نشریه نوآوری در علوم و فناوری غذایی
پیاپی 12 (تابستان 1391)

In this research, the Red beet juice was used at concentration 0, 1.5, 2, 2.5% and fruit flavored juice at 0, 6, 8 and 10% to increase diversity of set yogurt formulations. Sensory parameters, color, antioxidant activity and total water soluble phenols of fruit flavored set yogurt plain yogurt were evaluated during 21 day storage time. The results showed that the 6% of fruit flavored juice and 2% Red beet juice were the optimum concentration for production of fruit flavored set yogurt and this formulation showed higher acceptability compared to plain yogurt. The sensory of this formulation didn’t change during storage time. The total water soluble phenols and antioxidant activity of fruit flavored set yogurt was higher than set yogurt during storage which shows this formulation can have beneficial effects on consumer health.

There is great competition for cereal industry to improve dough properties, understanding and delaying the staling phenomenon in order to increase bread quality. To achieve those desired aims, we can use functional additives that improve bread quality. Gel improvers are novel groups of improvers that are largely used in bakery industry. Determination of the gel properties will help us to understand the gel formation process and gel profile concerning the mechanical properties. The properties of the formed gels are to be determined to have an understanding of the process of gelling, and more importantly, characterization of the gel with an emphasis on mechanical properties can lead to gelled food products. In this research, response surface methodology was used to investigate the influence of improver gel components of Barbari bread on the mechanical properties of that produced gel. Gel samples were prepared using sodium stearoyl-2-lactylate (SSL), diacetyl tartaric acid esters of monoglyceride (DATEM) and propylene glycol (PG) in the range of 0-0.5 g/100g. The results showed that hardness, gradient, cohesiveness and consistency of gel increased by increasing SSL. Thus, we can increase the elasticity of gel by control of SSL addition. PG had only an increasing effect on the viscosity index among gel properties. However, no significant difference was observed in mechanical properties of gel as a consequence of DATEM addition. Sometimes, negative quadratic and interaction effects of gel components were determined. The represented models have a high determination coefficient and could be used for predicting all investigated characteristics. The results for optimization using central composite design suggested that a mixture containing 0.5 g/100g of SSL, 0.28 g/100g of DATEM and 0.5 g/100g of PG could be a good improver gel to achieve the best characteristics.

Osmotic dehydration (OD) is the process by which there is partial removal of water from the cellular materials when these are placed in a hypertonic concentrated solution of soluble solute. Osmotic dehydration process of pumpkin was carried out at different temperature ranges 5, 25 and 50℃ with different concentrations of sodium chloride (5, 10 and 15% w/w) and constant concentration of sucrose (50% w/w). Ratio of sample to osmotic solution was chosen 1:20. Water loss and solid gain values were calculated for each temperature and concentration in different time interval. Equilibrium water loss and solid gain as well as mass transfer rate were calculated using proposed model of Azuara. The results indicated that water loss and solid gain were directly related to concentration and temperature of osmotic solution, which maximum water loss and solid gain were shown at 5℃ and 15% sodium chloride, whereas 50℃ and 15% sodium chloride didnt have a significant effect on water loss and solid gain.

In recent years application of different ingredients has been considered to improve cake quality and its nutritional properties. The effects of using different sweeteners as a sugar replacer have been evaluated in cakes and many other bread formulas, although there has not been extensive research about the usage of sugar factory's by-products such as molasses in the cake formulations. In this research, the effects of substituting 25, 50, 75 and 100% of sugar with molasses, on some cake properties, such as weight loss, moisture, water activity, texture, staling, color and sensory evaluation of final cake were studied. The results of these experiments showed that by increasing the level of substitution, firmness and staling increased and volume, weight loss, moisture and water activity decreased significantly (p≤0.05). Evaluating the color of crumb and crust showed that most of samples were darker than control, which is desirable in most cakes. According to the results, in order to increase the shelf life and improve the quality and nutritional values of industrial cakes, applying proper dosage of molasses in the formulation might be recommended.

At this study drying kinetic of kumquat fruit slabs was evaluated at 60, 70 and 80C temperature and 3, 5, and 7 millimeter thickness. Amount of effective moisture diffusivity (Deff) measured using Fic’s second low and drying process fitted by ten difference mathematical models. Results showed that Deff increases with drying temperature and thickness of slabs. The best model with the highest of fitting mid maximum of R2 and minimum of Root mean squares error (RMSE), Mean relative percent deviation(MRPD) and reduced chi - square(χ2) was midlli equation.

Achieving optimum drying conditions can affect the processing time and improvement of raisin quality. Temperature, air velocity and pretreatment are important factors in grape drying process and its quality. In this research, effect of the following conditions on quality of Black currant raisin was studied: air temperature at four levels of 50, 60, 70, and 80 ºC, air velocity at three levels of 1, 2 and 3 m/s, and four pretreatments including hot water, %5 potassium carbonate, %0.4 olive oil, %0.5 sodium hydroxide (caustic soda) and control without any pretreatment. The results showed that some factors such as air temperature, air velocity and pretreatment have qualitatively significant effects on browning index, rehydration ratio, and shrinkage. Similarly temperature and pretreatment factors have a significant effect on acidity. Raisins dried at 70ºC and pretreated in hot water, %5 potassium carbonate, %0.4 olive oil and %0.5 sodium hydroxide have better quality.

In this study, several physical and mechanical properties of hazelnut and its kernels were evaluated as a function of moisture content in 5-20% (w.b.) ranges. The physical properties of nuts and kernel such as dimensional characteristics (length, width and thickness), unit mass and geometrical properties (the geometric mean diameter, volume, surface area and projected area) increased with increasing moisture content. The sphericity of nuts and kernels decreased with increasing moisture content. The average of length, width, thickness, unit mass, the geometric mean diameter, volume, surface area and projected area and sphericity of nuts were 16.92, 17.51, 15.33, 16.55 mm, 1.95 g, 2.40 cm3, 8.63 cm2, 2.16 cm2, 93.52%, the respected value for kernels were 13.55, 13.59, 11.89, 13.00 mm, 0.92 g, 1.16 cm3, 5.02 cm2, 1.26 cm2, 92.85%. The shell ratio percent obtained 52.81%. In the mechanical test, hazelnut and its kernel were loaded between two parallel plates to determine the rupture force and specific deformation required to initiate shell and kernel rupture. These tests were carried out at two moisture contents of 5% and 10 % (w.b.) for nuts and 5% (w.b.) for kernel, and three axes (X, Y, Z) directions. The results showed that moisture content and loading direction have significant effects (P < 0.01) on the rupture force and specific deformation. By increasing the moisture content, rupture force decreased, while the specific deformation increased in magnitude. The maximum force for nut cracking occurred in the x-axis, while rupture force for kernel was in the z-axis loading directions. The average of rupture force at all loading directions for nuts was very higher than for kernels.

In this research, thin layer drying of potato slices was modeled by laboratory scale hot air convective drier. The aim of this study was investigating moisture loss kinetic and optimal mathematic Modeling of potato through regression analysis. The experimental data was processed at two temperature ranges of 65 and 70℃ in triplicates. Three standard mathematical models were fitted to empirical data and evaluation of models were analyzed by four parameters including the determination of correlation coefficient (R2), root mean square error (RMSE), chi-square (χ2) and mean bias error (MBE). The results showed that 'page' model was the best for evaluating drying stages potato slices.