Solar drying of Stevia (Rebaudiana Bertoni) leaves using direct and indirect technologies

Téllez, Margarita Castillo; Figueroa, Isaac Pilatowsky; Téllez, Beatríz Castillo; Vidaña, Erick C. López; López‐Ortiz, Anabel

doi:10.1016/j.solener.2017.11.031

Cited by 78 publications

(22 citation statements)

References 28 publications

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“…Figure 1 shows the moisture content reduction with values obtained from the interval of 76.28% for fresh stevia leaves at the initial time and at 11.57% at 7 h of dried, time, in which the sample no longer presented further reduction in moisture content and the leaves reached a constant weight. Castillo-Téllez et al [7] agreed that the best time to collect and store stevia leaves is when they become brittle with 10-12% moisture content. Previous studies also determined a significant (p < 0.05) increase in TPC after air drying reached the highest value at 40 • C with 55.05 ± 2.27 mg GAE/100 g dw, as reported by Lemus-Mondaca et al [17].…”

Section: Moisture Contentmentioning

confidence: 99%

“…Recently, these phytochemicals have become important in human health as protective agents against oxidative damage is due to their capabilities in delaying or inhibiting the formation and propagation of free radicals [4,5]. In an effort to extend the shelf life and preserve the quality of stevia leaves before the phenolic compounds extraction, a dehydration process is highly recommended in order to reduce the moisture content, to simplify the extraction process and increase the phytochemical compounds yield [6,7]. Previous studies have shown the influence of drying process on quality aspects of stevia leaves such as color, vitamin C, total phenols content and antioxidant activity [8,9].…”

Section: Introductionmentioning

confidence: 99%

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Antioxidant Capacity and UPLC-PDA ESI-MS Phenolic Profile of Stevia rebaudiana Dry Powder Extracts Obtained by Ultrasound Assisted Extraction

Covarrubias-Cárdenas¹,

Martínez-Castillo²,

Medina-Torres³

et al. 2018

Agronomy

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Stevia leaves, which are commonly used as a natural sweetener in food products, have increased in importance for antioxidant delivery due to their high content of phenolic compounds. In this study, the influence of the drying process on stevia leaves, with regards to phenolic content and antioxidant activity during drying kinetics 40 °C for 7 h, was studied. The effect of solvent concentration and extraction time using a 32 factorial design on total phenol content (TPC), and on antioxidant activity of extracts obtained from dried stevia leaves, by ultrasound assisted extraction (UAE) as alternative method was evaluated. Steviol glycosides contents were also evaluated by a conventional and UAE method. Phenols identification, quantification and purification were performed by Ultra Performance Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (UPLC-ESI-MS), Ultra Performance Liquid Chromatography-Photodiode Array (UPLC-PDA) and advanced automated flash purification, respectively. Drying time affected the moisture content of stevia leaves. A constant weight was reached after six hours of drying, and higher antioxidant activity was observed, while the highest TPC was obtained after seven hours of drying. The highest TPC (91.57 ± 8.8 mg GAE/g dw) and antioxidant activity (603.24 ± 3.5 μmol TE/g dw) in UAE method was obtained when ethanol 50% at 5 min was used. Steviol glycosides extracted by UAE were recorded with a content of 93.18 ± 1.36 mg/g dw and 98.97 ± 1.75 mg/g dw for stevioside and rebaudioside A respectively. Six phenolic compounds including four phenolic acids and two flavonoids were identified and quantified by UPLC-PDA, and confirmed by ESI-MS reporting its fragmentation pattern. Diosmin and chlorogenic acid were the most abundant compounds with values of 2032.36 μg/mL and 434.95 μg/mL respectively. As a novelty we found that the antioxidant activity evaluated in partially purified fractions suggested that biological activity might be attributed to the synergistic effect of the six phenols present in the stevia leaves extract. In addition to its sweeting properties, stevia leaves constitute a potential source of polyphenolic compounds, with antioxidant activity that could be used as a food additive.

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Section: Moisture Contentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Antioxidant Capacity and UPLC-PDA ESI-MS Phenolic Profile of Stevia rebaudiana Dry Powder Extracts Obtained by Ultrasound Assisted Extraction

Covarrubias-Cárdenas¹,

Martínez-Castillo²,

Medina-Torres³

et al. 2018

Agronomy

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“…Dried Stevia (Rebaudiana Bertoni) leaves contain an enormous amount of sweetening content (Castillo et al, 2018). Experimental investigation of the dehydration process of these leaves used direct (cabinet) (natural and forced convection) and indirect solar drying(tunnel type)methods.…”

Section: Classi Cation Of Dryers Used In Leaves Dryingmentioning

confidence: 99%

Analyzing environmental parameters for drying of neem and moringa leaves in solar greenhouse dryer regions of southern India

Rajesh¹,

N²,

Sivakumar³

2020

Preprint

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The green foliage of plants plays a vital role in the Traditional Medical System(TMS). Especially neem and moringa contains rich nutrients and hence used for medicinal purpose, preserving and drying of these leaves are found to be most important. Using a solar greenhouse dryer(GHD) for this purpose reduces the cost of energy and maintains herbal's own multifarious spectrum of constituent substances.Drying of these herbals in solar greenhouse dryer depends on the duration of sunshine hours in a particular day, atmospheric pressure, air temperature, relative humidity, wind speed, rainfall, turbidity parameters and transmission coefficients. In the above parameters, finding the longest duration sun shine hours and the best intensity rate of the sunshine are considered to be important to get better performance from the dryer. This communication throws light on the (1) Best time to start the drying process in a particular day ,month and year in GPS co-ordinates (12.2253° N, 79.0747° E) of Tiruvannamalai, Tamilnadu (2) Fabrication of the experimental setup of solar greenhouse dryer (3) Conducting the test for reduction of moisture up to safe limit of moisture content (4) Experimental results are to be validated with the theoretical results.to control the replications of Dengue virus type-2.

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“…Most stevia species contain sweetening compounds (Goyal & Samsher, 2010); their leaves are considered a natural source of sweetener and are a functional food of high scientific interest (Lemus‐Mondaca et al., 2015). Many studies about aromatic and medicinal plants have been developed, including studies on bioactive compounds (Kaushik et al., 2010; Periche et al., 2014; Zaidan et al.,), nutritional and medical applications (Kujur et al., 2010; Lemus‐Mondaca et al., 2018; Vega et al., 2007), reviews (Bueno‐Hernández et al., 2019; Goyal & Samsher, 2010), and drying characteristics (Castillo Téllez et al., 2018; Darchan et al., 2012; Lemus‐Mondaca et al., 2015; Periche et al., 2015).…”

Section: Introductionmentioning

confidence: 99%

“…medicinal plants have been developed, including studies on bioactive compounds (Kaushik et al, 2010;Periche et al, 2014;Zaidan et al,), nutritional and medical applications (Kujur et al, 2010;Lemus-Mondaca et al, 2018;Vega et al, 2007), reviews (Bueno-Hernández et al, 2019;Goyal & Samsher, 2010), and drying characteristics (Castillo Téllez et al, 2018;Darchan et al, 2012;Lemus-Mondaca et al, 2015;Periche et al, 2015).…”

mentioning

confidence: 99%

Moisture sorption isotherms, isosteric heat, and Gibbs free energy of stevia leaves

López-Vidaña

Téllez

Figueroa

et al. 2020

J Food Process Preserv

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There is scientific evidence that Stevia leaves, commonly used as a sugar substitute, can reduce the risk of obesity, diabetes, hypertension, or cardiovascular diseases. In this study, the moisture sorption isotherms of stevia leaves at 35°C, 45°C, and 55°C were analyzed by the static gravimetric method within a relative humidity range between 0.06 and 0.92. The experimental data obtained exhibits a J‐shaped Type II sorption isotherms. The data were fitted to six mathematical models: Iglesias & Chirife, Lewicki, Oswin, Hasley, GAB, and Khun. GAB model was the one best‐fitted to the isotherms obtained. The monolayer value was between 0.0479 and 0.0589 g water/g dry matter. The isosteric heat of adsorption and Gibbs free energy were obtained at different temperatures using the Clausius–Clapeyron equation. The isosteric heat of adsorption exponentially decreased from 2850 J/g to 2480 J/g as the equilibrium moisture content increased from 0.062 to 0.522 g water/g dry matter. The chemical potential of adsorption increased at high moisture content values. These results suggest an exothermic, spontaneous process. Novelty Impact Statement The importance of studying adsorption isotherms, and its fitting to a mathematical model, allows us to know the potential of the water that influences on the reactions of physical‐chemical deterioration correlated with the stevia leaves stability and quality. The thermodynamic properties derived from moisture adsorption isotherms provide relevant information about the water chemical potential and the energy amount required in moisture adsorption processes, and its relationship with stevia stability in different storage conditions.

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Solar drying of Stevia (Rebaudiana Bertoni) leaves using direct and indirect technologies

Cited by 78 publications

References 28 publications

Antioxidant Capacity and UPLC-PDA ESI-MS Phenolic Profile of Stevia rebaudiana Dry Powder Extracts Obtained by Ultrasound Assisted Extraction

Antioxidant Capacity and UPLC-PDA ESI-MS Phenolic Profile of Stevia rebaudiana Dry Powder Extracts Obtained by Ultrasound Assisted Extraction

Analyzing environmental parameters for drying of neem and moringa leaves in solar greenhouse dryer regions of southern India

Moisture sorption isotherms, isosteric heat, and Gibbs free energy of stevia leaves

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