فهرست مطالب مرتضی مشایخ

In recent years, studies have focused on biodegradable packaging films and increase of their antimicrobial ability. Therefore, this study was carried out to investigate usability of beta-glucan to produce antimicrobial films incorporated with extracts of oak trees.

In this study, physical, mechanical, optical and antioxidant characteristics of β-glucan based films incorporated by 1, 2 and 4% of oak tree extracts were investigated. Moreover, antimicrobial effects of the prepared films on four pathogens were studied.

Results showed that by addition of oak tree extracts, film thickness and water permeability rate significantly increased and decreased, respectively. Prepared films were more flexible, while their elongation in breaks significantly decreased. Film solubility decreased with increases in quantity of the added extracts. Addition of oak tree extracts increased redness and decreased lightness and yellowness parameters. Films incorporated with the extracts showed significant increases in antioxidant characteristics. Prepared films significantly (p < 0.05) inhibited the bacterial growth.

Oak tree extracts as natural antibacterial inhibitors include good potentials to incorporate into films of packaging to extend food shelf-life, in particular the oxygen sensible foods.

Production and export of Doogh as a Iranian fermented national drink have increased. Contamination of Doogh by yeasts and molds is one of the defects that results in spoilage and increasing the waste of the product. Drying and convertion of Doogh to its powder by spray dryer is one of the method for increasing the shelf life and decreasing the volume and the costs of transportation. In this study Doogh samples with fat content (0.5% and 1.5%), dry matter without fat and salt (3.5% and 4.5%) and 0.7% salt were first dried in preliminary tests including inlet air temperature (100, 150 and 200 oC), liquid feed flow rate (5,10 and 15 mL min˗1) and drying air flow rate (400, 600 and 800 L h˗). Best condition were adjusted accordingto the best results of solubility test and were conducted to drying the samples. fat content and dry matter had significant effect on physical, chemical and microbial characteristics of Doogh powder. First and forth formula had highest and lowest solubility. The solubility of first and forth formula was 82.11±0.62% at 25 oC and 63.18±0.33% at 15 oC respectively. Increasing the fat content results in decreasing the solubility, increasing the particle size and the rate of viable starter counts.

Propionibacteria are capable of producing many important industrial products such as propionic acid، vitamin B12 and bacteriocins. Also these bacteria show some probiotic health benefits and produce prebiotics as stimulator of intestinal bacteria. The aim of this research is evaluation of pH control on production of biomass propionic، acetic and lactic acids in fed-batch system، with feeding of molasses and lactose as carbon sources of co-fermentation of Propionibacterium freudenreichii ssp. shermanii and Lactobacillus acidophilus. Fermentation was conducted in a 3-liter fermentor containing base medium and molasses as the carbon source in which lactose was fed after 36th hat temperature at 30 °C. Total fermentation time was 96 hand sampling was done in every 24 h intervals to measure the biomass and organic acids. Two treatments were compared to each other: in one trial، pH was maintained at 6. 5 by using NaOH 1N، but in another، during fermentation pH was not controlled. Content of biomass and organic acid were measured by freeze drying and HPLC methods، respectively. The final concentration of the dependent variables for the two treatments with and without pH control obtained as following (g/L): biomass 1. 97±0. 07 and 1. 72 ±0. 07، propionic acid، 4. 87±0. 13 and 4. 16±0. 04، acetic acid 4. 87±0. 13 and 4. 16±0. 04 and lactic acid 7. 93±0. 06 and 6. 10±0. 09. In this study it was shown that production of mentioned organic acids was not affected significantly by adding NaOH for control of pH in medium.

In recent years, the demand of consumers for food safety as well as healthier products has promoted the investigation for food with harmful compounds. Among these toxic compounds, the presence of biogenic amines (BAs) in fermented foods, such as cheese have received considerable interest due to their undesirable physiological effects in humans. After fish, cheese is the next most commonly implicated food associated with histamine poisoning. The aim of this study was to present procedures for reduction of biogenic amines in cheese. Control measures for delying biogenic amines formation in cheese include improvement the raw milk quality, employment of quick detection methods of bacterial contamination, pasteurization of raw milk, high hydrostatic pressure, use of bacteriocins or bacteriocin producing starters, not passaged starters, amine negative starters, additives, control the ripening conditions, irradiation, appropriate packaging, and biogenic amines oxidizing MOs or enzymes. These methods delay biogenic amines formation in cheese primarily through the inhibition of bacteria or the decarboxylase enzyme activity responsible for amine production. The use of amine oxidizing bacteria and enzymes are the best options to eliminate already formed biogenic amines. Effective control of biogenic amines may require a combination of several factors that often described as hurdle technology. The control of biogenic amines with starters is likely to be most effective with good quality raw material.

There is an increasing public awareness of the health, environmental and safety hazards associated with the use of organic solvents in food processing and the possible solvent contamination of the final products. The food industry is always looking for the best separation technology to obtain natural compounds from high purity, healthy products that are of excellent quality. The high cost of organic solvents, increasingly stringent environmental regulations, and new requirements of the medical and food industries for ultra-pure and high added value products have increased the need for the development of new and clean technologies for the processing of food products Supercritical carbon dioxide (SC–CO2) extraction has attracted considerable attention in recent years as a promising alternative to conventional solvent extraction and mechanical pressing for extracting oils and other materials as it offers a number of advantages, including a lack of solvent residue and better retention of aromatic compounds. This article summarizes some of the advances and the latest developments in the field of supercritical fluid technology focusing on using supercritical carbon dioxide in extraction and refining of vegetable oils.

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 acidophilus and 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°C until the pH reached 4 ± 0. 1. Cell count of L. acidophilus was conducted on MRS Agar and incubation at 37 °C. Enumeration of P. freudenreichii ssp. shermanii was done on sodium lactate agar (NaLa agar) medium and incubation at 30 °C. 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°C. The maximum viable cell count of P. freudenreichii ssp. shermanii was occurred by inoculation ratio of 1 to 4 and incubation temperature of 30 °C. 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. acidophilus was observed in a mixed culture of L. acidophilus and P. freudenreichii ssp. shermanii at ratio of 1 to 8 and incubation temperature of 35°C. 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.

Increasing trends of overweight and obesity prevalence have prompted food producers to develop products that can enhance satiety signals. The role of short-chain fatty acids as satiety-inducing triggers seems to be of interest in this regard. The objective of this research was to investigate the impact of two process variables, namely, incubation temperature and inoculation ratio of starter bacteria, on propionic acid production in the fermented dairy beverages containing Propionibacterium immediately after fermentation and during cold storage. Fermented dairy beverage (FDB) samples were prepared using mixed cultures of Lactobacillus acidophilus and Propionibacterium freudenreichii ssp. shermanii at a ratio of 1:2, 1:4 and 1:8, repectively, at incubation temperatures of 30, 35 and 40°C, until the pH reached 4.0 ± 0.1. Propionic, lactic and acetic acid contents of the samples were measured immediately after fermentation using HPLC. The FBD samples were refrigerated for 28 days and the concentrations of the acids in the samples with the highest propionic acid content were measured. Sensory evaluation of the samples produced was made by 11 trained panelists using the hedonic scale. The maximum propionic acid content (w/w%) was observed in a mixed culture of L. acidophilus and P. freudenreichii ssp. shermanii at a ratio of 1:4 and an incubation temperature of 30 °C. It increased from 0.75 at day 0 to 1.2 at day 28 during storage at 4 °C. The incubation temperature had a statistically significant inverse effect (P<0.05) on the propionic acid production in the fermented dairy beverages.

Chocolate is very popular among consumers of all ages. However, its consumption is limited for the obese and diabetic people due to its high energy and sucrose contents. Replacing sucrose by low digestible carbohydrates (LDCS) will result in lowering its energy content and glycemic index, as well as in preventing tooth decay. The objective of the present study was to investigate the effects of replacing sucrose with 2 sugar substitutes, namely, D-tagatose and inulin, on the physical, chemical, rheological and sensory properties of dark chocolate Inulin, a dietary fiber, and D-tagatose, a natural keto-hexose with a degree of sweetness similar to that of sucrose, were used as sucrose substitutes in dark chocolate formulas. The inulin:tagatose ratios in the mixtures were 100:0, 75:25, 50:50, 25:75, and 0:100. The physical, chemical, rheological, and sensory properties of chocolate samples prepared with the mixtures were determined. With a reduction in the inulin content and an increase in the tagatose content, the moisture contents of the chocolate samples decreased, while their aw increased. Increased D-tagatose resulted in increased hardness of the samples, the sample with 100% being the hardest, comparable to the control (sucrose) value. With regard to color indices, the least amounts of L*,a*,b*,c* and hue° were observed in chocolate samples with 100% inulin. Increasing D-tagatose led to increases in the color indices. The data also showed that reductions in inulin resulted in decreases in apparent and plastic viscosity and increases in τ0 and τ1. Thus, the lowest real and linear yield stresses were found to be in the sample with 100% inulin. The least apparent viscosity and the lowest plastic viscosity were observed in samples with 25% inulin-75% tagatose and 100% tagatose, respectively, with no significant difference with the control value. Overall acceptability of the chocolate samples increased with increasing the D-tagatose level. It can be concluded that in chocolate formula samples an inulin-tagatose ratio of 25%-75% and 100% tagatose are the best sucrose substitutes. As inulin is a dietetic fiber and tagatose and inulin have prebiotic properties, chocolate samples prepared using them are also desirable from a nutritional point of view and can be considered as functional foods. Keywords: Dark chocolate, Inulin, Tagatose, Stevia, Rheology

The aim of this study was to produce Taftoon bread from wheat flour fortified with defatted soy flour and assess its chemical and organoleptic properties, as well as its growth-promoting effect in rats. Samples of wheat flour with extraction rates of 82–84%, fortified with 3, 7 or 12 % defatted soy flour were used to bake Taftoon bread. Bread produced from these blends was compared with regular Taftoon bread and tested for chemical and organoleptic characteristics. Forty Sprague Dawley rats were randomly divide into groups to be fed, for 30 days, on one of the three defatted soy flour fortified bread blends, a group fed on ordinary Taftoon bread serving as controls. Chemical, biological, and organoleptic assessments were made on the bread samples. The blending of wheat flour with defatted soy flour at different levels altered the organoleptic properties of breads. Addition of defatted soy flour significantly increased the protein and ash contents of the breads (P< 0.05). Organoleptic tests with 213 untrained panelists indicated that the best formulation is one containing 3 or 7% defatted soy flour. Rats fed on the control diet had the lowest weight gain and their feed efficiency ratio was significantly different (P < 0.05) from that of the group fed the 7% defatted soy flour formula. Based on chemical, organoleptic, and biological evaluations, it is concluded that the best Taftoon bread formulation is one containing wheat flour fortified with 3-7% defatted soy flour.