نشریه پژوهش های علوم و صنایع غذایی ایران
سال دوازدهم شماره 3 (پیاپی 39، امرداد و شهریور 1395)

In this study, potential application of image texture analysis as a non-destructive method for automation and prediction of mechanical properties of carrot chips was investigated. Samples were fried at different processing conditions and moisture content, colour parameters (i.e. L*, a*, b* and E) and mechanical properties (i.e. hardness and apparent modulus) were determined. Hardness and apparent modulus increased by increasing frying temperature and time. Four image texture features namely contrast, correlation, energy and homogeneity were calculated using gray level co-occurrence matrix. The results showed contrast and energy of gray level images were well correlated with hardness of fried samples in compression and puncture tests. Correlation coefficients of 0.97 and 0.98 between four image texture features and hardness were obtained in compression and puncture tests, respectively. Results indicate that image texture analysis can be successfully applied as a non-destructive method for estimation of mechanical properties of carrot.

The turbidity of sour orange juice after juice extraction affects on quality, shelf-life and concentration of juice. Therefore, juice clarification is an important operation in the fruit processing industry. The goal of this study was evaluating the effect of membrane operation parameters including pressure (120-220 kPa) and temperature (25-35 ºC) on the permeate flux and hydraulic resistance of sour orange juice during membrane clarification. Response surface methodology (RSM) was used to optimizing the operating parameters. Results of the experiments showed that the permeate flux was raised with increasing of temperature, but total hydraulic resistance (RT), concentration polarization resistance (Rcp) and gel layer resistance (Rg) was decreased in mentioned condition. The permeate flux, membrane resistance (Rm), RT, Rcp and fouling index was raised with increasing in pressure. The Rm and fouling index are showed different behavior depending on temperatures level. Results of process optimization indicated that the best conditions to maximize of permeate flux, and to minimize of fouling index and RT achieved at 35 ºC and 120 kPa for a maximum desirability of 0.761.

This research, presents mathematical modeling of drying process of Aloe vera slices with dimensions of 7×4×0.5±0.1 cm. Peeled Aloe vera slices with the initial moisture content of 5750% (d.b) were osmosed for 5 hours in NACL solution of 10% and temperature of 40 °C at a constant solution to fruit ratio of 5:1. Osmosed and unosmosed Aloe vera samples were hot air dried at 55, 70 and 85°C with different air flow rates of 0.015, 0.036 and 0.054 m3/s for 13200s. The moisture content of Aloe vera samples were measured over different intervals of drying time (1200, 2400, 6000, 9600, 13200s) for each experiment. The experimental results were used to obtain two different dimensionless models based on Buckingham’s pi-theorem for both drying methods. To this end, three independent π terms were identified and then the relation between dependent π term and each independent π term was sought. Finally, the dimensionless models incorporating the effect of all the independent π terms on the dependent one derived and evaluated. The RMSE, (R2), MRD and MBE for the modeling of osmotic-convective drying method were calculated as 0.0185, 0.99, 0.05 and 0.034, respectively. Also these statistical parameters for the convective drying method were as: 0.027, 0.98, 0.061 and 0.051, respectively. Therefore the dimensionless models could predict the moisture content of Aloe vera samples during drying, properly.

The effect of different mozzarella cheese manufacturing methods, i.e. direct acidification (DA), starter culture (SC) and their combination method (CM) on physicochemical, yield, texture, color and sensory properties of the product were compared. Chemical analyses of samples revealed that the SC cheese had higher fat, moisture, ash, titratable acidity, actual and adjusted yields and fat recovery than DA cheese. DA cheese showed higher springiness, cohesiveness, and hardness than CM and SC cheeses, due to denser and elastic protein network, whereas meltability and adhesiveness of DA cheese was lower than CM and SC samples. SC cheese had significantly higher b-value than DA sample. The sensory evaluation revealed that the SC cheese had higher sensory quality than other cheeses in fresh state and during 45 days of storage. In general, sensory scores of all mozzarella cheeses were acceptable up to 15th day of storage and thereafter decreased progressively till the end of storage period.

The aim of this work was to study the antimicrobial activity of tomato skin lycopene oleoresin against Pseudomonas aeruginosa¡ Escherichia coli¡ Staphylococcus ureuse¡ Salmonella typh ¡ L. monocytogenes ¡ Bacillus cereus¡ Bacillus licheniformis. Oleoresin was extracted from tomato peel. Lycopene content was measured by spectrophotometer. Lycopene oleoresin contained 2321mg lycopene/ 100 g oleoresin diluted in serial micro-dilution technique from 40,000 to 78.125 ppm. Microbial culturing was done in ELISA 96-well micro-titer plates in triplet and then MIC and MBC were determined. The results were shown that tomato peel oleoresin contained 2% lycopene, can inhibit and restrain the gram positive and negative bacteria.

Pathogens can be transmitted to the humans through the consumption of contaminated local dairy products such as cheese and, thus, cause pathogenic diseases. Shiga toxin produced by Escherichia coli can cause mild watery diarrhea as well as serious complications such as hemorrhagic colitis, and hemolytic uremic syndrome and may even lead to death. The present study was conducted to investigate the frequency of eaeA, stx1 and stx2 genes in Escherichia coli isolated from local cheese in Maragheh city through multiplex PCR. Thirty two Escherichia coli isolates from local cheese in Maragheh city were studied with regard to the frequency of stx1, stx2 and eaeA genes through multiplex PCR. The frequency of eaeA gene in Escherichia coli isolates was 15.62% (5:32). Stx1 and stx2 genes were not found in any isolate. It was concluded that shiga toxin produced by E.coli exists in local cheeses and can pose risks to the human health in this region.