نشریه پژوهش های علوم و صنایع غذایی ایران
سال دوازدهم شماره 6 (پیاپی 42، بهمن و اسفند 1395)

Lemon verbena leave is a flavoring food additive as well as a good source of valuable compounds such as essential oils, flavonoids and phenolic acids. However, similar to many other aromatic plants, lemon verbena leave is perishable due to its high moisture content. The aim of this work was to study the effect of air temperature (45, 55, and 65°C) on the quality attributes of lemon verbena leaves during hot-air drying (HAD). The drying kinetics were also modeled. The results showed that higher drying temperature led to a significant decrease (p˂0.05) in the rehydration ratio due to a change in the structural features of the dried leaves. The essential oil content of dried samples was also significantly different (p˂0.05) from that of the fresh leaves due to high loss of volatile components and ranged from 0.42 to 0.85. Moreover, a significant increase in the value of effective moisture diffusivity (Deff) and color change was observed when the samples were dried at 65°C compared to 45°C. The value of Deff varied from 1.140×10-10 to 2.280×10-9 m2/s and the activation energy was found to be 31.04 kJ/mol. The greatest R2 (≥0.999) and the lowest RMSE and SSE were obtained for the Naghavi et al. model (proposed in this research)

Sensory evaluation of food materials is an important factor to choose and even produce new formulations. Being time consuming, results in being difficult to interpret and the necessity to educate specialists make these methods kind of impractical. In this study, we have made an effort to introduce physical properties as a substitute for sensory evaluations in a semi solid food such as chocolate pudding. Higher reliability, reproducibility and higher pace are among some of the advantages of instrumental measurements. Thus, if sensory evaluation can be predicted based on physical properties solely, besides increasing the inspection pace, they would be available to be used online. The obtained results can also be used in designing new products for special consumers such as the dysphasia patients. The results showed that parameters such as shear viscosity, plastic viscosity, yield stress, extensional viscosity, apparent modulus and adhesive force can be used to design and produce new materials; they make sense beside each other though. In this way, the products which have been designed for the patients with swallowing difficulties should have suitable texture in mouth and also good swallow ease.

Natural materials are complicated compositions; therefore, a rapid screening of the active antioxidants is being challenged in the literature. Different polarity solvents were applied to isolate four fractions (F1, F2, F3 and F4) of methanolic extract of Cuminum cyminum. Their anti-oxidative properties were tested using radical scavenging and FRAP assays. F3 (with IC50=0.006mg/mL and FRAP= 521.95 mmolFe2) was significantly the most active fraction. Guided isolation through bio-autography on TLC using 1, 1- diphenyl- 2 – picryl- hydrazyl radical (DPPH) as a detection reagent led to the isolation of two antioxidant compounds from F3. F3 was injected to a preparative HPLC with the proper mobile phase (acetonitril: methanol/ water) and isolated two main compounds. These compounds were identified as Luteolin 7 glugoside and Apigenin 7 glucoside by means of 1HNMR and 13CNMR and compare them with references.

In this study, microwave drying conditions of quince pomace optimized with respect to quality attributes (moisture content, color change and consumer acceptance). Response surface methodology (RSM) technique was used to develop models to respond to the microwave power (100, 2000, 300 W), and microwave time (5, 10, 15 min). The models obtained from the responses were adequate and acceptable because the coefficient of determination R2 of the models was relatively high. Microwave power of 200W and microwave time of 8 minutes were concluded as the optimum conditions prior to air-drying at 50°C. To describe the drying process, the experimental data for moisture loss was converted to moisture ratios. The effective moisture diffusivity increased with increase in microwave power and its values varied from 1.83-4.87×10-9 m2/s. Using an exponential expression based on Arrhenius equation the activation energy and was found to be 16.41 W/mm.

In this research, an experimental and modeling study on mass transfer analysis during infrared drying of quince was undertaken. In the experimental part, the effects of various drying conditions in terms of infrared radiation power (150-375 W) and distance (5-15 cm) on drying characteristics of quince were investigated. Both the infrared power and distance influenced the drying time of quince slices. Moisture ratios were fitted to 8 different mathematical models using nonlinear regression analysis. The regression results showed that the logarithmic model satisfactorily described the drying behavior of quince slices with highest R value and lowest SE values. The effective moisture diffusivity increases as power increases and range between 1.15 and 3.72 ×10-8 m2/s. The rise in infrared power has a negative effect on the ΔE and with increasing in infrared radiation power it was increased. Chroma and hue values were in ranges between 43.28 and 46.99, 80.82° and 86.14°, respectively.

Adaptive neuro-fuzzy inference system (ANFIS) and genetic algorithm-artificial neural network (GA-ANN) were used for modeling of the hot-air drying kinetics of papaw slices. The ANFIS and GA-ANN were fed with 3 inputs of drying time (0-320 min), drying temperature (40, 50 and 60 °C) and slice thickness (3, 5 and 7 mm) for prediction of moisture ratio (MR). The triangular membership functions (MFs) were applied and 27 rules were provided for the ANFIS designing. The developed ANFIS predictions were close to the experimental data (R2 = 0.9967 and RMSE = 0.0161). The optimized GA-ANN, which included 7 hidden neurons, predicted the MR with a good precision (R2 = 0.9936 and RMSE = 0.0220). The effective diffusivity for papaw slices was within the range of 6.93 ×10-10 to 1.50×10-9 m2/s over the temperature range. The activation energy was found to be 32.5 kJ/mol indicating the effect of temperature on diffusivity.