The perception and influencing factors of astringency, and health-promoting effects associated with phytochemicals: A comprehensive review.

Astringency as the complex sensory of drying or shrinking can be perceived from natural foods, including abundant phenolic compounds. Up to now, there have been two possible astringency perception mechanisms of phenolic compounds. The first possible mechanism involved chemosensors and mechanosensors and took salivary binding proteins as the premise. Although piecemeal reports about chemosensors, friction mechanosensor's perception mechanisms were absent. There might be another perception way because a part of astringent phenolic compounds also triggered astringency although they could not bind with salivary proteins, however, the specific mechanism was unclear. Structures caused the differences in astringency perception mechanisms and intensities. Except for structures, other influencing factors also changed astringency perception intensity and aimed to decrease it, which probably ignored the health-promoting effects of phenolic compounds. Therefore, we roundly summarized the chemosensor's perception processes of the first mechanism. Meanwhile, we speculated that friction mechanosensor's probably activated Piezo2 ion channel on cell membranes. Phenolic compounds directly binds with oral epithelial cells, activating Piezo2 ion channel probably the another astringency perception mechanism. Except for structure, the increase of pH values, ethanol concentrations, and viscosity not only lowered astringency perception but were beneficial to improve the bioaccessibility and bioavailability of astringent phenolic compounds, which contributed to stronger antioxidant, anti-inflammatory, antiaging and anticancer effects.

Developing ultrasound-assisted hot-air and infrared drying technology for sweet potatoes.

The influence of ultrasound (US) pretreatments combined with infrared (IRD) and hot-air (HAD) drying on drying kinetics, mathematical modeling, bioactive compounds (antioxidant activities, Vitamin C, phenolics, and flavonoid contents), qualitative properties (ß-carotene, total carotenoids, color indexes, textural profile), enzyme inactivation, and exergetic analysis of sweet potatoes. The US pretreatment at 40 kHz combined with IRD and HAD (70 °C) significantly lessened the drying time and water contents. Besides, it did not affect the sweet potato's bioactive components and other quality-related attributes. The samples' activation energy (Ea) ranged from 17.60 to 29.86 kJ/mol for both dryers, with R2 (0.999-0.9809). Control samples had the highest specific energy consumption (SEC) due to the extended drying period, whereas ultrasound (40 kHz) treated samples had the lowest SEC during HAD and IRD at 80 °C. The thermodynamic parameters indicated that increasing the drying temperature lowers the enthalpy and Gibbs free energy, while entropy resulted in negative values. HAD had better textural qualities (hardness and resilience). The US pretreatments followed by HAD or IRD may lead to an energy-efficient method with acceptable quality maintenance.

Effect of multi-frequency ultrasound thawing on the structure and rheological properties of myofibrillar proteins from small yellow croaker.

The influence of multi-frequency combined ultrasound thawing on primary, secondary, and tertiary structures, electrophoresis pattern, particle size distribution, zeta potential values, thermal stability, rheological behavior, and microstructure of small yellow croaker myofibrillar proteins (MPs) were studied. Four treatments were used for thawing small yellow croakers: flow water thawing (FWT), mono-frequency ultrasonic thawing (MUT), dual-frequency ultrasonic thawing (DUT), and tri-frequency ultrasonic thawing (TUT). Compared with fresh samples (FS), the MPs of the sample pretreated by DUT had non-significant effect on protein primary (including free amino groups and surface hydrophobicity), secondary, tertiary structures, electrophoresis pattern, and microstructure. MPs pretreated by DUT had less aggregation and degradation. Besides, DUT treatment increased the thermal stability of MPs. The ultrasound had significant effects on the rheological properties of MPs. Overall, DUT effectively minimized the changes in MPs structure and protected the protein thermal stability and rheological behavior during the thawing process.

Modeling the drying of ultrasound and glucose pretreated sweet potatoes: The impact on phytochemical and functional groups.

The influence of ultrasonic frequency (20 kHz) and glucose pretreatments either alone or in combination on the drying of sweet potato slices (3 mm) using a hot-air dryer at 60 °C was tested to study the kinetics modeling, phytochemicals, antioxidant activities, and functional and textural changes of the final dried product. The results indicated that total phenolic content and total flavonoid content were significantly higher in glucose-pretreated samples while antioxidant activities were higher in ultrasound- and glucose-pretreated samples. For vitamin C, much degradation occurred in the glucose-pretreated samples when compared with the other pretreated samples apart from the control. Enzymatic browning made a minor contribution to the ultrasound/glucose-pretreated samples, while no significant differences were noted in the glucose-pretreated samples. A modified Henderson and Pabis (MHP) model, followed by the two-term and Hii models, fitted best among the 15 selected mathematical models. Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed the presence of glucose, phenols, and flavonols in all samples. Microstructural analysis confirmed the hardness (N) in the final glucose-pretreated samples due to glucose layers and less cell damage.