Iranian Food Science and Technology Research Journal
Year:2005 | Volume:1 | Issue:2|Papers Count:13

Halwa-Ardeh is a traditional food in Iran and Middle East countries, which is produced by crushing the dehulled sesame seeds and then mixing with a proper sweetener such as grape concentrate, date syrup, and honey. The oil content of this product is on the average of 57- 65% (w/w). In this research, the effect of different levels of fat substitutes including guar gum (of 0.1, 0.15 and 0.2%), Xanthan (0.01, 0.015 and 0.02%), and modified starch (0.75, 1.25 and 1.75%) on the emulsion stability and sensory characteristics (oiliness, firmness, spreadability, adhesiveness, color, mouth coating, taste, and total acceptance) of reduced fat sesame paste/date syrup blends have been investigated. The results showed that all fat replacers at each substitution level (except for 0.02% substitution of xanthan gum) increased the emulsion stability of samples in comparison with the control. In addition, the sensory evaluation by panelists showed that the effect of fat substitutes at each level of substitution on sensory properties of many samples was not significant (a=5%), but all fat replacers improved the spreadability and firmness of samples compared to the control.

Food preservatives are often added to food as preservation method. Mostly one preservative alone cannot preserve a product effectively. So it is required to create a preservation system to overcome limitations derived from each preservative. Using proper selection of different preservatives may lead to significant practical benefits. In this investigation, resistant strain of Bacillus cereus isolated from pizza cheese containing sodium citrate as a preservative was used to study its sensitivity to different chemical and biological preservatives. The MIC and MBC values of preservatives were measured. Results showed that this bacterium is resistant to permitted concentrations of sodium benzoate, sorbic acid, sodium citrate, potassium sorbate and acetic acid. The sensitivity of this strain was not different from Bacillus cereus PTCC1015.It was realized that citric and benzoic acids (0.187% and 0.006% respectively), sorbic and propionic acids (0.0018% and 0.156% respectively), propionic acid and potassium sorbate (0.019% and 0.019% respectively), sodium benzoate and propionic acid (0.026% and 0.019% respectively), citric acid and potassium sorbate (0.375% and 0.625% respectively), nisin and propionic acid (125 IU/ml and 0.156% respectively) had synergistic effect on Bacillus cereus.

In this study the possibility of utilizing date syrup as a sugar replacer in soft ice-cream was investigated. For this purpose control sample was formulated based on Iranian ice- cream standard. Data syrup which produced from third grade Kabkab dates, replaced sucrose in four levels (25, 50, 75 and 100%). Physical properties including overrun, viscosity and freezing point (drawing temperature) were measured for each treatment. Sensory properties including texture, flavor, odor and total acceptance were judged using 15 panelists. Data of physical properties were analyzed as a completely randomized design in triplicate and for analyzing sensory properties completely randomized block design was used to eliminate differences of panelists. Comparison between means was done with Duncan's test at level P=0.05. Results showed that replacement affected all above properties significantly (P<0.05). It was observed that overrun has ascending pattern up to 50% replacement and decreased at higher levels. Viscosity increased significantly as the level of substitution increased (P<0.05). Replacement resulted considerable decrease in freezing point. Results indicated that sensory properties were not affected by up to 50% replacement (P>0.05). However some properties at 75% replacement also had no significant difference with comparison to control sample. Sample with 100% replacement was rejected by panelists.

In this study, the extraction of carotenoids from a new strain of yeast (Sporobolomyces ruberrimus H110) by different chemical and physical methods was investigated. For chemical pretreatment methods, HCl at two different concentrations (0.2 and 0.5 N) and two different temperatures (55 and 75°C), and DMSO solvent (also at two different temperatures, 55 and 75°C) were used. Sonication and bead beater were applied as physical methods. Results showed that the highest pigment extraction level (~100%) obtained by using bead beater. The second best method was the pretreatment by DMSO. Compared to chemical solvents used in this study, the use of a bead beater for the extraction of pigments is the best approach to avoid the toxicity risk(s) involved in the extraction process by DMSO.

The objective of this study was to determine the effect of psychrotrophic bacteria and somatic cells on the physicochemical characteristics of Iranian ultrafiltered (UF) white cheese. Milks with different numbers of psychrotrophic bacteria (1×106, 5×106 and 10×106 cfu/ml) and low somatic cell counts (SCC, <2×105/ml) were selected and UF white cheese trials were produced. In a separate experiment, milks with different numbers (2×105, 4×105 and 6×105/ml) of somatic cells and low levels of psychrotrophic bacteria (<106 cfu/ml) were used for production of UF white cheeses. Results showed that soluble nitrogen at pH 4.6 and non protein nitrogen (NPN) increased in cheese with increasing the number of psychrotrophic bacteria in milk. Although the SCC had slight effect on soluble nitrogen at pH 4.6, but it did not have a significant effect on NPN. These factors did not have significant effect on textural properties of cheeses, although psychrotrophic bacteria had negative effect on the taste of UF white cheeses scored by Panelists.

Probiotic products highly affect the health of consumers by reducing the risk of heart attacks and improving of desirable microflora in intestinal tract. In this study the effect of yogurt (500g/d for 3 wk) enriched with either Bifidobacterium bifidum or Lactobacillus acidophilus on the level of cholesterol, low density lipoprotein (LDL) and high density lipoprotein (HDL) of serum and intestinal microflora were investigated in 24 healthy volunteers. Statistical analysis showed that decreased levels of cholesterol and HDL were found after consumption of both bioyogurts compared to the control (P<0.05), whereas change of LDL was insignificant. Also, in comparison with the control, the results of microbial counts indicated that the fecal coliforms excreted during the consumption of either yogurts were not noticeable, but numbers of Bifidobacterium bifidum and Lactobacillus acidophilus increased significantly (P<0.05).

The aim of this research was to investigate the enthalpy variations of Iranian flat breads during storage in room temperature and determining relationship between enthalpy and amount of staling development. For this purpose, the major Iranian Breads including Barbari, Taftoon, Lavash and Sangak beside Baguette, were prepared using standard ingredients, specific recipe, and under controlled conditions. After baking and cooling, breads were packed in bi layer PE, in order to minimize the interchanges of moisture and air of products with atmosphere. Each bread was then taken out from the package at different time intervals and 20 mg sample from its crumb was weighted. In next step, thermal properties such as: enthalpy, maximum and final temperature of reactions were determined by Simultaneous Thermal Analysis (STA) method. This evaluation was performed in triplicate during 4 days storage. A factorial experiment in completely randomized design was used for statistical analysis. The results shown that the fresh breads have exothermic curves. However with increasing the storage time, curve becomes more endothermic, and these changes was not similar in all breads. Generally, according to the statistical analysis, it was found that enthalpy is not suitable for evaluation of extent of staling and shelf life in Taftoon, Lavash and Sangak. However, these changes of enthalpy had a regular and documentary trend in Barbari during first three days, althoush, using the enthalpy as parameter for predicting the extent of staling in Barbari still requires more investigation.

Appearance of tomato used for preparing dried halves tomato and retention its colour during storage is very important factors. In order to study the physicochemical properties (brix, acidity, pH, moisture, average length, average diameter and the ratio of length over diameter), five different varieties of tomato (Kural, Riyogrande, Pilow and Pep) were selected. The experiment was designed in completely randomized plots with five treatments in four replications. The results showed that there was a significant difference between the average acidity and also between mean of ratio of length over diameter of different varieties of tomato (a=0.05). The Riyogrande variety had the highest (1.366) ratio of length over diameter. To choose the best variety of tomato for producing the dried halves, sensory evaluation (scoring difference test) of preference was performed. The results indicated that there was a significant difference between the averages of the acceptance of dried halves of different varieties of tomatoes, with respect to their taste, colour, apparent dimensions and general acceptability (a=0.01). So the panelists allocated the highest scores to the Riyogrande variety in respect of its general acceptability. Hence the Riyogrande variety was chosen as the most eligible one for making the dried halves. To dertermine the effect of sulphure dioxide level on the quality of taste and colour of dried halves which are produced from the Riyogrande variety, they were stored at 5°C for a period of 6 months and tasted organoleptically 45 days Intervals. Significant difference was observed between the scores that the panelists allocated in respect of both colour and taste qualities (a=0.01). The blank samples reserved the least scores. Whilst the increase of the concentration of sulphur dioxide effects the taste negatively, it effects the colour of dried halves of tomatoes positively.