IRANIAN JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
Year:2013 | Volume:9 | Issue:37|Papers Count:18

The concentrations of four major mineral elements (calcium, magnesium, potassium and sodium) in the muscles of kutum (Rutilus frisii kutum), golden grey mullet (Liza aurata) and common carp (Cyprinus carpio) were measured. The study was carried out in two seasons (spring and autumn) and the fish were obtained from four different fishery stations (Chalous, Anzali, roudsar and Fereidounkenar) in the south Caspian Sea. The dry ash digest method followed by flame atomic absorption spectroscopy was used to determine the concentration of minerals. Their values were expressed as milligram per kilogram dry matter. Calcium in golden grey mullet was the lowest (613.6 mg/kg) and potassium in kutum was the highest (11940.4 mg/kg) comparing among species. Calcium and sodium concentrations showed seasonal variation affected by fish species (P<0.05). There were no significant differences in magnesium concentration in golden grey mullet and kutum in both seasons (P>0.05). However, magnesium concentration in common carp showed a significant variation between spring and autumn (P<0.05).Concentrations for magnesium and potassium were affected by sampling place in all three species.

Milk, curd, fresh (1-day old) and ripened (90-days old) Lighvan cheese (10 samples from each one) have been investigated for lactic flora as one the most well-known starter free sheep raw milk cheeses. MRS, MRS+vancomycin, M17 and KAA media were used for determining of Lactobacilli and Pediococci, Leuconostocs, Lactoccoci and Enterococci genera, respectively.Isolated strains were identified up to genus level with gram staining and catalase test, morphology, colony pigmentation, gas production from glucose, growth in 10oC and 45oC, salt tolerance, growth at pH 9.6, argenine hydrolysis and citrate utilization. Random colonies were selected from each medium and confirmatory test showed Enterococcus (33.68%), Lactobacillus (33.68%) and Lactococcus (26.31%) as the most common genera during the all stages. Finally, these isolated colonies were subjected to carbohydrate fermentation with API 50 CH and API 20 STREP methods and were determined up to species and sub species level. Totally, 95 strains were isolated and identified during all production stages. API system results showed the following species: Lactobacillus plantarum, Lb. brevis, Lb. paracasei ssp. paracasei, Lb. delbrueckii ssp. delbreuckii, Lb. fructivorans, Lac. lactis. ssp. lactis, Enterococcus.faecalis, Ent. faecium, Ent.durans, P. pentosaceus, Leu. lactis, Leu. mesenteroides. The lactic acid bacteria changes revealed the pattern that Lactococcus and Lactobacillus were predominant at the first stages and replaced by Enterococcus at the end of production and ripening stage.The most dominant species during all satages follows as: Lac. Lactis ssp. lactis (25.26%), Lb. plantarum (20%), Ent. Faecalis (15.78%), Ent. Faecium (15.78%). Thus, we expect that these species may play an important role in ripening and production of Lighvan cheese and also have potential application in industrial scale.

Thermal processing is the most common and traditional method to extend the shelf life of food. Because of negative effects of this processing method on sensory and nutritional properties of food, using of cold methods for sanitization has often been interesting substitutes for thermal treatment. High pressure, pulsed electric field, microfiltration, using of high pressure carbon dioxide and irradiation are such an important of the cold sanitization methods. High pressure processing inactivates microorganisms through deformation of their membrane, changing cell morphology, protein denaturation and inactivation of genetic mechanisms, disruption of ribosomes and denaturation of essential enzymes. Pulsed electric field treatment causes electroporation of the cell membrane which results destruction of the microorganism.Microfiltration is based on the separation of microorganisms according to size differences with food components. High pressure carbon dioxide technique inactivates microorganisms through deformation of cell membrane, intercellular pH decrease, inactivation of essential enzymes, direct influence on metabolism, disordering of intracellular electrolyte balance, and removal of vital constituents from cell and cell membranes. Finally, irradiation inactivates microorganisms by causing some changes in biological systems. The benefits and defects of these mentioned methods have been investigated in this review paper and exhibited some examples for applications of each of them for sanitization of milk.

Barley flour is one of the cheap, nutritious and rich fiber food stuff and has many applications in food industries special in cooking products. Nowadays, regimen fibers role is very important on human health and preventing diseases such as fatness, heart and blood vessels diseases, diabet and digestive cancers. In this research, in the first stage, barley flour in levels of 15, 30 and 45 percent was added to wheat flour that used in toast breads. Then in order to evaluation of barley and wheat flour, different chemical experimental were done and results showed that wheat flour with 29.75% wet gluten and barley flour with 6.5% of fiber had the best quality of nutrition. Then dough prepared in two different stages. In the first, barley flour was added in different amounts and in the second, barley flour which had listed with 25% of sourdough that made of lactobacillus plantarum (ATCC43332). Then the rheological properties of dough were evaluated by Farinograph and Extensograph. Based on the results, B3 (45% barley flour) had the most rate of water adsorption and control treatment had the most rates of development time, dough stability, quality, valorimetry number and energy consumption.Staling rate and sensory properties were evaluated by Instron and panel groups respectively. B1 (15 percent barley flour) and BS1 treatment (15 percent barley flour with 25 percent Sourdough) had the least staling rate in comparison with other existed samples, also BS1 was the best in sensory evaluations.

Effects of adding whole soy flour and different extrusion conditions on microbial properties of spaghetti were investigated. Results showed that although the number of colonies of microorganisms in some treatments more than the limit, but not found relationship among microbial counts and added soy flour or production conditions. Thus it seems that because of high pollution due to use of raw materials with high microbial flora, conventional drying method, contamination after processing, high humidity of the final product and unsuitable packaging materials. However, moisture content of treatments among the formula components, influence in determining the number of microorganisms found. The interaction among water temperature, formulation and extruder screw speed increases microorganisms was counted.

The study of thermal processing on Persian Sturgeon caviar (Osetra) properties (color-texture) through pasteurization and determination of kinetic changes can be used for selection of suitable time-temperature combination to have a high quality product. In this study thermal processing was carried out at 55, 60, 65, 70, and 75oC for 120, 90, 70, 50 and 40 minutes, respectively, then textural indexes (hardness, cohesiveness, chewiness, pack ability, maximum force) and sensory properties of pasteurized caviar (appearance, odor, texture and taste) were investigated. The result showed that the pack ability of caviar samples was decreased between 55oc to 70oc but it was increased at 75oc temperature but the other textural properties (hardness, cohesiveness, chewiness, maximum force) were increased with increasing pasteurization temperature. The study of panelists’ sensory evaluation result showed that the temperature of 75oc in comparison with 55oc and 65oc caused significant differences (P<0.01) in appearance, texture and taste of pasteurized products.

The effect of Gelatin coating on the quality of rainbow trout fillet was investigated over a period of 20 days in cold storage conditions (4±1 oC). In this study, we tried using a gelatin coating to reduce spoilage process in trout fillet during storage at refrigerator temperature. Therefore, 4% gelatin solution was used to cover the fillets. Microbial tests, including total viable count and psychotropic viable count, chemical tests, including total volatile bases nitrogen, thiobarbituric acid index, peroxide index and sensory evaluation were periodically performed for without coating fillets (control) and coated fillets. The control fillets and samples that were covered with gelatin receipt to 7.88 and 7.44 (log cfu/g), respectively, in the tenth day that is not acceptable for human consumption. Also, in psychotropic count value did not observe difference between the treatments. ThioBarbituric Acid index in 10th and 15th day, and peroxide and free fatty acid index only in 15th day in the coated fillets were better than the control samples. The results of this research indicate that the gelatin coating alone don’t have antimicrobial properties and is not effective on the sensory properties preservation in chilled storage fish fillets, however, its effect on the inhibition of oxidation is tangible.

Determination of thermo-physical properties of pomegranate juice is necessary to control processes such as drying and concentration. These properties have been affected by soluble solid content and temperature. Therefore the properties including; density, specific heat and thermal conductivity were determined at three levels of soluble solid content, 12o, 40o and 65o Brix and temperature range from 25 to 70 oC. Thermal conductivity by co-axial cylinder apparatus, specific heat by differential scanning calorimeter and density by a volumetric pycnometer were measured. Regression analysis indicated that both soluble solid content and temperature affected on these properties but the soluble solid content has more influence.Increase of soluble solid content from 12 to 65 caused a decrease in thermal conductivity from 0.233 to 0.193 W/m. oC, specific heat from 5.19 to 3.34 kJ/kg. oC and an increase in density from 1027 to 1323 kg/m3 respectively. With increase in temperature from 30 to 70 oC, density decrease from 1173 to 1150 kg/m3 but thermal conductivity increase from 0.188 to 0.229 W/m. oC during temperature increasing from 28 to 42 oC and specific heat increase from 3.9 to 4.4 kJ/kg during temperature increasing from 40 to 60 oC. With regression analysis, the suitable empirical models of thermo physical properties of pomegranate juice with operating variables were obtained.

New food products derived from by-products of dairy plants in the food industry is very important, Lorek is a product derived from whey, which in some regions of Iran, including Kurdistan and Azerbaijan provinces is produced. This product due to high amounts of nutritious ingredients and processes generate highly susceptible to contamination with pathogenic microorganisms. The purpose of this study was to evaluate the inhibitory effects monolaurin against pathogenic bacteria Staphylococcus aurous and Listeria monocytogenesin lorek. lorek produced from whey by heating at 95 °C and 6.5-6.7. Staphylococcus aurous and L. monocytogenes (1.5×106 CFU/g) inoculate to lorek and same time monolaurin was also added in different concentration. This product was kept for three weeks at a temperature of 4 °C.Antibacterial activity against pathogenic bacteria was evaluated at the zero, 3, 7, 14 and 21 days using specific mediums. The results showed that monolaurin inhibit the growth of S. aurous and L.monocytogenesand its inhibitory effect on these bacteria is significant in comparison with a control group (P<0.05). The findings of this study was the most effective antimicrobial monolaurin against S. aurous, so that on days 14 and 21 in treatments containing 10000 and 20000 ppm monolaurin, S. aurous was not isolated (P<0.05). Over time can be quite significant on Antimicrobial effect of monolaurin (P<0.05).

Change in chemical deterioration index (peroxide value, PV; thiobarbituric acid index, TBA; free fatty acids, FFA; total volatile basic nitrogen, TVB-N) and sensory properties (texture, general appearance and eye) of kutum (Rutilus frisii kutum) during 6 months frozen storage (-18 oC) was investigated. PV were increased until month 3, then decreased (P<0/05). During storage period the amount of TBA and FFA increased (P<0/05). TVB-N value did not follow a regular pattern but on the whole increased during storage period. None of the chemical quality parameters exceeded the acceptability limits. These results were supported by the results of sensory analyses. Results of this study showed that kutum has acceptable quality during 6 month frozen storage.

The goal of this research is to compare the traditional and industrial methods in production of sour orange juice and to reach the optimum conditions for juice color maintenance. In the present study the juice was collected from three stages of sour orange juice production line namely prior to pasteurization process (UNP), following pasteurization and homogenization (PH) and after supplementing the juice with standard quantity of sodium metabisulfit (PHS). The juice from all three stages was poured into dark color air tight seal glass bottles. The samples were stored under ambient temperature (~ 20 oC and 35 oC), cold room temperature (~ 4 oC) and freezing (-18 oC). Various physicochemical characteristics including pH, total solid content (Bx), HMF and vitamin C contents and color parameters were assessed at one week intervals for 16 weeks. Results were analyzed with SPSS software in 95% confidence level. The analysis of the data indicates that the color quality decreased with time while HMF content shows an increasing trend. The vitamin C shows a decreasing trend with time and increasing temperature. The trend of color change in samples stored in refrigerated and freezing conditions were almost the same. Furthermore, sodium metabisulfit shows its color protecting effect only at higher storage temperatures (25 and 35 oC) and during final weeks of storage.In the present study the changes on pH and total solid content of the samples regardless of storage temperature and condition was negligible.

Emulsion coatings were formulated and films were developed using tragacanth gum as the basic structural component. Preliminary experiments were carried out to determine the proper concentration of tragacanth gum, lipid and plasticizers in the film. The effects of different concentrations of tragacanth gum (0.65, 1, 1.5, 2, 2.35 g/g distilled water), canola oil (23, 30, 40, 50, 58 g/g tragacanth dry wt basis) and glycerol (33, 40, 50, 60, 67 g/g tragacanth dry wt basis) on water vapor permeability (WVP), mechanical properties and opacity (OP) of the films were evaluated using the response surface methodology. WVP was observed in the range of (2.05-36) x 10-11 and increased by tragacanth and glycerol concentration and was decreased by oil concentration. Tensile strength and elongation at break ranged between 0.67-7.15 Mpa and 1.99-7.8%; respectively. Increasing the amount of tragacanth gum and decreasing the glycerol and oil concentration increased tensile strength (TS) while elongation at break (EB) increased by increasing both tragacanth and glycerol concentration and decreased by increasing oil concentration. Oil was the most influential factor that affected opacity, which increased with increasing oil concentration. Models developed for WVP, EB, TS and OP had high coefficient of multiple determination (R2) values (0.983, 0.952, 0.824, 0.94) respectively.

Traditional Kurdish cheese is one of the most consuming raw milk cheeses in Iran which there is a few studies accomplished about it. In this study, the effect of ripening period, type of containers (goat skin and plastic containers) and rennet type (traditional rennet and commercial rennet) were evaluated on the physicochemical and microbial characteristics of Kurdish cheese. Physicochemical analysis were involved the measuring of ash, dry matter, pH, fat to dry matter and protein to dry matter ratios and microbial analysis were including total count of mesophilic and termophilic lactobacilli, mesophilic and termophilic lactococci, aerobic psychrotrophic and mesophilic bacteria, entrobacters, entrococci and the total molds and yeasts. The results showed that, both rennet type and containers had no significant effect on microbial load of the cheeses (p>0.05) whereas the numbers of mesophilic lactobacilli, termophilic lactococci, aerobic psychrotrophic bacteria, entrobacters along with total molds and yeasts have changed during the time (p<0.05). The amount of dry matter, ash and pH of the cheeses were significantly affected by the containers (p<0.05) and rennet type also had a significant effect on dry matter, ash and ratio of fat to dry matter (p<0.05). All the characteristics of cheese were affected by the time of ripening (p<0.05) except the ratio of protein to dry matter. Finally, according to all results, it seems that cheeses produced by traditional rennet have more nutritional quality than the others manufactured by commercial rennet.Also, using of traditional rennet and goat skin (which traditionally use in the production of Kurdish cheese) had no significant effects on microbial quality of cheeses (p>0.05).

The objective of this research was to produce fermented dairy beverage with Propionibacterium freudenreichii ssp. shermanii and study the microbiological characteristics immediately after fermentation and during cold storage. In this study, impact of two process variables of incubation temperature and inoculation ratio on microbiological characteristics was studied by full factorial design. For the preparation of the fermented dairy beverage, a mixed culture of Lactobacillus acidophilusand Propionibacterium freudenreichii ssp. shermanii was grown at the ratio of 1: 2, 1: 4 and 1: 8 and incubation was performed at 30, 35 and 40 oC until the pH reached 4±0.1. Cell count of L. acidophilus was conducted on MRS Agar and incubation at 37 oC. Enumeration of P. freudenreichii ssp. shermanii was done on sodium lactate agar (NaLa agar) medium and incubation at 30 oC. In the most suitable condition for propionic acid production, profile of viability of microorganisms was determined in intervals of 0, 7, 14, 21 and 28 days. Also, phase separation of produced beverage was studied during the first week of storage at 4 oC. The maximum viable cell count of P. freudenreichii ssp. shermanii was occurred by inoculation ratio of 1 to 4 and incubation temperature of 30 oC. There was an adverse and significant (P<0.05) relationship between viability of P. freudenreichii ssp. shermanii and incubation temperature. The maximum cell count of L.acidophiluswas observed in a mixed culture of L. acidophilus and P. freudenreichii ssp. shermanii at ratio of 1 to 8 and incubation temperature of 35 oC. Considerable decreased cell counts of P. freudenreichii ssp. shermanii and L. acidophilus were obtained during the first and the last weeks of cold storage, respectively.