The muscle is a highly organized tissue, where there are three different moistures including free water, entrapped water, and bound water. These moistures were distributed in intercellular spaces, intracellular spaces, and other solute environments, respectively. Understanding the moisture migration in different environments is crucial to enhance energy efficiency and improve the quality of processed food. Therefore, the tilapia fillets were used to experiment, and the low‐field nuclear magnetic resonance technique is used to measure the change in different moistures during the drying process. The study found that free water is the highest when cell membranes started to rupture. In addition, it also observed that the cell membrane ruptures at different stages of drying. The result of this study provides critical information that could be used to guide the study of the dynamic mechanisms underlying drying and the development of drying technology for tilapia fillets and similar aquatic products.

Tilapia is an economically important fish worldwide, but its quality is affected by storage practices. To improve the quality of tilapia fillets during frozen storage, we examined the effect of pretreatment with various combinations of different concentrations of trehalose, potassium bicarbonate, and chitosan. Following pretreatment, we analyzed the tilapia fillets using quality indicators, including soaking weight gain, coating weight gain, water-holding capacity, thawing loss, pH, Ca²⁺-ATPase activity, and texture characteristics. Water distribution was analyzed using low-field nuclear magnetic resonance and the optimal combination of water-retaining agents was obtained using an L₈(2⁷) orthogonal experiment. The results showed that trehalose, potassium bicarbonate, and chitosan improved fillet quality at pretreatment concentrations of 5%–8%, 1.0%, and 0.5%, respectively. The optimal combination was 4% trehalose plus 1.2% potassium bicarbonate plus 0.2% chitosan. The Ca²⁺-ATPase activity and mastication property of the frozen fillets that were pretreated with the optimized formulation were 1.39 μmol Pi/mg protein·h and 8.55 mJ, respectively, which were 43.3% and 80.0% greater, respectively, than that of the control group. Using a suitable concentration and combination of water-retaining agents cannot only lock-in the internal water content of frozen tilapia fillets but also improve their quality during frozen storage. These results can inform practical storage practices of similar aquatic products.

In this study, ultrasonic assisted osmotic pretreatment and pulsed vacuum assisted osmotic pretreatment were applied to investigate their effects on water migration and volatile components of heat pump dried Tilapia fillets. To achieve that, some effective parameters including sample drying rate, water diffusivity, microstructure, water morphology, water distribution, and volatile components were compared and analyzed with some advanced measurement devices. The water diffusivity, water distribution characteristics, and composition of volatile components were obtained after different pretreatment methods. As the drying process progresses, the sample moisture content decreases. Meanwhile, the high-degree-of-freedom water migrates to the low-degree-of-freedom water and the water-solid bond strength increases. Subsequently, the effective water diffusion coefficients of control group (without pretreatment samples), ultrasonic assisted osmosis pretreatment group and pulsed vacuum assisted osmosis pretreatment group were measured as 4.304 × 10⁻⁷m²/s, 6.109 × 10⁻⁷m²/s, and 5.003 × 10⁻⁷m²/s, respectively. In addition, the control group, ultrasonic assisted osmosis group, and pulse vacuum assisted osmosis group contained 52, 59, and 41 volatile compounds, respectively. Compared to the results from the control group, the water diffusion coefficients of ultrasonic osmotic pretreatment and pulse vacuum osmotic pretreatment increased by 41.94% and 16.24%, respectively. From the point of view of increasing drying rate, the ultrasonic penetration pretreatment provided better improvement, which was exactly consistent with the results of microstructure. On the other hand, the ultrasonic assisted osmotic pretreatment group had more types of volatile compounds, which could stimulate more flavored substances to be released. Evidently, the samples with ultrasonic assisted osmotic pretreatment showed less drying time and more aromatic substances whereas the samples from the pulsed vacuum assisted osmotic pretreatment had better protein protection feature. Although the dried samples had higher ratio of bound water and better storage stability after these two pretreatment methods, from the point of view of increasing drying rate and stimulating flavor substances, the ultrasonic assisted osmosis pretreatment method had more advantages. The research outcomes can contribute to optimize better pretreatment methods for the process of heat pump dried Tilapia fillets.

In this study, an experiment is conducted to explore the potential to protect both the environment and resource shortage of soybean straw, for combustion in a tubular furnace. Then, the combustion characteristics, gas emissions, and energy consumption of soybean straw are analyzed at a combustion temperature range of 773–1173 K. The results show that the total emissions of CO and NO_X are the largest at a temperature of 873 K. For NO_X, the emission time is significantly improved at temperatures of 973–1173 K. At high temperatures, the reaction of NO_X with CO and coke reduces the total emission of NO_X. The average weight loss rate at combustion temperatures of 973, 1073, and 1173 K increased by 27.38%, 61.47% and 77.97%, respectively, relative to that of 873 K. However, the energy consumption increases with the increase in combustion temperature, resulting in unnecessary waste. To get an optimal characteristic between energy utilization and pollutant discharge, a temperature range of 873–973 K is determined as the appropriate temperature for burning soybean straw.

A three-dimensional physical and mathematical model of the lateral airflow for droplet breakup was established. Numerical simulation was used to study the impact of the pulsating airflow on the droplet breakup process and analyze the variation in deformation rate under different amplitudes and frequencies. The results show that compared with uniform airflow, pulsating airflow can enhance the effect of droplet breakup, with an optimal droplet crushing effect occurring when the relative amplitude of the pulsating airflow was A = 1 and the Womersley number of the pulsating airflow was 96.6.