فصلنامه پژوهش و نوآوری در علوم و صنایع غذایی
سال دوم شماره 3 (پاییز 1392)

The aim of this research was the use of Cellulose nanofibers (CNF) to improvement the properties of Poly (lactic acid) (PLA) biopolymer in order to increasing its applicability in food packaging. In order to improving the compatibility and miscibility with PLA matrix, CNF were treated by oleic acid. The resultant modified nanofibers (MCNF) were subsequently introduced into a PLA polymeric matrix and the effect of nanofiller on barrier, mechanical and optical properties of the polymer was studied. The morphology of fracture surface evaluated by scanning electron microscopy confirmed the uniform dispersion of MCNF at low levels. However, higher levels of MCNF (12%wt) causes to decreasing the uniform dispersibility and agglomeration of nanofibers. By adding MCNF, water vapor permeability decreased from 9.05×10-5g/m.h.Pa for pure PLA film to 6.96×10-5 g/m.h.Pa for PLA film containing 8% MCNF. Also the oxygen and light transmittance barrier properties improved by addition of MCNF. At the MCNF content of 12wt%, the tensile strength and Young’s modulus of the nanocomposites increased by 2.5 and 2 folds than those of pure PLA films respectively. However, addition of MCNF, caused to decrease in lightness and brightness and increase in yellowness of PLA films.

Fructan is widely used throughout the world for its health-promoting and functional properties. Eremurus spectabilis which has traditionally been used in different industries as well as in folk medicine is considered one of the valuable resources of fructan. However, there is little information about fructan extraction from this plant. Ultrasound-assisted extraction is considered one of the most important methods for extraction of the most valuable compounds from plant sources and is applicable in both laboratory and industrial scales. In this study, boxbehnken design was used in order to investigate the effect of time (5-40 min), temperature (30- 70º C) and ultrasound amplitude (20–100 %) on the yield of fructan extraction from Eremurus spectabilis and optimization the extraction process using ultrasound waves. To describe the extraction yield, a first-order model was developed and verified its performance. The model was subsequently used to assess the appropriate conditions affected by the interaction between parameters and estimate the best process conditions with maximum extraction yield. Results showed that maximum yield is achieved with extraction time of 29.31 min, extraction temperature of 60º C and ultrasound amplitude of 80.04%.

Extracted chitosan powder from crustacean crust has a high capacity for film forming; chitosan films are very resistant against breaking. On the other hand, cellulose nanoparticles have high biodegradability rates and are cheaper than other nanofillers. The aim of current research was to prepare and optimize chitosan-nanocellulose nanocomposites in order to utilize whole capabilities of these common materials. Chitosan powder with a high molecular weight, nanocellulose particles having diameters of 20-50 nm and glycerol were applied for optimisation purposes of nanocomposite properties. Addition of cellulose nanoparticles to chitosan films decreased moisture content, increased (till 30.1%) elongation-at-break and improved a* and b* values for final nanocomposites; decrease of glycerol concentration caused a decrease (till 28.7%) in water solubility and water vapour permeability rate and simoultanously increased (till 3.7 GPa) elastic module of nanocomposite. Nanocomposites containing 1 gr chitosan, 0.18% nanocellulose and 30% glycerol led to the highest desirability (75%). Scanning electron microscopy revealed that high concentrations of chitosan powder and cellulose nanoparticles could construct an intricate structure which justifies improvement of elongation capability after addition of nanoparticles to the chitosan films.

The main objective of this study is to design and construct the new, spouted bed dryer, for food drying sensitive foods specially. For this purpose, firstly a new design of dryer was planned to achieve the maximum efficiency and flexibility for liquids and solids drying. After constructing and initial setup of spouted bed, basic experiments such as investigation of an inert particles motion, pressure drop, energy consumption were conducted and optimal system requirements for two particle size (5.8 & 7.8 mm) were determined. The results indicated that changes in pressure drop in the dryer chamber containing inert particles are followed from the Ergun equation. Energy consumption in this system is variable in the range of 3-8 kW per hour. Also results reveals that the energy consumption of the new design of spouted bed dryer is less than the spray dryer for liquid foods drying.

The direct relation between high blood cholesterol and cardiovascular diseases has been proved. Food containing high amount of cholesterol such as meat and meat products, egg yolk, milk and dairy products can be elevated the cholesterol content in blood plasma. The possibility of cholesterol reduction in milk using beta cyclodextrin was investigated. In this research, various amounts of β- cyclodextrin (0, 0.5, 1 and 1.5 %) were mixed with raw (unhomogenized and unpasteurized) and homogenized milk at two temperature conditions of 8°C and 20 C. The cholesterol content of milk was measured for each treatment. The results that statistically were analyzed and showed that the cholesterol content of milk remarkably was decreased with increasing the amount of β- cyclodextrin, particularly in homogenized milk at 20 C. However, the reduction rate of cholesterol were decreased when extra β- cyclodextrin added due to its intermolecular reactions. The maximum cholesterol reduction was achieved when 1.5 % β- cyclodextrin added to homogenized milk at 20°C.

The aim of this study is to describe the physicochemical properties of khinjuk kernel oil and oxidative stability of it was compared to virgin olive oil. Investigation showed that Kernel of Khinjuk has 30٪ oil. Kernel oil contains more than 80 percentages unsaturated fatty acids (USFA) and dominant fatty acid is oleic acid (57. 39%). Iodine value, saponification number, total tocopherols, total sterols, Refractive Index and wax content were 98. 7 g I/g, 17. mg KoH/g, 619. 4 mg/Kg, 0. 25%, 1. 47 Degree and 0. 002% respectively. In this research, also oxidative stability during 8 hours of heating process at 170 Ċ for khinjuk kernel oil and virgin olive oil were determined and compared. Oxidative Stability results based on data such as Peroxide Value, acidity value, Conjugated Diene Value (CDV), Oil/Oxidative Stability Index (OSI) and Carbonyl value (CV) were analyzed. The results of the comparison at different times of the thermal process showed that there was statistically Significant differences between means of CDV and OSI, but the CV means was not significantly among the oils. Finally due to the low values of conjugate and peroxides compounds and high OSI, oxidative stability of khinjuk kernel oil was more than virgin olive oil, that can be attributed to antioxidant compound specifically tocopherols.

The aim of this study were evaluation the effects of adding satureja khosestanica essential oil (EO) at concentrations of 200, 400 and 600 ppm on bactericidal, chemical and sensory properties of frankfurter sausages formulated with different sodium nitrite (NaNO2) levels (0, 250, 500) and in combination of savory essential oil and sodium nitrite (300:250, 200:250) that were stored at 4℃ for 20 days. Among different concentrations of savory essential oil, 200 ppm concentration has similar effect as nitrite 500 ppm on lipid oxidation. Reduced value of Thiobarbituric acid reactive substance (TBARS) (p<0.05) was observed in frankfurter sausages with the lowest concentration of savory without added sodium nitrite. Among savory concentration tested none of them has considerable effect on formation red color. Nevertheless sodium nitrite and savory essential oil at concentrations (300-200) ppm increased L∗, a∗ values significantly (p<0.05). The effect of savory essential oil was added individually or in combination with sodium nitrite on microbiological tests (Total Viable Counts, Lactic acid bacteria, Entrobacteriaceae, yeast and molds) were showed that savory essential oil hasgreater antimicrobial power against G+ microorganism than the other kinds of microorganism such as Entrobacteriacea, molds and yeasts.