Impact of pretreatments with ethanol and freezing on drying slice papaya: drying performance and kinetic of ultrasound‐assisted extraction of phenolics compounds

Abstract

Background Pretreatments of drying can represent an alternative to minimize the negative aspect process on the dry samples. Thus, the influence of ethanol (ET) and freezing (FG) as drying pretreatments was analyzed for slices of papaya. The slices (5 mm) were submitted for drying kinetics (60 °C and 1.5 m s−1). Drying kinetics experimental data were fitted using Page's model and a diffusive model with boundary condition of types I and III. Also the thermophysical properties (thermal conductivity and specific heat) were determined and finally, the kinetics of ultrasound‐assisted (40 kHz and 132 W) extraction of total phenolic compounds (TPCs) were realized. Results The combined method (ET + FG) was more efficient in reducing the drying time of papaya slices (48%) and the model 2 simulating the boundary condition of the third type (type III) showed the best fit to the experimental data. Effective diffusivity and convective coefficient were higher for ET + FG, where the maximum reduction in water content was 91% compared to fresh slices. The pretreatments did not influence the thermal conductivity, however, they were significant in the specific heat and in the extraction of TPCs, being higher in the time of 180 min. Conclusion It was confirmed in the results presented that the combined pretreatment ET + FG is the most viable for drying papaya slices. Furthermore, it was found to be the most efficient in minimizing the loss of TPCs. Therefore, this pretreatment has great potential for application in the development of high value‐added foods. © 2022 Society of Chemical Industry.

Effect of Ultrasound and Freeze‐Drying to Enhance the Extraction of Phenolic Compounds in Dragon Fruit Peels and Apply Them in Edible Starch‐Based Films

“…Additionally, the water content of the samples may impact the powder's ability to absorb water molecules from the surrounding environment, resulting in particles having lower water content and higher hygroscopicity. These observations are in line with Santos et al [14]; as if particles have lower water content, this can result in a higher capacity to absorb moisture from the environment, leading to an increase in hygroscopicity. This relationship between water content and hygroscopicity is important to consider, especially in terms of material storage and stability [37].…”

“…For example, we have developed an approach to evaluate the effect of ultrasound pretreatment time to produce dehydrated guava slices [13]. Subsequently, we explored the synergy of this pretreatment with drying temperature to assess its effects on phenolic compound extraction from papaya pulp [14]. Now, we aim to assess the potential of this pretreatment for dragon fruit peels, which are rich in antioxidants, followed by FD of the same.…”

Impact of ultrasound pretreatment on banana chip production by convective drying using hot air: Consideration of shrinkage and variable effective mass diffusivity in the process description

“…Although it is cheaper and simpler to operate than other drying methods, such as freeze‐drying, CD usually requires a long processing time hence a large amount of energy, and may also be responsible for physical and chemical changes in the product (Mírian & Freitas, 2019; Orikasa et al, 2014; Ramos et al, 2017; Tello‐Ireland et al, 2011). To reduce production costs and minimize the impact on product quality, CD has been preceded by some type of pretreatment (Ferreira, Castro, et al, 2020; Santos et al, 2023; Tekin Cakmak et al, 2021). Thus, studies on emerging pretreatment technologies that can be additive to existing processes of conventional food processing, as in the case of CD, are an important line of research within food science and technology.…”