Effect Of Different Drying Techniques Research Articles

The effect of different drying techniques and microwave finish drying on the powder properties of the red pepper powder (Capsicum annuum L.).

The objective of this study was to investigate the effects of different drying processes (microwave, freeze, convective hot air, and vacuum drying) and microwave finish drying (FD + MD and CD + MD) on the physical and powder properties of the red pepper powder. The effect of moisture content on the powder properties and the relationship between microwave output power or drying temperature and physical and powder properties were also determined by using most common mathematical models (linear, power, logarithmic, and quadratic). Results showed that an increase in both microwave output power and temperature (for CD and VD) generally resulted in a decrease in drying time, moisture content, and chroma and an increase in bulk and tapped density values. The drying time, moisture content, and water activity values can be significantly decreased, whereas, the color values can be significantly increased by combining FD and CD with microwave finish drying (P < 0.05). The moisture content (y = - 1.94ln(x) + 7.6455, R2 = 0.9905), bulk (y = 54.224ln(x) + 153.71, R2 = 0.9705), tapped (y = 61.7ln(x) + 225.6, R2 = 0.9994) and particle densities (y = - 327.4ln(x) + 2260.5, R2 = 0.9966), and porosity (y = - 3.778ln(x) + 89.806, R2 = 0.9586) values followed a logarithmic trend depending on the increase in the convective hot air drying temperature. The inverse relationship was observed between the moisture content, bulk and tapped densities of the red pepper powders.

The effect of spray-drying and freeze-drying on encapsulation efficiency, in vitro bioaccessibility and oxidative stability of krill oil nanoemulsion system

A nanoemulsion system was employed to encapsulate the krill oil with different concentration. The combination of whey protein concentrate, maltodextrin and gum arabic with the ratio of 8:2:0.5 was used in nanoemulsion formulation to enhance nanoemulsion stability, as well as to construct the wall part of the encapsulates. Two different drying methods; freeze-drying and spray-drying were applied on krill oil nanoemulsion systems to obtained powder encapsulates. The physical characterization of nanoemulsions and chemical stability of krill oil in terms of oxidative stability and in vitro bioaccessibility (%) were evaluated before and after drying processes to understand the effect of different drying techniques on encapsulation ability of nanoemulsion systems. Dehydration of nanoemulsions with spray-drying caused approximately 7 folds increments on particle size. The sample with 8% (w/v) of krill oil concentration had an optimum encapsulation efficiency that was calculated 72% in spray-dried nanoemulsion and 67% in freeze-dried nanoemulsion. Both spray-dried and freeze-dried krill oil nanoemulsions showed similar oxidative stability in 8% (w/v) concentration during the 15 days storage period. In vitro bioaccessibility of encapsulated krill oil was changed between 32.7 to 72.4% and 20.0–83.0% in freeze-dried and spray-dried nanoemulsions, respectively. Still, the spray-drying process is recommended for the dehydration of krill oil nanoemulsion with 8% (w/v) concentration because a better encapsulation efficiency and the higher in vitro bioaccessibility was obtained compared to freeze-dried nanoemulsion systems at the same concentration of krill oil.

Effect of Different Drying Techniques on Dehydration Kinetics, Physical Properties, and Chemical Composition of Lemon Thyme

Lemon thyme contains several bioactive health-promoting compounds of high antioxidant capacity—such as polyphenols, carotenoids, and chlorophyll—which may undergo degradation during drying in incorrect processing conditions. This work is aimed at evaluating the impacts of different drying techniques and parameters on the chemical and physical properties of lemon thyme. In the experiment, lemon thyme leaves are dried using two traditional hot-air methods, convective drying (temperature 70°C or 80°C, air velocity 2 m/s), and fluidized bed drying (temperature 70°C or 80°C, air velocity 5–10 m/s); as well as two innovative drying methods, microwave-assisted fluidized bed (MFB) drying (microwaves at a power of 240 or 440 W, air temperature 40°C, air velocity 5–10 m/s) and microwave-vacuum (MV) drying (microwaves at a power of 240 or 440 W, under vacuum at 4–6 kPa). The kinetics of water delivery are described using the Page Model. After drying, the nutritional composition of the material is analyzed: polyphenol (total content and polyphenols profile by ultra-performance liquid chromatography), carotenoid, and chlorophyll total content, as well as antioxidant capacity (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt [ABTS+] and ferric reducing antioxidant power [FRAP]). Color changes ( L*, a*, b*, ΔE) are also analyzed using the visible effects of lemon thyme pigment disintegration. It is found that the MV drying method is the best for lemon thyme preservation, as it has the shortest process time and the highest retention of polyphenols (78.90%-82.14%), chlorophylls (51.54%-52.68%), antioxidant capacity (47.83%-48.63% of ABTS+ and 20.85%-45.45% of FRAP), and presented the least color change ( ΔE = 25.57-28.32). For preserving carotenoids, the most protective method is MFB (retention 68.46%-70.61 %).

Evaluation of Different Drying Techniques on Bombay Red Onion (Allium Cepa L) Basic Nutritional and Volatile Components

In this study performance of three drying methods on basic nutritional and important volatile components of red onion were evaluated. Onion (Allium cepa L.) is a strong-flavoring vegetable consumed in different ways, mainly due to its distinctive flavor or, simply pungency. It also has important natural compounds effective for medical functions such as inhibition of bone resorption, lower risk of cardiovascular disease, and cancer. This importance is directly related to a high content of organo-sulphur compounds. The shelf life of fresh onion bulbs are short enough about two weeks at ambient storage conditions in Fogera district, Amhara region, Ethiopia. This is mainly due to the presence of high moisture in fresh onion bulbs. Postharvest loss of onion bulbs also reaches up to 50% in the production season in Fogera district. Consequently, onion bulbs had extremely variable market price during production and off-season in the district, which directly influences both growers and consumers. The effects of different drying techniques on protein, carbohydrate, total sugar, fat, pyruvic acid, ascorbic acid, total phenol, total flavonoid, rehydration ratio, colour, and sensory properties of onion slice were evaluated and found insignificant at p &gt; 0.05 for microwave and modified direct solar dryers, taking fresh onion bulbs as the control. However, oven drying methods had a significant effect on onion physicochemical quality attributes at p &lt;0.05 as compared to fresh onion bulbs.

Comparison of structural characteristics and bioactivities of polysaccharides from loquat leaves prepared by different drying techniques

In the present study, freeze drying, hot-air drying, vacuum drying, and microwave drying at the microwave powers of 400, 600, and 800 W, respectively, were utilized to dry loquat leaves for evaluating the effects of different drying techniques on the physicochemical structures and bioactivities of polysaccharides extracted from loquat leaves (LLPs). Results demonstrated that the physicochemical structures and bioactivities of LLPs significantly affected by different drying techniques. The degrees of esterification, molar ratios of constituent monosaccharides, contents of uronic acids, apparent viscosities, and molecular weights of LLPs were varied by different drying techniques. Additionally, LLPs, particularly LLP-M4 which extracted from loquat leaves prepared by microwave drying at the power of 400 W, exerted remarkable in vitro binding capacities, strong inhibitory effects on α-amylase and α-glucosidase, and obvious antioxidant activities. Results indicated that the microwave drying could be an efficient drying technique before extraction of bioactive LLPs, and LLPs had great potential applications in the functional food and pharmaceutical industries.

Evaluation of drying techniques on nutritional and volatile components of Bombay red onion (Allium cepa)

In this study performance of three drying methods on nutritional and important volatile components of red onion were evaluated. Onion (Allium cepa L.) is a strong-flavoring vegetable consumed in different ways, mainly due to its distinctive flavor or, simply pungency. The shelf-life of fresh onion bulbs are short enough about two weeks at ambient storage conditions in Fogera district, Amhara region, Ethiopia. This is mainly due to the presence of high moisture in fresh onion bulbs. Postharvest loss of onion bulbs also reaches up to 50% in the production season in Fogera district. Consequently, onion bulbs had extremely variable market price during production and off-season in the district, which directlyinfluences both growers and consumers. The effects of different drying techniques on protein, carbohydrate, total sugar, fat, pyruvic acid, ascorbic acid, total phenol, total flavonoid, rehydration ratio, colour, and sensory properties of onion slice were evaluated and found insignificant at P&gt; 0.05 for microwave and modified direct solar dryers, taking fresh onion bulbs as the control. However, oven drying methods had a significant effect on onion physicochemical quality attributes at P &lt;0.05 as compared to fresh onion bulbs.

Effect of Different Drying Techniques on the Resistant Starch, Bioactive Components, Physicochemical and Pasting Properties of Cardaba Banana Flour

Abstract This study investigated the effect of different drying techniques on Cardaba banana flour. Cardaba banana was processed using sun, cabinet and freeze drying methods. The proximate, pasting, functional, starch profile and antioxidant properties of Cardaba banana flour were evaluated. The drying methods significantly (p ≤0.05) affected the chemical, functional, pasting and antioxidant properties of the Cardaba banana flour. Freeze dried (FD) flour sample had highest (6.69%) protein value, while sun dried (SD) flour sample had the lowest (6.13%). The crude fat of FD sample (2.38%) was not significantly different (p &gt;0.05) from cabinet dried (CD) flour (2.38%) sample. However, sun dried sample crude fibre content was the highest (0.84%). In addition, drying methods significantly (p ≤0.05) affected the pasting characteristics of Cardaba banana flours. Results of functional properties showed that the drying methods had no effect on the least gelation properties of the flour. The resistant and total starch was highest in CD, and least in SD. Freeze drying produced flour high in indigestible carbohydrate compared to the other methods. Cardaba banana flour samples from all the drying methods showed substantive total phenolic, flavonoid, ABTS and DPPH contents. The drying methods employed significantly (p ≤0.05) affected the functional, chemical, pasting and antioxidants properties of Cardaba banana flours. However, the study indicated that freeze drying and cabinet drying produce flours with better properties.

Effect of Different Drying Techniques on the Nutrients Content of Fish Feedstuffs

The study investigated the effect of different drying techniques (air dying, oven drying and sun drying) on the proximate composition of three fish feedstuffs; Horse radish (Moringa oleifera) leaves, water lily (Pistia stratiotes) leaves and soy bean (Glysine max) seed. The soy bean was boiled for 30 minutes at 100°C in water bath to reduce the effect of anti-nutritional factor (trypsin). Samples of each feedstuff were prepared and subjected to the three dying methods in triplicate treatments. Determination of proximate composition was carried out on the dried and fresh samples of each feedstuff. The results showed that moisture content of fresh M. oleifera leaves (65%) and P. stratiotes leaves (85.67%) were significantly higher (P&lt; 0.05) than fresh G. max (2.67%). Higher crude protein content of 23.97% and 22.50% were recorded for oven-dried M. oleifera and P. stratiotes leaves and 39.21% for fresh G. max with no significant difference (P&gt; 0.05) between the treatments. Crude lipid was significantly higher for sun dried samples of all the feedstuffs. Oven-dried samples of the three feedstuffs had the least ash, crude fiber and nitrogen free extract. The study concluded that oven drying at moderate temperature of 700C proved to be more effective in moisture removal and retention of crude protein. Furthermore, the study recommends a feeding trial to assess the potential of these feedstuffs subjected to various drying methods on growth and nutrients utilization of cultivable fish species.

Effect of different drying techniques on chemical composition, color and antioxidant properties of kinnow (Citrus reticulata) peel.

Aim of the present study was to evaluate the effect of different drying techniques on chemical composition, color and antioxidant activity of kinnow peel. Fresh peel was dehydrated by three different techniques (tray, vacuum and freeze) and regardless of the method results showed significant decreases in moisture, total phenols, flavonoids, antioxidant activity and color when compared to the fresh sample. Freeze drying was found superior in retention of polyphenolic characteristics and color attributes when compared with other drying techniques. The fresh and freeze-dried citrus peel extract was analyzed for individual phenolics and flavonoids with the help of HPLC indicating highest concentrations of ferulic acid and hesperidin.

The effect of different drying techniques on phytochemical content and in vitro antioxidant properties of Australian‐grown prickly pears ( Opuntia ficus indica )

Abstract Prickly Pear (Opuntia ficus indica) is commonly consumed but limited by short harvesting seasons and shelf life. Drying may resolve such issues. The effects of different methods were examined to investigate the phytochemicals in Australian prickly pear (PP). White, orange and purple fruits were dried using freeze-drying, microwave, draft-oven, and dehydrator-drying (35°C, 55°C, and 75°C). Total Phenolic Content (TPC), Total Flavonol Content (TFC), Total Betalain Content (TBC), Betacyanin (BE), and Betaxanthin (IE) and antioxidant characteristics (2,2-diphenyl-1-picrylhydrazyl [DPPH], Cupric Ion Antioxidant Reducing Capacity [CUPRAC], and Ferric Reducing Antioxidant Power [FRAP]) were determined as methanolic extracts (skin/flesh). The highest content is as follows: TPC (149 ± 5.06 µgGAE; microwave; purple skin), TFC (76.6 ± 1.98 µgCE; microwave; purple-skin), TBC (4.17 ± 0.846 mg/100 g; freeze-dried; orange-skin and flesh), BE (2.29 ± 1.00 mgBE/100 g; freeze-dried; purple-flesh), IE (3.42 ± 0.569 mgIE/100 g; freeze-dried; purple-flesh); DPPH (224 ± 41.2 µMTE; freeze-dried; white-flesh), CUPRAC (2,937 ± 43.3 µMTE; microwave; purple-skin) and FRAP (1,377 ± 27.0 µMTE; microwave; purple-skin). Significant differences (p < 0.05) occurred between drying methods. When compared to freeze drying, microwaving, in some cases elicited the highest content. Practical applications The gap between the nutrient-dense prickly pear fruit, and its consumption is prominent, particularly in Australia. This is potentially the consequences of social misconceptions, a short harvesting season and shelf life, thus potentially contributing to Australia's growing food waste challenge. Therefore, such obstacles could be reduced with the use of the most appropriate drying technique in order to extend the products shelf life. Our manuscript investigates the effect of different drying techniques on the phytochemical content of the prickly pear fruit. The investigated drying methods were considered accessible to small agricultural producers, the predominant farmers for this fruit in Australia. The findings of this paper can be potentially implemented in agricultural practice, assisting with year-round food supply and reduce on-site foods waste.

Effect of Different Drying Techniques on Some Functional Properties of Dried Fig

Fig as one of the major export products of Turkey, deteriorates very quickly due to its perishable nature. For this reason it is utilized as dried fruit. In traditional drying method of figs, it was observed that there are some problems caused by climate, especially due to rainfall during drying season,thus, quality losses occur. With this project fresh figs were dried at two different humidity levels in both the sun and the cabinet type dryer using different immersion solutions at 2015 to 2017. Additionally, ¼ cut fruits was dried in both methods without using solutions. According to the sensory analysis results, ¼ cut fruits take the highest score while the second was dried figs without using immersion solutions. The immersion solutions were effective in reducing the drying time of the figs but due to the adverse taste effect of alkali ethyl oleate solution, it was not preferred. In the ¼-cut fruits the total phenolic content and antioxidant activity identified as 343.30 (mgGA / 100 g DM) and 259.32 (μM trolox / 100 g DM), respectively, and this application gives better results compared to others. In this study where fresh figs are dried, aflatoxin analysis was performed on all products and it was not detected in any of the samples.

Qualitative and quantitative variations of the essential oils of Dracocephalum kotschyi Boiss. as affected by different drying methods

Using an appropriate drying method is the most important step in the postharvest processing of Dracocephalum kotschyi Boiss. to preserve its qualitative and quantitative essential oils. In this study, the effects of different drying techniques (sun, shade, conventional oven, vacuum oven, microwave, and infrared drying) were investigated on the essential oil content and composition of plants. Vacuum oven-drying at 40°C was the best method for the retention of the essential oils of the samples. The essential oil was relatively sensitive to temperature, so its content was decreased with increase in the drying temperature. The results showed that oxygenated monoterpenes represented the main chemical class of essential oil components. Although the highest content of α-pinene and geranyl acetate (as major compounds) was obtained by conventional oven-drying at 40°C, the highest content of limonene and α-terpineol was observed in the plants dried under the sun and by infrared drying at 0.5w/cm, respectively. Practical applications The results suggest that vacuum oven-drying could be the best method for obtaining the highest content of essential oils from Dracocephalum kotschyi Boiss along with its major bioactive components. In addition, the microwave drying method was known as the most desirable drying method with regard to the final color of the dried products.

Comparative evaluation of quality properties and volatile profiles of lemon peels subjected to different drying techniques

AbstractIn this study, effects of different drying techniques (open‐air drying [AD], hot air drying [HAD], microwave drying [MWD], and freeze‐drying [FD]) on quality properties and volatile compound profiles in lemon peels were examined. For those purpose, water‐holding capacity, water activity, bulk density, color, pH, titratable acidity, total phenolic content, antioxidant activity, ascorbic acid content, total carotenoid content, and volatile compounds of dried lemon peels were determined. Among the drying methods, the highest retention of phenolics, ascorbic acid, and carotenoids were provided by FD. A total of 56 volatile compounds were identified in dried lemon peel powders. MWD samples contained the largest number of volatiles, whereas HAD samples had the highest volatile content. Principal component analysis on volatiles indicated that there is a convenient relation between the AD, HAD, and FD samples.Practical applicationsDifferent drying techniques play significant roles in the storage of fruits and vegetables. However, the effect of these methods on the quality of various foods is still not clear. This article indicates the effects of open‐air, hot air, microwave, and freeze‐drying methods on certain quality parameters and volatile compounds of lemon peels. The obtained data from the present study will provide valuable information for setting up industrial‐scale dryer systems for products with high volatile content. It will provide contribution to the improvement in food companies on their production conditions.

Influence of dehydration techniques on colour retention and related traits of gerbera (Gerbera hybrida) flowers

Gerbera (Gerbera hybrida) is the most popular florist flower due to various colours, shapes and sizes. It belongs to the family Asteraceae. The present study was conducted to determine the effect of different drying techniques on retention of flower colour and its related traits of Gerbera hybrida var. Doni. Maximum flower colour acceptability score (3.67), high acceptability of texture of dry flowers (3.67), minimum brittleness of dried flowers (2.33), minimum damage of florets (1.33) and maximum score (2.67) for the shape of embedded dry flowers were observed with vacuum air oven drying upto 60 days. Maximum colour retention up to 60 days was observed on the adaxial surface of the floret in vacuum drying (Y-O14A); however, on the abaxial surface of the floret, colour retention was seen maximum up to 60 days at room temperature drying, i.e. control (Y-12B) technique. Minimum reduction in flower size (5.22 %) was observed in vacuum drying; however, minimum reduction in flower weight (82.21%) was foundin microwave drying technique. Vacuum air oven drying method was observed to be the best technique for retention of flower colour and related traits.

Effect of different drying techniques on quality characteristics of African palmyra palm (Borassus aethiopum) fruit flour

Effect of different drying techniques on quality characteristics of African palmyra palm (Borassus aethiopum) fruit flour

Effect of different drying techniques on physicochemical, thermal, and functional properties of seera

ABSTRACTSeera produced by different drying techniques was evaluated regarding its various physicochemical properties. The rheological properties of the batter showed a shear thinning behavior and Herschel–Bulkley model was best fitted with R2 = 0.9987. The results revealed that water absorption capacity increased as compared to the wheat flour and maximum absorption was found in freeze-dried seera (1.91 g g−1), followed by oven-dried (1.62 g g−1) and sun-dried (1.13 g g−1). Oil absorption capacity of seera decreased as compared to wheat flour, with minimum values obtained for freeze-dried (0.93 g g−1 of seera). Carbohydrate content increased significantly in seera sample to 81.76%, while fat, protein, and moisture content decreased significantly. L* values increased significantly, while as both a* and b* values decreased. Bulk density also showed an increasing trend with maximum value in freeze-dried seera. Transition temperatures changed significantly for the seera samples along with enthalpy of gelatinization. Fourier transform infrared pattern did not change with drying.

Effect of different drying techniques on the volatile compounds, morphological characteristics and thermal stability of &lt;i&gt;Stevia rebaudiana&lt;/i&gt; Bertoni leaf

Purpose: To examine the volatile compounds, thermal stability and morphological characteristics of stevia ( Stevia rebaudiana Bertoni ) leaves after sun, oven and microwave drying. Methods: Gas chromatography-mass spectrometry with a spectral analysis manager was used to separate the volatile compounds. Dried stevia leaf powder was characterized morphologically by scanning electron microscopy while thermal properties were determined by differential scanning calorimetry (DSC). Results: The plant material contained large amounts of spathulenol and caryophyllene oxide. The main compounds were 1-docosanol and hexanoic acid; trans-β-ionone, 5-methylundecane, 2,5,6-trimethyldecane, (+) spathulenol, propanoic acid and 1-chlorononadecane. The surface of the dried leaf powder varied with the treatment applied. Following microwave drying, the particles were even, regular, and compact while the sun- and oven dried particles resembled angular bricks. All samples exhibited a strong endothermic response, indicating stability up to 150 °C; from 150 to 200 °C, thermal decomposition occurred. Conclusion: Drying method has a significant effect on the structure, thermal stability and volatile compounds contents of stevia leaves. All drying methods examined in this study have potential applications in the preparation of stevia as a functional ingredient for the food and pharmaceutical industries. Keywords: Differential scanning calorimetry, Drying techniques, Stevia rebaudiana , Pharmaceuticals, Scanning electron microscopy, Volatile compounds

Effect of different drying techniques on bioactive components, fatty acid composition, and volatile profile of robusta coffee beans

This study investigated the effect of different drying techniques, namely, room-temperature drying (RTD), solar drying (SD), heat-pump drying (HPD), hot-air drying (HAD), and freeze drying (FD), on bioactive components, fatty acid composition, and the volatile compound profile of robusta coffee beans. The data showed that FD was an effective method to preserve fat, organic acids, and monounsaturated fatty acids. In contrast, HAD was ideal for retaining polyunsaturated fatty acids and amino acids. Sixty-two volatile compounds were identified in the differently dried coffee beans, representing 90% of the volatile compounds. HPD of the coffee beans produced the largest number of volatiles, whereas FD resulted in the highest volatile content. A principal component analysis demonstrated a close relationship between the HPD, SD, and RTD methods whereas the FD and HAD methods were significantly different. Overall, the results provide a basis for potential application to other similar thermal sensitive materials.

Effect of Different Drying Techniques on Physicochemical, Micro-structural and Bioactive Characteristics of Barberry Milk Smoothie Powder

Abstract In this study, new smoothies were formulated based on low fat milk and barberry concentrate, and their physicochemical and bioactive properties were investigated. Physicochemical parameters of functional smoothie powders were obtained by applying low and high temperature drying methods, and by a combination of procedures programmed to process smoothie powders. The effect of spray drying (SP), refractance window (RW), foam mat drying (FM), spouted bed drying (SB) and a combination of spouted bed drying were studied herein, while the infrared lamp system (SBIR) shows how these methods affect the smoothie’s physical properties (such as bulk density, porosity, color) and its chemical properties (such as total anthocyanin content and antioxidant capacity measured by the DPPH method). The study also proved that an increase in the speed of rotation from 10 rpm to 100 rpm would lead to a diminished apparent viscosity from 642.39 mPas to 381.98 mPas regarding all reconstituted dried powders, which thus verifies their shear thinning behavior. The work highlighted that this new approach to combining the drying methods for the production of functional smoothie powders at an inlet temperature of 80 °C can result in the best maintenance of antioxidant activity (11.67 %) with the least moisture content (3.19 %).

Effect of different drying techniques on physical properties, total polyphenols and antioxidant capacity of blackcurrant pomace powders

The effect of freeze-drying (FD), convective (50 °C–90 °C; CD), microwave vacuum (120W, 240W, 360W, 480W; MVD) and combined (CD-MVD) drying on the physico-chemical properties of blackcurrant pomace powders was examined. A relationship was analysed between moisture content, water activity, solubility, true and bulk density, porosity, colour, total polyphenolic compounds, and antioxidant capacity and drying parameters. The lowest water activity was noted after CD suggesting that CD is more effective in water removal from pomace than MVD or CD-MVD. CD decreased solubility of powders to significantly greater degree than MVD and CD-MVD. Drying processes improved the colour of the blackcurrant pomace powders in comparison to the raw material. Power function between the temperature of the process and the changes in chroma was established, whereas a rational function was found during MVD. Functional relation between the temperature and total polyphenolic content and antioxidant capacity was found.