Results (
Thai) 1:
[Copy]Copied!
Most of the studies on Stevia leaves are focused on the plant growing parameters and its adaptation to different edapho-climatic zones [2]. The medicinal and functional properties, such as antiviral and antibacterial capacities [3, 4] or antioxidant activity [5, 6] have also attracted much attention and interest, so that in published data complete and extensive research works on the extraction methods by all available technologies can be found [4, 6, 7]. The first stage in processing of Stevia leaves is by far the drying operation, commonly performed using solar energy. However, solar drying due to an intrinsic lack of systematic process control, often presents multiple disadvantages related to dried product quality, especially those aspects related to a deficient microbiological safety. In consequence, conducting research on dehydration of Stevia leaves is highly recommended. Drying by hot air is a very common and appropriate postharvest technology to extend shelf life of a product, preserving its quality and stability through reduction of moisture content. Furthermore, drying process also add value to food products and a proper management of the drying process, seen from an operational and capital investment point of view, can lead to a higher yield of a high quality product [8]. The undesirable effects of hot-air drying can be reduced to a minimum through proper monitoring of appropriate control variables, such as air drying temperature, which favors improvement of the nutritional value of the food product. Several investigations have clearly shown the influence of drying temperature on the relevant physical and biochemical quality aspects of various fruits and vegetables, especially on attributes such as color, total phenolic content, vitamin C, β-carotene or antioxidant capacity [8, 9]. In other investigations, the effect of drying methods on some quality characteristics of Stevia leaves has been reported [10, 11]. Knowledge on theseproperties are necessary to establish quality standard of the dried products and also in the development of new products with desired properties or for quality improvement. Pericheet al. [12] found high levels of phenolics and flavonoids compounds in Stevia infusions. Muanda et al. [13] identified 18 phenolic compounds in the Stevia leaves, which revealed ahigh antioxidant capacity that also come from the flavonoids like apigenin-4-O-β-D-glycoside, kaemp ferol-3-Orhamnoside, quercetin-3-O-β-D-arabinoside, quercetin-3-Oglucosideand quercetin-3-O-rutinoside, identified by Ghanta et al. [5] and Cacciola et al. [14].Consequently, a proper application of drying temperature that leads to final products with excellent quality characteristics is crucial. The effects of air drying temperature leading tochanges in the concentration profiles of the bioactive components and antioxidant capacity in the Stevia leaves have been reported only scarcely. Therefore, the aim of this study was toquantify the effect of drying temperature in a range between 30 and 80 °C on the Stevia leaves with respect to bioactive components, antioxidant capacity and natural sweeteners.
Being translated, please wait..
