Food Technology
Delaram Hami; Mohammad Goli
Abstract
Introduction: Ice cream contains a mixture of milk components, sweeteners, stabilizers, emulsifiers, and flavorings. The quality of the finished product depends not only on the processing conditions or the freezing efficiency, but also on the constituents, the amount of entrapped air, and the number ...
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Introduction: Ice cream contains a mixture of milk components, sweeteners, stabilizers, emulsifiers, and flavorings. The quality of the finished product depends not only on the processing conditions or the freezing efficiency, but also on the constituents, the amount of entrapped air, and the number of ice crystals. The physical structure of ice cream has a significant effect on the melting properties (melting rate) and texture (hardness) of ice cream (Mouse & Hartel, 2004). The improvement and expansion of the ice cream structure are attributed to the macromolecules present in the ice cream mixture; milk fat, protein, and carbohydrates (Adapa et al., 2000). Quinoa as a high biologically valuable protein can be used in various food products to enrich and positively affect the physical and sensory properties of the product (James, 2009). The purpose of the present study was to replace skim milk powder with quinoa flour (0 to 100%), hydrogenated vegetable oil (4.5 to 8.5%) and Panisol gum (0.25 to 0.65%) to obtain the optimal formulas of Vanilla ice cream using the response surface methodology. Materials and Methods: After adjusting the ratio of the ingredients in the various ice cream formulations, the amount of raw material of each formula was weighed. The milk was then heated to about 45 ° C, and then the remaining ingredients were slowly added and thoroughly mixed. The mixture was then pasteurized at 85 °C for 15 minutes. After the pasteurization operation, the mixture was immediately kept in a water-ice bath and cold down for 4 hours in a 4 °C refrigerator. After the ripening step, the mixture went through the freezing phase in a homemade ice cream maker. The ice cream samples were packed in plastic containers and stored at -18 °C for the period of hardening. To optimize the process conditions, the independent variables A (quinoa flour replacement from 0 to 100%), B (hydrogenated vegetable oil from 4.5 to 8.5%) and C (Panisol gum from 0.25 to 0.65%) were selected at five levels. To obtain optimal points, 34 experiments were recommended by design expert software. The volumetric overrun (%) and the melting rate (g/min.) were measured according to Hashemi et al., (2015) method. Ice cream textural properties were tested after 3 days storage at -18 °C using a Brookfield texture analyzer. It was equipped with a cylindrical probe with a diameter of 6 mm and a height of 15 mm. The probe was applied to the test samples twice at a speed of 1 mm / s and up to 50% of the probe height and the results were recorded by device software. Ice cream textural data used in this study included hardness (g) and adhesiveness (g. sec) (Hashemi et al., 2015). Results and Discussions: Reducing overrun of ice cream samples by increasing the replacement levels of quinoa flour can be attributed to an increase in the viscosity. As viscosity increases, due to the reduced mixing ability of the ice cream mixture, the ability of air to enter the mixture of ice cream containing quinoa flour has been reduced during freezing (Gelroth et al., 2001). The reason for the decrease in the melting rate of ice cream with increasing percentage of quinoa flour replacement can be attributed to the existence of polysaccharide compounds with high water holding capacity, which led to increase the product water intake intensity and viscosity and subsequently decreasethe overrun. One of the factors affecting the melting properties is the increase in volume. In addition, the role of quinoa flour in enhancing the melting resistance of ice cream can be attributed to the type of protein content, the emulsifier potential and the surface active properties of its proteins and lipids. The presence of high amounts of protein in quinoa flour has a significant effect on the stability of air molecules. Since quinoa flour contains high amounts of protein, this fraction of flour quinoa protein, increases the hardness of ice cream through creating hydrogen bonds between the amide-hydroxyl and hydroxyl-carbonyl groups with other polar groups of other ice cream components such as panisol gum. In addition, hydrogen bonds are likely to be formed by electrostatic interactions between the quinoa protein groups of the polar with the polar part of the gum panisol, which may also be the reason for the increased hardness of the ice cream in the presence of the quinoa flour. With polar groups, quinoa flour traps the water in its structure and ultimately increases the consistency and adhesiveness of the ice cream. It is also possible that the protein portion of quinoa flour binds to the water molecules present in the sample through hydrogen bonding and ion-dipole and dipole-dipole interactions, thereby reducing water activity, increasing sample adhesiveness (Fatemi, 2008). The optimal formulas were predicted for replacement of skim milk powder with quinoa flour at 25 and 53%, hydrogenated vegetable oil 8.5 and 8.2% and panisol gum 0.39 and 0.48%, respectively.
Negin Zangeneh; Hassan Barzegar; Behrooz Alizadeh Behbahani; Mohammad Amin Mehrnia
Abstract
Introduction: Spirulina platensis belongs to the Division of Cyanobacteria and the family of Oscillatoriaceae. It is autotroph and photo-synthesizer and can be reproduced through double cell division. Spirulina platensis is a filamentous blue-green multi-cellular microalgae naturally occurring in the ...
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Introduction: Spirulina platensis belongs to the Division of Cyanobacteria and the family of Oscillatoriaceae. It is autotroph and photo-synthesizer and can be reproduced through double cell division. Spirulina platensis is a filamentous blue-green multi-cellular microalgae naturally occurring in the tropical and alkaline lakes of America, Mexico, Asia and central Africa. It contains unique and extraordinary nutrients which can be used in the production of functional foods. Among bakery and flour products, cake has a relatively high diversity and long shelf-life and is famous among a variety of people, especially children. Since the knowledge associated with the enrichment of sponge cake, as a popular product among different communities (in particular, children) is limited, the aim of the present research is to produce a sponge cake enriched with spirulina platensis, and to examine its nutritional, physicochemical and sensory properties. Materials and methods: In this research, the effect of Spirulina platensis at four levels (0, 0.5, 1 and 1.5%) was investigated on the nutritional properties (protein, fat, iron, zinc and copper contents), physicochemical properties (moisture content, pH, total phenol content, antioxidant potential, textural properties and color indices) and sensory attributes (odor, color, texture, flavor and taste, chewiness and total acceptance) of the sponge cake samples prepared with wheat flour. Results and discussion: Results showed that algae powder was rich in protein (56.33%) and iron (13.18 ppm). The addition of Spirulina platensis to the sponge cake caused reduction in its moisture content during storage (days 1, 5 and 10). The results also revealed that the different levels of algae addition brought about significant differences in the moisture content of the samples (p<0.05). The results also indicated that the protein, fat and mineral contents as well as other nutritional properties of the sponge cake increased as the algae content was elevated. The total phenol content of the cake samples was also raised with an increase in the algae powder level, compared with the control. This could be attributed to the large amounts of phytochemical and biological active substances such as flavonoids, sterols and other phenolic compounds. The results demonstrated that the porosity values of the control and the sample containing 1.5% of the algae were not significantly (p<0.05) different. The percentage of porosity was equal to 24.94, 37.99, 33.39 and 27.81 in the control and the samples containing 0.5, 1 and 1.5% of Spirulina platensis. Overall, the sample with 0.5% of the algae and the control had the highest and lowest porosity percentage respectively. As the algae level rose, the textural parameters (hardness, cohesiveness and gumminess) of the sponge cake increased on days 1, 5 and 10 of the storage period. The colorimetry results showed that the effect of Spirulina platensis was significant (p<0.05) on color parameters (L*, a* and b*). Sensory evaluation revealed that the sponge cake with 0.5% of the microalgae was the most acceptable among the samples. The green color of the cake crumb was attractive to the panelists and a comparison between the total sensory scores indicated that the incorporation of Spirulina platensis into the sponge cake was desirable from the panelists` points of view. The results of this study demonstrated that the addition of Spirulina platensis to sponge cake for the enrichment of this product, caused an increase in its protein and mineral contents, antioxidant potential, in addition to other functional ingredients naturally occurring in this algae. The results revealed that different levels of this algae (0.5, 1, and 1.5%) did not significantly affect the cake texture, however, had a significant impact on its color. Incorporation of Spirulina platensis into sponge cake reduced its L*, a* and b*, which was highly noticed by the panelists. Therefore, it can be declared that enrichment of sponge cake, as a popular product among different people of societies, particularly children, is a desirable and easy way of transferring the useful and valuable compounds of this algae to human.
Amir Jajarmi; Bahareh Emadzadeh; Rassoul Kadkhodaee
Abstract
Introduction: Carrageenans are a family of linear sulphated polysaccharides that have broad applications in the food sector and pharmaceutical industry. Based on the degree of sulphation (polyelectrolytes) in carrageenan, only Kappa and Iota carrageenan have the ability of forming a gel structure. The ...
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Introduction: Carrageenans are a family of linear sulphated polysaccharides that have broad applications in the food sector and pharmaceutical industry. Based on the degree of sulphation (polyelectrolytes) in carrageenan, only Kappa and Iota carrageenan have the ability of forming a gel structure. The mechanical characteristics of their gels, however, is affected by the polyelectrolyte nature of their chains. Iota and kappa carrageenan provide elastic soft gel and brittle rigid one, respectively, in the presence of calcium and potassium salts as their favored ions; while their mixture provides a broad range of structures with unique textures. The combination of these two biopolymers would result in a broad range of unique textures for different applications. The aim of this Study was to determine the effect of chain association (molecular association) on the textural properties of kappa- Iota carrageenan mixed gel. The texture of gels was investigated through the puncture test to determine some properties including hardness, toughness, deformability modulus, resilience, yield point, and proportional limit. In addition, the stress relaxation test was applied to evaluate the effect of the chain association formed in the network on the stress decay parameter.
Materials and Methods: A commercial Kappa-carrageenan, Genugel type, and Iota- carrageenan, Genuvisco type without further purification were purchased from CP Kelco (Lille Skensved, Denmark). Potassium chloride (KCl) and calcium chloride dihydrate (CaCl2•2H2O) of analytical grade were purchased from Merck company. The mixtures were prepared in 2:1, 1.5:1.5 and 1:2 ratios and the final concentration of 0.3% w/w biopolymer. Both calcium and potassium chloride were added using a strategy adopted for each salt for keeping the same ionic strength of molar concentrations of 2.5, 5 and 7 mmol in the biopolymer dispersions. The mechanical properties of the gels were investigated using an XT. T2 Texture Analyzer (Stable Micro Systems, Surrey, UK). Peltier system was utilized in adjusting the temperature at 4oC. The samples were equilibrated at least 10 min before performing the test. Crosshead speed was adjusted at 10 mm/min to a 12 mm depth (50% from total length) from the surface of the samples using a 1 mm diameter cylindrical aluminum probe for puncture test and a 2 mm/min crosshead speed using a 75 mm diameter cylindrical aluminum probe in 20% strain was applied for the stress relaxation test during 60 second time interval. Pleg and Normand equation was applied for the determination of viscoelastic properties of samples.
Result & discussion: Among different methods in the mechanical study of biopolymer gel, the puncture test is a promising method due to its ability in applying normal and shear forces on and into the structure simultaneously. In the presence of calcium and Potassium salts, the same pattern in the puncture curve was observed with increasing of ionic strength in the medium. According to the chain association formed as a result of the ion type, the pattern shows a transient from the elastic to the plastic deformation with different limits. The hardness as a parameter that indicates a composite biopolymer network resistance to break up, showed a higher value for the network containing Potassium salt. It would be due to the formed intra chain association in the system. For calcium salt, the results revealed a small variation in the hardness parameter with increasing the ionic strength. The area under the curve of stress- time is defined as toughness of the structure. The network formed by the intra chain association in the presence of potassium shows a free chain movement which leads to a plastic deformation with absorbing more energy before breaking the gel structure. Concerning the type of chain association, higher values of deformability modulus in the gels containing calcium salt is reasonable. Resilience, yield point and proportional limit are the characters related to the network homogeneity and bond stretching. In the networks with no depletion region, applying an external force to the body would lead to a uniform change in the initial state of the structure. In this kind of netwoks, the force distributed in the whole structure uniformly and local stress is not created. The chain movement as a result of bond stretching, causes a back stress occurance in the structure. When the primary stress is eliminated, the accumulated back stress will make the polymer to return to its original form. Interweaving the network by the intra chain association will result in a homogenous network formation and subsequently, to a higher parameter values in the linear region. The large deformation measurements were performed through the stress relaxation test to study the response of the structure during the interval times and to evaluate the viscoelastic properties of biopolymers network. Longer stress decay time was observed for the network developed in the presence of Potassium salt. The result obtained by studying the stress decay rate was in agreement with the properties observed from the evaluation of the linear region in the puncture test. On the other hand, the deformability modulus values conform to the result from hypothetical asymptotic level of the normalized relaxation parameter.
Mohammad Hossein Naeli; Reza Esmaeilzadeh kenari
Abstract
Various mechanical, enzymatic and chemical techniques are used to improve the quality levels of meat. Such techniques have disadvantages such as being time-consuming and damaging to the meat quality indicators. Ultrasound is used as an effective method to modify technological properties and tenderize ...
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Various mechanical, enzymatic and chemical techniques are used to improve the quality levels of meat. Such techniques have disadvantages such as being time-consuming and damaging to the meat quality indicators. Ultrasound is used as an effective method to modify technological properties and tenderize the meat. The meat samples (Flank area) were put into brine solution or a mixture of the phosphate-brine solution under the ultrasound bath (at a frequency of 37 kHz) and probes (20 kHz) in 20, 25 and 30 minutes at 30, 40 and 50°C. The changes in the technological and textural properties of meat samples were then investigated. The results showed an increase in pH (from 5.55 for control up to 7.14), water-holding capacity (from 20.00 % for control up to 38.15 %), water-binding capacity (from 12.63 % for control up to 31.65 %) and a reduction in the drip loss (from 12.50 % for control up to 3.21 %), cooking loss (from 36.70 % for control up to 16.46 %), hardness and chewiness, whereas showed an increase in tenderness. In general, ultrasound treatment probe in a solution of mixed polyphosphate-brine was more efficient. It is concluded that ultrasound is an effective technique to improve the meat quality.
Hossein Jooyandeh; Majid Nooshkam; Amir Bahador Davari
Abstract
The effect of different mozzarella cheese manufacturing methods, i.e. direct acidification (DA), starter culture (SC) and their combination method (CM) on physicochemical, yield, texture, color and sensory properties of the product were compared. Chemical analyses of samples revealed that the SC cheese ...
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The effect of different mozzarella cheese manufacturing methods, i.e. direct acidification (DA), starter culture (SC) and their combination method (CM) on physicochemical, yield, texture, color and sensory properties of the product were compared. Chemical analyses of samples revealed that the SC cheese had higher fat, moisture, ash, titratable acidity, actual and adjusted yields and fat recovery than DA cheese. DA cheese showed higher springiness, cohesiveness, and hardness than CM and SC cheeses, due to denser and elastic protein network, whereas meltability and adhesiveness of DA cheese was lower than CM and SC samples. SC cheese had significantly higher b-value than DA sample. The sensory evaluation revealed that the SC cheese had higher sensory quality than other cheeses in fresh state and during 45 days of storage. In general, sensory scores of all mozzarella cheeses were acceptable up to 15th day of storage and thereafter decreased progressively till the end of storage period.
