Influence of vacuum drying temperature on: physico-chemical composition and antioxidant properties of murta berries

Authors: LOPEZ, JESSICA - University Of La Serena; VEGA-GALVEZ, ANTONIO - University Of La Serena; Bilbao-Sainz, Cristina; Chiou, Bor-Sen; URIBE, ELSA - University Of La Serena; QUISPE-FUENTES, ISSIS - University Of La Serena

Submitted to: Journal of Food Process Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2017
Publication Date: 4/17/2017
Citation: Lopez, J., Vega-Galvez, A., Bilbao-Sainz, C., Chiou, B., Uribe, E., Quispe-Fuentes, I. 2017. Influence of vacuum drying temperature on: physico-chemical composition and antioxidant properties of murta berries. Journal of Food Process Engineering. 40(6):e12569. https://doi.org/10.1111/jfpe.12569.
DOI: https://doi.org/10.1111/jfpe.12569

Interpretive Summary: Murta berries are native to Chile, Bolivia, and Argentina. They contain polyphenols that have potential anti-microbial, anti-inflammatory, and anti-carcinogenic properties. Vacuum drying at different temperatures was examined as an alternate drying method to preserve and stabilize the berries. Vacuum drying resulted in a loss of phenolic compounds and a decrease in antioxidant properties at 50C. However, these properties did not decrease much more at higher temperatures, indicating vacuum drying could be effectively used to stabilize the berries.

Technical Abstract: Murta (Ugni molinae T.) berries were vacuum dried at a constant pressure of 15 kPa. The effects of processing temperatures (50, 60, 70, 80 and 90 °C) on the physico-chemical characteristics, the phenolic and flavonoid compounds, the antioxidant activity (measured by DPPH and ORAC) and the sugar and ß-carotene contents of the fruit were evaluated. The dried samples had lower protein contents than the fresh sample. Also, drying temperatures significantly affected the phenolic compounds. Drying at 50°C resulted in 43.5 % and 43.8% reductions in total phenolic and flavonoid contents, respectively. The antioxidant activity also decreased in value after vacuum drying at each temperature. This decrease might be caused by the degradation of phenolic compounds. In addition, this study showed significant decreases in antioxidant activity at low temperatures (e.g. 50 °C), possibly due to longer drying times, with reductions of 50% and 85% as measured by DPPH and ORAC methods, respectively. Total phenolic and flavonoid contents showed good correlations with the antioxidant capacity. Fructose was the predominant sugar, followed by sucrose and glucose. Overall, sugar contents were affected by drying temperatures, especially at 50 °C with a noticeable sucrose content decrease. However, ß-carotene contents showed significant increases in value with an increase in temperature. These results indicated that vacuum drying might be a good alternative for dried murta production. Dried murta could be an important source of bioactive compounds with great potential in the food industry as a functional food ingredient.