نشریه پژوهش های علوم و صنایع غذایی ایران
سال ششم شماره 1 (پیاپی 11، بهار 1389)

In this study Lemon juice were packaged at three type of packaging (PET, PE and Glass bottles). The samples were stored ten weeks at 20 and 40 ◦C. Physicochemical (pH, acidity, brix, vitamin C, SO2 and formalin number) and sensory properties of Lemon juice were evaluated on every two weeks. The results showed that the two storage temperatures(20 and 40 ◦C) had not any significant effect on pH, acidity and brix of samples in different packaging (p≥0.05). The amount of vitamin C decreased on three type of packaging at the storage time that it was maximum in PE and minimum for glass bottles.

In this study formation and properties of o/w emulsion stabilized by a mixture of sodium caseinate (2, 5 and 10 wt %) and non-ionic emulsifier Tween 80, sorbitan mono-9-octadecenoate, (0, 0.5, 1 and 1.5 wt %) were investigated at various pH values(3, 5 and 7) and calcium ion concentrations (0, 0.2, 0.4 and 0.6 wt%). Emulsion samples were prepared by using a sonicator with a nominal power output of 750 W and an operating frequency of 20 kHz. Sonication of samples was carried out in a temperature-controlled chamber at a constant temperature of 20 ºC and the highest acoustic power available for 3 minutes. The results showed that increasing the concentration of sodium caseinate and Tween 80 generally reduced the size of droplets, although it was observed that Tween80 adversely affected the size of droplets at higher concentration under acidic conditions. Moreover, pH and calcium ion significantly affected the diameter and specific surface area of droplets.

The main aim of this study was to improve the bread quality and to postpone its staling. Therefore, sugar beet pulp powder was added to Barbari bread dough formulation at five levels of 1, 3, 5 and 10% (w/w, flour basis). Then the properties of dough and the resulting bread were studied. The results showed that with increasing the sugar beet pulp powder, the water absorption of the dough and the fiber content of the bread increased while, bread density and hardness decreased. The electro-micrographs of the bread crumb containing sugar beet pulp powder indicated the improved texture which can delay bread staling. Sensory evaluation of the samples revealed that the bread made with up to 5% sugar beet pulp powder had the highest general acceptability. However, higher levels of sugar beet pulp powder had diverse effects on bread color which would reduce general acceptability of the samples. It was concluded that sugar beet pulp powder can improve the quality of bread and delay its staling.

In this paper, the effect of two domestic seeds hydrocolloids (Basil seed and Sage seed gums) and one commercial hydrocolloid (pectin) on characteristics of non-fat concentrated yoghurt was studied. For this purpose, effect of different concentrations of these gums (0.05, 0.1, 0.15 and 0.2%) on physicochemical and sensory properties after 1 and 7 days were investigated and compared with control sample (without gum). Physicochemical characteristics were included total solids, syneresis, apparent viscosity and softness of concentrated yoghurt. Flavor, odor, color and mouth feeling were evaluated as sensory properties. With increasing the concentration of gums, total solids, syneresis, apparent viscosity and softness of samples decreased. Yogurts containing 0.05% gum was acceptable by panelists. The highest apparent viscosity and sensory acceptance were seen in samples containing sage seed gum, whereas samples containing pectin had the highest total solids and firmness. The apparent viscosity of samples decreased after 7 days storage, whereas the syneresis and softness increased, and sensory properties improved.

The seeds of Lepidium Sativum (Garden Cress) were selected as a new source of hydrocolloid and some of its fundamental Physico-chemical properties such as intrinsic viscosity and functional group were determined. FTIR analysis showed that this polymer was composed of carbohydrate with functional carboxyl and hydroxyl groups. Intrinsic viscosity was determined to be 1.33 ml/mg in water. The hydrodynamic behavior of hydrocolloid extract demonstrated a typical polyelectrolyte behavior, with affinity to salt as intrinsic viscosity decreased with increasing NaCl concentration.

In current research relationship between Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) (% of total fatty acids) in edible tissue (muscle) of Green Tiger Shrimp (Penaeus semisulcatus) and Lobster (Thenus orientalis) collected from Persian Gulf, was investigated with some biological factors (total length, total weight and sex). Results showed that in all two species, EPA and DHA percent was decreased in relation to increase of total length and weight, that was significantly for all relationships in Green Tiger Shrimp and relationship between DHA and total length for Lobster

The pomegranate juice with high nutritional value has turbid appearance that makes it difficult to preserve and concentrate. Microfiltration is useful process which can clarify it. One of the most important problems in this process is fouling phenomenon which affected by several parameters. The effects of fluid velocity, transmembrane pressure, membrane type and its pore size on membrane fouling were studied. The results showed that the membrane fouling increased with increase in the fluid velocity and transmembrane pressure. Also, more hydrophilic property and pore size resulted more membrane fouling due to greater flux which move more particles to membrane surface. Scanning electron microscopy (SEM) images support these results.

Banana samples were purchased from a local market in Sabzevar located at northeast of Iran. Then samples stored at refrigerator between 5–10oC during experiments, For prevention of chilling injury, 36 samples at three replications were prepared so as bananas were peeled and sliced with a sharp knife at three thicknesses (3, 5 and 10 mm) and then treated by three pretreatment methods (T1: chemical blanching in sodium bisulphate solution 1%, T2: first blanching in boiling water and then chemical blanching with sodium bisulphate, T3: first blanching in boiling water and then chemical blanching in ascorbic and citric acid mixture 1:1 solution 1% and T0: control sample without any treatment). All pretreated 36 samples initially were dried in hot air dryer at 60oC to reach to critical moisture content and then dried by a microwave oven with 300 W microwave power intensity to reach final moisture content. Dried samples were evaluated for some quality parameters such as color, sugar content and ascorbic acid along with dehydration parameters such as re-hydration ratio, drying time and drying rate. The results showed that pretreatments increased drying rate and decreased drying time, but drying time increased by increasing of slice thickness. Furthermore, pretreatments had positive influence on the quality parameters.

In current study, protein hydrolysates were produced using microbial proteases of Alcalase, Protamex and Flavourzyme from Yellowfin tuna viscera. The results indicated that, protein hydrolysate from Alcalase, had significantly higher protein content, nitrogen recovery and degree of hydrolysis than the others (P0.05). The results of amino acids composition revealed that all hydrolysates were almost similar in amino acids composition. In addition, the protein efficiency ratio (PER) showed that all hydrolysates had high nutritional value. The chemical score results showed that all hydrolysates could fulfill human amino acid requirements. While, in comparison with common carp requirements, the amino acids of methionine, lysine and phenyl alanine, were the limiting amino acids in all hydrolysates. According to the results of this study, Alcalase is the most affective enzyme. Also, Yellowfin tuna hydrolysates have high nutritional value, that can be used as protein source in diets.