مجله علوم و صنایع غذایی ایران
سال دوم شماره 4 (پیاپی 6، زمستان 1384)

Sugar cane juice contains soluble substance and solid suspension such as color compounds، polysaccharids،gums، proteins and etc that can effect on the quality and efficiency of the final product. Bentonit is a clay soil of montmorilonite and be used as a aid clarifier at industry. In order to make favourit clarification، is better that used type bentonit Na-calit for obtaining optimum point between surface sorption power and volum of sediment. After processing of target samples and obtaining of clarified juice with bentonit method brix، sucrose percent،purity، ash content، color and turbidity are comparced between clarified samples by bentonit method and cold liming method (Cold Defecation or calcium phosphate) as control samples until the best of requirement quantity bentonit and pH recognized. Purpose of this investigation is optimization of raw cane juice refining by bentonit.

In order to reduce egg cholesterol، two types of marine algae; Sargassum glaucescens and Nizimuddinia zanardinii were substituted 1%، 2. 5% and 5% of poultry routine diet. During 18 days period، effects of algae on cholesterol factors of hen blood and egg like LDL and HDL were studied. The efficiency of egg production as a result of algae impact also was determined. the results of this study showed that using of 1% Sargassum can reduce 34% cholesterol in egg and 2. 5% Sargassum sp can increase 11% egg production in comapare with control.

A total of 200 samples of traditional ice creams were obtained randomly from the retail stores in the city of Shahr-e-kord. All the samples were analyzed for microbial contaminations according to the Iran national standard. Out of 200 samples، 100 showed mesophilic aerobic bacteria count more than *105 per gram of ice cream. One hundred fourteen samples showed Staphylococcus aureus count more than 102 per gram of ice cream. Ninety nine samples showed Enterobacteriacea count more than 102 per gram of ice cream. From 200 samples، 2 samples were Escherichia coli positive، and 24 samples showed Bacillus cereus count more than 103 per gram of ice cream. No Listeria monocytogenes was isolated from 200 samples.

In this research، the rheological behavior of ribbon type Iranian gum tragacanth was investigated at different concentrations (1–5 g/L)، temperatures (5–55°C with 10 degree intervals)، pH (4، 7، and 10)، and rotational speeds (up to 200 rpm). At first، the apparent viscosity of gum tragacanth solutions were measured at 3 concentrations (1، 3، and 5 g/L) during 28 hours in 2 hour intervals. The results showed that the soaking has no significant effect on the apparent viscosity of gum tragacanth solutions. Regarding the influence of the abovementioned factors، our findings revealed that increasing rotational speed or shear rate at low concentrations (1 and 2 g/L) has no effect on the apparent viscosity of the solutions and those samples behaved likewise Newtonian fluids whereas، at higher concentrations (3 to 5 g/L)، with increasing the rotational speed the apparent viscosity diminished and the solution consequently showed a Pseudoplastic behavior. In all experiments، alongside increasing the concentration and temperature the apparent viscosity increased and decreased، respectively. In addition، pH had no considerable effect on apparent viscosity in most of our samples. For comparison purposes، using mathematical equations، experimental findings (namely rotational speed) were converted to fundamental parameters (shear rate and shear stress) as well.

One of the important factors which affect lactic starter cultures activity as well as lack of lactic coagulation in milk is antibiotic residues. Lack of lactic coagulation causes a number of problems such as economic loss in dairy industries when they produce fermented milk products specially cheese and yoghurt. In order to recognize such problem، the present study was undertaken to detect antibiotic residues in milk. The results obtain showed، cow milk which contaminated by ointment in a concentration about 100ppm and the cow under treatment by streptomycin (intramuscular injection) up to 72 hours after injection، no lactic coagulation was observed. Hence، the cow under treatment should be kept separate and the milk drawn should never be mixed with other animals until the antibiotic residues reduce to normal range. Above mentioned parameter have different affects on enzymatic coagulation of milk.

Foodstuffs are packaged in desirable packaging after processing due to preventing environment harmful effects. Packaging also has undesirable effects on food materials. Absorption، migration and penetration are three undesirable effects of packaging on food. Absorption of flavor compounds by can’s lacquer was studied in a model system containing orange flavors. Samples were exposed to three different temperatures (4،25 and 40) during 50 days. Analysis of the samples in these 50 days was done by gas chromatography (GC). The results show that flavor absorption increased from time 0-30 days in samples which were held in 4 and 25 degrees and after 30 days desorption accord، but in samples which were kept in 40 degrees no desorption was seen. The influence of flavor absorption on the taste was also studied by taste panelists. There was significant difference (P<0. 05) between samples stored in 4 and 25ºC and samples stored in 40ºC. Panelist also preferred sample stored in 4ºC.

A group of the natural antioxidants is the polyphenols in green tea leave extracts (GTE). In this research، the extraction of antioxidants from the leaves was done with aqueous solution and then the extract was purified and finally dried and made into powder. Then the antioxidant effects of produced powder and α -tocopherol at 200 and 500 ppm، butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) at 100 and 200 ppm، and the combination synergistic effect of mixtures: 200 ppm GTE+500 ppm α -tocopherol، 500 ppm GTE+200 ppm BHA and 500 ppm GTE+200 ppm BHT in two types of sunflower oil (with and without citric acid as a chelator) at 50oC and time intervals of 0، 5، 8، 12 days were examined and compared for peroxide value (PV) and thiobarbituric acid (TBA) test. Results showed that the individually antioxidant effect of GTE at both concentrations was better than that of other antioxidants. Combination of GTE+BHT demonstrated antagonistic effect but no remarkable synergism or antagonisim was observed in other combinations.

For investigation of potato starch properties، six potato cultivars were grown in Agricultural Research Field of Gorgan in 1381-2. Starches were extracted from these tubers and their physico-chemical properties were investigated in comparison with wheat starch. Dry matter and starch content and starch yield of potatoes were found to vary from 17. 2–22، 10. 6–14. 6 and 9. 2-12. 6 % (on fresh weight basis) and the maximum and minimum of these values related to Concord and Deraga varieties، respectively. No significant difference was found at reducing sugars among fresh potatoes.، Phosphorus content، viscosity and mean particle size were different among cultivars and were higher wheat starch، but amylose and protein content had no significant difference in potato starches whereas protein content of wheat starch was higher than potato starches.