نشریه پژوهش های علوم و صنایع غذایی ایران
سال نهم شماره 3 (پیاپی 25، پاییز 1392)

In this study, antimicrobial effects of Zataria Multiflora boiss added to sodium caseinate film on four bacterial species: Staphylococcus aurous, Escherichia coli, Bacillus subtilis and Salmonella intertidis was investigated. Disk diffusion method was used to study the antimicrobial activity of Zataria multiflora Boiss in sodium caseinate film. 9 mm disks were prepared from produced films with different concentrations of Zataria multiflora Boiss. with 1, 2, 3 and 4%. Surface culture was done under sterile condition using 0.1 ml of broth culture of each bacterial (106 -107 cfu/ml) on BHI agar. Then the disks were placed. Diameter of inhibition zone was considered as an index of antimicrobial activity of the film. Statistical analyses were done by means of SigmaSDAT software and mean comparison was carried out by LSD test. Results showed that disks containing essential oils of Zataria multiflora Boiss. in each concentration inhibited growth of E.coli, Sa.interitidis and B.cereus. Since there was no significant differences between 3% and 4% concentrations for these bacteria (p>0/05), concentration of 3% is the most appropriate and cost-effective concentration with the highest antimicrobial effect. Only the film containing 1% of essential oil of Zataria multiflora Boiss. Made no inhibition zone on S.aurous, in the other word had no inhibitory effect in this concentration. But inhibition zones created by 2, 3 and 4% for S.aurous were significantly different (05/0> p)

Lemon is one of the most important citrus fruit and is consumed as fresh and dry. In this study the effect of fruit moisture content on the size, sphericity, geometric mean diameters and kernel density were studied. The bulk density and porosity were also evaluated in three different arrangements. Airflow resistance is a fundamental parameter for designing an efficient drying and aeration systems for lemon fruit bed. Using a laboratory test rig, two sets of experiments were carried out: thick and thin layers. In the thick layer experiments 4 bed depths, 11 air flow rates and 4 air temperatures were adopted as independent variables. In the thin layer the effect of filling arrangements in three patterns: A, B and random, at 5 moisture contents and 11 flow rates on pressure drop were envisaged. Results showed that all the physical parameters listed decreased by reducing moisture content. Results indicated that resistance to airflow through a column of lemon fruit increased with increasing bed depth and airflow rate. In the latter experiment pressure drop decreased with a decrease in moisture content. Airflow rate was the most significant factor affecting the pressure drop of lemon fruit in the both experiment. Also the filling arrangement B has a higher affect on pressure drop comparing with other arrangements. Three applicable models (Shedd, Hukill & Ives, and Ergun) were used to evaluate the pressure drop data. The Ergun model, with higher values for coefficient of determination and lower values for root mean square error, is the best model for predicting pressure drop across lemon fruit bed for the conditions studied.

Since the waste of agricultural and horticultural products is high, appropriate methods should be used to produce products with high quality and shelf life for export. In Iran a great part of fruits and vegetables are dried conventionally and farmer use So2 gas for preservation and color stability of dried apricots, but this gas is allergic and carcinogenic and effort to find suitable substitutes for this substance would be an efficient method to the health of the society. So, in this study 3 apricot varieties were selected to evaluate the drying quality and to determine the so2 replacement methods. The selected varieties (Noori, Khaybei 2 and Nasiri) were treated with citric acid, (0.3%), ascorbic acid (0.3%), sodium meta bisulfate (0.4%) and a 50% mixture of ascorbic and citric before drying and then were compared with control samples(without any treatment). After drying, the characteristics such as Brix, pH, moisture contents, browning index, acidity and organoleptic properties were evaluated. Results showing that the effect of variety on moisture, browning, pH, acidity and organoleptic properties were significant (P