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Abstract

Green leafy vegetables which supply minerals and vitamins to the diet, are highly perishable. Therefore, post harvest losses are extremely high. Limited studies are available in the literature with regard to preservation of greens. The effect of microwave drying and storage on physical and sensory properties of selected greens (coriander, mint, fenugreek, amaranth and shepu) were therefore studied. Microwave drying was carried out at 100% power and a frequency of 2450 mHz. The drying time varied from 10 to 16 min for different greens. Microwave drying affected color, appearance and odor of all the greens. The relative reconstitution capacity (RRC) for different greens was coriander-10.3, mint-10.3, amaranth-38.3, fenugreek-31.7 and shepu-32.8. The RRC appeared to influence acceptability. Coriander and mint, which exhibited the lowest RRC (10.3%), had the lowest scores for flavor and color while amaranth, with the highest RRC (38.3%), had scores similar to those of fresh amaranth. Scores for the products prepared with dried fenugreek and shepu, although low, were not statistically significant. Microwave drying was highly suitable for greens such as amaranth; moderately suitable for shepu and fenugreek and less suitable for coriander and mint.

Drying Kinetics of Microwave-Dried Vegetable Amaranth (Amaranthus dubius) Leaves

“…Fathima et al (2001) reported a moisture content of 5% (wb) for hot water-blanched amaranth leaves (Amaranth sp.) dried at 100% power (microwave wattage not given) for 720 s. Rajeswari et al (2013) compared the quality and shelf life of Amranthus tricolor leaves dried for 2h 37min at 60°C in a cabinet drier and 3 min 31 s in a microwave oven at 900W power.…”

“…Until recently, drying of vegetable amaranth leaves as a method to extend shelf-life was not widely investigated. Research works on dried amaranth have focused primarily on quality and nutrient content of the dried material (Fathima, Begum, & Rajalakshmi, 2001;Rodriguez et al, 2011;Aletor & Abiodun, 2013;Peter, Elizabeth, Judith, & Hudson, 2014) and one study looked at the use of the ground, dried amaranth leaves in green pasta as a substitute for spinach (Borneo & Aguirre, 2008). Published works on drying of vegetable amaranth are limited.…”

“…Based on previous work, the three common factors that would appear to have an impact on the drying rate and quality of microwave-dried leafy vegetables are microwave power level, loading density (sample size), and pre-treatments. With respect to microwave drying of amaranth in particular, documentation is limited but suggests the potential for this method of drying (Fathima et al, 2001;Rajeswari, Bharati, Naik & Naganur, 2013). Fathima et al (2001) investigated the quality of microwave drying of selected greens, including hot water-blanched amaranth leaves (Amaranth sp.).…”

“…With respect to microwave drying of amaranth in particular, documentation is limited but suggests the potential for this method of drying (Fathima et al, 2001;Rajeswari, Bharati, Naik & Naganur, 2013). Fathima et al (2001) investigated the quality of microwave drying of selected greens, including hot water-blanched amaranth leaves (Amaranth sp.). The maximum power output of the microwave oven and the loading density or sample size used were not disclosed.…”

Effect of Variable Microwave Power and Vacuum Levels during Dehydration on the Quality Attributes of Potato Cubes

“…It has been reported that microwave-vacuum dried carrot slices received higher ratings for sensory properties such as texture, odour and overall acceptability as compared to air dried carrot slices (Lin et al, 1998). There was also an effect of microwave drying on the shelf life and sensory attributes of coriander, mint, fenugreek and shepu (Fathima et al, 2001). These authors suggested that microwave drying was highly suitable for amaranth, moderately suitable for shepu and fenugreek and less suitable for coriander and mint.…”