Mohammad Javad Golieh; Mohammad Goli
Abstract
Introduction: Recently, the prevalence of diseases related to diabetes, hypertension, and obesity, due to high and persistent consumption of sucrose is increasing rapidly. Concerns about the adverse effects of sugar consumptionon one hand, and manufacturers and consumers attention for natural sweeteners ...
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Introduction: Recently, the prevalence of diseases related to diabetes, hypertension, and obesity, due to high and persistent consumption of sucrose is increasing rapidly. Concerns about the adverse effects of sugar consumptionon one hand, and manufacturers and consumers attention for natural sweeteners to replace sugar, on the other hand, reveal that innovative approaches are needed to help develop a healthy diet which prevents such diseases. Stevia can be introduced as a good replacement for sucrose. Corchorus olitorius L. is a rich source of bioactive compounds such as protein, fiber, vitamins, minerals, sterols, tocopherols, and carotenoids, which has significant antioxidant, antibacterial, antifungal, antiviral, anti-inflammatory and anti-cancer properties. This study aimed to reduce the sugar level in Luz preparation and produced a high nutritive product by using Corchorus olitorius. Materials and methods: Materials used in Luz formulation consisted of isomalt, sorbitol, coconut powder, pistachio powder, cardamom, cinnamon and chlorophyll, stevia, and Corchorus olitorius were supplied from Salamat-gostaran arayan Co. All chemicals were from Merck Co. The formulations of Luz include sorbitol (29.68%), sugar (25.85%), coconut powder (38.75%), cardamom (0.3%), cinnamon (0.26%) and chlorophyll (58.5%). 2) were selected, and isomalt was used as filler. To produce Luz, the mixture of sorbitol and isomalt was heated to reach boiling temperature and complete dissolution. After the heat treatment (126°C for 1h), the mixture was cooled to 40°C and the other materials were added and mixed. The prepared samples were molded and placed at 15°C for 3 h. Moisture, ash, protein, fat, and sugar were determined according to AACC standard numbers. The density was also determined according to AACC standard number 54-21. Textural properties were determined using a texture analyzer. Atomic Spectroscopic measurement of minerals was performed according to Devatkal et al. (2004). The color evaluation was performed by the Image Processing method. In this study, the effects of Stevia replacement with sugar (0-100%), Corchorus olitorius replacement with pistachio powder (0-100%) and cooking temperature (50-70°C) on physical and textural properties (density, hardness) of Luz were investigated. Formulation optimization of enriched dietary Luz was performed using Response Surface Method in the form of a central composite design with 6 central points and two replications (α=2) in other locations. In optimum condition, the results of physicochemical, textural and color properties were analyzed by SPSS software. Results and discussion: The linear model was suggested for density changes, and independent effect of variables (stevia replacement, Corchorus olitorius replacement, cooking temperature), interaction effect of Stevia and Corchorus olitorius replacement, interaction effect of Corchorus olitorius replacement and cooking temperature, the quadratic effect of Stevia replacement and the quadratic effect of cooking temperature were significant on density (P <0.05 or P <0.001). The density of all treatments increased with increasing the levels of Stevia and Corchorus olitorius replacement. An increase in density was observed with increasing cooking temperature. The interaction effect of Corchorus olitorius and cooking temperature caused a significant (P<0.05), decrease in hardness. A reduction in the level of stevia replacement resulted in a decrease in hardness. The optimum formulation of dietary Luz was introduced containing 25% Stevia, 25% Corchorus olitorius and cooking temperature of 65°C, and 55% Stevia, 75% Corchorus Olitorius and cooking temperature of 55°C. Overall, the nutritional value of dietary Luz containing Corchorus olitorius was improved in terms of protein, ash, magnesium and calcium content. The total sugar content of the optimum samples was significantly lower than the control. The textural characteristics of the optimum samples had not changed significantly.
Shahram Beiraghi-Toosi; Mohebbat Mohebbi; Mehdi Varidi
Abstract
Introduction: Extrusion is one of the technologies used for solid foams production. In this process, pressure is the most important parameter and the most important variables affecting pressure are feed mixture, die diameter, barrel temperature and screw speed. A reduction of die diameter or plasticizer ...
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Introduction: Extrusion is one of the technologies used for solid foams production. In this process, pressure is the most important parameter and the most important variables affecting pressure are feed mixture, die diameter, barrel temperature and screw speed. A reduction of die diameter or plasticizer contents such as moisture and fats in the feed mixture or an increase in the screw speed or barrel temperature can increase the extruder barrel pressure. Also, the increased barrel temperature, in addition to changing cooking properties, escalates the temperature difference inside and outside of the die, raising the rate and amount of evaporation from melted mixtures, therefor affecting the solid foam structure and characteristics. On the other hand, the type and amount of feed mixture components are key factors affecting the extrudate properties (Moraru et al., 2003; Plews et al., 2009; O’Shea et al., 2014).
Sesame seed is one of the ancient edible oil seeds used in many food products. In addition to oil, it contains carbohydrate, protein and fiber (Namiki et al., 2001) which can provide a variety of compounds in the feed mixture to change the properties of foam. This study investigates the effect of partial replacement of corn starch with edible oil seed containing a mixture of various compounds and the effect of the extrusion process on the changes in the physicochemical properties of the produced solid foam relative to the foam produced from corn starch. In this regard, different proportions of sesame seeds were added to the corn starch with specific moisture contents, and following the application of the extrusion process, the effect of feed mixture, operation temperature, screw speed and die diameter on physicochemical properties of solid foams was evaluated.
Materials and methods: Solid foams made from corn starch with 0, 10, 20 and 30 percent of sesame seed in the formulation and 15 percent of moisture content were processed in a co-current twin-screw extruder at a screw speed of 120, 150 and 180 rpm, a barrel temperature of 120, 145 and 170°C, a die diameter of 2.5 and 4 mm, and a constant feed rate of 40 kg per hour. A completely randomized design was employed to investigate the effect of these variables on chemical and physical properties of extruded products. The moisture content of samples was measured using oven method at 105°C (AOAC, 1990). Water absorption and water solubility indices were measured through solving the sample powder in distilled water, which was followed by centrifuging, weighing gel, drying supernatant and weighing dried matter (Singh et al., 2015; Huang et al., 2014). In addition, particle density was measured using the rapeseed displacement method (Singh et al., 2015) and solid density was calculated by the weight /volume ratio of the sample powder, as measured by the gradient cylinder (Ushakumari et al., 2004; Yagci et al., 2008). The porosity of samples was measured in terms of the ratio of particle density to solid density (Plews et al., 2009; O’Shea et al., 2014) and the radial expansion ratio was calculated in terms of the ratio of sample diameter, as measured by the caliper, to die diameter (Chanlat et al., 2011; Huang et al., 2014).
Results and discussion: Results showed that adding 10% sesame seed, due to the variety of compounds and their increased interactions, produced foams of maximum expansion and porosity, and minimum particle density. Adding 30% sesame seed had an opposite effect due to increased fat content and reduced pressure effect on the melted mixture in the barrel. Moreover, increased die diameter demonstrated augmented residual moisture content, water absorption index, density and porosity, as well as decreased water solubility index and expansion ratio of solid foams caused by pressure reduction on the melted mixture in the barrel. The increased barrel temperature was associated with greater changes in cooking, escalated temperature difference between inside and outside of the die and production of foams with higher water solubility index and expansion ratio, as well as lower residual moisture content, water absorption index and solid density. The higher screw speed increased the applied energy, and despite decreasing the time of temperature effect, produced foams with properties comparable to those caused by temperature increase.
In general, it can be stated that the process factors that raise the energy applied to the extrusion material leads to the increased water solubility index and the expansion ratio of the solid foams and decreased residual moisture, water absorption index and density. Consequently, by selecting the right type and amount of feed mixture to create proportions in various compounds and determine the appropriate process conditions, solid foams with desired properties can be produced by means of extrusion using available raw materials.
Fatemeh Heidari Dalfard; Masoud Taghizadeh; Seyed Mohammad Ali Razavi
Abstract
Introduction: Malt extract is one of the malt products obtainedfrom concentrations of water soluble extract of grains such as barley and is a proper alternative to white sugar. It has a high diastasis properties andcontainshigh amount of different vitamins specially the group of vitamin B as well as ...
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Introduction: Malt extract is one of the malt products obtainedfrom concentrations of water soluble extract of grains such as barley and is a proper alternative to white sugar. It has a high diastasis properties andcontainshigh amount of different vitamins specially the group of vitamin B as well as high amount of fermentable sugars. Therefore, malt extract has high nutritional value and is recommended by nutritionist for children and people who are having growth problems. In addition, it has a high potential to be used as sweetening agent in different food products such as cookies, biscuits, ice cream, chocolates etc. Knowledge on the thermo-physical properties of malt extract such as density, specific heat, thermal conductivity as well as thermal diffusivity is highly necessary for the designing of processing equipments, formulation of derived products, heating and chilling processes, and other unit operations such as pasteurization, concentration, dehydration as well as final safety and quality of formulated products. Since, no research work has been reported on thermo-physical properties of malt extract, the aim of this study was to determine different thermal properties of malt extract as well as investigation of the effect of temperature and soluble solid contents (SSC) of the studied properties.Materials and methods: Barley malt was purchased from local market. 150 gr of malt was first grounded and added to 600ml water at 46°C and stored for 30 minutes. Then, its temperature was increased using a heater to reach 70°C. 300 ml water was then added to the mixture and stored at 70°C for 60 minutes. Then, the mixture was cooled at room temperature and filtered to gain a sweet solution. The obtained solution was concentrated to 60, 70 and 80 degree of Brix for further experiments.Specific heat and thermal conductivity of samples were determined using a differential scanning calorimeter (DSC). DSC is a powerful tool which is able to spontaneously measure different thermal propertiesof samples such as specific heat, thermal conductivity, glass transition temperature, melting point, crystallization point etc. as a function of time and temperature at the desired temperature levels. Density of samples was also measured using a 50ccvolumetric pycnometer. 25 grams of samples were first solved in hot water and then were placed in an isothermal bath to measure the density. Thermal diffusivity of samples was determined using the following equation:∝=k/〖pC〗_p Results and discussion: The obtained results on specific heat measurement showed that decreasing SSC from 80 to 60% and increasing the temperature from 25 to 90°C would increase cp from 2.074 to 3.063 kJ/kg°C in a linear manner. Following equations were obtained to predict specific heat as a function of temperature:C_p=2.756+0.004T R^2=0.893 ، X_s=60C_p =2.245 +0.005T 〖 R〗^2=0.868، X_s=70C_p=2.066 +0.001T R^2=0.75، X_s =80Thermal conductivity measurements were also showed that decreasing SSC from 80 to 60% and increasing temperature from 25 to 90°C would increase the K values from 0.1196 to 0.347 W/m°C in a linear manner. Increasing temperature would increase molecular movements and therefore it elevates the heat transfer velocity and K increases. Following equations were obtained to predict thermal conductivity as a function of temperature:K=0.152 +0.003T R^2=0.761، X_s=60K =0.097+0.002T R^2=0.851، X_s=70K=0.114+0.001T R^2=0.706،X_s =80In order to develop a model to predict thermal conductivity of malt extract based on its soluble solid content and temperature, multiple regressions was used. The obtained model was a two-parameter linear model with R2 of 0.858. The results showed that 1% increase in soluble solid content percentage would cause an increase of 6% in K, while 1% increase in temperature would cause only 49% increase in thermal conductivity value.Density measurements were also showed that increasing density from 60 to 80% and temperature from 25 to 90°C would increase density of malt extract. Following equations were obtained to predict density as a function of temperature:P=1328.699-0.402T R^2=0.999، X_s=60 P=1375.451-0.290T R^2=0.999، X_s=70 P=1426.201-0.286T R^2=0.998،X_s =80Thermal diffusivity of samples was also determined using indirect method for soluble solid content of 60 to 80 and in the temperature range of 25 to 90°C. It was found that thermal diffusivity would increase linearly by decreasing soluble solid content and increasing temperature. Following equations were obtained to predict thermal diffusivity as a function of temperature:∝=5.176〖×10〗^(-8)+0.049×〖10〗^(-8) T R^2=0.783، X_s=60∝=2.993×〖10〗^(-8)+0.050×〖10〗^(-8) T R^2=0.929، X_s=70∝=3.125×〖10〗^(-8)+0.036×〖10〗^(-8) T R^2=0.94،X_s =80The results of the present work were in agreement with the results reported by other researchers confirming that both SSC and temperature have significant effect on thermo-physical properties of malt extract.
Food Engineering
Seyed Mohammad Ali Razavi
Abstract
Viscosity (µ) and density (ρ) are important physical roperties for analysis of membrane processes performance and for designing a new membrane process. In addition, the energy requirement for fluid pumping is depend on these two physical properties magnitiude. In this study, firstly, the effects ...
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Viscosity (µ) and density (ρ) are important physical roperties for analysis of membrane processes performance and for designing a new membrane process. In addition, the energy requirement for fluid pumping is depend on these two physical properties magnitiude. In this study, firstly, the effects of different process factors such as transmembrane pressure (51, 101, 152, 203 and 253 kPa), temperature (30,40 and 50ºC) and the effects of physico-chemical properties such as milk pH (6.67, 6.43, 6.25 and 5.97), milk fat percent (0.09, 1.19, 2.4, 3.26) on the viscosity and density of permeate have been considered. Two linear multiple regression models were then developed by Sigmastat software for prediction of µ and ρ during milk ultrafiltration. The experimental results showed that µ and ρ decreased as fat percent or temperature increased. pH had no considerable effect on µ and ρ. Furtheremore, increasing transmembrane pressure to 152 kPa led to an increase in both µ and ρ, while further increasing to 253 kPa resulted in a decrease in both µ and ρ. The statistical modeling results showed that the viscosity is only significantly depend on temperature and there was an excellent agreement between actual and predicted data (R=0.976), whereas the density is siginificantly depends on both temperature and fat percent and there was a good agreement between experimental and predicted data (R=0.904).
