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

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 degrees 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.

Automated summary

This study evaluated the effects of ethanol pre-treatment on convective drying and its impacts on the bioactive compounds of uvaia. The results showed that pre-treatment times in combination with temperatures influenced drying time and were associated with ethanol penetration and volatility in the sample. Drying temperatures and pre-treatments reduced phenolics compounds and antioxidant capacity, but significant levels are still found in the final product.