A novel ultrasound-assisted vacuum drying technique for improving drying efficiency and physicochemical properties of Schisandra chinensis extract powder

Application progress of ultrasound in the production and processing of traditional Chinese herbal medicines

The quality of Chinese herbal medicines is the key to the quality of traditional Chinese medicine. The processing of Chinese herbal medicines is an important part of the production and quality formation of medicinal materials. Traditional processing methods have low productivity and cannot guarantee the quality of Chinese herbal medicines. Among various non-thermal processing methods, ultrasonic technology has been proved to be a very valuable green processing technology. This paper will discuss the application of ultrasonic technology in the production and processing of Chinese herbal medicines in recent years, including the extraction, cleaning, drying and sterilization of effective components of Chinese herbal medicines. This review summarizes its principle, characteristics and application progress in recent years, and discusses its existing problems. The effects of ultrasound on the chemical structure and biological activity of bioactive compounds extracted from Chinese herbal medicines are mainly introduced. In addition, this paper discusses the effects of different ultrasonic conditions such as frequency, power, time and temperature on the chemical properties and processing of Chinese herbal medicines. In general, the use of ultrasound in the production and processing of Chinese herbal medicines has great application potential.

The extraction, purification, structural features, bioactivities, and applications of Schisandra chinensis polysaccharides: A review

Schisandra chinensis, as a famous medicinal and food homologous plant, has a long history of medicinal and dietary therapy. It has the functions of nourishing the kidney, calming the heart, tranquilising the mind, tonifying Qi and producing fluid to relieve mental stress, based on the theory of traditional Chinese medicine. Accumulating evidence has shown that S. chinensis polysaccharides (SCPs) are one of the most important bioactive macromolecules and exhibit diverse biological activities in vitro and in vivo, including neuroprotective, hepatoprotective, immunomodulatory, antioxidant, hypoglycemic, cardioprotective, antitumour and anti-inflammatory activities, etc. This review aims to thoroughly review the recent advances in the extraction and purification methods, structural features, biological activities and structure-activity relationships, potential applications and quality assessment of SCPs, and further highlight the therapeutic potentials and health functions of SCPs in the fields of therapeutic agents and functional food development. Future insights and challenges of SCPs were also critically discussed. Overall, the present review provides a theoretical overview for the further development and utilization of S. chinensis polysaccharides in the health food and pharmaceutical fields.

Foliar application of selenium nanoparticles alleviates cadmium toxicity in maize (Zea mays L.) seedlings: Evidence on antioxidant, gene expression, and metabolomics analysis

The molecular and metabolic mechanisms of foliar selenium (Se) nanoparticles (SeNPs) application in mitigating cadmium (Cd) toxicity in crops have not been well studied. Herein, hydroponically cultured maize seedlings were exposed to Cd (20 μM) and treated without and with foliar SeNPs application. Effects of SeNPs on Cd transporter genes and plant metabolism were also explored. Results showed that compared to control plants without Cd exposure, Cd exposure decreased shoot height (16.8 %), root length (17.7 %), and fresh weight of root (24.2 %), stem (28.8 %), and foliar-applied leaves (Se-leaves) (15.0 %) via oxidative damage. Compared to Cd exposure alone, foliar SeNPs application at 20 mg/L (0.25 mg/plant) significantly alleviated the Cd toxicity by promoting photosynthesis and antioxidant capacity and fixing Cd in cell wall. Meanwhile, the mineral concentration of Ca (26.0 %), Fe (55.4 %), Mg (27.0 %), Na (28.6 %), and Zn (10.1 %) in Se-leaves was improved via foliar SeNPs application at 20 mg/L. QRT-PCR analysis further revealed that down- and up-regulation of the expression of ZmHMA2 and ZmHMA3 gene in Se-leaves contributed to reduced translocation of Cd in plants and enhanced Cd sequestration in the vacuole, respectively. Metabolomic results further indicated that metabolic pathways including carbohydrate metabolism, membrane transport, translation, amino acid metabolism, and energy metabolism were significantly affected by foliar SeNPs application. In conclusion, foliar SeNPs application at 20 mg/L could be a prospective strategy to mitigate Cd toxicity in maize.

Influence of Different Drying Techniques on the Drying Kinetics, Total Bioactive Compounds, Anthocyanin Profile, Color, and Microstructural Properties of Blueberry Fruit

In this study, four different drying techniques, namely, hot air drying (HAD), vacuum drying (VD), ultrasound-assisted vacuum drying (UAVD), and freeze-drying (FD), were applied to blueberries. The drying times of blueberries were 1290, 1050, and 990 min for HAD, VD, and UAVD, respectively, meaning that ultrasound application significantly reduced the drying time. All dried samples except those with FD showed lower total phenolic content and antioxidant capacity than fresh samples. Samples dried with FD had a higher content of bioactive compounds than those dried with other techniques followed by UAVD. The malvidin-3-O-galactoside was the most abundant anthocyanin in the blueberries and was significantly reduced after drying with HAD, VD, and UAVD. Scanning electron microscopy (SEM) analysis of the blueberries dried with FD and UAVD exhibited less shrinkage and cell disruption and more structure. The color parameters L*, a*, and b* values of the samples were significantly affected by the drying technique (p < 0.05). According to the findings of this study, ultrasound-assisted drying technology could be employed to shorten the drying time and improve bioactive retention in blueberry fruits.

Evaluating Kinetics of Convection Drying and Microstructure Characteristics of Asian Seabass Fish Skin without and with Ultrasound Pretreatment

Convection drying in combination with ultrasound pretreatment has emerged as a promising technology for seafood manufacturing. The primary objective of this research was to model the mass transfer process of Asian seabass (Lates calcarifer) fish skin without and with ultrasound pretreatment during convection drying at different temperatures (45, 55, and 65 °C). Additionally, the study aimed to examine the impact of ultrasound pretreatment and temperatures on the drying characteristics and specific energy consumption for drying of Asian seabass fish skin. Seven semi-theoretical models, namely Lewis, Page, modified Page, Vega-Lemus, Verma, Henderson and Pabis, and two-term models, were employed to characterize the moisture transfer process. The results of the study indicated a decrease in the moisture content as the drying time increased at different drying temperatures. Higher drying temperatures were associated with an increased drying rate. Among the mathematical models tested, the modified Page model provided a satisfactory description of the thin-layer drying characteristics of fish skin. Fick's law of diffusion was utilized to determine the effective moisture diffusivities. Comparing the drying of fish skin without (SS) and with ultrasound pretreatment (US-SS), the drying of the latter generally showed higher Deff values. The temperature dependence of the effective diffusivity coefficient was well described by the Arrhenius-type model. An increase in the drying temperature resulted in an increment of the effective moisture diffusivity. In general, the skin pretreated using ultrasound had a reduced drying time, by up to 28%. Additionally, this approach contributed to an approximate 22% reduction in the specific energy consumption, concurrently enhancing the energy efficiency. The microstructure analysis showed that fresh and dried US-SS samples had a more open structure and higher porosity, in comparison to the corresponding SS samples. These findings contribute to the knowledge on the application of ultrasound as the pretreatment of fish skin before drying and provide valuable insights for the development of potential drying techniques in the seafood industry.