Study on the splitting by hot-air drying of Camellia oleifera fruit

In order to explore the feasibility of hot air splitting of Camellia oleifera fruit, the effect of hot air temperature on peel splitting, the moisture state and moisture migration in peel, the peel microstructure and the seed color were studied. The results showed that higher hot air temperature could accelerate the splitting rate, the optimum temperature for splitting C. oleifera fruit was 90–110 °C considering the seed quality. Page model was the most suitable for describing the drying kinetic characteristics of C. oleifera fruit. Nuclear magnetic resonance (NMR) revealed the changing of the dehydration rate, the migration rate of bound water, immobilized water and free water in peel during hot air drying. The expansion of micro-channels in peel was conducive to moisture migration in the early splitting stage, but microstructure damaged in the late splitting stage accompanied by loose disorder of micro pores, serious shrinkage and deformation of peel.

Monitoring of drying-induced soil moisture loss with PZT-based EMI technique

Air-drying process of soil is a crucial procedure in geological and geotechnical engineering. Drying-induced ground subsidence and damage to overlying buildings is a widespread and urgent problem. Monitoring of drying-induced water evaporation in soil is of great importance. In this paper, soil moisture loss monitoring based on lead zirconate titanate (PZT) transducer using electro-mechanical impedance (EMI) technique was investigated. A physical model test in our laboratory was conducted to study the feasibility and applicability. In the experimental research, three identical PZT transducers that were wrapped with waterproof insulation glue were pre-embedded inside a cohesive soil specimen. In addition, another PZT transducer was embedded in a sandy soil specimen to explore the application effect in soil with different composition. EMI signatures of these four PZT patches during the air-drying process were collected and analyzed. Experimental results indicated that the peak frequency in the conductance signatures presented a rightward shift as the water evaporates. Moreover, the corresponding peak magnitude keep decreasing with the continuous development of soil moisture loss. To better quantify the variations, two statistical metrics including root mean square deviation (RMSD) and mean absolute percentage deviation (MAPD) were employed to study the changing characteristics of the EMI signatures. All these two metrics increase coincidentally in the process. Experimental results demonstrate that cohesive and sandy soil moisture loss monitoring by using the embedded PZT transducer is feasible and reliable. This work also serves as a proof-of-concept study to demonstrate the performance of the EMI technique in monitoring the soil moisture content.

Physicochemical Properties of Red Beetroot and Quince Fruit Extracts Instant Beverage Powder: Effect of Drying Method and Maltodextrin Concentration

In this study, production of instant beverage powder by the foam-mat drying method (foam-mat freeze- and hot-air drying) from red beetroot, quince fruit, and cinnamon extracts without and with maltodextrin (MD) (0%, 10%, 20%, and 30%) were investigated. The results showed that an increase in the MD level has led to a decrease in the moisture content of powders. Drying method and MD concentration had a significant effect on rehydration time, color, and total phenolic content ( p ≤ 0.05 ). Foam-mat hot-air-dried powder containing 20% MD had a good flowability. According to the statistical analysis, MD content had a more significant effect on the antioxidant activity of powders than the drying method ( p ≤ 0.05 ). The total phenolic content of foam-mat hot-air-dried powders was higher than that of foam-mat freeze-dried powders. Based on the results, the produced powder containing 20% MD via foam-mat hot-air drying (60°C) was the optimum sample.