Uvaia fruit ( Eugenia pyriformis Cambess) drying: Ethanol as pre‐treatment, convective drying kinetics and bioactive compounds

Abstract

This study evaluated the effects of ethanol pre‐treatment on convective drying and its impacts on the bioactive compounds of uvaia. The treatments consisting of control and samples pre‐treated by immersion in ethanol (99.8% v/v) for 10 and 20 min, followed by convective drying (1 m/s) at 40 and 60°C. The sample temperatures were traced over processing and the products were evaluated in relation to their content of phenolic compounds and antioxidant capacity. Pre‐treatment times in combination with temperatures influenced drying time and were associated with ethanol penetration and volatility in the sample. Furthermore, the high vapor pressure of ethanol reduced the initial temperature of the samples. Drying temperatures and pre‐treatments reduced by 16%–34% phenolics compounds and 13%–45% antioxidant capacity, which was associated with degradation and possible extraction by ethanol. The advantages of using ethanol were discussed, but also some limitations, especially on bioactive compounds. Practical applications Uvaia is a native fruit rich in sensory and healthy aspects. However, its high perishability and seasonality make it unfeasible for post‐harvest commercialization. This work demonstrated that drying and application of ethanol proved to be effective for preserving this fruit, resulting in a shorter processing time. Although ethanol partially extracted the bioactive compounds, significant levels are still found in the final product—which can be used as convenient products with a positive impact on consumers' health. Furthermore, the proposed approach is simple, relatively cheap, and viable techniques to obtain stable products for both industry and small producers.

Effect of gum Arabic and ethanol pretreatments on drying kinetics and quality attributes of dried carrot slices

“…Given that ethanol has higher vapour pressure than water, the gradient surface tension could have promoted moisture migration from the interface to the surface of the carrot slices during the drying process due to the Gibbs-Marangoni effect, a phenomenon based on the mass transfer at the interface between two fluids with different surface tensions ( Wang et al., 2022 ). In addition, ethanol pretreatment of carrot slices could have altered the cell wall structure through the dissolution of the polysaccharides on the cell wall, thereby enhancing the porosity and DR. Gomes et al. (2022) also reported increased DR in ethanol (99.8%) pretreated uvaia fruit.…”

Ethanol pretreatment and infrared drying of melon: Kinetics, quality parameters, and NIR spectra

“…The process is repeated, promoting the flow from the interior of the sample as many times as necessary to achieve surface tension equilibrium. Other researchers like Silva et al (2019), Gomes et al (2022), and Guedes et al (2021) also used the Marangoni effect to explain the increase in mass transfer during drying kinetics. Therefore, in the present study, osmotic dehydration and the Marangoni effect may explain the considerable time reduction in samples that were subjected to pretreatment with ethanol before drying.…”

“…It could be seen that different variables can influence the content of bioactive compounds present in the material, such as drying time, pretreatment, ethanol concentration, and immersion time. Also, as observed by Gomes et al (2022), the type of compound present and, in addition, the microstructure and particularities of the sample can affect the drying behavior. Thus, it is necessary to continue studying ethanol pretreatments to better understand the effect caused by drying as well as its influence on quality parameters.…”

Unlocking the potential of uvaia (Eugenia pyriformis Cambess): exploring its rich chemical composition and varied biological activities for innovations in the food industry

“…In another study, Gomes et al . (2022) investigated the impact of ethanol pre‐treatment during convective drying of uvaia (seedless fruit pieces). Samples were pre‐treated with 99.8% v/v ethanol for 10 and 20 min, followed by drying at 40 and 60 °C with an air velocity of 1 m/s.…”

“…They observed reductions in phenolic compounds (16–34%) and antioxidant capacity (13–45%) attributed to compound degradation and potential extraction by ethanol. The resulting dehydrated uvaia can be directly consumed or utilised in food products, such as cereal bars, granola, and cookies (Gomes et al ., 2022).…”