Production of dried ivy gourd sheet as a health snack

Ivy gourd (Coccinia grandis) has recently been recognized as a rich source of β-carotene. To add value to the fresh leaves a process to produce dried ivy gourd sheet as a health snack was the aim of this study. The effects of pretreatment, i.e., blanching in NaCl solution (0-3% w/v), and drying methods, i.e., hot air drying and vacuum drying at 60-80 °C, on the drying characteristics and quality, viz. colour, texture and β-carotene content of dried ivy gourd sheet were investigated. The results showed that dried sheet pretreated by brine blanching and vacuum drying resulted in better retention of colour and β-carotene as well as texture of the dried sheet as compared to the dried untreated and dried water blanched samples. Higher drying temperature also resulted in higher β-carotene retention due to shorter drying time.     

Effects of drying temperature and relative humidity on spaghetti characteristics

This study aimed at investigating the effect of drying conditions on spaghetti properties, i.e., its color, surface structure, rupture strength, rehydration characteristics, texture, and sauce retention capacity. The effects of temperature and humidity were independently examined under constant drying conditions, which were compared to those applied industrially, where the temperature and relative humidity are changed stepwise with time. The knowledge obtained in this study is considered useful for reasonably determining the drying conditions for producing spaghetti with desired properties.     

Combined Microwave-Vacuum and Freeze Drying of Carrot and Apple Chips

A combination of microwave-vacuum (MWV) drying and freeze drying was investigated as potential means for drying carrot and apple chips. The sample was first dried by microwave-vacuum to dehydrate some amount of internal free water and then by freeze drying to a final moisture content of less than 7% (wet basis). Chemical properties (carotene and vitamin C retention) and physical properties (shrinkage, color, texture, and rehydration ratio) of carrot and apple slices dried by this method were evaluated and compared with those dried by freeze drying alone, MWV drying alone, and conventional hot air drying, respectively. The comparison showed that the carotene retention of carrot slices and the vitamin C retention of apple slices dried by the current method were close to those of freeze-dried carrot and apple slices and much better than those of conventional hot air–dried ones. The samples prepared by the current method exhibited very close rehydration capacity, color retention, and texture with those of the freeze-dried ones but with a little higher shrinkage. However, the samples still showed the attractive external appearance without marked warp.     

Solvent-, ion- and pH-specific swelling of poly(2-acrylamido-2-methylpropane sulfonic acid) superabsorbing gels

Homopolymer hydrogel of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and its nanocomposite counterpart were prepared to study their swelling properties. The hydrogels showed ability to absorb and retain electrolytes as well as binary mixtures of water and organic solvents (i.e., methanol, ethanol, acetone, ethylene glycol (EG), polyethylene glycol, N-methyl-2-pyrrolidone (NMP), and dimethylsulfoxide (DMSO). The nanocomposite gel exhibited lower swelling in all solvent compositions in comparison with non-composite gel. Unlike conventional acrylic acid-based hydrogels, the poly(AMPS) gels showed superabsorbing capacity in pure ethanol, methanol, EG, DMSO and NMP. Meanwhile, swelling capacity of poly(AMPS) hydrogel in DMSO-water mixtures was surprisingly found to be even higher than that in water. This extraordinary superswelling behavior was explained based on the interactions involved in solvation as well as the solubility parameters. The gels showed pH-independent superabsorbency in a wide range of pH (3–11). Saline-induced swelling transitions were also investigated and the ionic interactions were confirmed by FTIR spectroscopy.     

Ultrasonication as pretreatment for drying of tomato slices in a hot air–microwave hybrid oven

This study aims to investigate the effect of ultrasonic pretreatment on drying time and quality properties of tomato slices dried by microwave combined with hot air at 60°C. The influence of ultrasound pretreatment (0, 20, and 40?min) and microwave power (120, 150, and 180?W) on drying time, color, total phenolic content, lycopene, vitamin C, and rehydration capacity of dried slices of tomato was studied. Results showed that as the microwave power level increased, drying time decreased significantly (about 46.4%). Ultrasound pretreatment decreased the drying time by 7.38% only at 120?W microwave power and 40?min of pretreatment compared to those without ultrasound pretreatment at the same microwave power. Depending on drying conditions, vitamin C and lycopene contents reduced from 433.94 to 81.89?mg AA/100?g dry solids and 3920.57 to 415.40?mg/100?g dry solids, respectively. The change in total phenolic content was not severe as much as vitamin C contents. Rehydration capacity of pretreated samples was larger than nontreated samples. The color values of dried tomato slices were in the acceptable range. Both microwave power and ultrasound pretreatment affected the quality of the final product significantly.     

Drying kinetics and quality of carrots subjected to microwave-assisted drying preceded by combined pulsed electric field and ultrasound treatment

Abstract

In the study the impact of combined pulsed electric field and ultrasound pretreatment on microwave-assisted air drying kinetics and quality of dried carrot was evaluated. Pretreatment of samples has been realized through sequential application of PEF followed by US or vice versa. Sonication was performed using either the contact or immersive method whereas PEF treatment was carried out at 5?kV·cm^?1 and 10 pulses. After pretreatment the samples were subjected to microwave-assisted convective drying. Combined pretreatment reduced drying time by 27–49%. The highest retention of carotenoids (93.7%) was noted for samples subjected to PEF treatment followed by contact sonication. Optical properties of pretreated carrots were similar to reference samples (without pretreatment) and total color change ranged from 2.8 to 5.8. Application of immersive sonication, regardless of the sequence, resulted in the highest rehydration capacity and the highest loss of soluble solids. Despite samples subjected to combined pretreatment exhibited the most porous structure, the hygroscopic properties remained almost unchanged in comparison to the reference sample.     

Foam mat drying of mango: Effect of processing parameters on the drying kinetic and product quality

This study investigated the foam mat drying process parameters (temperature and concentration of foaming agents, albumin, and an emulsifier blend) and evaluated their effects on drying kinetics, color, carotenoid retention, and solubility of the mango pulp powder. Fick’s model was able to represent the foam mat drying kinetics. The foaming agents and high temperatures enhanced the carotenoid retention. This was explained by the greater effective water diffusion coefficients that allowed obtaining products with low moisture contents and water activities in short processing times of up to 3?h, with high carotenoid retention and color maintenance.     

Bioactive and Physicochemical Properties of Persimmon as Affected by Drying Methods

In this study, the effects of three different drying methods (freeze drying, oven drying, and vacuum oven drying) on bioactive (total phenolics, total flavonoids, condensed tannin and total hydrolyzable tannin contents, antiradical activity, and antidiabetic activity) and some physicochemical (dry matter, ash, water activity (a _w ), color, protein, hydroxymethylfurfural, glucose and fructose content) properties of persimmon fruit were investigated. Simplex lattice mixture design methodology was applied to determine the best solvent mixture for the extraction of phenolics from the samples. It was found that the mixture of acetone:water at the ratio of 50:50 % (v/v) was the best solvent mixture for the extraction. The persimmon powder sample obtained from freeze drying showed significantly (p <0.05) higher bioactivity values than oven- and vacuum-oven-dried samples. Antiradical activity changed significantly depending on the drying method employed and it was superior in freeze-dried samples than that of the other drying methods.     

Multi-Pass Sorption Drying of Paddy Using Rice Husk Adsorbent: Experiments and Simulation

A single-stage sorption drying of paddy with rice husk adsorbent cannot reduce its moisture content to a safe level since the relative humidity of air inside the mixing tank is very high. To obtain a safe moisture content, multi-pass sorption drying was used and the effect of operating parameters—i.e., rice husk density, rice husk initial moisture content, and volumetric mixing ratio of paddy to rice husk—on the drying time and paddy quality were investigated for two paddy varieties, Suphanburi 1 and Khao Dawk Mali 105. A mathematical model associated with the transfers of heat and mass between the grain and adsorbent was also formulated to explore the sensitivity of the operating parameters to the drying time. Both the experiment and the simulation showed that the drying time was shorter by using a lower initial moisture content of rice husk, a higher rice husk bulk density, and a higher volumetric mixing ratio, the last factor being less important. For quality assessment, the color of white rice for both paddy varieties changed insignificantly under the influence of all the operating parameters, but the head rice quality was rather sensitive to the operating conditions especially for the Khao Dawk Mali 105, which had a 6–10% lower in head rice yield compared to that of the reference samples.     

Ultrasound-assisted drying of orange peel in atmospheric freeze-dryer and convective dryer operated at moderate temperature

Abstract

Atmospheric freeze-drying (AFD) at ?10?°C and moderate temperature convective drying (MTD) at 50?°C without and with ultrasound application (20.5?kW/m³) were carried out. Alcohol insoluble residue (AIR) and its swelling capacity (SC), water retention capacity (WRC) and fat retention capacity (FRC) were measured in the dried product. Ultrasound significantly shortened the drying time in both processes, the intensification effect being more significant in atmospheric freeze-drying (57% and 27% reduction in atmospheric freeze-drying and convective drying, respectively). As regards AIR and WRC, no effect was observed of either the drying temperature or ultrasound application. On the contrary, SC was significantly lower in AFD samples. The FRC of MTD samples was similar to that of the fresh ones and higher than the values obtained for atmospheric freeze-dried samples. Therefore, convective drying at moderate temperature preserved the AIR properties better than atmospheric freeze-drying.     

Chlorohydrin water‐swellable rubber compatibilized by an amphiphilic graft copolymer. III. Effects of PEG and PSA on water‐swelling behavior

Chlorohydrin water‐swellable rubber—composed of chlorohydrin rubber (CHR), crosslinked polyacrylate (CPA), the amphiphilic compatibilizer poly(vinyl alcohol)‐g‐poly(butyl acrylate) (PVA‐g‐PBA), precipitated silica (PSA), and poly(ethylene glycol) (PEG)—was prepared. The dispersion of PEG in the blend was characterized by wide‐angle X‐ray diffraction (WAXD). The dependence of the water absorbing ratio by weight, the water‐swelling ratio by volume, and the percentage loss by weight on PEG and PSA contents were investigated. The effects of PEG and PSA on the second water‐swelling behaviors and long‐term water‐retention behaviors were also studied. Optimums for the water‐absorbing and water‐swelling abilities within the range of the experiment were obtained. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2509–2516, 2001     

Comparison of Water Blanching and High Hydrostatic Pressure Effects on Drying Kinetics and Quality of Potato

Abstract

Drying kinetics and quality parameters of potato cubes were evaluated as affected by high pressure processing and hot water blanching. The potato cubes in 1% citric acid solution as immersion medium were pressure treated at 400 MPa for 15 min. Hot water blanching was conducted in boiling water for 3 min. Drying kinetics and quality parameters (i.e., rehydrability, texture, color and apparent density) were assessed for the high pressure–treated and water-blanched samples and for dehydrated and rehydrated samples. Drying rates were found to be higher (p < 0.05) in the initial period of drying for the pressure treated samples. The Page model was found to better fit drying data of the thermally treated samples, and the two-terms model better described the drying behavior of high pressure–treated samples. High pressure–treated samples had a similar rehydrability to thermally treated samples. It was found that pressure–treated samples had a hardness value close to that of fresh samples, whereas thermal treatment resulted in a softer texture. After rehydration, samples of both treatments returned their texture before drying. The total color difference for the thermally blanched samples was higher (p < 0.05) than for pressure–treated samples before drying and after drying. High pressure–treated and dried potato cubes had a color close to that of fresh potato cubes. High pressure–treated and air-dried samples were found to have higher (p < 0.05) apparent density than thermally treated samples.     

Spray Drying of Elderberry (Sambucus nigra L.) Juice to Maintain Its Phenolic Content

Spray drying was studied with Elderberry (Sambucus nigra L.) juice using a Buchi B-290 spray dryer. Different inlet temperatures ranging from 70°C to 120°C and two feed flow rates of 180 ml/hr and 300 ml/hr were considered for the experiment. The operating parameters were optimized in terms of total phenolic content retention, color, and powder recovery. The inlet temperature of 80°C with feed flow rate of 180 ml/hr gave high phenolic content retention with good color but lower recovery of the dried powder, i.e., less than 50%. To increase the recovery percentage during the drying process, the elderberry juice was spray dried with five different wall materials, i.e., soya milk powder, soya protein powder, isolated soya protein, gum acacia, and maltodextrin. Wall materials were evaluated in terms of total phenolic content retention, color of the powder, and mass recovery percentage. The gum acacia and maltodextrin gave better results and high recovery percentage, i.e., more than 70%. The best three combinations were stored under three different storage conditions in three different packagings to monitor the stability of the phenolic content and color of the powder.     

Drying of Lemon Myrtle (Backhousia citriodora) Leaves: Retention of Volatiles and Color

Lemon myrtle plant (Backhousia citriodora) leaves were dried at three different drying temperature conditions (30, 40, and 50°C) in a fluidized bed dryer. The retention of the principal volatile compound, citral, was analyzed in dried products obtained at these three drying conditions. The changes in the color parameters L?, a?, b? of leaves were also analyzed. More than 90% of citral was retained at 50°C drying temperature, whereas the retention at 30 and 40°C was 81 and 85%, respectively, suggesting that higher temperature is beneficial to achieve higher retention of volatiles. However, in terms of the color, all the color parameters were changed maximum at 50°C drying temperature unfavorably, suggesting that the higher temperature drying causes more degradation of the pigment. Blanching of the leaves in hot water at 80°C for 1 min prior to drying did not result in any improvement in volatile retention or color.     

Ultrasound-assisted osmotic process on quality of microwave vacuum drying sweet potato

The effects of pretreatment before microwave vacuum drying (MVD) on texture, color, expansion, rehydration, drying rate, microstructure, sensory evaluation, and other properties of sweet potato were investigated in this study. The pretreatment consisted in five processing conditions, using blanching; osmotic dehydration at 35°Brix of sucrose (OD); ultrasound in distilled water (US); ultrasound in distilled water before osmotic dehydration (US?+?OD), and ultrasound-assisted osmotic dehydration (USOD). Pretreatments of sweet potato before MVD have shown success in reducing drying time with US treatment relatively more effective regarding drying time than other treatments. Compared with other treatments, US showed the highest rehydration ratio values. The osmotic group pretreatment exhibited a pronounced effect on water loss and solid gain, improved the color, aroma, and taste of dried sweet potato, whereas sucrose impregnation resulted in a hard texture observed with OD sample. USOD samples had a higher expansion ratio, lower hardness and color difference values, appeared less cell damaged, and recorded better overall quality than the other samples. There was a slight difference between USOD and US?+?OD samples. Combining osmotic dehydration with ultrasound as a pretreatment can significantly accelerate the heat transfer rate, reducing the dried time accordingly and increasing energy efficiency.     

Synthesis of poly(AA‐co‐AM) superabsorbent composites by reinforcement of halloysite nanotubes

A novel poly(acrylic acid‐co‐acrylamide)/halloysite nanotubes [PAA‐AM/HNTs] superabsorbent composite was synthesized by free radical polymerization with using HNTs as an inorganic additive. The composite was characterized by Fourier transform infrared spectroscopy, scanning electron microscope, and thermogravimetric analysis. The results revealed that HNTs and PAA‐AM were combined well together to form a porous structure with a pore size of about 10 μm, and HNTs were uniformly distributed in the composite. The thermal stability was improved by adding HNTs in the composite. The influences of contents of initiator and halloysite, neutralization degree of AA, and molar ratio of AM to AA on water absorbency were investigated. The water absorbency and the water retention capacity were improved after adding HNTs into PAA‐AM. The composite containing 10% HNTs had the highest water absorbency of 1276 g/g in distilled water. Moreover, PAA‐AM/HNTs composite also had a high swelling rate within 60 min and could maintain 78% initial swelling capability after five reswelled test. The substantial enhancement of swelling properties enables PAA‐AM/HNTs suitable for numerous practical applications. POLYM. COMPOS., 36:229–236, 2015. © 2014 Society of Plastics Engineers     

Effect of Air-Drying Temperature on Kinetics of Quality Attributes of Lemon (Citrus limon cv. lunari) Peels

The aim of this work was to determine the effect of air drying temperature (40 °C, 50 °C, and 60 °C) on the degradation kinetics of quality parameters of lemon peels. Drying at 40 °C was in favor of maximal water and oil retention capacities and lowest color loss (35%), but it also induced lower phenolic and flavonoids residual contents. First-order reaction model showed a good fit for lightness and yellowness color parameter. Zero-order reaction model fitted well redness color parameter and total color difference. A higher value of activation energy indicated greater heat sensitivity of lightness and redness during air drying.     

Effects of Drying Methods and Tea Preparation Temperature on the Amount of Vitamin C in Indian Gooseberry Tea

Indian gooseberry is a rich source of vitamin C. The fruit can be consumed either fresh or after processing into different products including Indian gooseberry tea. Both drying and tea preparation steps affect quality of the gooseberry tea drink made using dried gooseberry. This study investigated the effects of different drying methods, i.e., hot air drying, vacuum drying, and low-pressure superheated steam drying, on the retention and degradation of vitamin C (in terms of the total ascorbic acid content, TAA) in dried gooseberry flakes. In addition, the effect of temperature of water used to prepare the tea on the release of TAA and on its later degradation was also investigated.     

A Comparative Study of Pork Drying Using Superheated Steam and Hot Air

Drying with superheated steam and hot air were comparatively studied for pork. Transport, physical, and chemical properties, i.e., effective diffusivity, color, microstructure, and rehydration ability, were investigated. The experimental results have shown that the decrease of pork moisture content in an early drying time was more rapid in superheated steam than in hot air and appeared to be lower in a latter time. The pork surface as examined by SEM was noticeably different for the samples dried by superheated steam and hot air. The fewer pores at the surface of superheated steam-dried pork caused a slower water penetration into the interior during rehydration, in addition to the lower drying rate. The color of the product from superheated steam was a relatively more intense brown than that obtained from hot air as presented by a lower L? value and a higher a? value.     

A Comparative Study of Pork Drying Using Superheated Steam and Hot Air

Drying with superheated steam and hot air were comparatively studied for pork. Transport, physical, and chemical properties, i.e., effective diffusivity, color, microstructure, and rehydration ability, were investigated. The experimental results have shown that the decrease of pork moisture content in an early drying time was more rapid in superheated steam than in hot air and appeared to be lower in a latter time. The pork surface as examined by SEM was noticeably different for the samples dried by superheated steam and hot air. The fewer pores at the surface of superheated steam-dried pork caused a slower water penetration into the interior during rehydration, in addition to the lower drying rate. The color of the product from superheated steam was a relatively more intense brown than that obtained from hot air as presented by a lower L* value and a higher a* value.