Marzieh Salami; Massoumeh Mehraban Sangatash; Ahmad Ehtiati
Abstract
Introduction: Yogurt is one of the most popular dairy products, which has numerous health effects on human body. Dietary fiber consumption is highly recommended. Fibers are highly hydrophilic and absorb water into the digestive track, increase the volume of food and thereby facilitating excretion. These ...
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Introduction: Yogurt is one of the most popular dairy products, which has numerous health effects on human body. Dietary fiber consumption is highly recommended. Fibers are highly hydrophilic and absorb water into the digestive track, increase the volume of food and thereby facilitating excretion. These are some health benefits of these compounds. Consumption of fiber-containing yogurt can be helpful for people who suffer from cardiovascular diseases, hypertension, diabetes and obesity. Zucchini, as a vegetable, is a source of fibers and due to its health-promoting effects, can be used in dairy products. The aim of this study is to evaluate the effects of different levels of dried zucchini on stirred yogurt during storage. Materials and Methods: The raw materials for the production of the functional yogurt were zucchini, milk, skim milk powder, whey powder, hydrocolloids stabilizer compound and starter culture. Fresh zucchini was hot-air dried at 70 °C for 7 hours. Two forms of the dried zucchini (powder and granule) were added to fresh yogurt at levels of 0.7, 1.4, and 2%. The samples were then tested on days 1, 5, 10 and 15 for acidity (titration method), pH, texture stiffness (back extrusion), syneresis, color (using image processing) and sensory properties, including color, taste, aroma, consistency, mouthfeel and overall acceptance. The experiments were triplicated and analysis of variance was performed using Minitab software at 95% confidence interval. For the significant variables, the means were compared using LSD method. Graphs were drawn using MS-Excel. Results and Discussion: The effects of zucchini form and level of addition, storage time and interaction of these variables were significant (P<0.05) on the titratable acidity, pH and firmness. Over time, pH decreased and acidity increased, which was related to the starter activity and acid production. Due to the use of stabilizer and whey protein, all samples showed no syneresis. The firmness of the samples containing zucchini powder was higher than that of the granule- (P<0.05). This might be related to the homogeneous structure of zucchini fiber, which increased water absorption regarding its lower particle size. Firmness increased from day one to day five, due to the high water absorption of hydrocolloids that bind to free water present in the yogurt structure. The presence of milk proteins and whey protein concentrate in the yogurt formula enhanced crosslinking in the particle gel network, which resulted in a stronger gel structure. During longer storage, firmness decreased from day 5 to day 10, probably was due to the increased pH, which affects the proteins and polysaccharides interaction. The effects of the form and level of zucchini and the interaction between these variables were significant (p <0.05) on the changes in L*, a*, and b*. The L* and a* values which were higher in the samples containing zucchini granules than in the zucchini powder, most probably due to the smaller particle sizes of the powder compared with the granules, causing the number of the powder particles per unit volume to be larger and the powder-containing samples to become darker. In terms of the level of addition, L* increased as the zucchini level rose to 1.4% and then declined to 2%. The sensory properties of all samples were significantly affected by the storage time (P<0.05). With increase in the storage time, all the sensory scores increased. The highest overall acceptance score belonged to the yogurt sample containing 1.4% granule on the 10th day of storage. Overall, zucchini is a good candidate for yogurt fortification. This incorporation results in a greenish yogurt with more health functionalities. The highest overall acceptance score was obtained for the yogurt containing 1.4% zucchini granule on the 10th day of storage (best consumption date) and the results showed acceptable firmness for this sample.
Narges Samanian; Seyed Mohammad Ali Razavi
Abstract
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 ...
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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.
Aziz Homayouni; Reza Rezaeemokaram; Sharareh Norouzi; Alireza Dehnad; Ali Barkhordari
Abstract
Nowadays, people tend to consume functional foods for the treatment and prevention of diseases. Production growth of functional foods obliged scientists to research about production, distribution and preservation conditions of these products. Use of probiotic microorganisms in soy-based products may ...
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Nowadays, people tend to consume functional foods for the treatment and prevention of diseases. Production growth of functional foods obliged scientists to research about production, distribution and preservation conditions of these products. Use of probiotic microorganisms in soy-based products may have advantages of both probiotics and soy on the human health. The probiotic soy-based ice-cream containing Lactobacillus paracasei was manufactured. Physicochemical and sensory properties of probiotic soy-based ice-cream and soy-based ice-cream without probiotic bacteria as a control sample were measured. MRS-Agar was used for enumeration of probiotic bacteria. There were significant differences in the density of probiotic soy-based ice-cream in comparison with control sample (P
Mahboubeh Ostadzadeh; Soleiman Abbasi; Mohammad Reza Ehsani
Abstract
Despite the potential of high intensity ultrasound treatment on homogenization of milk and dairy based products, this treatment, under certain conditions, may lead to produce off-odors which can influence its applicability in the food industry. Therefore, in this research, cacao flavored milk (chocolate ...
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Despite the potential of high intensity ultrasound treatment on homogenization of milk and dairy based products, this treatment, under certain conditions, may lead to produce off-odors which can influence its applicability in the food industry. Therefore, in this research, cacao flavored milk (chocolate milk) was treated using ultrasound at various levels of power intensity, exposure time, and treatment temperature. A light microscope equipped by high resolution digital camera was used to evaluate the size distribution of cocoa particles. Finally, the color, flow and viscosity, and sensory characteristics of stabilized samples were determined. According to the findings, increase of power intensity and exposure time led to a significant increase on the degree of homogenization, and subsequently a paramount decrease on the size of cocoa particles. The cocoa particle diameters of chocolate milk which sonicated at 65 ºC were significantly smaller than the other temperatures. Moreover, the stabilized samples showed Newtonian behavior where the viscosity of control was lower than those treated by ultrasonic. With increase of ultrasound power intensity and exposure time, the viscosity of treated samples decreased. In terms of color, the sonicated samples showed higher L* values and the increase of power intensity and exposure time led to a significant increase on L* value. These samples gained lower sensorial scores than control mostly due to their ‘rubbery’ aroma. But, overall acceptance of treated samples had no significant difference against control. The ultrasound is an effective, rapid, and novel technique which can reduce the size of cocoa particles in order to produce stabilized chocolate milk where its color, sensory and rheological properties was very similar to one treated by conventional heat treatment. These findings can open new approaches in terms of its applicability in dairy industry.
