Daniel I. Onwude

Daniel I. Onwude
Empa - Swiss Federal Laboratories for Materials Science and Technology | Empa · Department Materials meet Life

BEng, MSc, PhD (Agricultural Process Engineering)

About

79
Publications
29,387
Reads
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1,669
Citations
Citations since 2017
64 Research Items
1627 Citations
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20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
Introduction
Dr. Onwude is a Lecturer and an academic researcher. He is currently a Scientist at Empa, ETH Zürich. His research focus lies in modeling and simulation of postharvest process systems, heat and mass transfer processes, digital twinning, imaging technology as a non destructive quality determination approach and drying technology.
Additional affiliations
September 2019 - November 2020
Empa - Swiss Federal Laboratories for Materials Science and Technology
Position
  • Researcher
April 2014 - present
University of Uyo
Position
  • Lecturer
Education
April 2016 - July 2018
Universiti Putra Malaysia
Field of study
  • Agricultural Process Engineering

Publications

Publications (79)
Article
Full-text available
Fruits and vegetables are highly nutritious agricultural produce with tremendous human health benefits. They are also highly perishable and as such are easily susceptible to spoilage, leading to a reduction in quality attributes and induced food loss. Cold chain technologies have over the years been employed to reduce the quality loss of fruits and...
Article
Full-text available
Electrohydrodynamic (EHD) drying is a promising technology to better preserve the nutritional content and sensory appeal of dried fruits and vegetables. To successfully scale up this technology, we need to rethink the current EHD dryer designs. There is also a significant potential to further enhance the nutritional content and sensory quality of t...
Article
Full-text available
Electrohydrodynamic (EHD) drying is a novel non-thermal drying method to dry heat-sensitive foods faster and with lower energy. Upscaling EHD drying to dry large amounts of food is the current challenge of this technology. In this regard, we quantify how successful a newly-proposed electrode configuration for EHD dryers is for drying commercial amo...
Article
Full-text available
Drying processes reduce the amount of available essential nutrients in dried plant-based foods to a large extent compared to fresh produce. This reduction is much larger than the differences in the final quality of products dried using various processing parameters and, in most cases, different drying methods. This aspect is, however, rarely highli...
Article
Currently, there are differences in the quality loss between individual fruit upon arrival at retail. These differences in fruit quality stem from pre-harvest biological variability between individual fruit at harvest and postharvest variations in hygrothermal conditions between refrigerated shipments. The impact of these pre-harvest biological and...
Article
Soft fruits like strawberries are highly perishable and susceptible to postharvest decay caused by fungal infestation. Mold growth is favored by elevated temperatures in the cold chain or when water vapor condenses in the packaging induced by temperature fluctuations at high relative humidity. Optimal packaging for these products is required to imp...
Article
Full-text available
In light of increasing public pressure, retailers strive to remove plastic packaging as much as possible from fresh fruits and vegetables to reduce the environmental impacts along their supply chains. Plastic packaging, however, also has an important protective function, similar to the fruit's peel. For cucumbers transported from Spain and sold in...
Article
For better understanding of transport phenomena, local evaporation rate and water vapor concentration should be taken into consideration when predicting drying behavior. However, to the best of our knowledge, there is no model which explicitly represents this. Predictive modeling of combined infrared-heating and hot air drying (IR-HAD) is useful to...
Article
The most essential process of Acanthus ilicifolius L. tea production is drying. The current convective drying method (e.g., hot-air drying) of producing dried A. ilicifolius is inadequate due to its high energy consumption and long drying time, thus leading to undesirable final product quality. The objective of the present work was therefore to eva...
Article
In the postharvest chain of fresh horticultural produce, it is often challenging to quantify how much potential measures improve the supply chain. This study compares and quantifies the impact of the different measures in preserving the quality of fresh produce in the cold chain. We employed physics-based digital twins of fresh produce. This digita...
Article
Controlling the hygrothermal conditions around fresh fruit and vegetables is vital for their preservation. Therefore, cold chain stakeholders often measure temperature along the supply chain of fresh produce. However, the temperature is typically monitored only in one segment of the entire cold chain, namely from the supplier until the distribution...
Chapter
Food grains such as cereals, legumes, and oilseeds are important food crops that contribute to most of the world’s staple food, especially in developing countries. However, up to ~ 70% of food grains produced can be lost during postharvest management activities such as storage, transport, milling, drying, threshing, etc. The current challenge is to...
Article
Full-text available
In this study, a coupled heat and mass transfer model was developed using a finite element (FE) simulation approach to describe solar drying of red chilli integrated with Na2SO4.10H2O as PCM thermal storage. The coupled heat and mass transfer equation solution was achieved by using Comsol multiphysics with 3-D axisymmetric geometry mesh generation....
Article
Full-text available
Electrohydrodynamic drying (EHDD) is an energy-efficient and non-thermal technique for dehydrating heat-sensitive biological materials, like fruits, vegetables, or medicinal plants. However, little is known about the relative contribution of the different dehydration mechanisms in EHDD. An accurate understanding of the impact of the different EHD-d...
Article
Background Evaluation of the quality properties of papaya becomes essential due to the acceleration of the fruit shelf-life senescence and the deterioration factor of the expected postharvest operations. In this study, the colour features in RGB, normalised RGB, HSV and L*a*b* channels were extracted and correlated with mechanical properties, moist...
Article
Full-text available
The world population is predicted to increase from the present 7 [...]
Preprint
In light of increasing public pressure, retailers strive to remove plastic packaging as much as possible from fresh fruits and vegetables to reduce the environmental impacts along their supply chains. Plastic packaging, however, also has an important protective function, similar to the fruit's peel. For cucumbers transported from Spain and sold in...
Article
Full-text available
Fresh agricultural products are very susceptible to physical damage resulted from the mechanical impact during post-harvest operations such as packaging, storing and transporting. Defects produce are prone to cellular damage that can then serve as infection sites for numerous wound pathogens that result in much of the postharvest diseases This pape...
Article
Full-text available
Freezing is a well-established preservation method used to maintain the freshness of perishable food products during storage, transportation and retail distribution; however, food freezing is a complex process involving simultaneous heat and mass transfer and a progression of physical and chemical changes. This could affect the quality of the froze...
Article
Full-text available
In a tropical rainforest environment, different storage strategies are often adopted in the preservation of primary professed food crops, such as maize, sorghum etc.after drying and dehuling to increase the shelf life. For breadfruits seeds, the current challenge is identifying the most appropriate short term storage and packaging method that can r...
Article
Full-text available
This study aims to develop a finite element (FE) model to determine the mechanical responses of Exotica papayas during puncture loads. The FE model of the puncture-test was developed using the ANSYS 19.1 software. The proposed framework combined the finite element method and statistical procedure to validate the simulation with the experimental res...
Article
The discharge of the flue gas is rich in water vapor and its latent heat, which leads to the main heat and moisture loss for the natural gas. In this article, based on the falling film spray technology, a new test rig was set up to test the heat and moisture recovery performance from flue gas. The effects of water-air ratio and inlet air temperatur...
Article
Background Digital twins have advanced fast in various industries, but are just emerging in postharvest supply chains. A digital twin is a virtual representation of a certain product, such as fresh horticultural produce. This twin is linked to the real-world product by sensors supplying data of the environmental conditions near the target fruit or...
Article
This study investigated the effects of ultrasound pretreatments on the drying kinetics of yellow cassava during convective hot air drying. Sliced yellow cassava samples were pretreated using distilled water with ultrasound (DWU) and ultrasound‐assisted osmotic dehydration (ODU) prior to hot air drying. Ultrasound pretreatments were carried out usin...
Preprint
Electrohydrodynamic (EHD) drying is a promising technology to better preserve the nutritional content and sensory appeal of dried fruits and vegetables. To successfully scale up this technology, we need to rethink the current EHD dryer designs. There is also a significant potential to further enhance the nutritional content and sensory quality of t...
Preprint
Background. Digital twins have advanced fast in various industries, but are just emerging in postharvest supply chains. A digital twin is a virtual representation of fresh horticultural produce. This twin is linked to the real-world product by sensors supplying data of the environmental conditions near the target fruit or vegetable. Statistical and...
Article
Full-text available
This study provides an overview of the current energy deficit in Nigeria due to the massive challenges linked to the energy value-chain particularly the generation, distribution and decentralization in Nigeria. The review discusses in detail, the possibility of using alternative resources to increase the usage of clean energy. The resources are rep...
Article
Background Combined infrared and convective drying is a promising technology in dehydrating heat‐sensitive foods, such as fruits and vegetables. This novel thermal drying method, which involves the application of infrared (IR) energy and hot air during a drying process, can drastically enhance energy efficiency and improve overall product quality a...
Article
Full-text available
Non-destructive and laser-based technologies have been explored widely in recent years as a way to monitor fresh produce and crops quality in the agriculture sector. In this study, the effectiveness of laser-induced backscattering imaging (LLBI) was investigated to determine the firmness and colour of cocoa pods at different maturity stages. The LL...
Article
Full-text available
The effects of microwave power (MP, 100–600 W) on the drying kinetics, as well as the physical and antioxidant properties of papaya seeds dried under microwave vacuum drying (MVD) were investigated. The results found that moisture diffusivity increased in the order of 10⁻⁸ with an increase in MP. Shrinkage increased from 1.2 to 4.9% and bulk densit...
Article
Full-text available
The number of impeller slots, slot angle (angulations), and rotational speed are some of the operational parameters that influence kernel yield of centrifugal impact nut shellers. The effects of these three parameters on Bambara nut kernel extraction using a horizontal placed centrifugal Bambara nutcracker with a capacity of 150.6 kg/hr at a speed...
Article
Intermittent infrared and convective drying (IIRCD) is a novel drying method that can enhance energy efficiency and quality of dried product. The mechanism of drying using this method is not yet fully understood. Mathematical models that describe the drying process of IIRCD for agricultural crops do not exist. In this study, a physics based mathema...
Article
Full-text available
This study investigated the drying kinetics, mass and heat transfer characteristics of sweet potato slices (0.4–0.6 cm thickness) during drying based on mid-infrared experimental set-up (intensity of 1100–1400 W/m2). Thin layer drying models were used to evaluate the drying kinetics of sweet potato slices. Two analytical models (Fick’s diffusion mo...
Article
In this study, a numerical model was developed to accurately describe the changes in moisture content and temperature distribution of sweet potato during infrared drying, with the consideration of shrinkage‐dependent diffusivity and evaporation phenomena. The couple heat and mass transfer and 2D axisymmetric simulations were done using COMSOL Multi...
Article
This study examined the performance of different combined infrared (IR) and hot-air drying (HAD) strategies for sweet potato. Experiments were conducted for simultaneous infrared and hot-air drying, two-stage sequential hot-air and infrared drying, two-stage sequential infrared and hot-air drying, and intermittent infrared and hot-air drying in a l...
Article
This study seeks to investigate the potential of using combined computer vision (CV) and laser-induced back-scattering imaging (LLBI) in monitoring the quality attributes of sweet potato during drying. CV and back-scattered images of 4 mm thickness sweet potato slices were captured after every one-hour of drying, at drying temperatures of 50-70 °C....
Article
Commodities originating from tropical and subtropical climes are prone to chilling injury (CI). This injury could affect the quality and marketing potential of mango after harvest. This will later affect the quality of the produce and subsequent consumer acceptance. In this study, the appearance of CI symptoms in mango was evaluated non-destructive...
Article
This study investigated the drying kinetics, specific energy consumption (SEC), color, and microstructural changes of sweet potato (Ipomoea batatas L.) based on experimental set‐up of convective hot‐air drying (CHAD), infrared drying (IRD), and combined infrared and convective‐hot‐air drying (IR‐CHAD). The experiments were carried out at three air...
Chapter
Agricultural production involves almost all aspects of cultivation, harvesting, processing, storage, and transportation of crops, animals, food, and fiber. Agricultural production depends heavily on the availability of agricultural inputs such as labor, water, arable land, and other resources (energy, fertilizer, etc.), which are significantly affect...
Article
This study aims to develop a numerical model to accurately predict moisture content and temperature distribution for sweet potato during combined infrared and hot-air drying (IR-HAD). The coupled heat and mass transfer during drying was simulated considering both temperature and shrinkage dependent diffusivity. The simultaneous heat and mass transf...
Chapter
The energy study is very important for any energy system due to rise in fuel cost, raw materials cost, and higher environmental impact of the energy system. Hence, a study on energy analysis of solar drying system becomes indispensable. In order to highlight the energy requirements of solar drying system, this chapter attempts to show extensive ene...
Article
Fruits and vegetables are very perishable commodities that have enormous industrial and commercial importance. To preserve its quality attributes, increase shelf life, and reduce transport weight, fruit and vegetable can be processed by drying. Over the years, conventional drying techniques have been widely applied, both industrially and commercial...
Article
Background: Drying is a method used to preserve agricultural crops. During the drying of products with high moisture content, structural changes in shape, volume, area, density and porosity occur. This changes could affect the final quality of dried product and also the effective design of drying equipment. Therefore, this study investigated a nov...
Article
Full-text available
Plant diseases can greatly affect the total production of food and agricultural materials, which may lead to high amount of losses in terms of quality, quantity and also in economic sense. To reduce the losses due to plant diseases, early diseases detection either based on a visual inspection or laboratory tests are widely employed. However, these...
Article
The possibility of ultrasound assisted pretreatments of sweet potato to lower the moisture content and oil uptake during deep fat frying and its effects on the mass transfer rate was investigated. Sweet potato samples prior to frying were immersed in distilled water with ultrasound (UD), osmotic dehydration without ultrasound (OD) and ultrasound as...
Article
Frying is one of the methods of processing foods, which imparts flavour, taste, colour and crispness in the fried foods. In spite an increase in the demand for fried foods by consumers all over the world, the danger posed by consuming too much fat is still a challenge. Many researchers have come up with many ideas on how to reduce the oil uptake an...
Article
Full-text available
A direct passive solar dryer was designed and fabricated using plywood, aluminum foil and nails. A factorial experiment design having two factors at three levels and laid out in a completely randomized form was set up to dry tilapia fish fillets from a moisture content of 75% (wb) to a final moisture content of 15% (wb). Control experiment was also...
Article
Full-text available
Optical devices are increasingly used to inspect quality parameters of food and agricultural products. This research aimed to investigate the use of optical method to predict the moisture content of pumpkin during drying. Samples of peeled sliced pumpkin pulp of 3 mm thickness were dried at 70°C for 12 h. Images of the samples at different time int...
Article
Background: Drying is a preservation method that removes or reduces the moisture content of a product. This process could affect the nutritional properties of agricultural crops. Therefore, this research seeks to investigate the effect of microwave drying power (100-700 W) on drying rate, effective diffusivity, antioxidant value of beta-carotene c...
Article
Full-text available
The color changes kinetics of pumpkin slices during convective hot air drying was investigated at drying temperatures of 50, 60, 70 and 80°C. The hunter lab L* a* and b* color coordinates were used as assessment indicators. The total color change ∆E, Chroma value, hue angle and brownness index (BI) of the pumpkin slices where also determined. To de...
Article
Full-text available
A centrifugal bambara groundnut pod shelling machine was designed and constructed to crack various sizes and varieties of bambara groundnut. The sheller was fabricated with locally available materials from the formation of a new idea which aimed at easing the pain, stress, intensive labour, time consumption, undue cost and the cumbersome operation...
Article
Full-text available
This study investigated the drying kinetic of pumpkin under different drying temperatures (50, 60, 70 and 80°C), samples thickness (3, 4, 5 and 7mm), air velocity (1.2m/s) and relative humidity (40-50%). Kinetic models were developed using semi-theoretical thin layer models and multi-layer feed-forward artificial neural network (ANN) method. The Hi...
Article
Abstract Background: Developing an efficient drying system with combined novel thermal and conventional hot-air drying of agricultural crops has become potentially a viable substitute for conventional drying techniques. Due to the synergistic effect, the total energy and time required can be drastically reduced, and the final quality of agricultura...
Article
Full-text available
The thin layer drying kinetics of pumpkin slices (Cucurbita moschata) were experimentally investigated in a convective hot air dryer. In order to select the appropriate model for predicting the drying kinetics of pumpkin (Cucurbita moschata), twelve thin layer semi theoretical, theoretical and empirical models, widely used in describing the drying...
Article
Full-text available
This study seeks to investigate the effects of temperature (50, 60, 70 and 80 °C) and material thickness (3, 5 and 7 mm), on the drying characteristics of pumpkin (Cucurbita moschata). Experimental data were used to estimate the effective moisture diffusivities and activation energy of pumpkin by using solutions of Fick’s second law of diffusion or...
Article
A solar powered evaporative cooling storage system (SPECSS) was developed to improve the shelf life of fruits and vegetables for small-holder farmers in rural Nigeria where an electrical power distribution network is almost nonexistent. The capacity of the SPECSS chamber was 0.39 m3. A suction fan (24 W) and a water pump (18 W) were powered through...
Conference Paper
Full-text available
Drying kinetics of Pumpkin was investigated in a convective hot air dryer. The drying experiments were carried out to determine the effects of drying temperature, drying air velocity an