority over traditional methods in terms of accuracy and robustness is validated. A background subtraction method based on kernel density estimation (KDE) is presented to suppress the lift-off effect on the pipeline geometry. In addition, the principal-component-analysis-wavelet-based principal component extraction and fusion enhance the detection signal-to-noise ratio (SNR) and image contrast, while mitigating the annular artifacts around the corrosion. The experimental results demonstrate the feasibility of the proposed approach for the detection, imaging, and characterization of external corrosion beneath the 3LPE coating of pipelines. Full article

Feline infectious peritonitis virus (FIPV), caused by a mutated form of feline coronavirus, poses a significant threat to feline health worldwide, with limited therapeutic options available. This study investigated the antiviral potential of α-mangostin (α-MG) and its enriched extracts (AMEs), obtained via microwave-assisted extraction, against FIPV. We evaluated their cytotoxicity, direct virucidal activity, and antiviral activity in CRFK cells. Both α-MG and AMEs demonstrated significant antiviral activity, with EC₅₀ values from 2.71 to 2.88 μg/mL and favorable selectivity indices (3.25–3.66). Notably, AMEs exhibited direct virucidal effects, effectively reducing viral titers. Furthermore, treatment with these compounds significantly reduced inflammatory cytokine expression (IFN-β, TNF-α, and IL-6 mRNA levels) and decreased viral loads in FIPV-infected cells. Drug combination studies using the ZIP model revealed enhanced cooperative effects when AMEs and α-MG were combined with GC-376 or GS-441524, with GC-376 combinations showing particularly strong synergistic potential. These findings suggest that α-MG and AMEs are promising candidates for FIPV treatment, either as monotherapy or in combination therapy. This study provides insights into developing novel therapeutic strategies to combat FIPV infections and offers a foundation for future veterinary antiviral drug development. Full article

Black chokeberry (Aronia melanocarpa L.) pomace (BCP), a major by-product of juice production, is an underutilized source of polyphenols and anthocyanins with strong antioxidant properties. This study aimed to optimize and compare three green extraction techniques—pressurized liquid extraction (PLE), microwave-assisted extraction (MAE), and ultrasound-assisted extraction (UAE)—for recovering total polyphenols (TP) and total monomeric anthocyanins (TMA) from BCP, with reflux extraction as a benchmark. The effects of temperature, extraction time, and solid–solvent ratio were evaluated, and cryogrinding was assessed as a pre-treatment. PLE achieved the highest TP yields at elevated temperatures but reduced anthocyanin recovery, while MAE offered a balance of high TP and TMA, with strong antioxidant capacity. Cryogrinding enhanced TP extraction, with only 1 min of cryogrinding maximizing yield. UPLC-MS/MS analysis of optimized MAE extract confirmed cyanidin-3-glucoside and cyanidin-3-galactoside as dominant anthocyanins, alongside notable flavonols and phenolic acids, validating the rich phenolic profile. Overall, MAE combined with 1 min of cryogrinding proved to be the most effective approach for preserving heat-sensitive compounds while achieving high yields. These findings demonstrate that optimized green extraction can efficiently valorize BCP, supporting sustainable food processing and waste reduction in line with circular economy principles. Full article

In this in vitro experimental study, we compared four extraction techniques -dynamic maceration (DME), ultrasound-assisted (UAE), microwave-assisted (MAE), and pressurized liquid extraction (PLE)- to obtain bioactive extracts from two native Ecuadorian plants, Piper carpunya and Simira ecuadorensis. The effect of extraction techniques was evaluated separately for each specie based on extraction yield, total phenolic content (TPC), antioxidant capacity (DPPH, ABTS, FRAP, and ORAC assays), antimicrobial activity, and chemical composition. All analyses were performed in triplicate and analyzed statistically (ANOVA, p < 0.05). UAE and MAE exhibited the highest extraction yield, while PLE provided extracts with the greatest TPC. However, UAE extracts, particularly for S. ecuadorensis, exhibited superior antioxidant capacity across assays. GC/MS analysis revealed alkanes as predominant constituents, along with minor phenolic and ester compounds. Antimicrobial activity was observed in both species, especially against Listeria monocytogenes and Pseudomonas aeruginosa, with UAE and MAE extracts being most effective. Compounds such as isoelemicin, phytol, and ethyl linolenate may contribute to the observed bioactivities. These findings highlight the potential of P. carpunya and S. ecuadorensis as natural sources of antioxidants and antimicrobials for food and pharmaceutical applications. Full article

The production of biodiesel from microalgae presents a sustainable and renewable solution to the growing global energy demands, with catalysts playing a critical role in optimizing the transesterification process. This study examines the emerging catalysts and innovative techniques utilized in converting microalgal lipids into fatty acid methyl esters, emphasizing their impact on reaction efficiency, yield, and environmental sustainability. Sulfuric acid demonstrates excellent performance in in situ transesterification, while NaOH/zeolite achieves high biodiesel yields using ultrasound- and microwave-assisted methods. Metal oxides such as CuO, NiO, and MgO supported on zeolite, as well as ZnAl-layered double hydroxides (LDHs), further enhance reaction performance through their high activity and stability. Enzymatic catalysts, particularly immobilized lipases, provide a more environmentally friendly option, offering high yields (>90%) and the ability to operate under mild conditions. However, their high cost and limited reusability pose significant challenges. Ionic liquid catalysts, such as tetrabutylphosphonium carboxylate, streamline the process by eliminating the need for drying and lipid extraction, achieving yields as high as 98% from wet biomass. The key novelty of this work lies in its detailed focus on the use of ionic liquids and nanocatalysts in microalgae-based biodiesel production, which are often underrepresented in previous reviews that primarily discuss homogeneous and heterogeneous catalysts. Full article

Jerusalem artichoke (Helianthus tuberosus L.) is a valuable source of inulin and fructooligosaccharides—compounds with well-documented prebiotic and functional food properties. However, its high moisture content significantly limits storage stability. This study aimed to assess the effects of drying method and process temperature on the drying kinetics and selected physicochemical properties of Jerusalem artichoke. Convective drying (AD) and combined convective–microwave drying (AMD), using a microwave power of 100 W, were employed. Drying was conducted at air temperatures of 40 °C, 60 °C, and 80 °C. Among the mathematical models evaluated, the Page model provided the best fit to the experimental drying data for both methods. Samples dried at 80 °C using the AMD technique exhibited the most pronounced changes in color, significant polyphenol losses, and a substantial reduction in antioxidant capacity compared to the fresh material. The lowest polyphenol degradation and the highest retention were observed in products dried at 40 °C using both AD and AMD methods. Notably, the AMD method significantly reduced drying time and improved the grindability of the dried Jerusalem artichoke samples. Although AMD contributed to certain quality deterioration, it also promoted a higher degree of particle size reduction. However, this increased degree of particle size reduction had only a limited effect on the extraction efficiency of fructooligosaccharides and inulin. The results of the present study suggest that AMD may serve as a competitive alternative to AD for drying Jerusalem artichoke, particularly when processing time and grindability are critical considerations. Full article

Stevia rebaudiana leaves and extracts need to be promptly dried after harvest to prevent microbial activity and preserve their bioactive compounds, including glycosides, flavonoids, and essential oils. Effective drying also reduces moisture and volume, which lowers packaging, storage, and transportation costs. Therefore, innovative drying methods are necessary to maintain stevia’s physicochemical, sensory, and nutritional properties for functional food formulations. This review evaluates various drying technologies for stevia leaves and extracts, including convective hot air, infrared, vacuum, microwave, freeze, and shade drying, and their impacts on product quality and energy efficiency. It also explores the growing applications of dried and extracted stevia in food products. By comparing different drying methods and highlighting the benefits of stevia in these food formulations, this investigation aims to identify future research directions and optimization strategies for utilizing stevia as a natural sweetener and functional ingredient. Convective hot air drying at higher temperatures was found to be the most energy-efficient, though several studies have reported moderate degradation of key bioactive compounds such as stevioside and rebaudioside A, particularly at elevated temperatures and extended drying times. Infrared drying enhanced antimicrobial activity but resulted in lower levels of polyphenols and antioxidants. Vacuum drying effectively preserved anti-inflammatory compounds like flavonoids. Microwave drying presented strong protection of antioxidant activity and superior particle morphology. Freeze drying, while less energy-efficient, was the most effective at retaining antioxidants, polyphenols, and volatile compounds. Shade drying, though time-consuming, maintained high levels of polyphenols, flavonoids, and essential oils. Advanced techniques like spray drying and electrospraying have been reported to enhance the sensory qualities and stability of stevia extracts, making them ideal for food applications such as dairy and baked products, confectionery, syrups, snacks, jams, preserves, and meat products. Overall, stevia not only serves as a natural, zero-calorie sweetener but also contributes to improved health benefits and product quality in these diverse food formulations. Full article

Background: Silkworm cocoons are rich in bioactive compounds beneficial for cosmetic applications. This study presented a novel approach by comparing microwave and ultrasonic pretreatments to enhance silk protein extraction efficiency. The aim was to evaluate the effects of pretreatment methods and extraction solvents on the bioactive components, physicochemical properties, and biological activities of silkworm cocoon extracts for cosmetic applications. Methods: Cocoons of Bombyx mori (Nang Lai) were pretreated using conventional soaking (12 h), microwave (3 min), or ultrasonication (30 min), and then subjected to aqueous or enzymatic extraction. The extracts were analyzed for protein, phenolic, and flavonoid content. Structural and thermal properties were characterized using infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. Antioxidant and anti-aging properties were assessed by measuring the inhibition of nitric oxide, 2,2-diphenyl-1-picrylhydrazyl (DPPH^•), and collagenase. Skin moisturizing effects and irritation potential were tested. Results: Silkworm cocoons pretreated with microwave (ALM) and ultrasonication (ALS), followed by enzymatic extraction, had the highest yields (21.6 ± 0.5% and 21.7 ± 0.4%, respectively). Despite their slightly lower protein contents, these extracts showed elevated phenolic and flavonoid content. ALM and ALS demonstrated strong antioxidant activities, with DPPH^• scavenging of 65.9 ± 0.2% and 65.2 ± 0.3%, collagenase inhibition of 60.3 ± 0.8% and 59.7 ± 1.7%, and nitric oxide inhibition of 13.5 ± 0.4% and 12.9 ± 0.2%, respectively. Skin moisturizing effects increased by 63.6 ± 2.1% for ALM and 61.2 ± 1.5% for ALS, compared to 1.3 ± 0.6% in the control. All extracts were found to be non-irritating for topical application, indicating their safety for skincare formulations. Conclusions: Microwave and ultrasonication pretreatments, in combination with enzymatic extraction, provide an effective, time-efficient, and sustainable method for producing silkworm cocoon extracts with promising cosmetic applications. Full article

This study investigated the influence of process parameters on the recovery of phenolic compounds and antioxidant activity from pineapple peel using green extraction technologies: ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE). A two-level factorial design was used to evaluate the effects of the solvent-to-solid ratio, time, temperature, ethanol concentration, and power on the yield of hydrolyzable and condensed polyphenols. The extracts were characterized using HPLC-MS, and their antioxidant activity was assessed using DPPH, ABTS, and FRAP assays. UAE yielded the highest condensed polyphenol content (323.82 mg/g), while MAE extracts demonstrated superior antioxidant activity (FRAP: 90.40 mgEqTrolox/g). The predominant compound identified using both methods was 1-caffeoylquinic acid. The most influential variable in UAE was the solvent-to-solid ratio, whereas extraction time was the most significant variable in MAE. These findings highlight the potential of pineapple peel valorization through sustainable extraction methods, with UAE favoring phenolic yield and MAE enhancing bioactivity, thereby supporting their application in the food and nutraceutical industries. Full article