Advances in the construction and application of konjac glucomannan-based delivery systems.

Konjac glucomannan (KGM) has been widely used to deliver bioactive components due to its naturalness, non-toxicity, excellent biodegradability, biocompatibility, and other characteristics. This review presents an overview of konjac glucomannan as a matrix, and the types of konjac glucomannan-based delivery systems (such as hydrogels, food packaging films, microencapsulation, emulsions, nanomicelles) and their construction methods are introduced in detail. Furthermore, taking polyphenol compounds, probiotics, flavor substances, fatty acids, and other components as representatives, the applied research progress of konjac glucomannan-based delivery systems in food are summarized. Finally, the prospects for research directions in konjac glucomannan-based delivery systems are examined, thereby providing a theoretical basis for expanding the application of konjac glucomannan in other industries, such as food and medicine.

Machine Learning-Enhanced Biomass Pressure Sensor with Embedded Wrinkle Structures Created by Surface Buckling.

Flexible piezoresistive sensors are core components of many wearable devices to detect deformation and motion. However, it is still a challenge to conveniently prepare high-precision sensors using natural materials and identify similar short vibration signals. In this study, inspired by microstructures of human skins, biomass flexible piezoresistive sensors were prepared by assembling two wrinkled surfaces of konjac glucomannan and k-carrageenan composite hydrogel. The wrinkle structures were conveniently created by hardness gradient-induced surface buckling and coated with MXene sheets to capture weak pressure signals. The sensor was applied to detect various slight body movements, and a machine learning method was used to enhance the identification of similar and short throat vibration signals. The results showed that the sensor exhibited a high sensitivity of 5.1 kPa-1 under low pressure (50 Pa), a fast response time (104 ms), and high stability over 100 cycles. The XGBoost machine learning model accurately distinguished short voice vibrations similar to those of individual English letters. Moreover, experiments and numerical simulations were carried out to reveal the mechanism of the wrinkle structure preparation and the excellent sensing performance. This biomass sensor preparation and the machine learning method will promote the optimization and application of wearable devices.

Low temperature and freezing pretreatment for konjac glucomannan powder to improve gel strength.

Konjac glucomannan (KGM) gel has attracted widespread interest in the field of food. However, the low texture properties of gel limit its further application. In this study, the effect of KGM powder under different processing times (8 h, 12 h, 24 h and 48 h) and temperatures (4 °C, -18 °C, -80 °C) on the texture properties of gels were investigated. According to result of texture profile analysis (TPA) and puncture test, the gel prepared by pretreatment showed good texture characteristics. The gel prepared by freezing KGM powder at -18 °C for 8 h has the best gel strength in the sample, which is 1.6 times that of native KGM. The molecular weight of KGM decreased significantly after pretreatment (from 12.30 × 105 Da to 0.29 × 105 Da). In addition, low temperature and freezing treatment can influence the rheological behavior and regulate water composite in gel. According to experimental result, it can be attributed to that low temperature and the growth of ice crystal can make structures denser, promote KGM molecular chain entangled and increase the number of hydrogen bond. This study provides a convenient and effective method for improving the gel properties.

Highly Effective Multifunctional Solar Evaporator with Scaffolding Structured Carbonized Wood and Biohydrogel.

A solar evaporator that utilizes solar radiation energy can be a renewable approach to deal with energy crisis and fresh water shortage. In this study, a solar evaporator was prepared by assembling composite carbonized wood of Melaleuca Leucadendron L. and biobased hydrogel. The multilayer MXene (Ti3C2Tx) was embedded in the scaffolding structure of the wood to form composite carbonized wood, where the loose and ordered scaffolding structure of the carbonized wood significantly improves the efficiency of water transportation with increased capillary force. The MXene adsorbed in the carbonized wood has high binding energy with water molecules, leading to reduction of vaporization enthalpy and contact angle. Moreover, the addition of MXene can improve the light absorbance, especially for the infrared and ultraviolet light bands. The hydrogel was fabricated by crosslinking konjac glucomannan and sodium alginate polysaccharides with Ca2+, and it has a lower thermal conductivity than water and improves the evaporation efficiency by regulating the temperature distribution and concentrating the heat on the surface of the evaporator. This solar evaporator has an evaporation rate of 3.71 kg·m-2·h-1 and an evaporation efficiency of 129.64% under 2 sun illumination and is available to generate an open-circuit voltage of 1.8 mV after a 20 min hydrovoltaic, demonstrating a high performance and versatility. Also, experiments and numerical simulation were carried out to understand the mechanism and design principles of this solar evaporators.