121: Low-Temperature Vacuum Drying of Murta Berries (Ugni Molinae): Enhancing Their Functional Properties Compared to Other Drying Methods

Introduction

Murta (Ugni molinae), an endemic fruit from southern Chile, is rich in bioactive compounds with potential health benefits. However, it is a seasonal fruit and highly perishable due to its high moisture content. This study aimed to evaluate the retention of bioactive compounds in murta berries dehydrated using various drying methods.

Methods

Five drying methods were used to dry murta berries: low-temperature vacuum drying (LTVD, 20°C), hot air drying (HAD, 60°C), vacuum drying (VD, 60°C), infrared drying (IRD, 60°C), and freeze-drying (FD). Methanol (50%) and acetone (70%) extracts were used to assess the content of bioactive compounds, including total polyphenolic content (TPC) by Foli-Ciocalteu method, total anthocyanins content (TAC) by differential-pH, and antioxidant potential through DPPH and ORAC assays.

Results

LTVD and FD resulted in significant increases in TAC (14% and 48%, respectively) compared to the other drying methods, suggesting higher preservation of bioactive compounds under low temperature and vacuum conditions. In contrast, CD and IRD methods caused a reduction in TAC, likely due to the high temperatures involved. While TPC decreased across all dehydrated samples compared to fresh berries, vacuum drying conditions (VD and LTVD) exhibited better preservation of phenolic compounds. No significant differences in antioxidant activity, as measured by the DPPH assay, were observed between VD, IRD, and the fresh sample. However, the ORAC assay showed a decrease in antioxidant activity in most methods, except for IRD, which demonstrated a significant increase. These variations in antioxidant activity can be attributed to differences in drying times and the presence or absence of oxygen. In conclusion, low-temperature vacuum drying (LTVD) emerged as the most effective method for preserving the functional and antioxidant properties of murta berries.

Significance

This study highlights the effectiveness of low-temperature vacuum drying (LTVD) in preserving the bioactive and antioxidant properties of murta berries, an endemic Chilean fruit with significant health potential. LTVD demonstrated superior retention of anthocyanins and phenolic compounds compared to other drying methods, emphasizing its value in maintaining the fruit's functional properties.

Authors: Vega-Gálvez, A.*; Pastén, A; Uribe, E.; Mejías, N; Carvajal, M; Corco, I.