Effect Of Air Drying Temperature Research Articles

Effect of Air-Drying Temperature on Phenol Compound and Essential Oils Content in Lemon Leaves

The aim of this workis to study the effect of temperature on the drying kinetics, total phenolic and flavonoid compounds and finally on essential oils existing in lemon leaves. The experimental kinetics data isdivided into five empirical models and the best description is given by Logarithmic equation. For essential oil extraction, the highest yield was obtained at a drying temperature of 24.0°C, an extraction time of 125 min and at a water/vegetable matter ratio of 3.4. Volatile components were identified by GC-MS technique. The outcomes of the experiment indicate that temperature has a significant impact on the components of lemon leaves especially on essential oils. A temperature of 23.7°C produced the highest proportions main compounds (89.26%: Limonene, Monoyloxid, β-pinene). A queous extracts were prepared from the leaves of this plant dried at 30, 40, 50 and 60°C. The quantitative estimation of polyphenols and flavonoids by the UV. Visible spectrophotometer method revealed that the variation in the drying parameters has an influence on the content of these compounds.

Drying kinetics and effect of air-drying temperature on chemical composition of Phyllanthus amarus and Phyllanthus niruri

ABSTRACTIn this study, the drying kinetics of Phyllanthus amarus and Phyllanthus niruri were investigated experimentally in an air-drying oven as a function of drying temperature (50, 60, and 70°C). The effects of the air-drying temperature on the phenolic content and the LC–MS profile were also studied. Increases in air-drying temperature reduced the drying time and increased the effective moisture diffusivity. An Arrhenius relationship with activation energy values of 22.828 and 43.129 kJ/mol for P. niruri and P.amarus, respectively, expressed the effect of temperature on the diffusivity. Air drying at 70°C increased the availability of some phenolic compounds. However, the higher temperature negatively affected some sensitive components.

Effect of air-drying temperature on extractable and non-extractable phenolics and antioxidant capacity of lime wastes

The lime industry is generating more waste due to the increasing demand of juice. In this study, extractable and non-extractable phenolics in the Gallega lime waste, dried at different temperatures were determined and their antioxidant capacities were evaluated using DPPH (2,2-diphenyl-picrylhydrazyl), ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6/sulphonic acid) and, ORAC (oxygen radical absorbance capacity) methods. The amount of non-extractable phenolics measured in lime waste dried at 60, 90, and 120°C were 38.4%, 39.2%, and 33.5%, respectively higher, compared to the amount of extractable phenolics. Dried lime waste is rich in extractable and non-extractable hesperidin (213.87 and 181.32mg/g, respectively), and eriocitrin (55.22 and 97.24mg/g, respectively) and non-extractable gallic acid (42.45μg/g,). The antioxidant capacities of extractable and non-extractable phenolics were from highest to lowest: ABTS>ORAC>DPPH and ABTS>DPPH>ORAC, respectively. The information reported here may encourage lime industry operators to re-evaluate their by-products, extending the application of lime fruits and reducing waste.

Influence of Drying Temperature on Total Phenolic Content And Antioxidant Capacity of Grape Seeds

Grape seed, which is an organic waste arise from production of wine, juice and molasses, is considered as a functional food ingredient in food formulations because of its rich content of bioactive compounds. This study was performed in order to evaluate the effect of air-drying temperature on the bioactive compounds of grape seeds. In the study, total phenolic content and antioxidant activity of grape seeds that are dehydrated at different drying temperatures (40, 50 and 60°C) were determined. When comparing the fresh grape seeds with the corresponding dehydrated samples, it was shown that the drying operation led to reduction of total phenolic contents and the total phenolic contents decreased with an increase of the drying temperature. According to ABTS radical scavenging method, Trolox Equivalent Antioxidant Capacity (TEAC) was found to be highest for fresh grape seeds and presented lower values for grape seeds dried at three different temperatures. As a result of the study, it was demonstrated that grape seed is a powerful antioxidant source and it has still high antioxidant activity after drying process. However, drying at low temperatures was put forward to be advantageous in order to reduce the losses of phenolic components.

Effects of pre-treatments on the yield and carotenoid content of Gac oil using supercritical carbon dioxide extraction

The effects of air-drying temperature, particle size and enzymatic pre-treatment on the oil yield and content of carotenoids in the resultant Gac oil using supercritical CO2 extraction method were investigated. It was found that the highest oil yield was obtained when using the enzyme concentration at 0.1% (w/w) for pretreatment before air-drying. Furthermore, the content of carotenoids was also enhanced by suitable drying temperature and the particle size. High oil yield (34% g/g) and high content of β-carotene (83mg/100mL oil) and lycopene (508mg/100mL oil) were obtained using the drying temperature of 50°C and particle size of 0.45mm as pre-treatments prior to SC-CO2 extraction at pressure of 200bar and extraction temperature of 50°C. Results also indicated that the most suitable extraction time was 120min. It was concluded that Gac oil containing high amount of carotenoids could be extracted using the chosen air-drying temperature, particle size, enzymatic pre-treatment and extraction time.

Effect of air-drying temperature on physico-chemical properties, antioxidant capacity, colour and total phenolic content of red pepper (Capsicum annuum, L. var. Hungarian)

Abstract Red pepper has been recognised as an excellent source of antioxidants, being rich in ascorbic acid and other phytochemicals. Drying conditions, particularly temperature, leads to pepper modifications that can cause quality degradation. In this work, the effects of process temperatures between 50 and 90 °C on physico-chemical properties, rehydration, colour, texture, vitamin C, antioxidant capacity and total phenolics during the drying of red pepper were studied. The rehydration ratio decreased with temperature and the maximum water holding capacity was achieved at 50 °C. Both vitamin C content and the total phenolic content decreased as air-drying temperature decreased. The radical scavenging activity showed higher antioxidant activity at high temperatures (i.e. 80 and 90 °C) rather than at low temperatures (i.e. 50, 60 and 70 °C). Chromatic parameters (L*, a*, b*, C* and H°), non-enzymatic browning compounds and extractable colour were affected by drying temperature, which contributed to the discolouring of pepper during this process.

Effect of air-drying temperature on antioxidant capacity and stability of polyphenolic compounds in mulberry ( Morus alba L.) leaves

The mulberry ( Morus alba L.) leaf is a promising dietary source of antioxidants such as quercetin due to its relatively high content of that compound. We investigated effects of an air-drying process on the antioxidant capacity and stability of antioxidant polyphenolic compounds in mulberry leaves. Main compounds playing a central role in antioxidant activities in mulberry leaves are quercetin glycosides and chlorogenic acid. Raw mulberry leaves were air-dried at various temperatures, and antioxidant activity using DPPH radical scavenging assay and levels of antioxidant compounds were measured. DPPH radical scavenging activity and levels of polyphenolic compounds in mulberry leaves air-dried at 60 °C or below were not significantly different from those of freeze-dried mulberry leaves, whereas both values in mulberry leaves air-dried at 70 °C and over decreased significantly. These results indicate that strict temperature control is important in the production of mulberry leaf products to maintain antioxidant activity and levels of polyphenolic compounds.

Effects of air-drying temperature on the cell walls of kiwifruit processed at different stages of ripening

The effects of air-drying temperature on the cell wall components of three sets of fresh kiwifruits at different degrees of ripening, unripe, half-ripe and ripe samples, have been evaluated. The modifications affecting the physico-chemical properties of cell wall polysaccharides were largely dependent, not only on the air-drying temperature used (from 30 °C to 90 °C), but also on the initial stage of ripening of the processed kiwifruits. Thus, whereas in comparison with the fresh fruits, dehydrated unripe and half-ripe kiwifruits maintained their overall cell wall composition better, processed ripe kiwifruits seemed to be more sensitive to cell wall degradation/solubilisation. In fact, important losses of cell wall material (CWM), mainly pectins and, also, hemicelluloses, were detected in the riper kiwifruits when these samples were dehydrated at high temperature (up to 30% CWM losses when drying was carried out at 90 °C). Heating also promoted considerable modifications of the degree of methyl-esterification (DME) of pectins. In general, an increase in the DME corresponded to an increase in the degree of ripening of the processed samples, suggesting that methylated pectins exhibited a higher resistance to the degradation/solubilisation caused by heating. All these changes in composition were clearly reflected in the solubility and functional properties (FP) of processed CWMs. Hydration properties, swelling and water retention, and, in particular, the capacity to absorb lipids, were modified after processing. In general, CWMs from processed half-ripe kiwifruits exhibited the highest FP values. Overall, the study clearly reflects the importance of taking into consideration the stage of ripening of fruits in order to determine the final quality of CWMs, and therefore, the properties of the dietary fibre (DF) which could be obtained from processed kiwifruit samples.

Effect of air-drying temperature on physico-chemical properties of dietary fibre and antioxidant capacity of orange ( Citrus aurantium v. Canoneta) by-products

Dehydration promoted important modifications affecting both the physico-chemical properties of dietary fibre (DF) and the antioxidant capacity of orange by-products (peel and pulp remaining after juice extraction). The significance of such changes was largely dependent on the air-drying temperature used (from 30 °C to 90 °C). The major modifications on the DF components were observed when either extended drying periods, i.e. at lower temperatures, or elevated drying temperatures were applied. Dehydration around 50–60 °C apparently promoted the minor disruption of cell wall polymers, in particular of pectic substances. Pulp samples exhibited higher values of swelling (SW) and fat adsorption capacity (FAC) than those derived from orange peel. Although, significant decreases in water retention capacity (WRC), FAC and solubility values were detected for both by-products as the air-drying temperature increased. The antioxidant capacity associated to dehydrated citrus by-products was significantly higher for orange peel than for pulp samples. In general, the by-products studied proved to be quite resistant to the different heat treatments applied within the range of 40–70 °C. In overall, the study shows that, in order to preserve either the DF quality and/or the antioxidant capacity, air-drying temperature should be controlled since both types of compounds, DF components and antioxidants, might be degraded or modified either when extended drying periods and/or high drying temperatures are applied.

Dehydration of aloe vera: simulation of drying curves and evaluation of functional properties

The effect of air-drying temperature (from 30°C to 80°C) on dehydration curves and functional properties (water retention capacity, WRC; swelling, SW; fat adsorption capacity, FAC) of aloe vera cubes has been investigated. A diffusional model taking into account sample shrinkage has been proposed and solved by using a finite difference method. The effective diffusivities estimated with the proposed model varied with the air-drying temperature according to the Arrhenius law except for the experiment carried out at 80°C, where case-hardening took place. Simulation of aloe vera drying curves by using the model was accurate (percentage of explained variance (%var): 99.7 ± 0.1%). Furthermore, drying kinetics of aloe vera cubes of different sizes to those used to develop the model could be satisfactorily predicted (%var: 99.5 ± 0.2%). The three studied functional properties exhibited a maximum when drying temperature was 40°C decreasing either at higher or lower temperatures.