Ginger Slices Research Articles

Dehydration of infrared ginger slices: heat and mass transfer coefficient and modeling

ABSTRACT Dehydration of plant products extends its shelf life and reduces its mass and volume, which increases transport and storage efficiency and adds value to food. However, it is an intensive process in energy and time, making necessary the search for more efficient technologies, Thus, this study aimed to investigate the infrared ginger dehydration process by approaching the constant period of dehydration to the theory of mass and heat transfer process to the wet bulb thermometer and the decreasing period of dehydration to liquid diffusion theory. We submitted 5.0 mm thickness and 2.0 cm diameter slices to a dryer with infrared radiation at 50, 60, 70, 80, 90 and 100 °C until constant mass. Heat and mass transfer coefficients, and effective diffusion coefficient increased linearly with temperature increasing, resulting in values ranging from 69.40 to 92.23 W m-2 °C-1, 0.062 to 0.089 m s-1 and 3.81 x 10-9 to 1.13 x 10-8 m2 s-1. Variation of heat and mass transfer coefficients was described by a linear model and the variation of effective diffusion coefficient with the temperature was described with the Arrhenius relation, whose activation energy was 22.07 kJ mol-1. The modified Henderson and Pabis model was able to satisfactorily describe the period of decreasing drying rate.

MATHEMATICAL MODELS TO DETERMINE OF THIN LAYER DRYING KINETIC OF GINGER SLICES

In the present work, the effects of some parametric values on the thin layer drying process of ginger slices were investigated. Drying was done in the laboratory by using cyclone type convective dryer. The drying air temperature was varied as 40, 50, 60 and 70 ˚C and the air velocity is 0.8, 1.5 and 3 m/s. All drying experiments had only falling rate period. The drying data were fitted to the twelve mathematical models and performance of these models was investigated by comparing the determination of coefficient (R2), reduced chi-square (χ2) and root mean square error (RMSE) between the observed and predicted moisture ratios. Among these models, drying model developed by Midilli and Kucuk model showed good agreement with the data obtained from the experiments.

High pressure assisted osmotic dehydrated ginger slices

Experiments were conducted to investigate osmotic dehydration of ginger slices suspended in three different osmotic agents at 0.1–600 MPa and 40 °C for various pressure holding times. A Weibull distribution mathematical model was employed to predict the kinetics of moisture and solute transport during osmotic dehydration of ginger. Increased process pressure accelerated the water loss and solid gain and removed significant amount of water within a shorter time period. The effective moisture diffusivity values for glucose, fructose, and sucrose at 0.1 MPa and 40 °C were 0.322 × 10−9, 0.362 × 10−9 and 0.396 × 10−9 m2/s respectively. Pressure treatment at 600 MPa increased these values by approximately by 11–12 folds (3.725 × 10−9, 4.027 × 10−9 and 4.293 × 10−9 m2/s respectively). Among the osmotic agents tested, solute diffusivity was maximum in glucose followed by fructose and sucrose, whereas the moisture diffusivity was greatest in sucrose and lowest in glucose.

Electrohydrodynamic (edh) drying of ginger slices (zingiber officinale)

Electrohydrodynamic (EHD) flow or ion wind of corona discharges has been generated utilizing pin-multi ring concentred electrodes. The pin was made of stainless steel with a tip diameter of 0.018 mm. The multi-ring constructed electrodes by a metal material connected to each other and each ring has a diameter of 24 mm, 16 mm and 8 mm in the same width and thickness is 4 mm and 1 mm. EHD was generated by using a DC high voltage of 5 kV. Pin as an active electrode of corona discharge and multi-ring concentric electrodes as a collector and passive electrodes. The ion wind or EHD flow is produced through changes in voltage and distance between electrodes. The ionic wind generated system outputs through multi-ring concentric electrodes which will further dry the sample. A circle ginger slices as a sample with a diameter of 26 mm with a thickness of 2 mm. The drying is done at the distance between the fixed electrodes of 4 mm and the varied voltages are 1.2 kV, 1.4 kV, and 1.6 kV. The sample drying time varied 30 minutes, 60 minutes, 90 minutes, 120 minutes and 150 minutes. The result of drying the sample at a fixed voltage is obtained moisture of ginger slices decreased with increased drying time.

Ion wind generation and its application to drying of wild Ginger slices (Curcuma Xanthorhiza)

Temulawak or wild ginger is a herbal medicinal derived from lndonesia original. Wild ginger contains include an active compound as curcuminoid and antioxidant oleoresin components having a special quality to take care of health from various diseases. Drying is the important process to produce wild ginger (Curcuma xanthorrhiza) simplicia as raw material herbal medicine. In this study, has been dried of wild ginger using ion wind which yielded from corona discharge utilizing pin-multi ring concentred electrodes. Corona discharge was generated by using the fixed DC high voltage of 4,3 kV and drying was done at the distance between the fixed electrodes of 4 mm. Shaped of the five temulawak slices is a circle with a thickness of 2 mm and the diameter of 10 mm - 30 mm with 5 mm diameter interval. The sliced temulawak is placed just below the concentric multi-ring electrode and is 2 mm in distance. The wild ginger slices were dried with time varied 5-65 minutes with time interval 5 minutes. The researched result of drying of wild ginger slices obtained drying rate and shrinkage is inversely proportional to drying time.

Pulsed vacuum drying of Chinese ginger (Zingiber officinale Roscoe) slices: Effects on drying characteristics, rehydration ratio, water holding capacity, and microstructure

ABSTRACTEffects of vacuum pressure duration (t-VPD of 5, 10, 15, and 20 min), ambient pressure duration (t-APD of 3, 5, 7, and 9 min), drying temperature (60, 65, 70, and 75°C), and slice thickness (3, 5, 7, and 9 mm) on drying kinetics, rehydration ratio (RR), water holding capacity (WHC), and microstructure of Chinese ginger were investigated using a pulsed vacuum dryer. Various parameters affecting drying rate significantly of ginger slices except t-APD, and the shortest drying time of 300 min was obtained when the t-VPD, drying temperature, and slice thickness were 10 min, 70°C, and 3 mm, respectively. Weibull model fitted the experimental results better (R2 > 0.99) than first-order model. RR was increased with increasing of t-VPD while it was decreased with increasing of temperature, and a decreased trend of WHC was observed with increasing temperature or t-VPD. Microstructure observation indicated that increased t-VPD resulted in larger tunnel structure, and high temperature caused the formation of rigid structure, which well explained the changes of RR and WHC of dried ginger. The findings in current work contribute to good understanding of the pulsed vacuum drying behavior and quality of ginger.

Mathematical modeling of infrared assisted hot air drying of ginger slices

Infra-red assisted hot air drying studies were conducted on ginger slices of diameter 20±2.5 mm and thickness 5±0.5 mm. Drying experiments were executed under infra-red and hot air temperature of 60°C with two levels of air velocities: 0.8 m/s and 1.4 m/s. the drying rate was found to increase proportionately with the drying air velocity, thereby minimising the total drying time. Time taken for drying ginger slices from an initial moisture content of 442 per cent (d.b.) to a final moisture content of 8.4 per cent (d.b.) at 0.8 m/s air velocity was 300 min. Whereas, it took 210 min to lower the moisture content of ginger from 433.33 per cent (d.b.) to 6.67% (d.b.) under the drying air velocity of 1.4 m/s. Infrared drying temperature of 60°C in combination with air velocity of 0.8 m/s showed better results for quality evaluation with reduced drying times. Logarithmic model fitted the experimental data well for the whole range of temperatures (R 2 = 0.9989, RMSE= 0.0119 and λ 2 = 0.000140574).

Simulation and validation of a suitable model for thin layer drying of ginger rhizomes in an induced draft dryer

ABSTRACTVariation in drying material and their biological differences, coupled with heat supply method in different dryers, makes mathematical modeling of drying complicated. Attempt was made to simulate a drying process and to identify best suitable model out of six selected drying models, for drying of ginger slices in a solar-biomass integrated drying system designed and developed for spice drying. Moisture content data were converted into the moisture ratio (MR) expressions and curve fitting with drying time for the selected drying models was analyzed. Sigma Plot software was used for nonlinear regression to the data obtained during drying and for modeling of drying curves. The suitability of the models was evaluated in terms of statistical parameters such as coefficient of determination (R2), mean percentage error (P), and standard error estimate. Drying air temperature was in the range of 47–55°C and air velocity was between 1.0 and 1.3 m s−1. Ginger slices were dried from 88.13% to 7.65 ± 0.65% (wb) in 16 h. Trays were interchanged in a predetermined matrix sequence from 4 h onwards when moisture content was reduced to 60–70% (wb), for uniformity in drying. Highest value of R2 (0.997), lowest value of SEE (0.020), and P value < 0.0001 established Page model as the best suitable model for the developed drying system. The predicted MRs were in good agreement with the experimental values and the effective moisture diffusivity for ginger was found to be 2.97 × 10–7 m2 s−1.

Drying characteristics of ginger slices using different drying methods and pretreatments

Drying is an essential process in the preservation of agricultural products. Various drying methods are employed to dry different agricultural products. Each method has its own advantages and limitations. Choosing the right drying system is thus important in the process of drying agricultural products. Care must be taken in choosing the drying system. Study comparing traditional drying and other drying methods for the reduction of the drying time and to a significant improvement of the product quality in terms of color texture and taste. Drying reduces the possibilities of the contamination by insects and micro organisms so that product is prevented. An experimental study was performed to determine the drying characteristics of ginger slices subjected to drying in open sun, microwave oven at 60 watt and cabinet tray dryer at 500 C, 600 C and 700 C with pre-treatment indicated that T0 (Control), T1(KMS) and T2 (NaHSO4). The entire drying process took place in the falling rate period. Drying curves were constructed using non-dimensional moisture ratio (MR) and time. Drying is the most widely used and a primary method for preservation. The result indicated that the cabinet tray dryer at 600C was found better quality compare to other drying methods and microwave oven at 60 watt resulted very less time to dry the samples.

Quality and shelf-life of ready to use brined ginger (Zingiber officinale Rosc.) slices

Ginger ( Zingiber officinale Rosc.) is one of the widely grown commercially important spices of North East India. Storage of fresh ginger for more than one month is problematic due to severe weight loss and sprouting. The present study was conducted to preserve the peeled ginger slices in acidified brine solution in plastic containers at ambient condition. The ginger rhizomes of Bhola variety harvested at 270 days after planting was found better for preservation of ginger slices of 1.5-2.0 mm thickness in brine. The ginger slices treated with 9 per cent brined solution acidified with 2 per cent citric acid and potassium metabisulphite and benzoic acid 50 ppm each as preservative resulted in better retention of biochemical qualities like crude protein (5.67%), total soluble carbohydrate (12.89%), oleoresin (4.17%) with better organoleptic qualities and no microbial growth after 180 days of storage. The ginger slices could be safely stored up to 180 days. The brined ginger slices may serve as substitute for fresh ginger during the lean period.

EFFECT OF HOT DRYING ON THE CHEMICAL CONTENT AND COLOUR SENSORY QUALITY OF GINGER POWDER (ZINGIBER OFFICINALE

The main objective of this study was to investigate the effect of different temperature of hot air drying on the qualities of ginger powder included chemical content, colour parameters and colour sensory quality. The drying experiments were carried out at four air temperature of 50, 60, 70 and 80oC. The colour parameters for colour change of the materials were quantified by the Hunter L (whiteness/darkness), a (redness/greenness) and b (yellowness/blueness) system. These values were also used for calculation of total change (DE). A consumer preference test was conducted with 80 consumers to assess the colour quality of 04 ginger powders. The results showed that the decreasing of essential oils content at low drying temperature is higher than at high temperature. While the fats content was significantly decreased during drying at high temperature as compared with low temperature due to oxidation process of fat occurring at high temperature. The ginger powder was dried at high temperature showed a highly reduced content of protein and carbohydrate. Least Squares regression was used to determine the relationship between colour sensory scores of consumer taster and quantification of three Hunter parameters. In that, variable “L” and “b” could be distributed to increasing while variable “a” contributory decrease the colour quality of ginger powder products. The zero-order, first-order and quadratic models were used to explain the colour change kinietics during hot drying ginger slices at 50oC and it was observed that L, b and a were fitted to quadratic model.

Study of the drying process of ginger (Zingiber officinale Roscoe) slices in microwave fluidized bed dryer

ABSTRACTTo research about the temperature and moisture characteristics of ginger slices in microwave fluidized bed drying (MFD), some microwave drying experiments in different powers and hot-air drying experiment were used, and the drying quality and moisture drying curves were studied in contrast, finding MFD with advantages such as good quality and high efficiency. In order to understand the water flow characteristics of ginger slices in MFD, low nuclear magnetic resonance was used to detect the materials in different drying stages, and it was found that free water (FW), immobilized water (IW), and bond water (BW) could be converted to the other forms, especially the form that combined with the dry matter is much firmer. FW is the main water state in fresh ginger slices and converts to the IW quickly in the beginning stage, and then both FW and IW decreased until the final stage is reached. Finally, the content of BW increased, and the material can be stored safely. Gingerol is the main flavor component of ginger, and it was detected through LC-20A high-performance liquid chromatography; it was found that the content of 6-gingerol, 8-gingerol, and 10-gingerol increased in various drying processes, especially 10-gingerol that has a positive role to protect the taste of the ginger.

Determination of drying kinetics and convective heat transfer coefficients of ginger slices

In the present work, the effects of some parametric values on convective heat transfer coefficients and the thin layer drying process of ginger slices were investigated. Drying was done in the laboratory by using cyclone type convective dryer. The drying air temperature was varied as 40, 50, 60 and 70 °C and the air velocity is 0.8, 1.5 and 3 m/s. All drying experiments had only falling rate period. The drying data were fitted to the twelve mathematical models and performance of these models was investigated by comparing the determination of coefficient (R2), reduced Chi-square (χ2) and root mean square error between the observed and predicted moisture ratios. The effective moisture diffusivity and activation energy were calculated using an infinite series solution of Fick’s diffusion equation. The average effective moisture diffusivity values and activation energy values varied from 2.807 × 10−10 to 6.977 × 10−10 m2/s and 19.313–22.722 kJ/mol over the drying air temperature and velocity range, respectively. Experimental data was used to evaluate the values of constants in Nusselt number expression by using linear regression analysis and consequently, convective heat transfer coefficients were determined in forced convection mode. Convective heat transfer coefficient of ginger slices showed changes in ranges 0.33–2.11 W/m2 °C.

Survival of Salmonella during Drying of Fresh Ginger Root (Zingiber officinale) and Storage of Ground Ginger

The survival of Salmonella on fresh ginger root (Zingiber officinale) during drying was examined using both a laboratory oven at 51 and 60°C with two different fan settings and a small commercially available food dehydrator. The survival of Salmonella in ground ginger stored at 25 and 37°C at 33% (low) and 97% (high) relative humidity (RH) was also examined. To inoculate ginger, a four-serovar cocktail of Salmonella was collected by harvesting agar lawn cells. For drying experiments, ginger slices (1 ± 0.5 mm thickness) were surface inoculated at a starting level of approximately 9 log CFU/g. Higher temperature (60°C) coupled with a slow fan speed (nonstringent condition) to promote a slower reduction in the water activity (aw) of the ginger resulted in a 3- to 4-log reduction in Salmonella populations in the first 4 to 6 h with an additional 2- to 3-log reduction by 24 h. Higher temperature with a higher fan speed (stringent condition) resulted in significantly less destruction of Salmonella throughout the 24-h period (P < 0.001). Survival appeared related to the rate of reduction in the aw. The aw also influenced Salmonella survival during storage of ground ginger. During storage at 97% RH, the maximum aw values were 0.85 at 25°C and 0.87 at 37°C; Salmonella was no longer detected after 25 and 5 days of storage, respectively, under these conditions. At 33% RH, the aw stabilized to approximately 0.35 at 25°C and 0.31 at 37°C. Salmonella levels remained relatively constant throughout the 365-day and 170-day storage periods for the respective temperatures. These results indicate a relationship between temperature and aw and the survival of Salmonella during both drying and storage of ginger.

MICROWAVE DRYING CHARACTERISTICS FOR GINGER ROOT (Zingiber officinale)

This experiment was carried out at Agricultural Engineering DepartmentMinofiya University to study microwave drying characteristics for ginger root. Five microwave drying powers (180, 360, 540, 720 and 900 Watt) and four levels of ginger thickness (0.5, 1, 1.5 and 2 cm) were used. Drying characteristics and quality aspects of the dried ginger were studied. The drying time to achieve the save storage moisture content was 14 minutes at 900 Watt with 0.5cm thickness. Total phenolic content of fresh ginger was 0.40 mg/g.d.m. and the highest phenol content in dried ginger was detected at the 900 Watt power with 1.5cm thickness, and the lowest phenolic value was recorded at 180 Watt with 2 cm thickness. The fresh ginger hardness ranged from 0.5 to 1 kg /cm2 and the highest hardness of dried ginger was 6 kg /cm2 at both 720 and 900 W with all thickness. The highest drying efficiency of ginger slices was 78% at 720 and 900 Watt with 2 cm thickness and the lowest efficiency (less than 10%) was recorded at 180 Watt with all used thicknesses (except at 2 cm. thickness). The highest value of energy consumption (10.2 MJ) was detected at 180 Watt and 2 cm thickness, while drying at 900 Watt with both 0.5 and 1 cm. thickness represent the lowest energy consumption (1.13 MJ). Veirma model can be used to describe the behavior of microwave drying of ginger, which gave the best results. Key word: microwave, drying, ginger, thickness

Effect of Waste Heat Recovery on Drying Characteristics of Sliced Ginger in a Natural Convection Dryer

In the present work, quality drying characteristics of sliced ginger were studied utilizing the concept of waste heat recovery in a biomass operated natural convection dryer with sensible heat storage material (SHSM) and phase change material (PCM). Ginger slices (2 and 4mm thick) were dried from initial moisture content (MC) 88-90% (w.b.) to final moisture content 11-12% (w.b.) with hot air maintained at temperature 600C, air velocity 0.2m/sec, atmospheric average relative humidity 74% and ambient temperature 250C. It was observed that the biomass consumption and melting time of PCM were significantly reduced due to the use of waste heat. The optimum drying time was found to be 5.5h for 2mm thick ginger slices. Color, texture and aroma were found better in treated sample.

Fluidized bed drying characteristics and modeling of ginger (zingiber officinale) slices

In this study fluidized bed drying characteristics of ginger have been investigated. The effects of the fluidizing air temperature, velocity, humidity and bed height on the drying performance of ginger slices have been found. The experimental moisture loss data of ginger slices has been fitted to the eight thin layer drying models. Two-term model drying model has shown a better fit to the experimental data with R2 of 0.998 as compared to others.

Effects of Pretreatments and Drying Temperatures on Drying Characteristics, Antioxidant Properties and Color of Ginger Slice

To reduce the adverse effects of hot air drying, ginger slices were pretreated prior to drying. The effects of 2 pretreatment methods (blanching versus dipping in 0.1% ascorbic acid solution) and drying temperatures (60, 70 and 80 °C) on the drying characteristics and the qualities of the dried ginger slices in terms of total phenolic content (TPC), antioxidant activities (DPPH and ABTS methods) and color were investigated. It was noted that the moisture content for both un-pretreated and pretreated samples decreased more rapidly when drying was performed at higher drying temperatures. However, the drying time of un-pretreated and pretreated samples was not significantly different. The TPC and antioxidant activities of the ginger slices increased markedly after drying. The increase in these values was higher for pretreated samples. The dried ascorbic acid solution dipped sample exhibited the highest values of TPC and antioxidant activity. Moreover, the total color difference of the ascorbic acid solution dipped ginger was slightly lower than the total color difference of the un-pretreated ginger. However, the tested drying temperatures, ranging from 60 to 80 °C, did not affect the final TPC, antioxidant activities, and color of the ginger samples.

Influence of Drying Conditions on the Effective Moisture Diffusivity and Energy Requirements of Ginger Slices

&lt;p&gt;The thin layer drying behaviour of ginger slices in a laboratory dryer was examined. The slices of 5 mm, 10 mm and 15 mm thicknesses were dried using heated ambient air at temperatures from 40 to 70 ºC and air velocity of 1.5 m/s. The effects of drying air temperature and slice thickness on the drying characteristics, drying time and energy requirement of drying process was determined. The results have shown that an increase in the drying air temperature causes shorter drying times. Thinner slices also causes a shorter drying time. The effective moisture diffusivity values increased from 3.36814 × 10&lt;sup&gt;-10&lt;/sup&gt; m&lt;sup&gt;2&lt;/sup&gt;/s to 5.82524 × 10&lt;sup&gt;-9&lt;/sup&gt; m&lt;sup&gt;2&lt;/sup&gt;/s while the activation energy values for different slice thickness of ginger varied from 196.15 to 198.79 kJ/mol. The total needed energy varied from 735.3 to 868.5 kWh while the value of specific energy requirement varied from 3676.6 to 4342.4 kWh/kg respectively.&lt;/p&gt;

Investigation of Solar Drying of Ginger (Zingiber officinale): Emprical Modelling, Drying Characteristics, and Quality Study

Drying is a simultaneous heat and mass transfer energy intensive operation, widely used as a food preservation technique. In view of improper postharvest methods, energy constraint, and environmental impact of conventional drying methods, solar drying could be a practical, economical, and environmentally reliable alternative. In the present paper applicability of mixed mode solar cabinet dryer was investigated for drying of commercially important and export oriented ginger. Freshly harvested ginger slices were successfully dried from initial moisture content of 621.50 to 12.19% (d.b.) and their drying characteristics, quality parameters, and kinetics were evaluated. The results showed that present solar dryer could be successfully applied for drying of ginger in view of quality, reduced drying time, and zero energy requirement as compared to conventional open sun drying and convective drying techniques, respectively. Drying curves showed that drying occurred in falling rate period and no constant period was observed. The effective moisture diffusivity was determined by using Fick’s second law and found to be 1.789×10-9 m2/s. The drying data was fitted to five thin layer drying models and compared using statistical criteria. Page model was found to be most suitable to describe the drying kinetics of ginger in solar dryer under natural convection among the tested models.