Elsa Uribe

Assessment of vacuum-dried peppermint (Mentha piperita L.) as a source of natural antioxidants

The purpose of this study was to investigate the effect of temperature in the vacuum drying process of Mentha piperita L. (50 to 90 °C). Generally, drying processes affect the quality of product, however, vacuum drying works under sub-atmospheric pressures. In order to investigate how temperature affects this herb, as to color, chlorophyll, total phenolic (TPC), total flavonoid (TFC) contents, antioxidant activity by DPPH and ORAC methods. Mineral, vitamin C and sugar contents were also evaluated. A slight change in color and chlorophyll content was observed in the samples. The highest values for TPC, TFC and antioxidant activity methods were obtained at 50 and 70 °C however, a decrease in the vitamin C content was observed. Minerals such as K, Ca, Mg and Na were found. Sucrose showed the highest sugar content. This work suggests that M. piperita L. can be used as a natural antioxidant, whether fresh or dried.

Dehydrated olive-waste cake as a source of high value-added bioproduct: Drying kinetics, physicochemical properties, and bioactive compounds

Olive (Olea europaea L.) oil processing produces significant amount of waste that can be utilized for the production of high value-added ingredients for various industrial applications. In this work, the effects of temperature on drying kinetics and quality indexes of the olive-waste cake during convective dehydration (40-90 °C) were investigated. Results on effective moisture diffusivity, physicochemical parameters, fatty acid profile, total phenolic, flavonoid, and flavanol contents as well as antioxidant capacity are also reported. Most of the fatty acids increased their content with respect to control sample with a temperature increase, i.e. oleic and linoleic acids increased 48% and 43% at 70 and 40 °C, respectively. Total flavanol content increased with temperature (48-62 mg catechin equivalents [CTE] 100 g-1 DM) except for 80 °C. Total phenolic and total flavonoid contents were highly correlated to antioxidant capacity (0.923 < r < 0.992), except for 70 and 80 °C, the rest of the samples maintained their initial antioxidant capacity by ORAC analysis. Thus, these parameters show that dried olive-waste cake has a high bioactive compounds with potential use as additives for the food or other industries.

Extraction Techniques for Bioactive Compounds and Antioxidant Capacity Determination of Chilean Papaya (Vasconcellea pubescens) Fruit

The aim of this work was to assess and compare different extraction methods by using high hydrostatic pressure (HHPE), ultrasound (UE), agitation (AE), and their combinations for the extraction of bioactive compounds of Chilean papaya. Extract antioxidant capacity was evaluated by three methods (i.e., DPPH, FRAP, and Voltammetry) and phenolic compounds and vitamin C were determined by HPLC. Papaya sample extraction was performed by HHPE at 500 MPa for 10 min and UE and AE for 30 min, respectively. The combined-extractions: HHPE-UE and HHPE-AE, were carried out for 5 min and 15 min, respectively. The highest values found were total phenolic 129.1 mg GAE/100 g FW, antioxidant capacity by DPPH 20.6 mM TE/100 g FW, and voltammetry 141.0 mM TE/100 g FW for HHPE-UE method in free compound extraction. Regarding vitamin C content, its highest value was found by HHPE-UE (74 mg/100 g FW) a combined extraction method. The phenolic compounds rutin and p-coumaric acid were found in all the extracts, both in free and bound forms, respectively. Besides, the combined techniques improved the extraction of bioactive compounds.