mohammad reza ehsani

Butter is the product of milk fat, sometimes adulterations occurs with low-cost animal fat, which affects food safety and quality. The aim of this study was to evaluate the authenticity of butter in combination with bovine tallow (0-15% w/w) using FTIR and NMR methods. These studies have shown that by adding bovine tallow fat, there was a significant difference on peaks height in FTIR and value of NMR peaks. According to the statistical analysis obtained, L_Pseudo equations showed that in the FTIR spectra of 3473-3470, 723-720, 590-587 and 458-455 cm-1, by increase in bovine tallow percentage, the height of these spectra was decreased. L_Pseudo equations for each 1H NMR and 13C NMR peak indicated that value (ppm) of these peaks decreased by increase percentage of tallow. Given value of R2, it was found that none of the spectra were capable of estimating the presence of foreign fat.

Kopeh cheese is one of the traditional Iranian cheeses. In this study, the effect of ripening time on its physicochemical properties was investigated during 187 days of ripening. The results showed that ripening index and pH increased significantly, while "salt in dry matter" decreased (p <0.05). The maximum delta tangent (TD) ranged from 0.35 to 0.4. The Differential Scanning Calorimeter (DSC) curve showed two exothermic peaks for cheese-extracted fat ripened on days 7, 37, 67, and 127; three exothermic peaks for the sample ripened on 97 days, while two exothermic and endothermic peaks for the sample ripened on 187 days, in the cooling phase. The results of principal component analysis (PCA) showed that PC1 and PC2 divided cheeses into four different groups, and PC3 identified only one group, including cheese day 127, with a high correlation with "moisture in the non-fat dry matter", "salt in dry matter," and "fat in dry matter". Also, they showed a significant correlation with TD (p<0.05). These chemicals had the most important impact on the physical properties of Kopeh cheese.

Nowadays, due to the spread of diseases and their complications as well as the high cost of treatment, the use of functional and healthy foods has been considered by the scientist. In this context, more attention is paid to complications such as infection and disease development due to the spread of free radicals. One of the options currently considered in the prevention, treatment and reduction of disease complications is biologically active peptides extracted from plant and animal sources. In the present study, peptides derived from milk hydrolysis, including peptides derived from whey and lactoferrin combined with vanillin flavors, were investigated in the laboratory to reduce infection and increase the potency of the antioxidant system. Antimicrobial tests against Staphylococcus aureus and Escherichia coli were performed after the preparation of milk hydrolyzed proteins and food supplementation with vanillin flavoring. The antioxidant effects of these peptides individually and along with a mixture of also tested. The results showed that the peptides derived from lactoferrin and whey protein concentrate alone and in combination, had antimicrobial effects at concentrations of 2000, 4000 and 1000 μg / ml, respectively. Also, the results of antioxidant tests in DPPH, ABTS and Reducting power system showed the appropriate ability of these components at 400 mg / ml concentration and the highest antioxidant activity was related to the hydrolyzed whey protein among the components participating in the supplement. Based on the results, it can be concluded that milk-derived peptides with vanillin can be used as an effective supplement to reduce the therapeutic effects in diseases, which will be complemented by animal and clinical studies.

Bio-nanocomposite films based on sago starch containing 2% cinnamon essential oil and 3% titanium dioxide nanoparticles were used in the packaging of fresh pistachios and stored at different temperatures (4, 25, and 35 ˚C) and relative humidity (30, 50, and 70%) for 20 days, and pistachio properties were evaluated in five-day intervals. Using these films in packaging improved the physicochemical properties of pistachios, including moisture, fat, shrinkage, color characteristics, and sensory characteristics improved, and the growth of Aspergillus flavus, aflatoxin production, and the amount of hydro-peroxide increased much more slowly compared to the control samples. Temperature and relative humidity had significant effects on the physicochemical properties and deterioration of fresh pistachios (p < 0.05) as, at higher levels of temperature and relative humidity, the count of Aspergillus flavus, peroxide index, and aflatoxin ​​had the highest values. The most desirable conditions for fresh pistachio storage were the temperature of 4˚C and 30% relative humidity. Therefore, this active packaging can be utilized as a proper alternative to conventional packaging.

The purpose of this study was to compare the effects of extracted inulin from chicory root and commercial inulin on synbiotic yogurt properties during 21 days at refrigerator storage. Inulin powder from chicory root (0, 1.5, 3 and 4%) and commercial inulin (0, 1, 2 and 3%) were used in synbiotic yogurt containing Lactobacillus acidophilus and Bifidobacterium lactis. The addition of commercial inulin and the extracted inulin powder increased acidity and consequently decreased pH. Adding commercial inulin to milk increased the viscosity and reduced the final product syneresis. The extracted inulin powder at low concentrations had a positive effect on these properties. By increasing storage time, the acidity and syneresis of the synbiotic yogurt increased and pH decreased. The presence of these compounds in milk had a positive effect on the viability of the probiotics bacteria in yogurt, which the effect of commercial inulin on the survival of probiotic bacteria being greater than that of the extracted inulin. Addition of commercial inulin had no significant effect on the color properties of the yogurt samples, while the addition of the extracted inulin powder significantly reduced the brightness index (L*) compared to the control sample and increased the redness (a*) and yellowness (b*) indexes. All sensory properties improved by increasing commercial inulin, whereas 1.5% of the extracted inulin powder had no negative effect on sensory properties of the synbiotic yogurt compared to control.

Several mesoporous nickel-based catalysts with MgO-Al2O3 as the catalyst support were prepared using a co-precipitation method at a constant pH. The supports were prepared from the decomposition of an Mg-Al hydrotalcite-like structure which had already been prepared with Mg/Al=1. Prior to impregnating 10 wt.% nickel on the supports, the precursor was decomposed at several temperatures of 500, 600, 700, and 800 °C in order to elucidate the effect of calcination temperature on the physical and chemical characteristics of Mg-Al mixed oxides and the ultimate catalytic performance of the synthesized catalysts in the combined steam and dry reforming (CSDRM). The catalyst the precursor of which was calcined at 700 °C shows an excellent nickel dispersion and the highest activity among the other samples. It also exhibits the most stable performance during the long-term 36-hour run with high resistance against coke formation in the harsh condition of CSDRM.

In this work, new correlations are proposed to predict the products yield of delayed coking as a function of CCR and temperature based on the experimental results. For this purpose, selected Iranian vacuum residues with Conradson carbon residue (CCR) values between 13.40-22.19 wt.% were heated at a 10 °C/min heating rate and thermally cracked in a temperature range of 400-500 °C in a laboratory batch atmospheric delayed coking reactor for 2 hours. The amount of distillate (C5+-500 °C) and coke yield were measured in all the experiments, and the gas (C1-C4) product yield was calculated based on mass balance between products and feedstock in each experiment. According to the developed functions, products yield changes with CCR value linearly and is a power function of temperature. The further investigation of the results show that by a 1 wt.% increase in CCR value, the distillate yield decreases by about 2.1 wt.%, but the amount of coke and gas yields rise by 1.2 wt.% and 0.9 wt.% respectively.

Spontaneous counter-current imbibition is one of the most important crude oil recovery processes in water-wet fractured reservoirs with low matrix permeability. This paper presents a numerical modeling of imbibition process when water is imbibed by capillarity and gravity forces in to an oil saturated vertical cube core to examine the effect of gravity force on spontaneous imbibition. In this modeling, we assumed that imbibition is a diffusion process. Finite difference implicit method was used to solve the spontaneous imbibition equations. Accuracy of the modeling is investigated with comparison of the modeling results and the experimental data.

Microencapsulation with hydrocolloids as a modern technique has been used to prolong the survival of probiotics during exposure to harsh conditions. In this study, alginate-Hylon starch microcapsules with genipin cross-linked chitosan and poly-L-lysine coatings were developed to encapsulate four strains of probiotic bacteria, including Lactobacillus casei (ATCC 39392), Bifidobacterium bifidum (ATCC 29521), Lactobacillus rhamnosus (ATCC 7469), and Bifidobacterium adolescentis (ATCC 15703). The viability of probiotics was investigated under heat treatment (72, 85, and 90 °C, 0.5 min), simulated gastric juice (along with pepsin, pH = 2, 2 h at 37 C), and simulated intestinal juice (along with pancreatin and bile salts, pH = 8 2 h at 37 C). The morphology and size of microcapsules were measured by scanning electron and optical microscopy. Results of this research demonstrated that, compared with the free form, microencapsulated probiotics had significantly (P

The petroleum industry requires the best materials to reverse the rock wettability to water-wet state which give significantly improved oil recovery.Nanoparticles are suggested as enhanced oil recovery potential agents to decrease viscosity and alter the wettability of reservoir towards more water-wet. This study provides new insights into CuO nanoparticles effects on wettability alteration of different core types (sandstone and carbonate) and increases oil recovery. The first objective of this research is to determine the potential of CuO nanoparticles to imbibe through spontaneous imbibition cell and raise the oil recovery experimentally. The second goal is to prove that CuO nanoparticles have the ability to alter wettability of sandstone and carbonate cores quantitatively. Laboratory tests were conducted in two experiments on four cylindrical core samples taken from Iranian heavy oil reservoir. In the first experiment, core samples were saturated by crude oil and in the second test, nanoparticles were flooded and then saturated by crude oil, immersed in distilled water and the amount of recovery was monitored during 30 days. Experimental results show that oil recoveries for sandstone cores change from 20.74, 4.3 and 3.5% of OOIP without nanoparticles to 31.77, 17.3 and 14.42% of OOIP with CuO nanoparticles, respectively. The oil recoveries for carbonate core vary from zero without nanoparticles to 6.92% of OOIP with nanoparticles, respectively. By investigation of relative permeability curve, the crossover-point is shifted to the right by adding CuO nanoparticles which means nanoparticles succeed in altering the wettability to more water- wet for sandstone and even carbonate cores.

Due to the recent emerging information on the antioxidant properties of soy products, substitution of soy milk for milk in the diet has been proposed by some nutritionists. We aimed to compare four distinct antioxidant measuring methods in the evaluation of antioxidant properties of industrial ultra-high temperature (UHT) milk, UHT soy milk, and their fermented products by Lactobacillus plantarum A7.

Ascorbate auto-oxidation inhibition assay, 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical scavenging method, hydrogen peroxide neutralization assay and reducing activity test were compared for the homogeneity and accuracy of the results.

The results obtained by the four tested methods did not completely match with each other. The results of the DPPH assay and the reducing activity were more coordinated than the other methods. By the use of these methods, the antioxidant capability of UHT soy milk was measured more than UHT milk (33.51 ± 6.00% and 945 ± 56 μM cysteine compared to 8.70 ± 3.20% and 795 ± 82 μM cysteine). The negative effect of fermentation on the antioxidant potential of UHT soy milk was revealed as ascorbate auto-oxidation inhibition assay, DPPH method and reducing activity tests ended to approximately 52%, 58%, and 80% reduction in antioxidant potential of UHT soy milk, respectively.

The antioxidative properties of UHT soy milk could not be solely due to its phenolic components. Peptides and amino acids derived from thermal processing in soy milk probably have a main role in its antioxidant activity, which should be studied in the future.

One of the industrial problems is the phenomenon of wax precipitation of oil fractions. One of the ways to prevent wax precipitation is the use of chemical inhibitors to reduce the pour point. Studying the effect of additives on specific oil samples could help in solving the wax precipitation problems at various oil processing stages. Despite the studies that have been done, finding materials that can decrease the pour point and be economically acceptable from one view, and well optimized and acceptable from other chemical and environmental view is still an unsolved problem. So it’s important to use effective materials that can act on preventing wax precipitation,or on decreasing the amount of precipitate, thus as a result it can decrease the pour point temperature. In this study, the effect of industrial polymer additives and surfactants which are economically acceptable on the decrement of pour point temperature was studied using three oil products samples: light diesel, heavy diesel and the fuel oil, products of Esfahan Oil Refining Co. In this study, optimized type and concentration of additive was studied before additive was chosen. The results showed that the copolymer ethylene vinyl acetate 28% at a concentration of 500 ppm reduced the pour point temperature by 12°C for diesel, also the copolymer ethylene vinyl acetate 19% at a concentration of 300 ppm reduced the pour point temperature by 9°C for fuel oil. Also results of this study showed ethylene vinyl acetate copolymer can be used as the pour point depressant of diesel and fuel oil instead of kerosene and other refinery products.

Water is critically important, because its supply is under stress. In oil fields, the ratio-of-water-to-oil (WCUT%) can be 95% or higher. Managing this produced water is a great challenge whereas the best opportunity to reduce costs, improve profitability and preserve the natural environment. The oil industry is looking for more effective ways to reduce water consuming and improve the recovery rates. Nano materials are an obvious place to look. This study provides new insights into ZnO nanoparticles effects on residual oil saturation (SOR) and WCUT% through steam assisted gravity drainage (SAGD) process by experimental work. Laboratory tests were conducted in two experiments through the use of 2 dimensional scaled SAGD cell from an Iranian heavy oil reservoir. In the first experiment, the SAGD cell was saturated with heavy oil and in the second one, the cell was flooded with nanoparticles before saturation with oil. The amount of recoveries were monitored during 12 hours. Results show that the ultimate oil recoveries increase from 52.43% to 87.93% by adding ZnO nanoparticles, respectively. The experimental results provide the nanoparticles ability to reduce produced water and minimize fresh water use can contribute to water conservation.

Efforts to enhance oil recovery through wettability alteration by nanoparticles have been attracted in recent years. However, many basic questions have been ambiguous up until now. Nanoparticles penetrate into pore volume of porous media, stick on the core surface, and by creating homogeneous water-wet area, cause to alter wettability. This work introduces the new concept of adding ZnO nanoparticles by an experimental work on wettability alteration and oil recovery through spontaneous imbibition mechanism. Laboratory tests were conducted in two experimental steps on four cylindrical core samples (three sandstones and one carbonate) taken from a real Iranian heavy oil reservoir in Amott cell. In the first step, the core samples were saturated by crude oil. Next, the core samples were flooded with nanoparticles and saturated by crude oil for about two weeks. Then, the core samples were immersed in distilled water and the amount of recovery was monitored during 30 days for both steps. The experimental results showed that oil recovery for three sandstone cores changed from 20.74, 4.3, and 3.5% of original oil in place (OOIP) in the absence of nanoparticles to 3 . , 17.57, and 20.68% of OOIP when nanoparticles were added respectively. Moreover, for the carbonate core, the recovery changed from zero to 8.89% of OOIP by adding nanoparticles. By the investigation of relative permeability curves, it was found that by adding ZnO nanoparticles, the crossover point of curves shifted to the right for both sandstone and carbonate cores, which meant wettability was altered to water- wet. This study, for the first time, illustrated the remarkable role of ZnO nanoparticles in wettability alteration toward more water-wet for both sandstone and carbonate cores and enhancing oil recovery.

In recent years، substitution of soy milk with cow milk in the individuals'' diet suffering from inflammatory diseases have been considered in clinical studies. However، soy milk is more prone to oxidation compared to cow milk due to its unsaturated fatty acid. Oxidative stability of soy milk fat and its comparison with cow milk fat has been barely discussed in the literature. Present study aimed at comparing the oxidative stability of commercial pasteurized milk and soy milk samples and their fermented counterparts by L. plantarum A7 during 14 days refrigerated period. Commercial pasteurized milk and soy milk with the same concentration of fatty compound were subjected to fermentation using a native lactobacillus strain، Lactobacillus plantarum A7. Peroxide number and thiobarbitoric acid in the four trials including milk، soymilk، fermented milk and fermented soy milk were investigated during 14 days of cold storage in the controlled condition. The results showed that milk and soy milk fermentation by Lactobacillus plantarum significantly reduced the amounts of both oxidative indices. In non fermented products، peroxide value was found to increase by a similar trend، reaching to the pick after five days of refrigeration. No significant difference was observed between such an increase between milk and soy milk. Instead، TBA value was measured at higher level in soy milk samples all through the study period. Discussion and Despite the higher non saturated fatty acid، soy milk appeared to be as sensitive as milk regarding oxidative damage، However، comparing the great impact of fermentation on retarding oxidation، the difference between no fermented products can be regarded as negligible.

Fast proteolysis of cheese in ripening process may lead to the premature attack of casein, release of the majority of enzymes into the whey, and loss of cheese composition from curd to whey. In this study, the effect of liposomal Flavourzyme on proteolysis of Iranian white brined cheese, as well as on the yield and composition of whey and curd was investigated. Heating method (without using any toxic, volatile organic solvent or detergent) was used to nanoliposomal encapsulation of Flavourzyme. So, 0.15% and 0.3% (w/v) Flavourzyme-loaded liposome were incorporated to pasteurized cow milk. Iranian brined cheese was produced in triplicate using a complete randomized design. Then total solids were determined by drying them in an Infrared Oven. Water soluble nitrogen/total nitrogen and non-protein nitrogen/total nitrogen was determined by Kjeldahl method. Encapsulation efficiency of liposomal Flavourzyme was 25%. No significant differences between chemical components of cheese curd (total solid, protein, TCA-soluble nitrogen, water soluble nitrogen) and whey (total solid, protein) were observed between encapsulated cheese and the control. Cheese production yield in experimental cheese was not different from that in the control cheese (P>0.05). The results suggest that application of liposomal Flavourzyme for acceleration of Iranian white brined cheese inhibits premature attack of casein and the release of the majority of cheese compositions into the whey.

In this paper, the development of a new potassium carbonateon alumina support sorbent prepared by impregnating K2CO3 with an industrial grade of Al2O3 support was investigated. The CO2 capture capacity was measured using real flue gas with 8% CO2 and 12% H2O in a fixed-bed reactor at a temperature of 65 °C using breakthrough curves. The developed sorbent showed an adsorption capacity of 66.2 mgCO2/(gr sorbent). The stability of sorbent capture capacity was higher than the reference sorbent. The SO2 impurity decreased sorbent capacity about 10%. The free carbon had a small effect on sorbent capacity after 5 cycles. After 5 cycles of adsorption and regeneration, the changes in the pore volume and surface area were 0.020 cm3/gr and 5.5 m2/gr respectively. Small changes occurred in the pore size distribution and surface area of sorbent after 5 cycles.

Nanotechnology has the potential to introduce revolutionary changes to several areas of oil and gas industry such as exploration, production, enhanced oil recovery, and refining. In this paper, the effect of different concentrations of Fe2O3 nanoparticles as a catalyst on the heavy oil viscosity at various temperatures is studied. Furthermore, the effect of a mixture of Fe2O3 nanoparticles and steam injection on heavy oil recovery is studied in laboratory. The experimental tests show that some of these nanoparticles decrease the heavy oil viscosity less than 50% at certain concentrations at different temperatures. The reason for this viscosity reduction is that, similar to a catalyst, thesenanoparticles activate some reactions. Our results of steam injection tests show that the injection of a Fe2O3 nanoparticle mixture increases heavy oil recovery because of cracking reactions which crack the C-S, C=C, and C≡C bonds of the heavy components of heavy oil and change them to light components.

Copper trimesate (Cu-BTC) MOF has been pointed out as a promising adsorbent for separating carbon dioxide from methane. However, MOF’s need to be shaped prior to their use in packed bed adsorbers in order to reduce pressure drop; on the other hand, the production of mechanically resistant shaped bodies reduces their adsorption performance. In this work, Cu-BTC tablets provided by BASF are evaluated to perform CO2/CH4 separation through adsorption. The adsorption capacity of pure carbon dioxide from methane was measured in a magnetic suspension balance between temperatures of 308 and 373 K up to a pressure of 700 kPa. The evaluated material presents higher adsorption capacity than previously studied shaped samples with a carbon dioxide and methane adsorption capacity up to 3.07 and 0.63 mol/kg at 100 kPa and 308 K respectively. Moreover, the experimental data were fitted with the Langmuir model. Isosteric heats of adsorption were obtained to be 22.8 and 15.1 kJ/mol for CO2 and CH4 on Cu-BTC tablets respectively, which indicates a strong adsorption of carbon dioxide on these adsorbents. Also, single and binary breakthrough curves were measured in the same temperature range and atmospheric pressure by using Cu-BTC tablets as the adsorbent. The preferential adsorption capacity of CO2 on nanoporous copper trimesate (Cu-BTC) indicates that this material can be used for methane purification from natural gas.

Absorption of flavor compounds from food into the package is one of the interactions which occur between food and packaging material. This phenomenon is of high importance، because absorption of flavors into the packaging material could diminish the flavor intensity of the product as well as loss of mechanical/border properties of the packaging material، so the final loss of quality in the food product will be appear. Absorption of menthol (mint flavor agent) from yogurt drink into the PET was studied at three storage temperature (4، 25 and 45°C). Solvent extraction method used for extraction of menthol from PET bottle and dispersive liquid-liquid mixroextraction used for preconcentration of extracted solution before instrumental analysis by GC. Quantification of menthol performed using gas chromatograph coupled with FID detector. The results showed that the absorption of menthol into the packaging material is a time and temperature dependent phenomenon so that the content of menthol absorbed into bottle increases with elevation in time and temperatures. The mathematical model represented fickian diffusion in the absorption of menthol into polyethylene terephthalate bottles.

It has been shown that lactic fermentation of both milk and soy milk could boost their ant oxidative properties، in our previous study، using a native strain of lactobacillus planetarium for ultra-high-temperature (UHT) processed milk and soy milk fermentation، resulted in an increase in anti-oxidative properties of UHT milk، where the output was opposite for UHT soy milk. Since the obtained results were not expectable، here، in this study the effect of fermentation of the given samples were studied using three different lactobacillus strains as well as using less heated commercial milk and soy milk. The objective of the present study was to compare the lactic fermentation effects on anti-oxidative properties of sterilized and pasteurized milk and soy milk using three different lactobacillus strains. Commercial UHT milk and soy milk and their pasteurized type of products were used; Lactobacillus acidophilus، Lactobacillus Plantarum and Lactobacillus Rhamnosus were used as the lactic cultures and DPPH radical scavenging effect was applied as anti-oxidative index. The DPPH radical scavenging effects of unfermented UHT and pasteurized soy milk were obtained as 31. 8 ± 6. 7 and 35. 9 ± 1. 0، respectively; such data، for milk were shown to be 15. 0 ± 2. 3 and 15. 2 ± 2. 4. For both UHT and pasteurized milk، by individual usage of all three strains، fermentation increased the anti-oxidative index. Accordingly، despite different types of fermenting microorganism، the average of the observed data were 24. 4 ± 4. 0and 25. 1 ± 5. 2; however، in sterilized soy milk، DPPH (1، 1-diphenyl-2-picrylhydrazy) radical scavenging activity decreased to 24. 4 ± 12. 1، whereas the pasteurized one showed a considerable increase in this property up to the value of 45. 0 ± 3. 5 after fermentation. Difference in fermenting microbial stains did not make significant difference on the change in antioxidant properties of soy and soymilk. The results of this study confirmed our previous results that lactic fermentation would reduce the anti-oxidative characteristic of UHT soy milk. The type of thermal processing must be considered as the main reason; the fact that after fermentation، the pasteurized soy milk just showed as increase in anti-oxidative property as the milk samples.

In this article, MFI nanocrystals have been synthesized in two crystal sizes by two stage varying temperature synthesis procedure using reflux and microwave-assisted hydrothermal method. S-Alumina tubular support was seeded with MFI nanocrystals and ZSM-5 zeolite membrane synthesized on it by secondary growth synthesis technique. Characterization of the membrane by using scanning electron microscopy (SEM) confirmed formation of monotonous zeolite film. The results of X-ray diffraction (XRD) asserted ZSM-5 crystalline structure in this membrane. Four different gases including H2, CO, N2, CH4 were used for investigation of permeation process through the synthesized membrane. The effect of pressure and temperature on permeability and selectivity was investigated. The best permeance result was obtained wa 2.58× 10-8 mol/ (m2.s.Pa) for H2 at 298 K and 1.2 bar feed pressure.

Interactions within a package system refer to the exchange of mass and energy inside the packaged food, the packaging material and the external environment. Absorption of flavours into packaging material causes the loss of aroma or changes in the mechanical properties of package. Therefore, it results in reduced perception of the product quality. In this research, the effect of menthol absorption by polyethylene terephthalate (PET) bottles on mechanical properties of the PET bottles was investigated through tensile test. The PET samples containing yogurt drinks with 100 ppm initial concentration of menthol were stored for about three months at 4ºC, 25ºC, and 45ºC and the mechanical properties (tensile strength, modulus of elasticity and elongation) of PET bottles were measured periodically during the storage time. A new technique, dispersive liquid-liquid microextraction (DLLME), was used before GC analysis for concentrating the acetone extraction solution containing menthol. The effect of menthol on mechanical properties of PET bottles was compared through tensile test results of the PET bottles containing yogurt drinks with 100 ppm menthol against PET bottles containing yogurt drink without initial concentration of menthol solution. Maximum effect of menthol on mechanical properties of PET bottles was observed on the samples stored at 45ºC that could be due to the high amount of absorbed menthol at higher storage temperatures. It was also found that tensile strength and modulus of elasticity of PET bottles decreased with the absorption of menthol, while the elongation increased.

The physical protection by microencapsulation is a new method to increase the survival of probiotic bacteria. The size of beads containing probiotics has significant effect on organoleptic properties of foods. Reduction of the sphere size to less than 100 μm would be advantageous for texture considerations and allow direct addition of encapsulated probiotics to a large number of foods. In microencapsulation process, Tween 80 can be replaced by lecithin in order to prevent its detrimental effect on the viability of probiotic bacteria. Calcium alginate as an edible polymer was used for the microencapsulation of probiotic bacteria by emulsion technique. A modified microencapsulation method based on emulsion technique was investigated in this study to produce microcapsules with diameters below 100 μm. A completely randomized design (CRD) experiment was applied in triplicates to evaluate the effect of surfactant (0, 0.2, 0.4 and 1% lecithin with 0.2% Tween 80 as control) and calcium chloride solution (100 and 200 mL) on the microencapsulation process yield of microencapsulated Lactobacillus casei. Microsphere characterization was performed by scanning electron microscopy (SEM). The microencapsulation process yield increased with increasing the volume of calcium chloride solution and it decreased with increasing the amount of lecithin. The highest microencapsulation process yield was obtained whe 0.2% Tween 80 was used as surfactant. The shape of beads was spherical and their mean diameter was 17.80±3.55 μm.

Worldwide popularity of probiotic- microorganisms and their products on the one hand, and their general weak viability in food products (especially fermented types) as well as gastrointestinal conditions on the other hand, has encouraged researchers to innovate different methods of probiotics viability improvement. Microencapsulation of the probiotic cells is one of the newest and highly efficient methods, which is now under the especial attention and is being developed by various researchers. This article reviews the principles and methods of probiotic cell microencapsulation.