Volume 11, Issue 2 -

In this study, a new approach for numerically modeling of an entire cabinet solar dryer is proposed. Collector, drying chamber and chimney are the three principle sections considered in the present modeling. The collector section containing a cover and an absorber plate is modeled applying energy and fluid flow equations to obtain temperature distribution inside the collector. Due to the non-linear behavior of the governing equations as well as variety of effective variables, an iterative method is employed for solution. Regarding the geometry complexity of the drying chamber along with the air compressibility (that in turn causes coupling of momentum and energy equations) drying chamber is simulated by CFD method. Chimney’s effect and effective parameters in suction are comprehensively considered in the present model. The numerical results are in line with experimental results which show that the model can be applied with certainty to employ the dryer for drying highly demanded and time-consuming products in a scientific, sanitary, and timely manner. The model is then optimized by adding some baffles to achieve higher efficiencies and accelerate the drying process.

Tomato quality is determined by metabolite content which is governed by post-harvest physiological changes. A 30-day full factorial experiment investigated pre-packaging, disinfection and storage temperatures on 18 different biochemical, microbiological, enzymatic and subjective quality attributes of tomato quality. Principal component analysis revealed associations among the variables such as PC1 (28.85%): coliform/enzymatic softening; PC2 (21.52%): free sugars/sweetness; and PC3 (18.20%): sucrose hydrolysis/microbial spoilage/defense metabolites. Discriminant analysis showed that some specific parameters were highly significant ( P <0.001) in determining quality changes in relation to the washing procedures and storage temperature. The prominence of ascorbic acid was observed in the equations which discriminate mostly on the basis of microbial deterioration. Further works in this respect entail fine-tuning through model verification of the equations. Multivariate analysis techniques are, therefore, recommended in studies whereby understanding of the phenomenon driving the post-harvest system’s dynamics has to be understood through diverse interrelated metabolic parameters.

The effects of the addition of grape seed powder (GSP) on the thermorheological properties of frying batters were investigated in this study. Thermal properties, including gelatinization ( T G ) and melting ( T m ) temperatures, as well as enthalpies (Δ H G , Δ H m ), were determined by a differential scanning calorimeter (DSC). The addition of GSP decreased the T G and T m as the GSP levels increased. When compared with the control batter, the addition of GSP significantly decreased the apparent viscosity and viscoelastic modules ( G ′, G ′′). The mechanical spectra of batters carried out at 15–80°C showed a transition from fluid-like to gel-like behavior. The batter pick-up values were found to be directly proportional to the batter viscosity. Both water retention capacities (WRC) and consistency index values ( K ) of the batters were significantly affected by the GSP addition and temperature ( p < 0.05). Grape seeds have health-promoting components on a scientific basis; thus, this study provides helpful results in the development of novel frying batters.

Vitamin E (VE) nanoemulsions confront physical instabilities and chemical degradation during processing and/or storage. Therefore, thermal stability and degradation kinetics of VE in nanoemulsions fabricated using low-energy emulsification method as a function of temperature under light and in the dark were studied. Nanoemulsions had small droplet diameter (≈110 nm). The thermal degradation of VE followed the first-order kinetics with samples heated at 75°C and above presenting the highest degradation rate and short half-life (5.22 min). The degradation of VE in long-term storage fitted the Weibull model with highest degradation in nanoemulsions stored under light at 40°C. However, VE retained in nanoemulsions after certain period of time might be boosted up when nanoemulsions are stored in the dark. Results showed that the physical stability tests alone are not enough to judge the stability of VE delivery systems, as the encapsulated VE might be lost during processing and storage.

In China, there are about 1.6 million tons of thinned young apples (TYAs) every year after blossoming and fruit thinning. These resulting fruits, in reality, could be utilized as agricultural and food resource. This study was undertaken to evaluate the influence on physical properties, bioactive attributes of TYAs that were subjected to chosen drying techniques. In general, significant differences ( p < 0.05) exist in physical appearance and polyphenol. Antioxidant capacity was also investigated on the basis of assay for Trolox equivalent antioxidant capacity (TEAC) by 2,2ʹ-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), reducing power and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) scavenging ability. Judging from the results, it was concluded that hot air drying at 60℃ is appropriate for large-scale production; furthermore, vacuum freeze drying tends to manufacture high-value up-market TYA products that are available to give the best results for dehydrated fruits. It is suggested that TYA has great potential in the food industry as functional ingredient.

Noodles promote health as a source of essential nutrients and fiber. This study evaluated the effects of incorporating various levels of betel leaf extract on the quality and sensory acceptability of Hokkien noodles. Hokkien noodles incorporated with betel leaf extract (0, 5, 10, 15, and 20% based on flour weight) were prepared from wheat flour with a moisture content of 14%. The hardness, elongation, adhesiveness, color, and sensory evaluation of the noodles were then determined. Results clearly show that the incorporation of betel leaf extract at various levels led to the structural modification of the noodles and to a soft product compare to the control. However, the product scores in all sensory attributes were higher than the control scores. The sample was incorporated 15% betel leaf extract had the best acceptance quality wherein the beneficial effects of betel leaf polyphenols can be utilized.

Mathematical modeling of thin-layer solar drying of eland jerky was investigated in this study. Eland jerky was compared to traditional beef jerky, inasmuch as both were treated with traditional jerky marinade (TM), traditional marinade with honey (TMH) and compared to an untreated control (C). The influence of the marinades on the drying process was statistically significant. Based on the coefficients of determination, the root mean square errors and the chi-squares, the two-term model was found to be the most suitable model for describing the solar drying kinetics of eland jerky. The mean effective moisture diffusivities of solar dried eland meat for the C, TM and TMH samples were 2.07×10 −10 , 1.45×10 −10 and 1.43×10 −10 m 2 .s −1 , respectively. The activation energy values for solar dried eland jerky were 23.75, 26.22 and 26.97 kJ mol −1 for C, TM and TMH, respectively.

Rambutan ( Nephelium lappaceum L.) kernels contain a high amount of fat and it has a potential to be used as a new alternative source of edible vegetable fat. Drying of fat seed can improve the fat yield and prolong the seed storage shelf life. Therefore the drying behaviour of rambutan kernels was investigated using a hot air dryer for 6 h at each of three temperatures, 45°C, 55°C and 65°C. Based on the coefficient of determination ( R 2 ) and root mean square error (RMSE), modified Henderson and Pabis model was found to be the best thin-layer drying model for rambutan kernels ( R 2 > 0.99 and RMSE < 0.02). The effective moisture diffusivity of rambutan kernels, estimated from a modified equation of Fick’s second law of diffusion, was 2.56 × 10 –10 to 3.68 × 10 –10 m 2 s –1 . The result of fat extraction significantly indicates the effect of low moisture rambutan kernels on the fat yield enhancing ( P < 0.05).

In the present study, the effect of microwave power and sample amount on color change kinetics of tea leaves was investigated during microwave drying. Hunter L , a and b system was used for the color change of the materials; and the total color change (Δ E ), chroma, hue angle and browning index (BI) were calculated by using these values. The color of the tea leaves was shifted towards the darker region after the microwave drying process. The mathematical modeling study of color change kinetic showed that a , b , chroma and BI fitted to a first-order kinetic model, while L , total color change (Δ E ) and hue angle followed a zero-order kinetic model. For calculation of the activation energy for color change kinetic parameters, the exponential expression based on Arrhenius equation was used.

The hot air drying with blanching pretreatment may provide a practical method for the production of dried cherry tomatoes. The influences of drying temperature (50°C, 60°C, 70°C and 80°C) and blanching on the drying kinetics of cherry tomatoes were studied. Nine mathematical models were evaluated and the determination of coefficient ( R 2 ), chi-square ( χ 2 ) and root mean square errors (RMSE) were compared. The Logarithmic model gave best results with R 2 of 0.9992 and 0.9995 for fresh and blanched cherry tomatoes, respectively. The values of effective moisture diffusivity coefficient D eff varied in the range of 1.7281 × 10 −9 to 4.6306 × 10 −9 m 2 s −1 for the fresh cherry tomatoes, while 2.1034 × 10 −9 to 6.6487 × 10 −9 m 2 s −1 for the blanched samples. The values of activation energy were 31.99 and 36.21 kJ mol −1 for the raw and blanched cherry tomatoes, respectively. Furthermore, the effect of temperature and blanching on color change of cherry tomatoes was measured.

Fenugreek ( Trigonella foenum-graecum ) seed known for its many medicinal properties is studied for its grinding characteristics in an impact-type hammer mill. The particle size distribution (PSD) data of powder was found to regress very well with well-known mathematical Rosin–Rammler–Bennet model. Several statistical parameters of the PSD such as mass relative span, size guide number, skewness, uniformity index, uniformity coefficient were also estimated. Weight mean diameter for the entire range of grinding was between 395.8 and 620.8 µm. Specific energy consumption (32.4–115.2 kJ/kg) increased linearly with increase in size reduction ratio (4.53–7.10). Fenugreek powder fraction with less than 200 µm resulted in highest oil yield. Oil yield was found increasing with increase in size reduction ratio.

Dragon fruit ( Hylocereus polyrhizus ) peel is high in antioxidants and fiber; however, it is discarded during processing. In this study, changes in physico-chemical properties of dragon fruit peel after drum drying were determined. Ground dragon fruit peel was drum dried at 1 rpm with 2 bar steam pressure, then analyzed for physical, chemical and functional properties. The betacyanin content was twofold higher in drum-dried powder (41.55 mg/g dm) than in a fresh sample (80.21 mg/g dm), yet up to 98.62% of the total phenolic content was retained with a 3.328 mg trolox/g dm reduction in the radical scavenging activity. The density of the powder was 0.1315 g/mL with 51.44% soluble in water. The functional properties determined included water holding capacity (2.523 g water/g sample), oil holding capacity (3.565 g oil/g sample) and swelling capacity (6.233 mL/g). The results of this study indicate that drum-dried dragon fruit peel can be considered to contain potentially functional ingredients.

Curing and drying are important unit operations in turmeric processing for production of good quality products. Optimization of the process parameters for curing and microwave drying of turmeric is the need of hour for quality production of dried turmeric. These parameters were optimized by conducting trials for curing (boiling in 0.1% sodium carbonate solution for 15, 30 and 45 min) and microwave drying (power levels of 1, 1.5 and 2 kW). The cured as well as dried rhizomes were evaluated for quality parameters. The optimum boiling time for curing and power level for microwave drying of turmeric rhizomes was found to be 30 min and 1.5 kW for quality production.

A Chinese soypaste-derived fraction with potent angiotensin I-converting enzyme (ACE) inhibitory activity (IC 50 = 25.9 μg/mL) was obtained by treating soypaste extract with 80% ethanol. The result of gradient reversed-phase high-performance liquid chromatography (RP-HPLC) suggested that bioactive peptides bearing some polarity groups made a substantial contribution to the ACE inhibitory activity. By mass spectrometric analysis, a component was separated as Glu-Ser-Gly-Asp which was then found to act in a dose-dependent manner against ACE activity as a non-competitive inhibitor, with an IC 50 value of 2.297 mM.