INNOVATION IN FOOD SCIENCE AND TECHNOLOGY
Year:2010 | Volume:1 | Issue:3|Papers Count:9

Tomato is one of the important agricultural products from which tomato paste is much famous.Effect of heat processing on rheological properties of tomato paste in two methods of hot and cold break was studied. Results showed that power law and casson models best fitted cold break but power law and Herschel-Bulkley models best fitted hot break tomato paste. Also, consistency coefficient of hot break tomato paste was 2-3 times as much as this coefficient in cold break tomato paste. Both yield stress and consistency coefficient increased with concentration rise and decreased with temperature rise.

In this research some physico-mechanical properties such as physical properties (length, width, thickness, arithmetic and geometrical mean diameter, surface area and sphericity coefficient), gravimetrical properties (true and bulk density), and frictional properties (filling and emptying angle of ripose, coefficient of static friction against surface of wood, aluminium and galvanized iron of three varieties of soybean (Gorgan 3, Williams and Sahar) were investigated. For data analysis, a Completely Randomized experimental Design (CRD) and Duncans test at 1% significant level (SAS software program) were used. The result showed that the effect of variety were significant (P< 0.01) in all geometrical, gravimetrical (expected true density) and frictional properties investigated. The most coefficient of sphericity belongs to Sahar, with%88 and the least coefficient one belongs to Gorgan 3, with%86. The domain of bulk density is between 732.372 and 720.000 Kg/m3 and the domain of true density is between 1278.03 and 1182.000 Kg/m3. The results demonstrated that the effect of the variety on bulk density is significant (P< 0.01) but about true density, there was not any noticeable differences statistically. Coefficient of static friction for wood is obtained between 0.41 and 0.49 which the largest amount is for Sahar and the smallest one for Williams.

Heavy metals composition of foods is of interest because of their essential or toxic nature. Liquid curdle may be manufactured from dried curdle or pasteurized yoghurt. The concentrations of heavy metals are probably more in curdle produced via the first method, so this research was carried out to study and compare these methods. Twenty four curdle samples were analyzed for Fe, Cu, Zn, As, Pb, Cd and Ca by atomic absorption spectrophotometer. The average metals concentration was respectively 3.22, 33.55, 8.19, 3.54, 0.21, 0.1 and 1146 ppm. Cu and Fe concentrations were found to be more than the permitted limits in national standard. The concentration of Pb in samples manufactured from dried curdle was more than the permitted limit in Codex standard. Arsenic concentration was more than the permitted limit in both methods. The concentrations of As, Cu, Zn & Fe in the samples manufactured from dried curdle were more than the other method and the differences were statistically significant (p<0.05). We can conclude that the high concentration of heavy metals in samples manufactured from dried curdle is due to the process conditions, specially drying and storage parameters.

Carboxy methyl starch is a cold water – soluble starch ether. In this research, the optimal reaction conditions for wheat granular starch carboxymethylation were determined. These reactions took place with sodium monocholoro acetate (SMCA) as the carboxymethylation reagent in the presence of alkali (NaoH) and alcohol. In this research, two types of alcohol, ethanol and isopropanol were used, and the effect of reaction medium, reaction temperature, and NaoH to SMCA molar ratio on the viscosity, yield, and temperature of starch gelatinization was investigated. The results showed that isopropyl alcohol performs better than ethyl alcohol as the reaction medium. Also, 40oC and 50oC temperatures, and NaoH to SMCA molar ratio of 1.25 (mol/mol) produced the highest viscosity and yield, and had lower temperature threshold for gelatinization. Since there was no significant difference between 40oC and 50oC temperatures in their effect on the yield and temperature of gelatinization, the temperature of 40oC was selected as the optimum temperature.

Dairy beverages have low pH and after period of time casein curb separated from serum. In this research, Guar gum was added at 0.08, 0.1, 0.15 and 0.2% to prevent serum separation and thus reducing volatility of essential oils. In order to investigate the effect of different levels of added hydrocolloid, the quantity of serum separation, pH and organoleptic were evaluated weekly for a month. The rheological properties of the sample were also measured a week after production. The obtained results demonstrated that adding hydrocolloid reduces the volatility of added essential oils due to its effect on viscosity and Prevention on serum separation. For that reason, generally, appraiser group preferred treatments containing.10 and.15 of hydrocolloid to control the sample.The investigation of rheological properties also demonstrated that the viscosity of all treatments reduces with increase in shear rate.  

In this study, inhibitory effect of Bacillus licheniformis on B1 and B2 aflatoxins was examined in two scales (culture media and Kilka fish meal).In culture media, two concentrations of aflatoxins (12 and 16 ppb for B1, 8 and 12 ppb for B2) and two doses of the bacillus (3 and 4%) were used.In fish meal, were also two concentrations of aflatoxins (2 and 4 ml from aflatoxins standard/ 50g of fish meal). Concentration of bacillus was similar to culture media. Changes of aflatoxins and the bacterium growth were evaluated by HPLC and spectrophotometer (OD: 600 l) respectively.Culture media results were showed that B1 and B2 concentrations have been decreased to 88.6 and 84.7%, 98.1 and 92.4% respectively (for 3% Bacillus) and 95.2 and 90.6%, 99.1 and 97.3% respectively (for 4% Bacillus). In fish meal, concentrations of B1 and B2 have been decreased to 76.5 and 70.6% (for 3% Bacillus) and 96.9 and 80.4% (for 4% Bacillus) respectively. The conclusion showed that Bacillus licheniformis is able to significantly decrease B1 and B2 aflatoxins in culture media and meal and can be used as a biological tool in different feeds particularly fish meal.

In this research, PT index was studied on nine local samples of olive oil and two foreign ones using High Performance Size – Exclusion Chromatography. The results indicated that PT was available in nearly all samples. In other words, most of the purchased brands had some purified oil though all had phrases like %100 purified or virgin olive oil imprinted on them. Namely the M3%1, M4%0.78 and M5% 0.36 had the most and M6%0.04 and M2%0.09 the least PT respectively.

High spoilage of fish has caused preservation of fresh fish quality to be one of the notable important issues in fishery industry and for consumers. In this study the effects of Nisin Z (%0.02) and sodium acetate (2g/100ml) were reviewed separately and simultaneously on silver carp (Hypophthalmichthys molitrix) filet. samples were studied in vacuum for around 9 days at 4oc in packed and fillet form and then microbial parameters (the total viable, psycrotrophic and lactic bacteria counts) and chemical parameters (PV, TBA, TVB-N) and so pH value (all over days), total protein, moisture and ash (in first time) were analyzed during 0, 3, 6 and 9 days.TVN and TBA levels in samples containing Nisin and those combined with sodium acetate maintenance increased during the storage period but did not exceed the set limit until day 9, but the control samples had maintained to be unacceptable for consumption to day 4. Review of microbial factors showed that the amount of Psycrophil bacteria, lactic and total bacteria in control samples were higher than the samples containing Nisin and that was also higher than sample containing combined Nisin and sodium acetate, where the amount of total bacteria in control samples, containing Nisin and containing combined sodium acetate and Nisin was set higher than the threshold in the days 4, 6 and 9. Results from chemical and microbial analysis showed that simultaneous use of sodium acetate and Nisin Z could increases the lasting life of silver carp fillet packed in vacuum at temperatures of 4oc for 5 days.