Alberto Claudio Miano

Ultrasound pre-treatment enhances the carrot drying and rehydration

The present work aimed to describe the mechanisms involved in the enhancement of the drying and rehydration process of carrot slices caused by the pre-treatment using the ultrasound technology. For that, carrot slices of 4mm of thickness were pre-treated for 30 and 60min using an ultrasonic bath (41W/L; 25kHz). The convective drying process was performed at 40 and 60°C with 2.0m/s of air velocity, while the rehydration process was performed at 25°C. The Henderson & Pabis model was used to describe the drying kinetics and the Peleg model to describe the rehydration process of the carrots slices. As a result, the drying and rehydration kinetics were described, at the different conditions of process, correlating the results with the main effects that the ultrasound cause as a pre-treatment (cell bloating and micro-channels) and the air-drying temperature. Depending on the length of the pre-treatment, the effects caused by the ultrasound in the following processes were different. In addition, it was corroborated that when the drying temperature is increased, less evidenced is the ultrasound effect. The ultrasound, when is applied for long times, enhanced the drying and further rehydration rate at low temperatures, due to the tissue damage. Moreover, vacuum-packed samples were pre-treated with ultrasound in order to exclude the water gain and to evaluate only the micro-channels formation effect. It was concluded that the ultrasound pre-treatment enhances the drying and rehydration processes; however, future optimization studies are recommended.

Enhancing mung bean hydration using the ultrasound technology: description of mechanisms and impact on its germination and main components

The ultrasound technology was successfully used to improve the mass transfer processes on food. However, the study of this technology on the grain hydration and on its main components properties was still not appropriately described. This work studied the application of the ultrasound technology on the hydration process of mung beans (Vigna radiata). This grain showed sigmoidal hydration behavior with a specific water entrance pathway. The ultrasound reduced ~25% of the hydration process time. In addition, this technology caused acceleration of the seed germination – and some hypothesis for this enhancement were proposed. Moreover, it was demonstrated that the ultrasound did not change both structure and pasting properties of the bean starch. Finally, the flour rheological properties proved that the ultrasound increased its apparent viscosity, and as the starch was not modified, this alteration was attributed to the proteins. All these results are very desirable for industry since the ultrasound technology improves the hydration process without altering the starch properties, accelerates the germination process (that is important for the malting and sprouting process) and increases the flour apparent viscosity, which is desirable to produce bean-based products that need higher consistency.

The Hydration of Grains: A Critical Review from Description of Phenomena to Process Improvements: Hydration of grains: a review…

Hydration is a crucial step during grain processing. It is performed prior to many other processes, such as germination, cooking, extraction, malting and fermentation. The number of publications on this topic studying the description of the mechanisms involved and recent technologies for processing enhancement has increased recently. However, due to the complexity of the hydration process, there are still many aspects that are little understood. For that reason, this review provides not only an overview of recent developments in this field, but also a critical discussion of publications from the last 2 decades, as well as suggestions for future innovative studies. This review discusses the importance of hydration in the grain industries, the pathway for water entry into the various grains, the mass transfer and fluid flow mechanisms in the process, the behavior of the hydration kinetics, the mathematical modelling, the technologies used to accelerate the process and other necessary requirements that must be performed to complement and complete our knowledge of this process.

Other Mass Transfer Unit Operations Enhanced by Ultrasound

Ultrasound is a promising technology, which has been used in many mass transfer unit operations with excellent results, such as drying, osmotic dehydration, extraction, hydration, salting/brining, and desalting. During a mass transfer unit operation, external and internal resistances can exist. Then, the reduction of both is necessary to accelerate the process. Ultrasound can reduce one or both resistances by different mechanisms such as acoustic cavitation, the sponge effect, microchannel formation, and others. Furthermore, the ultrasound enhancement differs in each unit operation. Consequently, the use of this technology for assisting the entire process or as a pretreatment can change the way the process is improved.

Ultrasound Processing of Fruit and Vegetable Juices

Abstract The quality of juices is defined by their physical, enzymatic, microbiological, and sensory stability. Many studies have evaluated the use of ultrasound as an alternative for processing fruit and vegetable juices, taking advantage of the physical and chemical effects resulting from the use of this technology. Ultrasound can improve the juice consistency (apparent viscosity), color, cloudiness stability, and sensory acceptance, as well as enhancing the microbial and enzymatic stability and the biocompounds stability. The changes in microscopic structure, the consequent changes in composition, and the relative magnitude of the coexistent forces in the system influence the obtained properties and stability. Therefore, the combination of several factors makes each ultrasound process and its corresponding final effects on a juice a particular case, which makes this technology interesting and promising.

Ultrasound assisted acidification of model foods: Kinetics and impact on structure and viscoelastic properties

This work aimed to describe the acidification process of two specific model foods using the ultrasound technology, as well as to evaluate the changes on its viscoelasticity properties. For that, two types of model food were used, with similar composition but different structures: natural melon cylinders and restructured melon-agar cylinders. The acidification process was performed using a citric acid solution (0.2% w/w) assisted with and without ultrasound (40W/L of volumetric power and 20kHz of frequency) at constant temperature (25°C). In addition, the stress relaxation analysis was performed on the cylinders in order to evaluate the changes on the viscoelastic properties. As a result, both ultrasound processing and the different structural conformation of the model foods affected the acidification kinetics, being improved by ultrasound. Further, the acidification process with and without ultrasound affected the mechanical properties of both products, reducing their elasticity. The relaxation data could be described by a Maxwell model with two bodies and a residual spring, providing a possible explanation of the association between the mechanical model parameters and the microstructural conformation of both studied cases.

Evaluating the Guo–Campanella viscoelastic model

Biological materials are characterized by complex structures and compositions, leading to viscoelastic behavior. Their viscoelastic characterization is important for the evaluation, design, and optimization of processes to ensure high quality products. Proposals of methodologies of analysis and modeling are critical steps in studying the rheological properties of these materials. In this context, a new model, the Guo-Campanella Model, was recently proposed to describe the stress-relaxation behavior of biological material. This work is an independent and impartial evaluation of this new model. It considers 10 different samples, comprising in natura and processed foods, from both plant and animal bases. For comparison, a Generalized Maxwell Model and the Peleg Model were also evaluated. The Guo-Campanella Model fitted the stress-relaxation data of evaluated products well, demonstrating its validity for describing the viscoelastic behavior of biological materials with different structures, sources, and processing. Finally, the Guo-Campanella Model parameters were evaluated and their interpretations and possible uses described. It was shown that the Guo-Campanella Model can be successfully used for future studies. PRACTICAL APPLICATIONS The stress-relaxation assay is a common technique for characterizing the viscoelastic properties of biological materials. The results obtained are generally evaluated using such compound models as the Generalized Maxwell model. Although this approach is interesting from a fundamental point of view, it results in many parameters to evaluate, thus increasing the complexity and limiting the interpretation. In this sense, the Guo-Campanella Model has only two parameters, which facilitates interpretation, especially for practical applications. This work validated this model, also contributing to its interpretation by discussing the meaning of its parameters. Consequently, this is potentially useful for future studies on food properties and process design.

The ultrasound assisted hydration as an opportunity to incorporate nutrients into grains

Hydration is an important but long step in processing beans. Consequently, any ways of taking advantage of this processing time are desirable. One possibility is to fortify the beans during the hydration process, especially with water-soluble nutrients. This work studied the incorporation of iron into beans during hydration with and without ultrasound, describing the kinetics of water and iron uptake, the entrance pathway and its effect on germination and the cooking process. For that, carioca beans were soaked in ferrous sulfate solution (0.271% w/v) with and without ultrasound (91 W/L; 25 kHz) at 25 °C. It was demonstrated that iron could be incorporated during the hydration process, describing a similar kinetics behavior to the water uptake. In addition, ultrasound accelerated this process, achieving 60.1 mg Fe/100 g w.b. after 510 min of process, in contrast to 34.4 mg Fe/100 g w.b. when the beans were hydrated without ultrasound. Finally, by hydrating the beans with ferrous sulfate, the cooking process was accelerated, which is desirable. However, the capacity for germination of the beans was reduced. In conclusion, the hydration process time can be used to fortify the beans with iron (and, possibly, other water-soluble nutrients). Nevertheless, future studies must be performed to determine if the incorporated iron is bioavailable and bioaccessible, as well as how relevant this approach is as a nutritional policy.

Correlating the properties of different carioca bean cultivars (Phaseolus vulgaris) with their hydration kinetics

This work explained how the intrinsic properties of beans affects the hydration process. For that, different properties of six cultivars of carioca bean (a variety of common bean) were analyzed to verify the correlation with their hydration kinetics characteristics (hydration rate, lag phase time and equilibrium moisture content), using a Multiple Factorial Analysis (MFA): the chemical composition (starch, protein, lipids, minerals (Mg, P, S, K, Ca, Mn, Fe, Cu, Zn), functional groups from the seed coat analyzed by FT-IR), physical properties (size, 1000 grain weight, seed coat thickness, energy to penetrate the bean) and microstructure. Only few properties correlated with the hydration kinetics characteristics of the studied bean, comprising both composition and structure. The fat content, potassium content, specific surface, and the protein to lipids ratio correlated with the lag phase time, which is related with the seed coat impermeability to water. The necessary energy to perforate the seed coat correlated negatively with the hydration rate. It was concluded that the hydration of beans process is a complex phenomenon and that despite being from the same variety of legume, any change due to agronomic enhancement may affect their hydration process kinetics.