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Freeze drying (FD) yields the best quality of dried mushroom but at the cost of a long drying time and high overall cost. Air drying (AD) gives an unacceptably poor quality product. To achieve faster drying along with a high-quality product, a microwave–freeze drying (MFD) technique was developed to dry mushrooms. The relationship between dried mushroom quality and the glass transition temperature during the MFD process was studied to optimize the MFD process. According to the change tendency of the glass transition temperature of mushroom during MFD, a step-down microwave loading scheme for the MFD process was developed to obtain good product quality. [ABSTRACT FROM AUTHOR]

A mathematical model of mass and heat transfer for vacuum far-infrared drying of potato slices is introduced in this study on the basis of energy and diffusion equations. The finite difference method is used to mathematically simulate the sample temperature and moisture content in different drying conditions. Calculated results are compared with the experimental findings at varying conditions of heater temperature (120°C, 140°C, and 160°C), chamber pressure (1500, 8000, and 15000 Pa), sample thickness (0.004, 0.006, and 0.008 m), and radiation distance (0.08, 0.12, and 0.16 m). Comparison results show that the model fits well the changes in sample temperature and moisture content at different times of drying, with the values of the coefficient of determination close to 1.0 and the relative error values less than 10%. [ABSTRACT FROM AUTHOR]

Bovine bone wastes can be used to produce high-quality collagen products. Freeze drying (FD) can yield the best quality of dried collagen but at the cost of long drying time, high energy consumption, and also the overall cost. A microwave-freeze-drying (MFD) technique was developed to dry collagens extracted from bovine bone. The relationship between corona discharge and microwave power at various pressures and moisture content conditions was studied to avoid the possibility of corona discharge during MFD collagens. A microwave loading scheme was optimized to avoid the corona discharge and resulted in high product quality with greatly reduced drying time. The results suggested that MFD has the potential to substitute for traditional FD in drying of high-value products. [ABSTRACT FROM AUTHOR]

The bacterial endogenous hydrogen peroxide (H2O2) was detected cytochemically by its reaction with cerium chloride (CeCl3) to produce electron-dense deposits of cerium perhydroxides. The sequence of fixation and CeCl3 staining of H2O2 in the processing of transmission electron microscope (TEM) sample preparation is crucial to the localization of endogenous H2O2 in Escherichia coli. In this study, results confirmed that the process that fixation simultaneously with CeCl3 staining provided optimum effects for H2O2 localization in E. coli. The modified process of TEM provides very efficient protection for H2O2 localization and more accurate quantization for the H2O2 accumulation in bacterial cells. Microsc. Res. Tech., 2013. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Freeze drying (FD) yields the best quality of dried apple slices but requires a long drying time and is not cost-effective. To mitigate these problems, a microwave freeze drying (MFD) technique was developed to dry apple slices. The relationship between corona discharge and microwave power at various pressures and initial moisture content conditions was studied to avoid the possibility of corona discharge during MFD. It was found that with change of moisture content and temperature of samples during MFD, the dielectric property also changed, which resulted in dynamic microwave dissipation. Based on the dielectric property of samples, a changed microwave loading scheme can lead to perfect product quality and greatly reduce the drying time; thus, MFD can be used to replace the traditional FD technique. [ABSTRACT FROM PUBLISHER]

BACKGROUND RESULTS CONCLUSION The delayed drying of newly harvested tiger nuts can lead to mold and rancidity. Timely drying is therefore important. However, few studies have analyzed the impact of hot‐air drying on the quality of tiger‐nut oil and starch, making it essential to establish optimal drying conditions.The results showed that the drying temperature was the most important factor affecting the drying speed, followed by drying airflow rate and loading capacity. A logarithmic model can describe the hot‐air drying process of tiger nuts. The oil yield of tiger nut was highest after drying at 60 °C, reaching 22.40%. Meanwhile, the starch extracted from after drying at 60 °C had the highest solubility and expansion rate, 4.77% and 9.74%, respectively. Starch has the highest viscosity after drying at 70 °C, and it forms gel easily after aging.High‐quality tiger nuts should be produced under optimal conditions: a hot‐air drying temperature of 60 °C, an airflow rate of 1.0 m s−1, and a loading capacity of 100 g. The results of this study have practical implications for the effective drying of tiger nuts. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Vacuum far-infrared radiation (VFIR) drying has recently received many attentions because of its effective and successful applications in drying some agricultural products. The VFIR drying of Radix Rehmanniae was conducted and Weibull distribution function was applied to fit the drying kinetics in this study. The results showed that the increase of radiation heater temperature and the decrease of chamber pressure could reduce drying time obviously. Compared with single diffusion equation, Weibull distribution function had higher precision to fit the drying curves of VFIR drying of Rehmanniae. The effective moisture diffusivity (Deff) increased with the increase of heater temperature and the decrease of pressure. Scanning electron telescope (SEM) analysis showed that more porous surface could be observed after VFIR drying, which is beneficial to enhance moisture diffusivity and drying rate as well. [ABSTRACT FROM AUTHOR]

To investigate the change law of functional components and exterior color of honeysuckle flowers (HF) during controlled-atmosphere heat pump drying, nitrogen was used as drying medium in this study to reduce the oxygen concentration. The influences of drying temperature, HF's loading amount and oxygen concentration on chlorogenic acid content, cynaroside content and L value (on behalf of browning degree) were explored, and the degradation kinetics models of chlorogenic acid and cynaroside were constructed. The results showed that chlorogenic acid content, cynaroside content and L value decreased with the rise of temperature, HF's loading amount and oxygen concentration. The degradation kinetics models of chlorogenic acid and cynaroside during the drying process were established through introducing an exponent r related to time t in the first order reaction kinetics equation. The models had good fitting precision and can be used to predict the degradation law of chlorogenic acid and cynaroside. [ABSTRACT FROM AUTHOR]

The aim of this study was to study the strengthening effect of ultrasonic vacuum technique on the drying kinetics, moisture distribution, and microstructure of honey using low-field nuclear magnetic resonance and scanning electron microscopy. Results showed that ultrasonic vacuum drying technique could substantially shorten the drying time from 600 to 60 min, compared with vacuum drying. The sonochemical effects of ultrasonic vacuum drying were enhanced with the increased ultrasonic power and were more obvious in the initial stage of drying. This finding is consistent with the effective water diffusion coefficient results. The non-linear fitting analysis of experimental data on seven kinds of thin-layer drying mathematical models showed that logarithmic model is more suitable for describing the law of moisture change in honey during ultrasonic vacuum drying than the other models because of its higher regression coefficient value (≥0.99) and smaller reduced chi-square and root mean square error values (≤0.01). In addition, low-field nuclear magnetic resonance results showed that the increase in ultrasonic power accelerated the migration of bound water to immobilized water in honey samples. Scanning electron microscopy results showed that the porous structure formed by increasing the ultrasonic power is also conducive to the rapid migration and drying of moisture. In conclusion, ultrasonic vacuum drying technique is an effective and safe way for drying viscous materials compared with vacuum drying technique.

The bacterial endogenous hydrogen peroxide (H(2)O(2)) was detected cytochemically by its reaction with cerium chloride (CeCl(3)) to produce electron-dense deposits of cerium perhydroxides. The sequence of fixation and CeCl(3) staining of H(2)O(2) in the processing of transmission electron microscope (TEM) sample preparation is crucial to the localization of endogenous H(2)O(2) in Escherichia coli. In this study, results confirmed that the process that fixation simultaneously with CeCl(3) staining provided optimum effects for H(2)O(2) localization in E. coli. The modified process of TEM provides very efficient protection for H(2)O(2) localization and more accurate quantization for the H(2)O(2) accumulation in bacterial cells., (Copyright © 2012 Wiley Periodicals, Inc.)