Band 11, Heft 5 -

Variable diffusivity and volume of the grains are taken into account in the diffusion model that describes mass transfer in soybean hydration. The variable space grid method (VSGM) was used to consider the increase in grain size, and the diffusivity was considered an exponential function of the moisture content. An equation for the behavior of the grain radius as a function of time was obtained by global mass balance over the soybean grain and the differential equation considered that the increase in radius happens due to the influence of the convective and diffusive fluxes at the surface of the grains. The model was solved by an explicit numerical scheme which presented satisfactory results. The results showed the behavior of moisture profiles obtained as a function of time and radial position and also showed how the grain radius increased with time and changed the solution domain of the diffusion equation.

The objective of this work, based on a theoretical and experimental study, is to investigate the energy and economic performance of a totally solar drying unit with storage for aromatic and medicinal plants, to satisfy a dimensioning already carried out on a macroscopic scale for an energy request well defined: to dry a quantity of a given agricultural products during 1 day of harvest season, so between September and May, with a heat storage which relays at night. Drying experiments were conducted for spearmint grown in Tunisia. Mathematical formulation of the physical process of this solar drying unit based on conventional heat and mass transfer equations showed a certain agreement with the experimental results under climatic conditions of Tunis (Tunisia). All the experimental drying curves showed only a falling drying rate period. The main factor in controlling the drying rate was found to be the drying air temperature. It was observed that this unit is able to dry more than 2.5 kg of spearmint per day with a moisture reduction efficiency of 70%. It was found that for all the period of harvest, so for 5 months assumed dryer used per year, the payback period is 3.6 years.

Curcumin is the main gradient of “Turmeric” a famous Indian spice and food additive. The marvelous nutritional and medicinal effects of curcumin made it a good alternative to some conventional drugs and food flavoring or coloring materials. However, the low solubility of curcumin is a challenging hindrance which should be seriously addressed. In this work, we prepared nano-curcumin with enhanced aqueous dispersion and dissolution rate. Ultrasonic-assisted supercritical anti-solvent (UA-SAS) technique was used to convert the commercial curcumin to uniform distributed nano-particles with the average size of 20 nm and yielding of 65%. The effect of process parameters including pressure, temperature, solution flow rate, and nature of organic solvent on the average particle size and yielding of products was investigated. The morphology, size, and crystalline pattern of processed curcumin particles were characterized by scanning electron microscopy, mean particle size analyzer, and X-ray diffraction. The champion specimen was achieved when the supercritical fluid was employed at 16 MPa and 35°C. Aqueous suspension of processed nano-curcumin can be stable for more than 2 months. In vitro dissolution experiments showed a remarkable enhancement in dissolution rate of UA-SAS-treated curcumin respecting to the commercial curcumin powder.

β-Cyclodextrin inclusion complexes with trans -Cinnamaldehyde (β-CD–CIN) were manufactured with various self-assembly conditions. The encapsulation efficiency of the β-CD–CIN was >90%. Interestingly, the β-CD–CIN had high retention of CIN (>80%) during assembling time at higher β-CD concentration. CIN was released fastest from lowest β-CD–CIN and molar ratio of CIN. In the microscopic observations, higher-concentration β-CD complexes were larger and more easily aggregated. Many individual particles became aggregated or combined with each other to form a single particle. The concentrations of the wall material and core material as well as the self-assembly or storage time affected characteristics of the inclusion complexes.

The purpose of this study was to determine the effects of amount of batter in paper baking cup on the quality characteristics of three different muffin samples. Volume index, volume and muffin yield values increased with the increase in batter amount in baking cup, whereas upside shrinkage value and weight loss values decreased linearly. Moreover, batter weight affected the scores of sensory properties of different muffin samples. Muffins prepared with 70 g of batter gave the highest scores for appearance, crumb grain, and overall acceptability. It was found that putting optimum amount of batter in baking cup was critical to obtain expected product quality characteristics. None of the muffins prepared by using 50, 60, 65, 80 g of batter were acceptable in terms of their quality. In conclusion, muffins were satisfactorily improved in terms of physical, structural, physicochemical, and sensory properties by using 70 or 75 g of batter weight for the baking cup used in the study.

The effect of tapioca starch (TS) on the pasting and thermal properties of wheat flour (WF)-based batter and on the quality of fried, battered chicken wingsticks was investigated. A dry mix (91.4% WF/TS flour blend (100/0, 75/25 and 50/50), 3.1% leavening agent and 5.5% salt) was mixed with water (1:1.3) for batter preparation. The peak viscosity of the diluted batters increased with increasing TS replacement whereas the peak time and viscosity after holding at 95°C for 4 min decreased. Substitution of TS in the WF-based batter decreased pickup but increased the onset and conclusion temperatures from differential scanning calorimetry. A lower oil content was observed in the pre-fried crusts containing TS which was expected from the gelatinization behaviour of the batters. The TS substitution enhanced both the lightness and crispness of the final fried crust and the liking scores of the fried, battered chicken wingsticks. The results suggest that TS substitution modified the gelatinization behaviour of the WF-based batters affecting the oil uptake and quality in the fried battered products.

The present work studies the removal of colored components from date syrup by activated carbon powder. The clarification process was carried out at an experimental batch set up and the role of activated carbon content, temperature and residence time was investigated on adsorption efficiency. The experimental data were analyzed by intra-particle diffusion, pseudo first- and second-order models. The adsorption capacity of activated carbon increases with increase of process temperature. Adsorption kinetics could be best modeled by the pseudo second-order model. Also, Langmuir isotherm describes the equilibrium data variation better than Freundlich and Temkin equations. The feasibility of adsorption was evaluated by measuring color removal at three temperatures and Van’t Hoff equation was used for computation of Gibbs energy. Thermodynamically, the process is endothermic accompanied with increase in randomness and decrease in Gibbs energy. Finally, the optimum temperature for clarification of date syrup was determined to be 50°C.

Angiotensin converting enzyme (ACE)-inhibitory activity in water soluble extracts (WSEs) of kefir was investigated. Kefir was produced traditionally using kefir grains and stored at refrigerated temperature for 20 days. During storage period (on 1, 5, 10, 15 and 20 days) in vitro ACE-inhibitory activity in WSEs was determined. ACE was purified from human plasma to determine kinetic parameters. Purified ACE had a specific activity of 20.75 EU.mg −1 , a yield of 16.6% with a factor of 22100. The inhibition effects of kefir on ACE increased at 15 storage days than other storage days. Some microbiological and physicochemical characteristics of kefir were also studied. Counts of presumptive LAB on M-17 and presumptive LAB on MRS in the kefir were about 10 8 CFU.ml −1 throughout the storage period. Yeast counts were lower than lactic acid bacteria counts and the average of the counts was approximately 10 6 log CFU.ml −1 . Storage period had a significant effect ( P < 0.05) on titratable acidity and pH values. On the contrary, it had no significant effect ( P > 0.05) on viscosity and serum separation values of kefir.

This study quantifies the drying characteristics and quality attributes of culinary banana at various temperatures (40–70°C) which exhibited falling rate period. Among the different drying models, Wang and Singh model was found the best fitted model with lowest Ӽ 2 and highest R 2 values. The coefficients of Wang and Singh model were expressed in nonlinear form as a function of temperature and a new model was developed in which moisture ratio is expressed as a function of time and temperature. Effective moisture diffusivity increased with increase in drying temperature. Scanning electron micrographs showed that samples dried at 70°C produced larger pores which resulted in better rehydration ratio and minimum hardness. The nonenzymatic browning occurred faster at 70°C and in addition, the chemical properties were not significantly affected by drying temperatures.

The influence of particle size (PZ) and processing temperature (PT) on quality attributes and processing time of pumpkin cubes packaged in glass jars were evaluated during their pasteurization. Second-order polynomial models were developed for the following responses: texture retention (TR), total colour change (TCC) and heating time (HT), using multiple linear regression for a range of operating conditions (20–30 mm and 85–100°C for PZ and PT, respectively). A combination of the polynomial models with the methodology of desirability function was used for optimization of the pumpkin pasteurization process. The obtained optimal conditions were 20 mm and 100°C for PZ and PT, respectively; in order to obtain TR of 82.21%, TCC of 7.54 and HT of 44.97 min. However, these optimal conditions change to 100°C and 21 mm and the responses obtained are TR of 73.60%, TCC of 7.52 and HT of 39.66 min, when the processing time is prioritized.

The objective of this study is to investigate the drying kinetics of Yarrow, Coriander and Hollyhock flowers. These three medicinal products were dried using a solar hybrid photovoltaic-thermal dryer. The drying process was examined at the air temperatures of 40°C, 50°C and 60°C and air velocities of 0.5, 1 and 1.5 m/s. The experimental drying data were fitted to different theoretical models to predict the drying kinetics. Nonlinear regression analysis was performed to relate the parameters of the model with the drying conditions. The performance of these models was evaluated by comparing the correlation coefficient (R2$${R^2}$$), root mean square error (RMSE) and the chi-square (χ2$${\chi ^2}$$) between the observed and the predicted moisture ratios. Among all the models, the exponential two-term was found to have the best fit in this study. Also the influence of plant type, air temperature and velocity was investigated.

Thin-layer air impingement drying kinetics of American ginseng slices were investigated under different drying temperatures (35, 40, 45, 50, 55, 60, and 65°C), air velocities (3, 6, 9, and 12 m/s), and sample thicknesses (1, 2, 3, and 4 mm). Results indicated that the drying time is more significantly affected by drying temperature followed by sample thickness and air velocity. Drying rate curves illustrated that the whole drying process happened in the falling rate period. Additionally, from initial drying to the moisture content of about 0.5 kg/kg, the drying rate increased with the increase of drying temperature and air velocity or decreased with the increase of sample thickness. The moisture effective diffusivity ( D eff ) was determined both neglecting shrinkage and considering shrinkage. The drying activation energy of American ginseng slices was 46.64 kJ/mol determined by Arrhenius relationship. The moisture effective diffusivity and drying activation energy of American ginseng slices were compared to other biomaterials and related issues were also discussed. The current work is useful for designing air impingement drying system, evaluating and saving energy consumption of American ginseng slices.