Showing papers by "Arun S. Mujumdar published in 2018"
TL;DR: In this paper, a new model was proposed for the effective thermal conductivity of the GNP nanofluid considering Brownian motion, length, thickness, average flatness ratio and interfacial thermal resistance of GNP, and it was compared with Maxwell, H-C and Chu models.
82 citations
TL;DR: In this article, the authors investigated the relationship between surface color and natural pigment, as well as non-enzymatic browning of red pepper during hot air drying at drying temperatures of 60, 70, and 80 °C.
77 citations
TL;DR: In this article, the relative merits of selected recently developed drying techniques with focus on solar-assisted and microwave-assisted hybrid drying techniques which offer high-quality drying with excellent efficiency are discussed.
Abstract: Spices and herbs are important parts of human daily food consumption and play an essential role in seasoning and/or preserving food, curing illness, and enhancing cosmetics. Proper processing is necessary because the fresh produce has high moisture content and often high load of microorganisms. Dehydration is the most common method used to lower moisture content and hence the water activity to a safe limit which prolongs shelf life. However, consumers’ demand on processed products with most of the original characteristics of the fresh plants has increased. Consequently, drying must be executed carefully in the interest of retaining the taste, aroma, color, appearance, as well as nutritional value of the plants to maximum possible extent. In addition to quality considerations, drying efficiency is another key aspect for evaluating drying performance. This article reviews recent developments in the production of high dried spices and herbs. It attempts to detail the relative merits of selected recently developed drying techniques with focus on solar-assisted and microwave-assisted hybrid drying techniques which offer high-quality drying with excellent efficiency. Outlook for future research trends and challenges for dehydration of spices and herbs is also discussed.
75 citations
TL;DR: A deeper understanding in tissue softening and moisture variation of blanched berries is provided and HHAIB treatment resulted in a water loss and migration from berry interior to surface tissue.
66 citations
TL;DR: The current findings indicate proper blanching pretreatment prevents phytochemicals degradation of dried pepper during storage, and the antioxidant capacity of samples was found to increase after drying.
65 citations
TL;DR: In this paper, 3D printing properties of orange leather were characterized and simultaneously comparative assessment was carried out while making it from orange concentrate (OC) by adding varying proportions (15, 20, 25, and 30%) of wheat starch (WS).
Abstract: Three‐dimensional (3D) food printing is a promising technology that attracted the attention of both academia and industry since it is considered as a major paradigm shift in the fabrication of intricate and personalized food design with the choices of altering the nutritional profile. In this study, 3D printing (3DP) properties of orange leather (OL) were characterized and simultaneously comparative assessment was carried out while making it from orange concentrate (OC) by adding varying proportions (15, 20, 25, and 30%) of wheat starch (WS). Rheological data suggest that steam cooking of OC–WS mixture for 16 ± 0.5 min exhibit shear‐thinning behavior, which is essential for extrusion‐type 3DP of food mixtures. A variation of 5% WS with OC significantly increase the yield stress (τ₀) and viscosity (n). Nuclear magnetic resonance (NMR) study revealed that the maximum amount of partially immobilized water was converted to bound water and developed the highest mechanical strength but poor extrudability for 30% WS containing sample. Texture profile analysis suggests that the 20% WS containing samples provide the best mastication properties among the four samples. To optimize the printing conditions and test the reproducibility of OL 3DP process effects of nozzle diameter (dₙ), nozzle tip‐print bed height (hc), extrusion rate (vd), and nozzle moving speed (vₙ) were tested experimentally. It was found that, at dₙ = 1.5 mm, hc = 1.54 ± 0.02 mm, vd = 245 mm³/s, and vₙ = 35 mm/s the printed objects remain consistent, achieve the best resolution and maximum fidelity. PRACTICAL APPLICATIONS: The 3D food printing process has a great potential to improve the quality and utility of the food and food products. The 3DP of fruit concentrates combined with healthy additives, bioactive compounds could be a novel attractive way for fabricating food to serve people with special requirements, as a snack item or cold dish before main meal. This study suggests that, food mixtures with similar rheological, moisture, and textural properties at similar printing conditions could be used as supply material, that is, the “ink” for an extrusion‐type 3D food printer.
57 citations
TL;DR: In this paper, the effects of drying temperature (50, 53, 56, 59, 62, and 65°C) and pulsed vacuum ratio defined as the vacuum pressure duration versus atmosphere pressure duration (3:3, 6:6, 9:2, 12:5, 15:1, 18:4 min/min) on PVD characteristics and quality attributes of wolfberry in terms of polysaccharide content, color parameters (L*, a*, b*, ΔE, and C), rehydration ratio and microstructure were investigated.
Abstract: The effects of drying temperature (50, 53, 56, 59, 62, and 65°C) and pulsed vacuum ratio defined as the vacuum pressure duration versus atmosphere pressure duration (3:3, 6:6, 9:2, 12:5, 15:1, 18:4 min/min) on pulsed vacuum drying (PVD) characteristics and quality attributes of wolfberry in terms of polysaccharide content, color parameters (L*, a*, b*, ΔE, and C), rehydration ratio and microstructure were investigated. Results revealed that appropriate PVD can reduce drying time by 73.2% compared to hot air drying at the same drying temperature. The moisture effective diffusivity (Deff) ranged from 5.23 × 10−10 to 9.73 × 10−10 m2/s, calculated using the Weibull distribution model. The polysaccharide content, L* (lightness), a* (redness/greenness) of the PVD products were higher than those of the hot air-dried samples at the same drying temperature. The total color difference (ΔE) and color intensity (C) of PVD samples were close to those of the fresh ones. The retention rate of total polysaccharid...
49 citations
TL;DR: In this article, the authors investigated the effects of low-frequency ultrasound and the synergistic effect of ultrasound and microwave on the efficiency and quality of vacuum frying with potato chips as experimental material.
Abstract: The effectiveness of hybrid frying based on vacuum frying with application of ultrasound (USVF) and combined ultrasound and microwave (USMVF) enhancement was presented in this study. The ultrasound revealed significantly the “vibration effect”, and the combination of ultrasound and microwave had a synergistic effect on the energy efficiency and quality attributes of vacuum fried potato chips, shortening the frying time by 36.4%–54.5% and improving the effective moisture diffusivity by 60.5%–144.5% with the ultrasound power levels ranged 300 W–600 W. The USMVF process was found to consume about 34.9%–48.3% less energy compared to that in VF. The oil uptake of vacuum fried potato chips was reduced by 27.4%–32.3%, the texture (crispness) and the color was greatly improved, and the volume shrinkage and water activity were diminished by the combination of ultrasound and microwave. The moisture loss kinetics and quality parameters were also improved markedly when higher ultrasound power was used. The SEM revealed a more porous microstructure in USMVF samples. The vacuum frying technology that combines both ultrasound and microwave found to be much more effective technology in terms of energy efficiency and product quality. Industrial relevance In recent years, the fruit-vegetable crisp produced by vacuum frying (VF) has been widely concerned due to natural color, superior sensory and nutritional quality. However, there are certain defects in the application of VF technology, such as backward heating method, low efficiency especially with low-temperature frying, relatively high oil uptake in products and the quality attributes of fried products need to be improved. One of the recommended methods to overcome the limitation of low-temperature dehydration is to utilize the synergistic effect of different energy, which providing the energy by a combination of several mechanisms, such as vacuum frying with microwave radiation, or with ultrasounds, which leads to a significant improvement in energy efficiency and quality attributes of fried fruits and vegetables. Focused on these problems, this research investigated the effects of low-frequency ultrasound and the synergistic effect of ultrasound and microwave on the efficiency and quality of vacuum frying with potato chips as experimental material. The effect of variable hybrid drying conditions was analyzed with different power levels of ultrasound. The application of ultrasound showed improve the moisture loss rate and quality attributes of vacuum fried products as a non-thermal technology. The combination of ultrasound and microwave in vacuum frying system achieved better energy efficiency, lower oil uptake, crispier, better shaped and colored products compared to the VF produced samples. The storage stability and safety of vacuum fried products also improved by the combined ultrasound and microwave. Thereby, the experimental results will contribute to the development of modern vacuum frying technologies of fruits and vegetables, which reduced the oil uptake and retained their high quality, with reduced process time and lower power consumption at much lower frying temperature.
30 citations
TL;DR: In this article, polyaniline nanofibers, PANI/SnO2, and rGO nanocomposites were successfully prepared by an in-situ polymerization method.
29 citations
TL;DR: Microwave freeze drying retains chlorophyll and flavonoids, as well as colors and odors of samples, and also decreases energy consumption in the freeze drying of barley grass.
Abstract: Young barley grass leaves are well-known for containing the antioxidant substances flavonoid and chlorophyll. However, low product quality and energy efficiency exist with respect to the dehydration of barley grass leaves. To improve energy supply and the quality of barley grass, microwave heating instead of contact heat was applied for the freeze drying of barley grass at a pilot scale at 1, 1.5 and 2 W g-1 , respectively; After drying, energy supply and quality parameters of color, moisture content, chlorophyll, flavonoids, odors of dried barley grass were determined to evaluate the feasibility of the study.; Results: Microwave freeze drying (MFD) allowed a low energy supply and high contents of chlorophyll and flavonoids. A lightness value of 60.0, a green value of -11.5 and an energy supply of 0.61 kW h-1 g-1 were observed in 1.5 W g-1 MFD; whereas drying time (7 h) decreased by 42% compared to contact heating. Maximum content of flavonoid and chlorophyll was 11.7 and 12.8 g kg-1 barley grass. Microwave heating leads to an odor change larger than that for contact heating observed for the freeze drying of barley grass.; Conclusion: MFD retains chlorophyll and flavonoids, as well as colors and odors of samples, and also decreases energy consumption in the freeze drying of barley grass. © 2017 Society of Chemical Industry.; © 2017 Society of Chemical Industry.
24 citations
TL;DR: In this paper, the authors investigated the water mobility and distribution of dried barley grass, microwave vacuum drying (MVD) was conducted at different scales at different locations in the US.
Abstract: Water mobility is an indicator of product quality of dried barley grass. To investigate the water mobility and distribution of dried barley grass, microwave vacuum drying (MVD) was conducted at dif...
TL;DR: To enhance solubility and dispersibility of nutritional elements of barley grass for rehabilitation therapy, high-energy ball-milling was conducted to obtain nano-scale powder of barley Grass.
TL;DR: In this article, the authors characterized polymeric micro/nanoparticles of aceclofenac produced using a high-pressure homogenizer and a spray dryer in terms of their encapsulation efficiency, particle size, morphology, and in vitro drug release performance.
Abstract: The aim of the present study was to characterize polymeric micro/nanoparticles of aceclofenac produced using a high-pressure homogenizer and a spray dryer. The micro/nanoparticles were characterized in terms of their encapsulation efficiency (E.E.), particle size, morphology, and in vitro drug release performance. Interaction between the drug and the polymer (Eudragit RS 100 and ethylcellulose) was evaluated using Fourier transform infrared (FTIR) spectroscopy and X-ray powder diffractometry. Analysis of the results showed that speed and operating pressure have significant negative effect on E.E. of the micro/nanoparticles. The nanoparticles (970–197 nm) had E.E. of 74.09 ± 1.17 to 83.66 ± 1.63% while microparticles displayed EE. of 72.15 ± 2.5%. The micro/nanoparticles were observed to be discrete and spherical. The FTIR analysis confirmed compatibility of aceclofenac with Eudragit RS 100 as well as ethylcellulose. In vitro study showed sustained drug release of 65 and 90% over a period of 12 h, ...
TL;DR: In this article, a tubular microreactor was used for transesterification of cottonseed oil with methanol in the presence of catalyst (NaOH) in an acrylic sheet.
Abstract: Transesterification of crude cottonseed oil with methanol in the presence of catalyst (NaOH) in tubular microreactor has been investigated experimentally. The transesterification reaction was performed in a silicon tube of 0.8 mm inner diameter, mounted in serpentine manner configuration on an acrylic sheet. Influence of process variables such as reaction temperature $$(35{-}45\,{^{\circ }}\hbox {C})$$
, NaOH concentration (0.5–1.5 wt%) and oil/methanol molar ratio (1:7–1:9) on fatty acid methyl ester (FAME) was studied. In order to further improve biodiesel yield, an experimental design was employed using the Box–Behnken method and analysis of variance. The %FAME was calculated by gas chromatography using methyl arachidate as an internal standard. Fourier transform infrared spectroscopy was used to investigate the functional groups present in biodiesel. Thermal stability of biodiesel was evaluated using a thermogravimetric analyser. The optimal condition found was oil/methanol molar ratio (1:8), catalyst concentration (1 wt%) and reaction temperature $$(45\,{^{\circ }}\hbox {C})$$
while %FAME yield of about 94.1% at a residence time of 90 s.
TL;DR: In this article, the quality characteristics of fermented plant extract powder prepared by hot air-drying, spray drying, vacuum microwave drying, and freeze drying are compared for an FPE product.
Abstract: Fermented plant extract (FPE) is a kind of plant functional food fermented by various microorganisms to make a beverage or other physical forms. To provide technical support for the industrial production of fermented plant extract powder, the quality characteristics of fermented plant extract powder prepared by hot air-drying, spray drying, vacuum microwave drying, and freeze-drying are compared for an FPE product. The effects of maltodextrin, soluble starch, and β-cyclodextrin as a drying agent on drying effect were studied. Results show that spray-dried FPE powder has the highest bulk density, the smallest average particle size, while the FPE powder produced by freeze-drying has the best color and flavor, the highest content of key components including total sugar, soluble protein, vitamin C, total polyphenol content, and highest antioxidant capacity.
03 Sep 2018