Tray Dryer Research Articles

Osmo hydrocolloid assisted dehydration of onion slices: Effect on Bioactive Components, Rehydration, Microstructure

The present study aimed to develop pretreatments and dehydration strategies for onions to retain the structure so that improved rehydration could be achieved with better quality attributes and shelf life. Effect of osmotic treatment at NaCl concentrations of 5, 10, 15 and 20 % for the duration of 60, 120, and 180 min and hydrocolloid coating (5, 10, 15 and 20%) on onion slices was studied. Osmotic pretreatments with 10% NaCl for 120 min followed by dipping in 5% gum Arabic solution were found optimum in increasing the total soluble solids content in onion slices for further effective dehydration. The pretreated onions were dried at temperatures of 50, 60, and 70°C using a tray dryer (air velocity of ∼1.5 m/s), drying kinetics and dried onion quality were evaluated. The results revealed that osmotic pretreatment and higher drying temperatures significantly increased the drying rate and decreased drying time for onion slices. However, the drying temperature of 60°C was optimum for reducing the drying time with better retention of ascorbic acid (62%), and pyruvic acid (77%) with a nearly 2-fold increase in total phenolics and total flavonoids compared to fresh onions. A positive change in color attributes and rehydration ratio was observed for osmo-hydrocolloid-treated and dried onion slices. Scanning electron microscopic images of fresh onion slices showed elongated well-arranged cells whereas in dried onions, cell walls were disrupted due to the sudden expulsion of moisture from the onion cells. The microstructure of osmo-hydrocolloid pretreated and dried onion cells showed less structural damage due to the protective effect of hydrocolloid coating and an increase in the solid content during osmotic treatment. Prospects of the current research could focus on exploring different hydrocolloids with innovative drying techniques to further enhance the nutritional and structural retention in dehydrated onions and the potential application of these strategies to other vegetables.

Characterization and evaluation of a tray dryer with change of position: kinetics and thermodynamic properties of the process, preserving the nutraceutical properties in Golden Delicious apple slices.

The drying kinetics in apple slices between 45–55 °C was studied until reach a moisture ratio of 10±2%. 8 thin layer drying models were statistically fitted where the Midilli-Kucuk model presented the best performance, moreover its drying constant increased with the temperature, effective diffusivity was ranged from 68.16 E-10 – 2.28 E-08 m2 s-1, the Arrhenius factor and activation energy were 3.74 E-02 m2 s-1 and 28.11 kJ mol-1, the enthalpy decreased from 25.46–25.38 kJ mol-1, the entropy was ranged between (-0.2728 – -0.2730) kJ mol-1 K-1, and the Gibbs free energy increased from 112.25–114.98 kJ mol-1. The 45 °C treatment preserved the highest phenolic compounds (51.1±1.54 mg EAG 100 g-1), while the initial activity of elimination of radicals was 766.9±91.4 and 973.3±103.4 µg mg-1 according to the DPPH and ABTS methods, the antioxidant activity shows an inverse behavior to the drying temperature. This work will allow to establish the temperature, time, moisture ratio and energy to drying apple slices according to local weather or under controlled conditions.

Analysis of the influence of different drying processes on the quality attributes of orange peel

The present research aimed to assess the effect of different drying processes on kinetics, antioxidant content and activity, texture, colour, morphology, and β-carotene content of orange peel (OP). The utilization of microwave drying resulted in a notable increase in the rate of evaporation of water present in the orange peel. This process facilitated the release of bound polyphenols. The OP dried at 600 W exhibited the highest total phenolic compound (24.65 mg GAE/g) and total flavonoid compound (11.73 mg QE/g), as observed in the recorded data. The total antioxidant value exhibited a decrease at both elevated and reduced levels of microwave power compared to raw OP. The study found that the drying model proposed by the Weibull model exhibited the most optimal fit, as evidenced by a low SSerror (1.6 × 10−3-16.12 × 10−3), RMSE (0.02–0.05) and high R2 (0.99–1.00). Among dried products, high hardness (30.92 ± 1.26 N), fracturability (28.31 ± 1.22 N), and lightness (74.01 ± 0.38) were observed in freeze-dried (FD) OP. The browning index was high in microwave drying at 180 W (MWD 180 W), and tray drying (TD) which also produced more vibrant colours, as observed in their high chroma value. The high performance liquid chromatography (HPLC) showed that the retention of β-carotene was observed highest in FD (0.057 ± 0.003 mg/g) and lowest in TD (0.032 ± 0.002 mg/g). The morphological study revealed small-sized particles in high-temperature drying methods (MWD 900 W and TD). Large pores and frequent cracking were observed in microwave drying compared to FD. Four clusters are formed in Principal component analysis (PCA) loading of Fourier transform infrared (FTIR) spectra based on their similar characteristics as found in FTIR. Antioxidant content and texture are closely related to the chemical moieties, as observed in PCA.

Effect of Different Pretreatments on Drying Characteristics and Physicochemical Properties of Apricot (Prunus armeniaca L.)

ABSTRACTIn this study, apricot samples were dried by using different drying methods (tray drying, microwave drying, and freeze drying). Moreover, different pretreatments (infrared, ultrasound, and treatment with dipping green tea extract) were also applied to the samples. The effect of process conditions on physical and chemical quality of dried apricot samples were investigated. It was aimed to come of age of these technologies as an alternative to conventional pretreatments. Among all drying techniques, the shortest processing time was achieved by microwave drying at 270 W. Midilli was found to be the best model that fits the moisture ratio values among 10 thin layer models. Freeze dried samples had the lowest water activity which ranged from 0.2260 to 0.4868 and rehydration capacity of dried samples were found to be between 2.40 and 3.09. Besides, it was found that the total phenolic content of dried apricots varied between 99.24 and 512.60 mg GAE/100 g dry matter. In addition, the maximum antioxidant activity values for microwave drying (270 W) were obtained in the green tea extract pretreated samples and calculated to be 1.85 ± 0.01 mg TE/g dry matter. NMR and SEM analysis were also applied to the samples. To sum up, it can be declared that microwave technology and green tea extract pretreatments were superior and had beneficial impacts on the end product's quality.

Influence of drying method on the shelf life of artisanal pasta

Efforts to optimize pasta drying often face challenges due to the complexity of operational variables. This study aimed to optimize conventional fixed-bed convective drying of artisanal pasta using a desirability function approach and assess the influence of drying methods on shelf life. Three methods were compared: optimized conventional fixed-bed convective drying (O-CFBCD), hot air microwave drying (HAMD), and convective tray drying (CTD). This study underscores the importance of exploring and regulating pasta quality parameters to meet both industry standards and consumer preferences for marketable products with sensory appeal. While all three drying methods show promise for producing quality pasta, there is a need for improved initial moisture control, particularly in the CTD condition, to ensure compliance with regulatory standards and mitigate microbiological risks associated with high water content. Over time, most sensory parameters exhibited enhancement, aligning with consumer expectations for high-quality products. This suggests that continuous monitoring and optimization of drying processes are essential for maintaining and improving pasta quality throughout its shelf life.

A Comprehensive Review on the Advantages and Applications of Fluidized Bed Dryer: From Lab scale to Industrial scale

This article also discusses the demonstration of a fluidized bed dryer, its principles, application, and other processing. This has led to the development of technology, processes, and equipment that not only reduce time but also increase output. A fluidized bed dryer significantly reduces drying time compared with a vacuum dryer or tray dryer. In the pharmaceutical industry, fluidized bed dryers are typically used for pellet drying, coating, andgranulation. Fluidized bed drying is very well known to yield high heat and mass transfer and is hence adopted in many industrial drying processes, particularly pharmacy products. In this paper, we show the construction and working of the fluidized bed dryer. It works on the drying principle. It has several advantages and disadvantages.

Effect of drying techniques, conditions and feed types on the quality of dried curry leaf powder

Curry leaf (Murraya koenigii L.) is valued for its characteristic flavor and is used in varied cuisines and formulations. In this work, the effect of three different drying techniques: tray drying (TD), conductive hydro drying (CHD), and freeze drying (FD), at varying temperatures (40 °C, 60 °C, 80 °C) on the phytochemical and physical properties of curry leaf dried as leaf or as pulp was evaluated. Drying behavior was studied using the Page model and effective diffusivity was found to increase with temperature. CHD at 40 °C resulted in the lowest moisture content (4.98 ± 0.03 %) while FD resulted in the lowest water activity (0.54 ± 0.04). Excellent flow properties were observed in TD 60 °C and CHD 80 °C. However, CHD at 40 °C exhibited superior color retention. TD 80 °C and CHD 80 °C, with reduced drying duration resulted in higher phenolics, flavonoids and alkaloid contents. On the contrary, CHD 40 °C sample showed better antioxidant activity and flavor retention through GC–MS. Similarly, SEM analysis showed intact cell structures in samples dried at lower temperatures. Overall, considering drying time, product quality, and process costs, CHD, often regarded as a nonthermal approach, is an excellent approach for the production of curry leaf powder.

Analisis Studi Kelayakan Usaha Briket Limbah Tongkol Jagung

The use of energy resources that are not environmentally friendly is a problem in Indonesia today. Briquettes are also the primary material because they are abundant, and the primary material has yet to be optimally utilized, including corn cobs. The purpose of this study is to analyze the economic feasibility of corn cob waste briquettes in this study using data analysis of technological technical aspects, financial feasibility analysis such as Payback Period (PP), Net Present Value (NPV), Internal Rate of Return (IRR) and Benefit and Cost Ratio (B/C). The results showed that it takes 19,800 kg of corn cobs to produce charcoal, as much as 3,168 kg and 158.4 kg with tapioca starch adhesive material, as much as 5% of the total weight of charcoal powder, requiring four pieces of equipment, namely pyrolyzer machines, Hammer mills, Planetary mixers, and Tray dryers. Furthermore, the feasibility analysis of this corn cob briquette business was declared feasible with the four categories: Payback Period (PP) for 3.1319 years, Net Present Value (NPV) of Rp 28,129,336,212; IRR of 17.77%, and Net B/C of 1.55. The corn cob briquette agro-industry will remain profitable even if the production capacity decreases by 28% from the original capacity. The agro-industry can also still operate despite an 8% decrease in the selling price of briquettes and will remain profitable if raw materials increase by 17%.

Optimization of process parameter and quality evaluation of tray dried bori: A traditional Indian nugget

The effects of moisture content of batter, air integration in batter, and temperature of tray dryer were studied on hardness, whiteness index, water absorption capacity, and oil uptake ratio of black gram nugget (bori), and it was optimized using response surface methodology. The optimized conditions were: moisture content 67.01 %, air incorporation 21.68 % (v/v) of batter and 60 °C temperature required to attain maximum whiteness index of 81.21, water absorption capacity 41.86 ml/min, minimum hardness value 44.59 N and oil uptake ratio 14 % of nuggets. Optimized black gram nuggets' carbohydrate, protein, fat, and ash contents were 65.49 %, 25.70 %, 1.45 %, and 1.87 %. HPLC analysis showed the presence of different antioxidants in it. The optimized black gram nuggets' color, texture, porosity, and diameter changes during cooking indicated good quality.

Effect of Drying Methods and Temperature on Physical Properties of Spine Gourd (Momordica dioica Roxb.)

The present investigation entitled “Effect of Drying Method and Temperature on Physical Properties of Spine Gourd (Momordica dioica Roxb.)” was conducted at the Post Harvest Technology Laboratory, Department of Horticulture, Rajasthan College of Agriculture and Department of Processing and Food Engineering, College of Technology and Engineering, MPUAT, Udaipur, Rajasthan during August to December, 2023. The study consisted of 4 different drying methods (sun drying, tray drying, heat pump drying and fluidized bed drying), pretreatment (water blanching) and different temperatures (50°C, 60°C and 70°C). The experimental design used for this study was completely randomized design with three replications. The various physical observations were also recorded after drying. Among different types of drying methods and temperatures, water blanched and dried at 60°C tray dryer was found best with maximum dehydration ratio (0.174) and recovery % (17.43).

Non-Invasive, Continuous, Quantitative Detection of Solvent Content in Vacuum Tray Drying

A non-invasive capacitance instrument was embedded in the base of a vacuum-drying tray to monitor continuously the residual amount of solvent left in a pharmaceutical powder. Proof of concept was validated with Microcrystalline Cellulose laced with water, as well as water/acetone mixtures absorbed in a spray-dried Copovidone powder. To illustrate the role of impermeability of the base, we derive a model of vapor sorption that reveals the existence of a kinetic limit when solids are thinly spread, and a diffusion limit with greatly diminished effective diffusivity at large powder thickness. By monitoring the residual solvent content of powders, this new in situ technique offers advantages over indirect methods like mass spectrometry of vapor effluents, but without complications associated with probe fouling. To prescribe design guidelines and interpret signals, we model the electric field shed by the probe when a powder holds variable solvent mass fraction in the vertical direction.Graphical abstract

Evaluation of energy efficiency and quality parameters by drying beets with a refractive window (Betavulgaris)

This study evaluated the energy efficiency associated with drying by refractance window™ and its effect on the physical and chemical properties of beetroot in two different physical states, in semisolid (puree type) and solid (slices) were compared. The refractance window™ drier was compared to a tray dryer at 70 °C on the food surface. The drying time was calculated through the kinetics in both dryers in both physical states of the beetroot determining the moisture content at the beginning and the end of the drying process after which water activity and color retention were determined. Total polyphenol and flavonoid contents respectively, and antioxidant activity were evaluated. Overall energetic efficiency for both dryers was calculated. The beetroot dried in semisolid state using the refractance window™ technology retained color and showed no differences when compared with fresh beetroot. No significant differences in total polyphenol content and total flavonoid content when compared with the fresh sample after application of the refractance window™ were found. The overall energetic efficiency was higher after using refractance window™ drying in beetroot in the two physical states and produced greater retention of quality parameters when compared with the tray dryer.

Optimization of Dehumidification Air Flow Distribution in Temulawak Tray Dryer with Computational Fluid Dynamics

Optimization of Dehumidification Air Flow Distribution in Temulawak Tray Dryer with Computational Fluid Dynamics

Heat transfer simulation for re-design of tray dryer to reduce the energy consumption in the cocoa bean drying process

Abstract The tray dryer for the cocoa bean drying process is a solution to overcome conventional drying methods that rely on solar heat. The tray dryer is expected to facilitate the cocoa farmers to dry cocoa beans because it is faster and does not depend on weather conditions. However, even though the current condition of the tray dryer can reduce the energy consumption of drying cocoa beans (from Gunung Kidul, Yogyakarta, Indonesia) compared to the solar heat method, it remains unknown whether the cocoa beans drying quality is good enough. Therefore, this research analyzed the heat transfer phenomena of the cocoa drying process using the computational simulation method to re-design the current tray dryer design so that the new design can fit the drying characteristic of the cocoa bean and reduce energy consumption. As a result, for the air velocity of 25.91 m/s and the ½ opening of the gas valve in 10 minutes, which is already at steady-state conditions, the temperature distribution in the existing tray dryer is not suitable with the characteristics of the cocoa beans drying process. The temperature can be increased by reducing the airflow velocity or increasing the heating value by opening the valve. However, with a new design, the temperature can be increased by up to 37.00% at a velocity of 25.91 m/s with a ½ gas valve opening. Furthermore, the new design can achieve the same conditions as the existing design by only using an opening for a 1/8 gas valve. Thus, using the new design, the tray dryer can achieve the drying characteristics of cocoa beans and reduce energy consumption.

Osmotic assisted convective drying of pomegranate arils: Process optimisation, structural characterisation, and bioactive compound evaluation

Convective drying of pomegranate arils is time-consuming, energy-intensive, and affects the quality. Osmotic pre-treatment has been resorted prior to convective drying to improve drying performance and quality. In the present work, the osmosis factors such as temperature (30 - 60°C), time (50 - 250 min), and total soluble solids (TSS) (40 - 60°B) were studied using Box-Behnken design of response surface methodology. The quadratic models obtained adequately explained the process, and the optimum conditions were temperature (48.52°C), time (209.65 min), and TSS (51.31°B). The osmotic pre-treatment at optimum conditions followed by the convective tray drying reduced the drying time by nine hours, and the mean energy consumption by 0.172 MJ/g. Light microscopy revealed rupture and breakage of the honeycomb-like cellular structure of the pomegranate aril. Quality analysis of dried arils revealed that the texture (softness) and TSS improved by 11.75 N and 4.2°B, respectively. Likewise, sensorial quality parameters such as taste, mouth feel, and overall acceptability of the OATD (osmo-assisted tray-dried) arils significantly improved over the TD (tray-dried). However, there was a minor higher loss of 15.48, 12.52, and 15.88% in anthocyanin, phenols, and antioxidant capacity in OATD compared to TD. The OATD arils can be stored for up to six months in a modified atmosphere package (MAP).

Studies on Different Drying Techniques to Utilized it for Powder Properties for Dried Dill (Anethum graveolens)

Fresh dill (Anethum graveolens) was dried using a recirculating tray dryer (RTD) and cross flow dryer (CFD) at 35°C, 40°C and 45°C, respectively to determine the best drying treatment and temperature combination for the preparation of dried dill powder. The dried dill was subjected to a grinding process to obtain powder, its engineering properties and techno-functional properties were analysed. The dill powder displayed significant differences in techno-functional properties and engineering properties. The dill dried at 40°C using CFDT2 resulted in better technofunctional and engineering properties as bulk density - 114.4 kg/m3, tap density - 130.6 kg/m3, Carr Index - 12.40, Hausner Ratio - 1.141, swelling power - 0.29, dispersibility - 27.72, water holding capacity - 14.83, oil holding capacity - 35.65, foaming Capacity - 34.97, foam stability - 1.96, emulsion capacity - 55.14, water solubility index – 0.23 and water absorption index – 0.14, respectively. Compared to samples of RTDT1 (35°C), RTDT2 (40°C) RTDT3 (45°C), the samples CFDT1, and CFDT3 findings showed increasing and decreasing trends which kept on changing with drying technique and temperatures. However, it can be concluded that CFDT2 found better results compared to other samples.

Evaluation of Different Drying Methods and Leaf Age on the Retention of Phytochemical and Nutritional Attributes of Moringa Leaf Powder

Moringa (Moringa oleifera), indigenous to India and Africa, is esteemed for its dual utility as a minor timber source and, more importantly, as a vegetable crop. The leaves of the moringa tree are exceptionally nutrient-dense, containing essential elements such as iron, calcium, proteins, vitamins A, C, and E, dietary fiber, phosphorus, and potassium, all vital for human health. Furthermore, these leaves are rich in antioxidants, including flavonoids and phenolics, which endow them with significant medicinal properties. Despite its sporadic cultivation hindering global availability, the production of moringa leaf powder presents a viable strategy to bolster its international export potential. This study aims to assess the efficacy of various drying techniques in producing moringa leaf powder while preserving its nutritional integrity. Conducted at the Post-Harvest Technology Laboratory within the Department of Horticulture, Rajasthan College of Agriculture, and the Department of Processing and Food Engineering, College of Technology and Agricultural Engineering at Maharana Pratap University of Agriculture and Technology, Udaipur, Rajasthan, India, this research evaluates the nutritional quality of moringa leaf powder produced via different drying methods and from leaves of varying ages. Our findings indicate that the fluidized bed dryer excels in preserving the nutritional quality of the powder compared to tray and heat pump dryers. Additionally, the study concludes that heat pump dryers are unsuitable for producing high-quality moringa leaf powder.

Effect of Different Drying Techniques on Quality Attributes of Ready to Reconstitute (RTR) Coffee Mix

Coffee is one of the most ubiquitous and culturally significant beverages worldwide, transcending borders and influencing societies in myriad ways. Ready-to-reconstitute (RTR) coffee, often referred to as instant coffee, occupies a unique and significant niche in the global coffee market. In the present study, A mixture of Arabica to Robusta coffee beans in the ratio of 70:30 was found most suitable for manufacture of ready to reconstitute coffee mix. The concentrated coffee decoction prepared using this mixture is to be blended with concentrated milk (30%TS) in the ratio of 1:5 and dried using vacuum tray dryer, tray dryer and freeze dryer. The coffee mix is vacuum-dried at 30 to 45 degrees Celsius with a vacuum of 600 to 650 mm of Hg, gives better quality of dried product. The optimized final product has better rheological and physico chemical characteristics. In present study found that ready to reconstitute coffee mix has solubility in hot water 26.4 seconds and 2.74 minutes in cold water at 16◦C. The freeze-dried coffee mix powder exhibited reduced flowability 42.08 seconds compare to vacuum try dried and tray-dried coffee mix power that was 47.41 and 46.27 seconds respectively. Same as bulk density of freeze-dried powder (0.64 g/cm3) found lowest compare to vacuum tray dried (0.78 g/cm3) and tray dried (0.82 g/cm3) coffee mix powder.

Drying effects on physicochemical and functional properties of cuttlefish (Sepia officinalis) ink powder

This study investigated the physicochemical, functional, and organoleptic properties of cuttlefish (Sepia officinalis) ink powder prepared by freeze drying and hot air tray drying. Key proximate and physicochemical properties were measured to assess differences due to drying method. In addition, organoleptic tests were conducted on cuttlefish ink powder incorporated into spaghetti sauce. Freeze-dried powders had slightly higher moisture (9.86 %) than tray-dried powders (7.65 %) and more ash (15.04 versus 13.19 %). Both samples had ∼43 % protein, a light-brown to black color and a pH of 5.5–5.6 when rehydrated. There were no differences in loose or tapped density and Hausner ratios of 1.30–1.35 suggest the powders had ‘passable’ flow. Overall protein solubility varied with pH and freeze-dried materials generally had greater solubility. FT-IR showed no differences in peaks derived from organic components. FE-SEM showed both samples had spherical granules that formed 100–200 nm clusters; however, the surface texture of tray-dried powders was rougher than the freeze-dried samples. Consumer tests showed higher overall likability for spaghetti sauce with fresh ink compared to dried ink powders. Differences were attributed more to texture than to flavor or appearance. Cuttlefish ink can be utilized in the food industry, particularly as a natural flavor, food coloring or additive.

Comprehensive study on potato drying in convective air dryer: experimental observations, mathematical modeling, and model validation

We studied the drying kinetics of sliced potatoes (Solanum tuberosum) using a tray dryer. An experiment was conducted on how the drying rate was impacted by air temperature, sample thickness, and air velocity. The study was conducted under varying temperature ranges (50°C, 60°C, and 70°C), air velocities (0.6 ms−1, 0.7 m s−1, and 0.8 m s−1), and potato slice thickness (2 mm, 4 mm, and 6 mm). The findings revealed that a higher air temperature was correlated with an increase in the drying rate, while thicker layers demonstrated a decrease in the drying rate. We further evaluated five mathematical models, with the Page Model emerging as the most suitable based on the lowest residual standard error (RSE) and Akaike's Information Criteria (AIC), which are 0.06421 and -1123.947, respectively. After plotting the predicted moisture ratio against the experimental moisture ratio, we observed an exceptional predictive accuracy (R2 > 0.99) across various conditions. These findings underscore the critical importance of precise parameter control for optimizing potato drying processes in industrial settings, providing valuable insights for enhanced efficiency and resource utilization. Further exploration into real-time optimization and scalability can extend the practical applications of this study.