Volume 12, Issue 1 -

Two different types of CTC (Crush, Tear and Curl) teas were used for infusion kinetics study. Infusion kinetics for these and their ground and sieved fractions were studied over a 15-min period at 60°C and 80°C. Samples were analyzed using UV-Vis spectroscopy. Results of infusion have been interpreted in terms of gallic acid equivalence (GAE). Fractions with smaller particle size show faster infusion. First-order rate constants for largest and smallest fractions were 0.257–0.685 min −1 , respectively, at 60°C. A quasi-steady-state model was developed, which determines initial dissolution rate, diffusion rate from actual infusion rate and hence rate controlling step. At 80°C, the infusion rate of the 0.33 mm granules was found to be 98% of the dissolution rate as compared to 68% in case of 1.99 mm granules. The diffusivity values were found to be 2.23×10 −10 m 2 /s and 4.34×10 −10 m 2 /s at 60°C and 80°C, respectively.

Electrohydrodynamic (EHD) drying of banana slices was modeled both numerically and empirically. The drying process was conducted using the EHD technique at 6, 8, and 10 kV cm −1 with banana slices 3 mm thick. Based on the maximum coefficient of determination ( R 2 ) and minimum value of root mean square of error (RMSE) observed in the experimental and predicted values of moisture ratio, the diffusion model was identified as the best prediction model. The values for effective moisture diffusivity were calculated to be in the range of 3.12 × 10 −10 to 4.23 × 10 −10 m 2 s −1 . In addition, a theoretical model was developed using the numerical (implicit) solution of the second Fick’s equation based on low variation in the external resistance by applying EHD. Moisture ratio versus time showed a falling rate period indicating that the internal moisture transfer is dominant at EHD. Results of numerical solution showed adequate consistency with experimental data, having the maximum difference of less than 0.16 g g −1 in moisture content.

Kinetics of thermal texture softening, color change and loss of ascorbic acid in potato ( Solanum tuberosum ) were investigated at selected temperature range (70–100°C) and heating time range (0–50 min). Cut samples of potatoes were heated in a constant temperature water bath at various temperatures. Heat-treated samples were evaluated for texture, color and ascorbic acid by use of a texture-testing machine, a color meter and spectrophotometer, respectively. The biphasic first-order model, the fractional conversion model and the simple first-order model were used for fitting experimental data of time dependence kinetics, while the simple first-order model and Arrhenius model were used for temperature dependence kinetics. The results indicated that the biphasic first-order model can match well to the texture softening of potato samples, the fractional conversion model can well describe the kinetics of color, and the simple first-order model can be used for the kinetics of ascorbic acid. The kinetic parameters including decimal deduction time ( D ), reaction rate ( k ), temperature dependence ( z ) and activation energy ( E a ) were determined by the nonlinear regression method. The correlation matrix between quality attributes including texture properties, color and ascorbic acid loss was developed based on the kinetic models. The results obtained from this study were compared with those previously reported.

The goal of this work was to compare the barrier, mechanical, and thermal properties of two types of starch–polyvinyl alcohol (PVA) nanocomposites. Sodium montmorillonite (MMT) and nanocrystalline cellulose were chosen as nanoreinforcements. X-ray diffraction (XRD) test showed well-distributed MMT in the starch–PVA matrix, possibly implying that the clay nanolayers formed an exfoliated structure. The moisture sorption, solubility and water vapor permeability (WVP) studies revealed that the addition of MMT and nanocrystalline cellulose reduced the moisture affinity of starch–PVA biocomposite. At the level of 7 % MMT, the nanocomposite films showed the highest ultimate tensile strength (UTS) (4.93 MPa) and the lowest strain to break (SB) (57.65 %). The differential scanning calorimetry (DSC) results showed an improvement in thermal properties for the starch–PVA–MMT nanocomposites, but not for the starch–PVA–NCC nanocomposites. Results of this study demonstrated that the use of MMT in the fabrication of starch–PVA nanocomposites is more favorable than that of nanocrystalline cellulose to produce a desirable biodegradable film for food packaging applications.

The objective of this study is to investigate the preservative characteristics of ascorbic acid (A) on the color, texture and fatty acids (FA) of cold-smoked fish. The fish (~250 g) were treated with six different formulation of brine prepared with 10% salt, which is the control(C), treated with 0.4% NaNO 2 (N4), 0.2% NaNO 2 (N2) and only 2.5% A and their combinations (N4A, N2A). The sample groups were cold smoked, then stored at ±4°C and analyzed for 15 days intervals. The results showed that ascorbic acid did not have any negative effect on color, texture or sensory characteristics while there were significant preservative effects on FA. The most stable groups were N and A combinations. The PUFA (Polyunsaturated FA), PUFAω-3, PUFAω-6 and UFA (Unsaturated FA) of N4A and N2A were higher than group C and A. Accordingly, it is expected that, in terms of PUFAω-3 and PUFAω-6, the combination of N and A can contribute to the lipid stability.

The ability of Lactobacillus plantarum for biological treatment of dairy wastewater was investigated using a response surface method. The effects of three culture condition parameters of temperature (24.93–40.07°C), pH (4.3–6.7), and agitation rate (99.5–200.5 rpm) on the removal efficiency of sugar, total protein content (TPC), and chemical oxygen demand (COD) of the wastewater were studied. For each response parameter, a second-order polynomial model versus independent variables ( p < 0.0001) was determined and statistically obtained with high coefficient of determination values ( R 2 > 0.95). Numerical optimization defined the optimum treatment conditions for achieving the highest removal efficiency was temperature of 28°C, pH of 5.03, and agitation rate of 147.51 rpm. Under the optimum condition, the removal efficiency values for sugar, TPC, and COD were predicted to be 72.18%, 54.51%, and 78.99%, respectively.

The color and aroma properties of Pandanus amaryllifolius Roxb. leaves (pandan) were studied by mechanical extraction using normal and turbo blade blenders under different blending times (60–180 s). The extracted juice was freeze-dried into powders and its aroma components were measured in a solid-phase microextraction using gas chromatography/mass spectrometry (SPME-GC/MS) analysis. The turbo blade blender provided maximum color pigment of greenness and yellowness at blending time of 90 s as compared to the normal blender that required 180 s. In GC-MS analysis, the major component, 2-acetyl-1-pyrroline, was found to be one time higher in the freeze-dried pandan juice samples obtained from turbo blade blender than normal blender. Other components including the cis -3-hexanal, 2-methylene-4-pentenenitrile and 1,2,4-trimethylbenzene were also detected in the samples. In conclusion, the turbo blade blender is more effective than normal laboratory blender in terms of color extraction, particle size reduction and the aroma retention.

Osmotic dehydration offers an alternative to air-drying for reducing moisture content at ambient temperature. Of four different solutes investigated, 22% (mass basis) sodium chloride (NaCl) and 60% (mass basis) sucrose solutions were the most successful, with each achieving approximately a 10% reduction in wet basis moisture content after 8 h without significant detrimental side effects, although NaCl solutions cause noticeable darkening in the pits on the surface of the chestnuts. The presence of the shell and pellicle did not significantly affect the dehydration rate. Osmotic dehydration by NaCl or sucrose prior to mechanical shell removal produced a small increase in efficiency of the shell removal process.

The effect of moisture content on some properties of two varieties (Meymeh and Maragheh) of Russian olives was studied. The physical and mechanical properties including: dimensions, geometric mean diameter, thousand mass, volume, sphericity, surface area, true and bulk densities, porosity, angle of repose, coefficient of friction, rupture force, and rupture energy. The changes of moisture content levels from 17% to 25% (w.b.) indicated a statistically significant effect on all studied physical properties, except bulk density for Russian olive fruits. Shearing force was applied to the fruit using a testing machine in double shear mode. Shear strength and shearing energy increased with increase of loading rate; however, they were higher in Meymeh variety than Maragheh variety. Therefore, the lowest loading rate, with up to about 10 mm/min is desirable to design a suitable pulverizing mill in the herbal medicine industries.

The analytical model developed by Dincer and Dost [3] for the estimation of diffusivities and mass transfer coefficients has been reviewed, and the equations used for the evaluation of the mass transfer coefficients have been corrected. The corrected equations have been used for the calculation of mass transfer coefficients from literature data. It was observed that the corrected diffusivities showed significant differences from the previously calculated values. The use of the modified equations in future drying calculations will lead to more realistic mass transfer coefficient values.