نشریه پژوهش های علوم و صنایع غذایی ایران
سال هفتم شماره 4 (پیاپی 18، زمستان 1390)

Possibility of replacing whole soy flour for chocolate fat in chocolate production and its impact on textural, rheological and sensory properties of low fat chocolate was explored. For doing this, whole soy flour in 5 levels (0, 2,4,6,8 percent) and two refining times (105 and 135 minutes) was employed. Results indicated that longer refining time gave rise to reduction in particles size and increase in hardness of chocolate. With increasing refining time from 105 minutes to 135 minutes, hardness showed an upward trend which rose from 7100g to 8180g. Casson yield value and Casson viscosity ranged between 9.02 Pa to 35.09 Pa and 2.55 to 5.99 (Pa.s), respectively. Data revealed that whole soy flour up to 4% can be successfully substituted for chocolate fat, without causing significant difference in textural, rheological and sensory properties of chocolate samples (P

Banana is one of the most important tropical fruit from commercial and industrial point of view. This fruit is an extremely perishable fruit which can not be preserved using freezing process. Therefore, drying is the most promising method. Conventional air drying is energy intensive and consequently expensive method. Pre-treatments can be used to reduce the initial water content or to modify the fruit tissue which will result in higher yield with lower costs. In this research, the effect of osmotic dehydration and ultrasonic pre-treatment variables prior to air drying of bananas, including the type of solution (Glucose, Sucrose), time of immersion in osmotic solution (30, 45, 60 min), solution concentration (Brix 30 and 50), ultrasonication time (10, 20, 30 min) on water loss, solid gain, shrinkage, effective diffusivities and color in the process were studied. Results showed that the highest rate of water loss and solid gain and also the lowest rate of shrinkage were obtained in both pre-treatments when 50% glucose concentration was applied. The results indicated that unlike ultrasonication, osmotic pretreatment had a significant effect on color parameters of dried bananas.

The aim of this research was to use ultrasound pre-treatment and studying the time of drying and rehydration in dried samples of kiwifruit (Hayvard variety). The samples were dehydrated for different lengths of time, 10, 20 and 30 minutes at room temperature in distilled water in Ultrasound bath (45 kHz). The results of drying time showed that by decreasing the thickness of samples from 8 to 6 mm and increasing the ultrasound time, the time required reducing the moisture content down to 20% for each treatment. It was also found that the minimum time for bringing the moisture down to 20% in 6 and 8 mm kiwi fruits in pre-treated samples with 30 minutes sonication time was 299 and 404 minutes, respectively. The results of rehydration in samples showed that by increasing the time of sonication and decreasing the kiwifruits samples thickness from 8 to 6 mm, the rehydration increased compared to control sample. The results of organoleptic valuations about to totality acception of dried kiwifruit product showed that using pre-treated ultrasound sample was more acceptable than the control sample.

Efforts to improve the quality of bakery products are increasing every day. Several techniques were developed for this purpose. In this study the possibility of betterment and optimization of quality properties of dough and Barbari bread with emphasis on process variables using rotatable response surface methodology were investigated. The independent process variables for baking process were dough mixing time at low speed (MTLS) (63 rpm) and high speed (MTHS) (180 rpm) from 2 to 8 min and dependent process variables were dough adhesiveness, dough cohesiveness, dough hardness, dough resilience, dough stickiness and specific volume of Barbari bread. Statistical results showed that all the process variables have a significant effect on all the responses. The linear terms of MTHS was the most effective factor on dough stickiness and dough resilience. Quadratic terms of MTHS and MTLS were the most effective factor on dough cohesiveness and dough hardness and specific volume of Barbari bread, respectively. Interaction terms of process variables have significant effect (p

In order to estimate the reducing sugar in tubers of potato by using a manual Glucose determiner, an experiment was conducted in factorial arrangement based on completely randomized design with three replications. In this research reducing sugar of four cultivars of potato – Agria, Sante, with two enzymatic and a manual Glucose determiner. The results Picaso and Kizer – that maintained in two temperatures of germinator, 3 and 7.5ºC, were measured indicated that there was no significant difference between determinated glucose by using a manual Glucose determiner and enzymatic procedure, but there was a significant difference between determinated glucose by using a manual Glucose determiner and total reducing sugar measured by enzymatic procedure. The effect of maintenance conditions on glucose content and total reducing sugar in both procedures was significant and treatments that were maintained at higher temperatures had less sugar. The effect of cultivar on glucose content and total reducing sugar in both procedures was significant and in temperature 3ºC, Agria and Sante had the highest sugar content, but in temperature 7.5ºC, there was no significant difference among reducing sugar content of four cultivars.

All of the food products are required to be packaged due to hygienic regard, storage, suitable transportation and preservation of quality and vacuum packaging is one of the prevention methods of spoilage. Hence in this study, some of the quality factores changes of Rutilus frissi kutum fillets storaged in vacuum and air packages were examined during 18 days in ice alike total volatile base-nitrogen (TVB-N), pH, water holding capacity (WHC), thiobarbituric acid reactive substances (TBARS), sensory characteristics and psychrophilic bacterial level. pH of the air packaged samples, rised with increasing psychrophilic bacterial load. Results of microbiological examination, indicated changes in bacterial of Rutilus frissi kutum fillets, has direct relation with sensory quality of packaged fillets in both vacuum and air packs, and shelf life and quality of vacuum packaged fillets was better as compared to air packaging, as cause fillets shelf life increase, 3 days more than air packaged fillets and effectively, controlled volatile bases-nitrogen level but alone was not able to controled lipid oxidation during ice storage. Therefore vacuum packaging cause shelf life time increase and better preservation of sensory, chemical and microbiological qualities of Rutilus frissi kutum fillets in ice.

The effect of pH, different concentration of Tween 80 and calcium ion on the stability of limonene-in-water emulsions stabilized by various concentration of sodium caseinate (2, 5 and 10%) was evaluated. To this end, emulsions were prepared by ultrasound and their quality attributes including size distribution, mean diameter of droplets, specific surface area and span number were studied as a result of the contribution of experimental parameters. The results showed that emulsions stabilized by 10% sodium caseinate had finer droplets with smaller span values as well as narrower and sharper size distribution curves compared to others. It was also found that by increasing the concentration of Tween 80 up to 1.5% the size of emulsion droplets and the span value decreased but increased afterwards. Moreover, pH and calcium ion significantly affected the diameter and specific surface area of droplets

Fruit leather is one of dried product with variable production, good marketing and popular consumption in many countries of the world. In this research, the effect of concentration temperature (55-75 °C) and time (20-40 min) and drying temperature (40-70 °C) on the chemical composition (Brix, pH, sugars and vitamin C) and the microbial properties of apple leather investigated. The results showed that increasing the concentration time and temperature caused increase in Brix and percentage of sugars, while decreased vitamin C. Increasing the drying temperature on the chemical properties (exception Brix) was not significant. Microbial analysis showed that dominant microbial flora of apple leather was spore-forming bacteria, Lactobacillus, molds and yeasts.

Consumption of food containing cholesterol and saturated fatty acids such as butter can increase serum cholesterol and cause cardiovascular diseases. Therefore many efforts have been done for decreasing these constituents in foods. In this study, hazelnut and walnut powders were added to butter samples in amounts of 0 (not enriched sample), 10, 20 and 30% for evaluation of chemical characteristics (acid value, peroxide value and oxidative stability). Samples were then packed in 2 forms; vacuum and common packed and stored for 90 days at 5°C in refrigerator and were analyzed every 30 days. Adding hazelnut and walnut to butter samples caused significant increase in acid value of samples. Also rising trend of acid value in nut enriched samples was higher during storage. Control samples (without nut) showed higher peroxide value than nut enriched samples. During storage both control and nut enriched samples showed significant increase in peroxide value. Although all of nut enriched samples’ peroxide value were lower than standard limit during storage. Vacuum packed samples also showed lower acid and peroxide value than common packed samples. Adding nuts to butter samples also caused a decrease in oxidative stability of butter samples. This study shows that butter enriched in hazelnut and walnut can be introduced as a new and functional dairy product to consumers, because of its essential fatty acids content.

Every year more than a third of people of the developed countries disease caused by the food they are having and the mortality rate of disease resulted from the pollutants of food in the developing countries, 2.2 million people have been reported annually. Heavy metals are such environmental pollutants that if human have any face with some of them through the water and food poisoning can be caused chronic and acute venenation. Among them we can mention to some metals like chromium, nickel and cobalt in all kinds of salt. In this research the aim was to determination of some heavy metals amount like Ni, Cr, Mn and Co in the samples of washed salt by water and rock salt by the flame atomic absorption spectroscopy. The amount average of heavy metals for salt washed was like below: Ni (1.860±0.689), Cr (0.345±0.144), Mn (0.171±0.120) and Co (3.747±0.832) (μg g-1) dry weight (Mean±Standard Error) and for rock salt was like below: Ni (2.001±0.021), Cr (2.549±0.011), Mn (0.200±0.025) and Co (9.041±0.100) (μg g-1) dry weight (Mean±Standard Error). By comparison, and paying attention to the difference between the quantities and reducing the amount of elements in the washed salt we can sense the importance of rock salt infiltration. By statistical analysis (t-Test: mail this article-demonstration equal Assuming Variances) we can be found that quantities of heavy metal (chromium, cobalt, manganese) in unrefined salt with quantities of them in refined salt have meaningful difference of P0.05. And also results showed that with washing the rock salt we can see meaningful change in degree of purity 96.96-98.83%.