Combination of contact ultrasound and infrared radiation for improving the quality and flavor of air-dried beef during hot air drying.

Air-dried beef, a traditional dry fermented meat product in China, whose quality is largely influenced by processing conditions. In this study, contact ultrasound (CU) and infrared radiation (IR) were employed to enhance hot air drying (HAD), with an investigation into the mechanisms underlying improvements in quality and flavor. Samples subjected to CU and IR treatments during HAD (CU-IRD) demonstrated superior color (L* = 42.68, a* = 5.05, b* = -3.86) and tenderness (140.59 N) than HAD group, primarily attributed to reduced drying times and alterations in ultrastructure. Analyses utilizing SDS-PAGE and total volatile basic nitrogen (TVB-N) revealed that HAD and CU-HAD resulted in significant protein oxidation (197.85 mg TVB-N/kg and 202.23 mg TVB-N/kg, respectively), while IR treatments were associated with increased thermal degradation of proteins, producing lower molecular weight peptides. Compared with HAD group, the activities of certain lipases and proteases were enhanced by ultrasound and infrared treatments, leading to the release of greater amounts of free fatty acids and flavor amino acids. Furthermore, the thermal effects of infrared and the cavitation effects of ultrasound contributed to increased fat oxidation, amino acid Strecker degradation, and esterification reactions, thereby augmenting the diversity and concentration of volatile flavor compounds, including alkanes, ketones, aldehydes, and esters. These findings indicate that the synergistic application of CU and IR represents a promising strategy for enhancing the quality of air-dried beef.

Effects of contact ultrasound coupled with infrared radiation on drying kinetics, water migration and physical properties of beef during hot air drying.

Drying, as a critical step in the production of air-dried beef, has a direct impact on the quality of the final product. Innovatively, a composite system incorporating contact ultrasound (CU) and infrared radiation (IR) as auxiliary measures within a hot air drying (HAD) framework was built in this research, and the effects of these techniques on the drying kinetics, protein denaturation, and moisture transformation of air-dried beef were investigated. In comparison to HAD treatment, the integrated CU and IR (CU-IRD) system displayed marked enhancements in heat and moisture transport efficiency, thereby saving 36.84% of time expenditure and contributing favorably to the improved moisture distribution of the end-product. This was mainly ascribed to the denaturation of myosin induced by IR thermal effect and the micro-channel produced by CU sponge effect, thus increasing T2 relaxation time and the proportion of free water. In conclusion, the composite system solved the problem of surface hardening and reduces hardness and chewiness of air-dried beef by 40.42% and 45.25% respectively, but inevitably increased the energy burden by 41.60%.

Comparison between airborne ultrasound and contact ultrasound to intensify air drying of blackberry: Heat and mass transfer simulation, energy consumption and quality evaluation.

This study aimed at investigating the performances of air drying of blackberries assisted by airborne ultrasound and contact ultrasound. The drying experiments were conducted in a self-designed dryer coupled with a 20-kHz ultrasound probe. A numerical model for unsteady heat and mass transfer considering temperature dependent diffusivity, shrinkage pattern and input ultrasonic energies were applied to explore the drying mechanism, while the energy consumption and quality were analyzed experimentally. Generally, both airborne ultrasound and contact ultrasound accelerated the drying process, reduced the energy consumption and enhanced the retentions of blackberry anthocyanins and organic acids in comparison to air drying alone. At the same input ultrasound intensity level, blackberries received more ultrasound energies under contact sonication (0.299 W) than airborne sonication (0.245 W), thus avoiding the attenuation of ultrasonic energies by air. The modeling results revealed that contact ultrasound was more capable than airborne ultrasound to intensify the inner moisture diffusion and heat conduction, as well as surface exchange of heat and moisture with air. During air drying, contact ultrasound treatment eliminated the gradients of temperature and moisture inside blackberry easier than airborne ultrasound, leading to more homogenous distributions. Moreover, the total energy consumption under air drying with contact ultrasound assistance was 27.0% lower than that with airborne ultrasound assistance. Besides, blackberries dehydrated by contact ultrasound contained more anthocyanins and organic acids than those dried by airborne ultrasound, implying a higher quality. Overall, direct contact sonication can well benefit blackberry drying in both energy and quality aspects.

Effect of ultrasonic power on drying process and quality properties of far-infrared radiation drying on potato slices.

The experiments of contact ultrasound-assisted far-infrared radiation (FIR) drying on potato slices were conducted to investigate the effects of ultrasonic power on drying characteristics and quality properties. The results showed that contact ultrasound was helpful for accelerating mass transfer of the samples, and the improvement of ultrasonic power could significantly shorten drying time. The ultrasonic reinforcement effect on drying rate declined along with the decrease in moisture content. D eff values were within 1.15 × 10-10 and 1.96 × 10-10 m2/s, and improved with an increase in ultrasound power. Compared with FIR dried ones, more and larger pore size of microcapillaries in the samples' tissue structure could be observed with contact ultrasound application, and higher ultrasonic power produced more microtunnels. Contact ultrasound in FIR drying could reduce the color difference of dried potato slices, and decrease the hardness and brittleness values. Higher TPC and TFC could be achieved as ultrasonic power increased.

Airborne non-contact and contact broadband ultrasounds for frequency attenuation profile estimation of cementitious materials.

In this paper, the study of frequency-dependent ultrasonic attenuation in strongly heterogeneous cementitious materials is addressed. To accurately determine the attenuation over a wide frequency range, it is necessary to have suitable excitation techniques. We have analysed two kinds of ultrasound techniques: contact ultrasound and airborne non-contact ultrasound. The mathematical formulation for frequency-dependent attenuation has been established and it has been revealed that each technique may achieve similar results but requires specific different calibration processes. In particular, the airborne non-contact technique suffers high attenuation due to energy losses at the air-material interfaces. Thus, its bandwidth is limited to low frequencies but it does not require physical contact between transducer and specimen. In contrast, the classical contact technique can manage higher frequencies but the measurement depends on the pressure between the transducer and the specimen. Cement specimens have been tested with both techniques and frequency attenuation dependence has been estimated. Similar results were achieved at overlapping bandwidth and it has been demonstrated that the airborne non-contact ultrasound technique could be a viable alternative to the classical contact technique.

Inactivation of filter bound aerosolized MS2 bacteriophages using a non-conductive ultrasound transducer.

The inactivation of viruses that retain their infectivity when transmitted through the air is challenging. To address this issue, this study used a non-contact ultrasound transducer (NCUT) to generate shock waves in the air at specific distances, input voltages, and exposure durations, targeting bacteriophage virus aerosols captured on to H14 HEPA filters. Initially, a frequency of 27.56 kHz (50V) at 25-mm distance was used, which yielded an inactivation efficiency of up to 32.69 ±â€¯12.10%. Other frequencies at shorter distances were investigated, where 29.10 kHz had the highest inactivation efficiency (up to 81.95 ±â€¯9.79% at 8.5-mm distance and 100 V). Longer exposure times also influenced virus inactivation, but the results were inconclusive because the NCUT overheated with time. Overall, NCUT appears to be a promising method for inactivating virus aerosols that may be safer than other forms of inactivation, which can cause genetic mutations or produce dangerous by-products.

Endoluminal MR-guided ultrasonic applicator embedding cylindrical phased-array transducers and opposed-solenoid detection coil.

PURPOSE: MR-guided high-intensity contact ultrasound (HICU) was suggested as an alternative therapy for esophageal and rectal cancer. To offer high-quality MR guidance, two prototypes of receive-only opposed-solenoid coil were integrated with 64-element cylindrical phased-array ultrasound transducers (rectal/esophageal). METHODS: The design of integrated coils took into account the transducer geometry (360° acoustic window within endoluminal space). The rectal coil was sealed on a plastic support and placed reversibly on the transducer head. The esophageal coil was fully embedded within the transducer head, resulting in one indivisible device. Comparison of integrated versus external coils was performed on a clinical 1.5T scanner. RESULTS: The integrated coils showed higher sensitivity compared with the standard extracorporeal coil with factors of up to 7.5 (rectal applicator) and 3.3 (esophageal applicator). High-resolution MR images for both anatomy (voxel 0.4 × 0.4 × 5 mm(3)) and thermometry (voxel 0.75 × 0.75 × 8 mm(3), 2 s/image) were acquired in vivo with the rectal endoscopic device. The temperature feedback loop accurately controlled multiple control points over the region of interest. CONCLUSION: This study showed significant improvement of MR data quality using endoluminal integrated coils versus standard external coil. Inframillimeter spatial resolution and accurate feedback control of MR-guided HICU thermotherapy were achieved.