Search Results (22)

The current study aimed to investigate mathematical modeling, drying kinetics, and thermodynamic properties for cost-effectively drying marjoram leaves under different operating pressures (OPs) and drying temperatures (DTs). Three DTs of 40, 50, and 60 °C and three OPs of (atm) atmospheric, −5 kPa, and −10 kPa were used in this study. All drying processes were conducted using the developed vacuum dryer (DVD) and a constant layer thickness of 1 cm and initial moisture content of 817.43 on a dry basis (d.b.). The results obtained showed that increasing the DT from 40 to 60 °C at OPs of atm, −5 kPa, and −10 kPa led to a decrease in the drying time by about 55.6%, 36.4%, and 42.9%, respectively. On the other hand, decreasing the OP from atm to −10 kPa resulted in a decrease in drying time of about 58.8%, 45.5%, and 50% at DTs of 40, 50, and 60 °C, respectively. The moisture diffusivity (D_eff) ranged between 1.13 and 5.51 × 10⁻⁹ m²/s, with the highest value of D_eff observed at an OP of −10 kPa and a DT of 60 °C. Under these conditions, the activation energy (AE) was minimal, at approximately 2.68 kJ/mol. Mathematical modeling revealed that the Modified Midilli (I) model was the most suitable for describing the drying kinetics of marjoram leaves under experimental conditions. Among the thermodynamic parameters of marjoram leaves, it was observed that enthalpy values decrease with increasing DT and decreasing OP. Additionally, all tests showed negative entropy, suggesting that the chemical adsorption and/or structural modifications of the adsorbent are responsible for these results. The economic analysis revealed that drying marjoram leaves at an OP of 10 kPa and a DT of 60 °C resulted in yearly cost savings of up to USD 2054.19 and reduced the investment payback period to approximately 0.139 years (about 2 months). Full article

Common designs of workwear drying units require not only energy efficiency but also effective disinfection. One possibility of sanitising clothes during drying is to use the ozone generated inside the drying chamber. This process requires precise management of airflow and a uniform distribution of ozone in the chamber. Therefore, optimising the shape of the drying chamber must include not only the correct flow of drying air but also the correct distribution of ozone. This paper addresses the difficult problem of modelling the flow of sanitising ozone in an innovative drying chamber. The innovative shape of the chamber is shown in this article. Due to the low percentage of ozone in the air (up to 10 ppm), CFD simulation models of the usual mixture type are too inaccurate; therefore, special models have to be used. Therefore, this paper presents an experimentally verified methodology to simulate ozone flow in an innovative drying and sanitising cabinet using two methods: Discrete Phase Model (DPM) and Species Transport (ST). The DPM method uses a Euler–Lagrange approach to qualitatively assess the spread of ozone particles, treated with a description of the movement of the particles and not as a continuous gaseous substance. On the other hand, this already allows the verification of ozone concentrations, with an appropriate conversion of the measured quantities. The ANSYS/FLUENT 2023R1 program was used for the simulations after careful selection of the mesh, closing models, boundary conditions, etc. Simulations made it possible to analyse the distribution of ozone in the workspace and assess the effectiveness of the sanitisation process. The results of the simulations were verified on the basis of empirical tests, which showed the correctness of the model and the correct distribution of the sanitising ozone in the entire volume of the drying chamber in the innovative drying–sanitising chamber. The complete simulation of the air and ozone distribution using the presented models allowed for the optimisation of the opening and shapes, which contributed to improving the energy efficiency of the unit and increasing the efficiency of the sanitisation processes, making the described methodology very effective for optimising the chambers of various types of dryers. Full article

Apple chips, which are in the snack product category, are the forefront of research due to their nutritional value and high fiber and low fat contents. Sodium metabisulfite (E223) is widely used in the food industry to prevent the browning reactions that occur during drying processes. Sodium metabisulfite (Na₂S₂O₅) is a powder that is easy and safe to use, is highly accessible and is also inexpensive in terms of cost. However, in recent years, industry and academia have focused on reducing the sulfur dioxide concentration in foods. The objective of this study was to investigate the effect of sodium metabisulfite as a pretreatment on the bioactive and technological properties of apple chips using an air-circulated tray dryer. In this context, apple discs were immersed in Na₂S₂O₅ solutions prepared at three different concentrations (0.02, 0.1 and 0.5%), and then drying was carried out at 55 °C and 1.5 m/s air flow rates. The apple chips were also produced out of unpretreated discs using both a tray dryer and freeze dryer. The differences among the sample groups were compared by performing browning index, water activity, rehydration rate, total phenolic content and antioxidant capacity analyses. The findings showed that water activity (aw) values of the apple chips (0.28–0.32) were within reliable limits in terms of storage stability and shelf life. There was no significant difference between the aw values of the apple chips produced using different Na₂S₂O₅ concentrations, but the apple chips produced through the freeze-drying had the lowest aw value. The increasing concentration of Na₂S₂O₅ gradually increased the rehydration ratio of the chips produced in the tray dryer. On the other hand, the chips produced with the freeze dryer had significantly higher rehydration ratio (4.3) due to the porous structure. The browning index values of the chips gradually decreased with the increase in Na₂S₂O₅ concentration. Freeze-drying resulted in a higher conserved total phenolic content and antioxidant capacity value. Still, the Na₂S₂O₅ pretreatment also protected the bioactive components of the products when compared with those of the untreated apple discs. Full article

Maize is the crop which is most commonly exposed to toxigenic fungi that produce many toxins that are harmful to humans and animals alike. Preharvest grain yield loss, preharvest toxin contamination (at harvest), and storage loss are estimated to be between 220 and 265 million metric tons. In the past ten years, the preharvest mycotoxin damage was stable or increased mainly in aflatoxin and fumonisins. The presence of multiple toxins is characteristic. The few breeding programs concentrate on one of the three main toxigenic fungi. About 90% of the experiments except AFB1 rarely test toxin contamination. As disease resistance and resistance to toxin contamination often differ in regard to F. graminearum, F. verticillioides, and A. flavus and their toxins, it is not possible to make a food safety evaluation according to symptom severity alone. The inheritance of the resistance is polygenic, often mixed with epistatic and additive effects, but only a minor part of their phenotypic variation can be explained. All tests are made by a single inoculum (pure isolate or mixture). Genotype ranking differs between isolates and according to aggressiveness level; therefore, the reliability of such resistance data is often problematic. Silk channel inoculation often causes lower ear rot severity than we find in kernel resistance tests. These explain the slow progress and raise skepticism towards resistance breeding. On the other hand, during genetic research, several effective putative resistance genes were identified, and some overlapped with known QTLs. QTLs were identified as securing specific or general resistance to different toxicogenic species. Hybrids were identified with good disease and toxin resistance to the three toxigenic species. Resistance and toxin differences were often tenfold or higher, allowing for the introduction of the resistance and resistance to toxin accumulation tests in the variety testing and the evaluation of the food safety risks of the hybrids within 2–3 years. Beyond this, resistance breeding programs and genetic investigations (QTL-analyses, GWAM tests, etc.) can be improved. All other research may use it with success, where artificial inoculation is necessary. The multi-toxin data reveal more toxins than we can treat now. Their control is not solved. As limits for nonregulated toxins can be introduced, or the existing regulations can be made to be stricter, the research should start. We should mention that a higher resistance to F. verticillioides and A. flavus can be very useful to balance the detrimental effect of hotter and dryer seasons on aflatoxin and fumonisin contamination. This is a new aspect to secure food and feed safety under otherwise damaging climatic conditions. The more resistant hybrids are to the three main agents, the more likely we are to reduce the toxin losses mentioned by about 50% or higher. Full article

Good hand hygiene has proven to be essential in reducing the uncontrolled spread of human pathogens. Cold atmospheric plasma (CAP) may provide an alternative to disinfecting hands with ethanol-based handrubs when handwashing facilities are unavailable. CAP can be safely applied to the skin if the energy is well controlled. In this study, radio frequency (RF) and direct current (DC) plasma sources were built with a pin-to-mesh electrodes configuration inside a fused silica tube with a 5 mm inner diameter. Microbiological assays based on EN 13697:2015+A1:2019 using Escherichia coli DSM 682 or Staphylococcus epidermidis DSM 20044 were used to examine the antimicrobial effect of various plasma conditions. Metal and silicone disks that model skin were used as inoculation matrices. The prototype air RF CAP achieved significant disinfection in the MHz range on stainless steel and silicone substrates. This is equivalent to half the performance of direct current CAP, which is only effective on conductive substrates. Using only electricity and air CAP could, with further optimization to increase its efficacy, replace or complement current hand disinfection methods, and mitigate the economic burden of public health crises in the future. Full article

Evaluations of nonintrusive load monitoring (NILM) algorithms and technologies have mostly occurred in constrained, artificial environments. However, few field evaluations of NILM products have taken place in actual buildings under normal operating conditions. This paper describes a field evaluation of a state-of-the-art NILM product, tested in eight homes. The match rate metric—a technique recommended by a technical advisory group—was used to measure the NILM’s success in identifying specific loads and the accuracy of the energy consumption estimates. A performance assessment protocol was also developed to address common issues with NILM mislabeling and ground-truth comparisons that have not been sufficiently addressed in past evaluations. The NILM product’s estimates were compared to the submetered consumption of eight major appliances. Overall, the product had good performance in disaggregating the energy consumption of the electric water heaters, which included both electric resistance and heat-pump water heaters, but only a fair accuracy with refrigerators, dryers, and air conditioners. The performance was poor for cooking equipment, furnace fans, clothes washers, and dishwashers. Moreover, the product was often unable to detect major loads in homes. Typically, two or more appliances were not detected in a home. At least two dryers, furnace fans, and air conditioners went undetected across the eight homes. On the other hand, the dishwasher was detected in all homes where available or monitored. The key findings were qualitatively compared to those of past field evaluations. Potential areas for improvement in NILM product performance were determined along with areas where complementary technologies may be able to aid in load-disaggregation applications. Full article

Native potato clones grown in Peru contain bioactive compounds beneficial to human health. This study aimed to optimize the spray-drying nanoencapsulation of native potato phenolic extracts utilizing a central composite design and response surface methodology, obtaining the optimal treatment to an inlet temperature of 120 °C and an airflow of 141 L/h in the nano spray dryer B-90, which allowed maximizing the yield of encapsulation, antioxidant capacity (DPPH), encapsulation efficiency (EE), total phenolic compounds, and total flavonoids; on the other hand, it allowed minimizing hygroscopicity, water activity (Aw), and moisture. Instrumental characterization of the nanocapsules was also carried out, observing a gain in lightness, reddening of the color, and spherical nanoparticles of heterogeneous size (133.09–165.13 nm) with a negative ζ potential. Thermal, infrared, and morphological analyses confirmed the encapsulation of the core in the wall materials. Furthermore, an in vitro release study of phenolic compounds in an aqueous solution achieved a maximum value of 9.86 mg GAE/g after 12 h. Finally, the obtained nanocapsules could be used in the food and pharmaceutical industry. Full article

This study aims to evaluate the effects of drying in a forced-air oven or solar dryer on the drying rates, physicochemical and microbiological characteristics, and antioxidant properties of rosemary, mint, common fennel, lemon grass, and basil. The drying rates of all herbs were higher in the forced-air oven in comparison to the solar dryer. According to results obtained for herbal properties after this different drying process, mint was less affected by both drying conditions. On the other hand, regardless of the method of drying used, all dried herbs exhibited similar antioxidant properties, mainly due to the presence of total phenolics. The antioxidant activities of oven-dried herbs ranged from 19.18 to 71.55% and increased in the order common fennel < lemon grass < mint < basil < rosemary, while the activities of sun-dried samples varied from 17.73 to 58.27% and increased in the order basil < common fennel < lemon grass < mint < rosemary. The results obtained demonstrate that the process of drying can alter the quality of an herbal product, implying that standardization of post-harvest steps is essential to ensure the consistency of an herbal product. Full article

Efficient hand hygiene is essential for preventing the transmission of microorganisms. Alcohol-based hand rub (ABHR) is a recommended method. We compared health personnel (skilled nurse students) with random adults to study the effect of an ABHR procedure. A water-based hand rub (WBHR) procedure, using running tap water and a hand-drying machine, was also investigated. The study included 27 nurse students and 26 random adults. Hands were contaminated with Escherichia coli, and concentrations of colony forming units (CFU/mL) were determined before and after ABHR or WBHR. Concentrations after ABHR were 1537 CFU/mL (nurse students) and 13,508 CFU/mL (random adults) (p < 0.001). One-third of participants reported skin irritation from daily ABHR. Concentrations after WBHR were 41 CFU/mL (nurse students) and 115 CFU/mL (random adults) (p < 0.011). The majority of participants (88.5%) preferred the WBHR method. Results from 50 air samples from filtered air from the hand dryer outlet showed no CFU in 47 samples. A significant difference between the two groups was shown for the ABHR method, indicating that training skills are important for efficient hand hygiene. Surprisingly, the WBHR method seemed to have a significant effect in largely removing transient bacteria from hands. Full article

This paper presents a mathematical model of heat pump exchangers and their thermal interaction with a fan for an air dryer. The calculation algorithm developed for the finned heat exchangers is based on the ε-NTU method, allowing the determination of air side and refrigerant side heat transfer coefficients, evaporator and condenser heat capacity and air parameters at the dehumidifier outlet with known exchanger geometries, initial air parameters and mass flow rate. The model was verified on an industrial dehumidifier test bench. This enabled the heat transfer coefficients for the exchanger to be calculated as a function of the speed and, therefore, the power of the fan’s drive motor. An increase in fan performance on the one hand results in an increase in the heat transfer rate, but, on the other hand, it causes an increase in the total energy consumption of the motor. Thus, while it causes an increase in drying capacity, it also causes an increase in the energy consumption of the dehumidifier. In order to optimise the unit in terms of energy consumption, it is therefore necessary to determine a function that relates the amount of heat exchanged to the efficiency of the fan. Full article

The effects of phosphorylation pre-treatments at 1.5, 2.5, and 3.5% levels, as well as microwave application at 200, 400, and 700 watts levels for 2 min, on the functional parameters of egg white powder obtained by the freeze dryer procedure were investigated. P1.5-M200 had the highest oil-holding capacity, emulsion stability, and emulsion activity, while P2.5-M200 had the highest foam capacity. The P2.5-M400 had the largest particle size, and P3.5-M200 had the highest degree of phosphorylation and protein solubility. On the other hand, P3.5-M200 had the highest solution viscosity by 1% (w/v), water-holding capacity, and foam stability, in the treatments that used phosphorylation and microwave treatment simultaneously. FTIR spectroscopy of the unfolding structure of egg white protein revealed changes in the protein’s secondary structure, such as the development of β-sheets and β-turns, as well as the binding of negatively charged phosphate groups on the serine, threonine, and tyrosine side chains. The phosphorylation and microwave treatments reduced the particle size of the egg white protein powder while increasing the surface area of the protein molecules, according to SEM analyses. Full article

Microalgae are considered a promising resource of proteins, lipids, carbohydrates, and other functional biomolecules for food and feed markets. Competitive drying solutions are required to meet future demands for high-quality algal biomass while ensuring proper preservation at reduced costs. Since often used drying methods, such as freeze or spray drying, are energy and time consuming, more sustainable processes remain to be developed. This study tested an indirect and hybrid solar dryer as an alternative to conventional freeze drying of industrially produced Tetraselmis chui and Nannochloropsis oceanica wet paste. The effects of the drying method on biomass quality parameters, including biochemical profiles, functional properties, and microbial safety, were assessed. No significant differences were found between the applied drying technologies for total proteins, carbohydrates, lipids, and fatty acid profiles. On the other hand, some pigments showed significant differences, displaying up to 44.5% higher contents in freeze-dried samples. Minor differences were also registered in the mineral profiles (<10%). Analyses of microbial safety and functional properties of the solar-dried biomass appear adequate for food and feed products. In conclusion, industrial solar drying is a sustainable technology with a high potential to preserve high-quality microalgal biomass for various markets at expected lower costs. Full article

Nano spray drying has emerged as an outstanding platform for engineering micro- and nanoparticles, with growing applications in various areas of drug delivery. As a new technology involving distinct technical design, parameters of the nano spray drying process are not fully elucidated. In a quality-by-design approach, the aim of the current study was to gain thorough understanding of critical determinants of product characteristics in the Büchi Nano Spray Dryer B-90. Following a factorial experimental design, a series of spray drying experiments were conducted to gain new insights into the influences of the inlet temperature, the spray solvent, and the solute concentration in the spray solution on the yield, the moisture content, and the particle size of the nano spray-dried powder material. Special consideration was given to the potential of using hydroethanolic in comparison with aqueous solvent systems and to particle engineering for pulmonary drug delivery. Lactose and mannitol, widely used as excipients in dry powder inhalation formulations, were used as model materials. Lactose and mannitol are known to spray dry in amorphous and crystalline forms, respectively. The yields of spray drying of lactose and mannitol amounted generally to 71.1 ± 6.6% w/w and 66.1 ± 3.5% w/w, respectively. The spray-dried materials exhibited generally a number-weighted median particle diameter of 1.6 ± 0.2 μm and a volume-weighted median particle diameter of 5.1 ± 1.0 μm. A detailed analysis of the results improved understanding of the interplay between process parameters in the Nano Spray Dryer. The results demonstrate that optimization of spray generation is the key to yield optimization. On the other hand, particle size is determined by the spray mesh pore size and the spray solution degree of saturation. Selection of an appropriate spray solvent and using spray solution additives could optimize spray flow. In parallel, the spray solvent and the solute concentration in the spray solution determine the degree of saturation. Guidance on optimization of particle engineering by nano spray drying is provided. Full article

In Colombia, most commercial drying processes are frequently performed through the burning of wood and fossil fuels with high costs and environmental damage. Nevertheless, solar drying is a technique that could also be used to reduce many of the problems present in traditional drying techniques. Finding low-cost technology to install a solar dryer in a vulnerable community of women is an appropriate alternative; the transfer of knowledge on this technique could lead to greater empowerment of women and prevent gender inequality. This study evaluated the color and water activity of the mango (Mangifera indica L.) after a drying process in a greenhouse dryer. Furthermore, this study showed the relevance of implementing this technique in a community of women affected by the military conflict in Colombia. Results showed that a solar dryer achieved drying times of around 23–26 h, reaching water activity values below the 0.5 threshold which, according to international standards, has been considered as a food safety value. In addition, the color of the dry mango is slightly affected through this drying technique, providing a more acceptable consumer product. The application of the solar dryer has proven to be an easy-to-use and environmentally friendly method. On the other hand, it is also an opportunity to improve, with a low-cost investment, the living conditions of vulnerable communities. Full article

Adsorption dehumidification and drying equipment is essential general equipment for domestic and industrial use. The most commonly used type in industry is the compressed air adsorption dryer. The analysis results show that the heat loss of the traditional heat air regeneration system of the compressor dryer is 39.4%, and the exhaust waste heat is 32.4%. The actual use of heat energy for desiccant regeneration is only 28.2%. Therefore, this study uses an innovative electrothermal adsorbent unit (ETAU) to regenerate the desiccant. By directly heating the adsorbent, heat loss can be effectively improved. On the other hand, the composite arrangement of zeolite and activated alumina is used. The inlet compressed air is firstly treated by the activated alumina, which has a high adsorption capacity in the high relative humidity condition, then a zeolite is used as a second part to make the dew point reach –40 °C. In the regeneration step, the airflow direction is reversed, whereby the zeolite is regenerated by the ETAU, and the waste heat of the exhaust air is used to regenerate the activated alumina, which reduces the temperature of the exhaust air. Compared with the traditional heat air compressed air system, the two technologies can save about 27% energy in total. Full article