فهرست مطالب a. farahnaky

In this study، texture profile analysis and a creep test were used to determine the textural quality attributes of fish protein isolates and conventional surimi. These isolates were made from raw materials obtained from filleting processes of Silver carp (Hypophthalmichthys molitrix) using acid and alkaline aided treatments. Texture profile analysis was performed in order to obtain hardness، cohesiveness، springiness and chewiness of the samples. Added to this، a creep test was applied to measure the elasticity value of the samples. Results were compared to the attributes of conventional surimi produced from the fish. Textural assessment was performed on gel samples formed by heating in hot water at 85 °C for 30 min. Comparison of fish protein isolate gels and the conventional surimi indicated significant differences in texture profile analysis parameters except for springiness value. Furthermore، the results of the creep test revealed that conventional surimi had significantly lower elasticity (29. 8±0. 9%) than fish protein isolate gels.

Mazafati date is a wet and semi-dried date fruit type with dark red to black color that has premier quality. Because of its high moisture content, date fruits of this variety are very perishable at room temperature and therefore must be refrigerated during storage. In this study, effect of air temperature (50, 60, 70, 80 and 90 ˚C) and air flow rate (1, 1.5 and 2 m/s) in hot air drying of Mazafati date were investigated. The results showed that for all samples, drying occurred at the falling rate stage of drying and the main factor affecting the drying rate was air temperature. Air flow rate did not have significant effect on drying rate. Overall, it was concluded that moisture of Mazafati dates can be reduced by cabinet drying and therefore using drying process, the need for their cold storage can be eliminated.

In this study the effects of acetic acid and sodium chloride solutions on accelerated ripening of Mazafati date cultivar were investigated. Mazafatti dates at the Khalal stage were immersed in acetic acid solution (0. 5، 1. 5 and 2. 5%) and NaCl (1، 2 and 3%) solution for 5 minutes and then incubated at 39±1 C for 80 hrs. The results indicated that incubation was the main factor in accelerated ripening of Mazafati date and about 85% of the samples ripened only by incubation. Acetic acid and NaCl solutions had little effect compared to the incubation treatment and played a complimentary role on ripening of date fruit. Dry weight and total soluble solid of the samples increased، while pH and total insoluble solid in water and textural hardness decreased during ripening. Overall، the treatments discussed in this paper can be regarded as a good method for accelerated ripening of Mazafati date.

Bread is the most consumed food of human. Amongst different types of breads, white breads are   of great favorite, however these kinds of breads contain low amount of dietary fiber compared to dark breads. On the other hand, the positive effects of fibers on human health have been well documented. In order to increase the fiber content of the bread, it is possible to use different fiber sources other than the bran in order to keep the favorable appearance of the bread. In this research the effects of addition of two fiber sources: cross-linked wheat starch and short barns at three levels of zero, 5 and 10 % on the quality of dough and flat bread (Barbari) were studied. The results showed that addition of 5% of cross-linked wheat starch had the best effects on dough and bread quality. In many aspects both fibers used, had similar effects, while in the case of color, cross-linked wheat starch (opposite to bran) did not change the color of the bread. Therefore it is possible to use cross-linked wheat starch to increase the dietary fiber content of the bread without any undesirable effects on bread quality.

Color and appearance are among the first parameters perceived by consumers to judge the quality of foods. L*a*b* are used to report foods’ colors quantitatively. In this study the use of digital imaging and Photoshop software was evaluated for measurement of L*, a* and b* color parameters. The results showed that L*, a*, and b* values from Hunter colorimeter and the digital imaging method had a good correlation with R2 more than 0.95, but the values from digital imaging method can be used only to monitor the trend of color changes and the actual numbers of digital imaging L*, a* and b* obtained by digital imaging do not have the same value as the L*, a* and b* given by a Hunter colorimeter. Using two equations for the three parameters the values obtained from digital imaging method can be successfully converted to Hunter Lab color corresponding parameters. The color change of Mazafati date during accelerated ripening using acetic acid solutions was monitored by the proposed method. L*, a*, and b* of the samples all decreased over the ripening.