IRANIAN JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
Year:2016 | Volume:13 | Issue:55|Papers Count:20

In recent years, many advances have been made in improving the biocatalytic activities of enzymes. Interaction of enzymes and macromolecules have important role in stabilization of enzyme’s structure and function. Lysozyme lyses the bacterial cell wall by splitting b (1-4) linkages between Nacetylmuramic acid and N-acetylglucosamine of the peptidoglycan in bacterial cell walls. Tragacanth is a polysaccharide obtained from exudates of the species of Astragalus. It is a very complex heterogeneous anionic polysaccharide of high molecular weight. Tragacanth consists of two main fractions: a water-insoluble component called bassorin, and a water-soluble component called tragacanthin. The aim of this investigation was to attach tragacanthin (water-soluble componen t of tragacanth) to lysozyme by Maillard reaction. The covalent attachment of this hydrocolloid with lysozyme was confirmed by SDS-PAGE and ion exchange chromatography. The conjugates exhibited improved solubility, foaming and emulsion properties. In addition, thermal stability of lysozyme in this conjugate was increased significantly. According to these results, attachment of lysozyme to tragacanthin can increase the application of this hydrocolloid as a functional component and lysozyme as a natural antimicrobial component in food and pharmaceutical industry.

The combined effects of salt percentage (0.5 or 1%), its adding order (before or after the fermentation) and different ratios of NaCl/KCl (100/0 and 50/50) were used in the probiotic Doogh. Two probiotic bacteria (Lactobacillus acidophilus LA-5 and Bifidobacterium lactis BB-12), along with the yogurt bacteria were used. pH, acidification and redox potential were measured during the fermentation period. Moreover, viability of probiotic bacteria was determined within 7-day intervals during the storage period. The sensory parameters were also evaluated at days 0 and 21. The partial substitution of NaCl with KCl in the studied concentration had a positive influence on the viability of probiotics. Treatments containing 1% NaCl/KCl and 0.5% NaCl/KCl which were added before fermentation showed the maximum viability of probiotics. The treatments with 0.5% NaCl and then 0.5% NaCl/KCl before fermentation showed higher acceptance. Thus the substitution of 0.5% NaCl with KCl was acceptable. In whole, the treatment containing 0.5% NaCl/KCl before fermentation was the best one for probiotic Doogh with substituted salt.

Infectious diseases created by strains of Antibiotic resistance Escherichia coli and Staphylococcus aureus, is increasing in many countries such as Iran. Therefore, many efforts are performing in order to find a new composition as replacement for antibiotics. In this experimental research, an antimicrobial effect of the ethanolic and aqueous extract of Hibiscus Sabdariffa was investigated on several strains of Escherichia coli and Staphylococcus aureus resistant to common clinical antibiotics. The extract of Hibiscus Sabdariffa was prepared using rotary. Twenty strains of Escherichia coli and Staphylococcus aureus were provided from Mashhad University of Medical Sciences. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using Serial Dilution Method in six concentrations onto strains of Escherichia coli and Staphylococcus aureus in broth media. The results showed that Escherichia coli was resistant to antibiotics of penicillin (75.9%), erythromycin (58.3%), tetracycline (56.9%), and cefixime (37%), and Staphylococcus aureus showed resistant to antibiotics of penicillin (83.5%), cefixime (80%), erythromycin (55.6%), and tetracycline (26.1%), respectively. Also, the ethanolic extract of Hibiscus Sabdariffa has acceptable effect on antibiotic resistant strains of Escherichia coli and Staphylococcus aureus that MIC of the Hibiscus Sabdariffa ethanolic extract was 4 and 16 mg/mL for Escherichia coli and Staphylococcus aureus, respectively. The overall, the Hibiscus Sabdariffa extract has inhibitory ability on Antibiotic resistant Escherichia coli and Staphylococcus aureus strains. So, the ethanolic and aqueous extract of Hibiscus tea can be used in in pharmaceutical industry for medical treatments with perfect study.

Ice cream is a complex food colloid including fat droplet and air cells that dispersed on the relatively frosted aqueous phase. In this research work, the effect of the fat at the four level (2.5, 5, 7.5, 10%), pekmez at the three level (0, 9, 18%), two types of hydrocolloids (Carboxyl Methyl Cellulose and balangu) each at the four level (0.1, 0.3, 0.5, 0.7%) on the viscous flow properties and total acceptance of ice cream by response surface methodology (RSM) was investigated. The flow behavior of all samples using Power law, Casson, Bingham and Herschel- Bulkley models was investigated. According to the R2 (≥0.99) and RMSE (£0.9314) values, it is obvious that the Power law model is highly appreciated for describe flow behavior of ice cream samples. Also the Result indicated that casson plastic model was highly significant for evaluate yield stress of ice cream samples. Samples containing Balangu gum has higher consistency coefficient and yield stress and lower flow behavior index than samples containing CMC. Its worth to mention that Herschel-Bulkley model gave negative values for yield stress which has no physical meaning. Balangu seed gum (BSG) in comparison to carboxyl methyl cellulose did not have a significant effect (P>0.05) on the total acceptance. The Desirability function has been achieved as 0.93 which, itself, indicates the accuracy of optimization. The optimum formulation has been found as following: fat of 5.6%, BSG of 0.6%, Pekmez of 18%, respectively.

With emerging of infectious diseases and spread of antibiotic resistant strains, use of antimicrobial compounds with plant origin seems necessary. In this study, ethanolic extract of Cordia myxa fruit was used to evaluate antimicrobial effects against microorganisms including Bacillus cereus, Staphylococcus aureus, Escherichia coli, Salmonella typhi, Aspergillus niger and Candida albicans. Ultrasound-assisted extraction was performed to investigate three independent variables: time (5-40 min), temperature (20-50oC) and sonic power (20-100%). Response surface methodology was also employed to optimize multiple variables to predict the best process conditions. Antimicrobial activity was done by methods including disk diffusion agar, pour-plate, minimum inhibition concentration and minimum bactericide (fungicide) concentration. The results showed that the highest amount of extraction rate of ethanolic extract which was equal to 8.5%, was obtained in extraction time of 39.8 min, temperature of 42.2oC and sonic power of 94.4%. In all above-mentioned methods, inhibitory effect of optimum ethanolic extract was more significant against Bacillus cereus, Staphylococcus aureus and Candida albicansthan other strains (p≤0.05).

Raw cane sugar is the one of the most important products in sugar industry. Quality characteristics of raw sugar are the main influence factor in type and quality of refined sugars. The purpose of this research was to find agrrement between the CIE color coordinates and certain quality parameters of various imported raw cane sugar samples. The spectral reflectance of such raw sugar samples were determined with the aid of a spectrophotoradiometer in the range 380 to 780 nm and were then converted to their corresponding CIE color coordinates. The correlation between such color coordinate values and certain quality parameters of samples such as; ash content, sucrose, invert sugar, color solution, pH, starch, dextran content, moisture and refractive index were determined. Results show good to very good correlations between some quality parameters such as starch content, ash content and color solution and various CIE color coordinates values such as L*, a*, b*, C*, h, X, Y, Z, x, y and Y.I.

Food adulteration is done in various forms. The most common adulteration in sesame oil is done with adding by sunflower oil, corn oil and hazelnut oil. This study examines the pure sesame oil using Differential Scanning Calorimetry (DSC) analysis deals. Samples of pure sesame oil, 5%, 10% and 15% corn oil and sunflower oil was mixed with sesame oil. With the increase of corn oil and sunflower oil, sesame oil, peak displaced towards lower temperatures and the temperatures start, maximum and end of both large and small melting peak was reduced. According to the triglycerides of saturated fatty acids at higher temperatures than triglycerides with unsaturated fatty acids are melted. The peak shift toward lower temperatures can be increased by addition of unsaturated lipid components of corn and sunflower oils.

Chemical preservatives are usually used to reduce or eliminate pathogenic or spoilage microorganisms but their inordinate applications have resulted in toxigenic residuals and adverse effects on consumers, So many researches have been done to substitute the chemicals with naturally occurring compounds, especially plant essential oils.In this study, the chemical compositions of essential Thymus kotschyanus were identified with set GC-MS. Then organoleptic properties, microbial and physicochemical quality of Doogh sample prepared with adding different concentration Thymus kotschyanus essential oil were investigated during 14 day storage.Results of GC-MS analysis indicated that thymol (51.1%), p-cymene (13.78%) and γ-terpinene (9.03%) comprised the highest amount of this EO. T. kotschyanus EO destroyed E. coli O157:H7 in additive low concentrations to Doogh in same the early days and the MIC that determined by the micro dilution method was 470mg/ml. Based on the results, essential oil doesn’t have significant changes in Doogh physico-chemical properties excepion total solid that essentail Doogh free comparsion with Doogh contain 100 and 200 ppm make significant changes (p<0.05), the Doogh that contain 50 ppm was accepted by panelist.The addition of this EO has no adverse effect on the physicochemical and organoleptic properties of Doogh, also this EO effective substances could be purified and used as natural antibacterial agent, solely or along with others techniques, to prolong food shelf life.

In this study, antimicrobial activity of lactic acid bacteria isolated from traditional Kurdish cheese was evaluated. At first, cell free culture supernatant was prepared, and then divided into three groups (control, treated by heat and treated by NaOH). Antimicrobial activity of supernatant treated or no treated was investigated utilizing Agar diffusion, Disk diffusion and Minimum Inhibition Concentration. In addition, coaggregation of lactic acid bacteria against pathogens was determined. Results showed native lactic acid bacteria were suitable antimicrobial activity in comparison to commercial lactic acid bacteria. Heating of supernatant hadn’t effect on antimicrobial activity, while treating by NaOH didn’t show antimicrobial activity. In addition, native lactic acid bacteria didn’t show significant difference in minimum inhibition concentration with commercial lactic acid bacteria. Native lactic acid bacteria also have a suitable coaggregation with pathogens. Results of this study showed native lactic acid bacteria isolated from traditional Kurdish cheese can be used as natural antimicrobial agents.

The effect of xanthan gum (0-0.3%) on corn oil-in-water (pH=7) emulsions prepaired by 0.5% grass pea (Lathyrus sativus) protein isolate was studied. Particle size, PDI, zeta-potential, emulsion capacity, emulsion stability and creaming index of emulsions were measured inorder to find the effect of xanthan gum on the stability of emulsion. Results showed that increasing concentrations of gum caused depletion flocculation and thus increased the particle size but had no significant effect on the zeta potential. Study on creaming index, emulsion capacity and stability also showed that with increasing xanthan gum, emulsion capacity and stability increased, while, creaming index decreased. Therefore, after 28 days of storage at 4oC, no changes were observed in the emulsions containing xanthan gum.

Snacks are amongst popular foods, therefore improving the quality of the snacks is of great importance. Half-products are a kind of cereal based snacks that are sold in the form of dried pellets and then deep fried for a few minutes by the consumer to form puffed crispy edible snacks. The main aim of this study was to determine the sufficient pellet moisture content in order to reach an appropriate snack quality. Pellets were produced using a single screw extruder by mixing wheat flour and starch to reach moisture content of 7.5%. The moisture content of the pellets was then adjusted on 5, 10, 12, 14 and 16%. Pellets were deep-fried at 185oC to reach their maximum volume and then their physical and sensory characteristics were studied. Increasing the moisture content from 5 to 16% reduced the density, increased lightness, reduced redness and yellowness of the snacks. The fracture force to break of snacks reduced with increasing the moisture up to 10% but it reduced with further increase in pellet moisture content. Increasing pellet moisture up to 14% improved the sensory characteristics of the snacks while further increase in the moisture content reduced these properties. Adjustment of the pellet moisture content is a practical solution in the industry to improve the quality of the snacks. The most appropriate moisture content of the pellet was in the range of 10-12%. At higher or lower moisture levels, the sensory characteristics of product were affected, negatively.

Verjuice is a popular fruit juice mainly consumed as salad dressing. However, there is very little information regarding its characteristics. The objective of the present study was to determine verjuice and its concentrate physicochemical properties during storage at 4oC. Firstly, verjuice characteristics such as pH, acidity, specific weight, density, total soluble solids, total solid, reducing sugar content, ash, rare minerals, vitamin C, phenolic content and antioxidant activity were evaluated. In the next phase variation of acidity, pH, total solid and colour parameter (L, a, b) and total phenolic content of pasteurized concentrate verjuice during 6 months storage at 4oC were assessed. Findings revealed that not only verjuice has a high acidity value but also it is a good source of bioactives such as vitamin C, antioxidant and phenolics components. Storing the concentrate at 4oC resulted in reduced acidity, phenolic content, parameter L and b but increased value of parameter a, and total solid.

This Research was to investigate the antibacterial effects of aqueous and ethanolic extracts of Aloe Vera on pathogenic bacteria such as Staphylococcus aureus (ATCC25923), Escherichia coli (ATCC25922), Listeria monocytogenes (ATCC33090) using disk diffusion and broth Microdilution methods. The results illustrated that gram-positive bacteria are more sensitive to ethanolic extract of Aloe Vera as compared with gram-negatives bacteria. This phenomenon is due to the structure and the strength of cell wall in gram-negative bacteria as well as the nature and active compounds of Aloe Vera. Ethanolic extract of Aloe Vera showed that the maximum antibacterial activity on Staphylococcus aureus and Listeria monocytogenes in which the minimum inhibitory concentration (MIC) was 0.132 and 0.625 mg/ml respectively. The maximum inhibition zone was observed on Staphylococcus aureus and Listeria monocytogenes with 12 and 8 mm respectively. On the other hand, aqueous extract of Aloe Vera did not show any antibacterial activity. It is supposed that antibacterial compounds such as Anthraquinone, Hydroxyanthra and Saponin had the most roles for antibacterial activity in ethanolic extract on Aloe Vera.

Biosurfactants are amphiphilic compounds that are produced by bacteria and fungi and they are able to reduce surface tension. These compounds are preferred due to less toxicity and better degradation than chemical surfactants and they have many applications in the petroleum, food and pharmaceutical industries. The purpose of this study was the investigation of production conditions of biosurfactant from Bacillus strains identified in Biotechnology Laboratory, Chemical Engineering Department, Tehran university, that been named HR1, HR2, and HR3. Materials and Methods: After performing the inoculation, the culture medium incubated at different temperatures and times and rotation rates and then obtained biosurfactant extracted and measured by solvent. According to the results, temperature, incubation time and rotation rate are affecting factors on biosurfactant production. The maximum amount of biosurfactant was obtained by HR1 in 33oC and 150 rpm after 5 days incubation. acillus HR1 is appropriate for biosurfactant production for use in various industries, especially in the food industry.

Food security and access to healthy food and its’ quality is the primary and most basic of human needs. Food Security exists when all people, at all times, have physical and economic access to sufficient, safe and nutritious food to meet their dietary needsand food preference for an active and healthy life. The main purpose of the study was survey of the food insecurity situation and access to food in urban households of the Alborz Province. The research method was descriptive and Crosscorrelation that was conducted by a survey. The population consists of all urban households in Alborz Province (N=652,466) and 185 households were chosen by the stratified random sampling method. The main instrument was a questionnaire where its’ validity confirmed by panel of experts in agricultural extension and education department at Tarbiat Modares and Tehran universities. Consistency and reliability of Research tools were assiumed by Cronbach’s alpha coefficient (0.74). The food security situation results show that 64.4 percent of households were in food safety category and 17.2 percent was in low levels of food insecurity, 10.3 percent were in medium food insecurity level and 8 percent were severely in food insecurity level. Also the results showed that there is significant differences at the 0.01 level in food access Between urban households in Alborz Province, This mean that, Nazarabad city households were in highly level than the other households.

In this study egg and saturated fat were eliminated from cake formulation and microcrystalline cellulose (MCC), hydroxypropylmethylcellulose (HPMC), xanthan, whey protein isolate (WPI), glycerol monostearate (GMS) and sodium stearoyl-2-lactylate (SSL) were used as replacement. Effect of mentioned ingredient on the batter viscosity, density, cake volume and sensory scores was studied. Addition of hydrocolloids to wheat flour in the presence of SSL and GMS increased cake batter viscosity and density and xanthan showed the highest value followed by MCC and HPMC. Batter with hydrocolloids was heavier and lacks the proper aeration. Sensory evaluation of cakes with different hydrocolloids showed that the use of xanthan decrease quality scores and samples with HPMC received the highest quality scores. Use of HPMC improved crumb color and MCC improved cake texture. Results of this study indicated that some of hydrocolloids in combination with emulsifiers and WPI can be a good substitution for egg and saturated fat in cake formulation.

In this research, physicochemical properties and oxidative stability of Roghani virgin olive oil grown in two regions of Roodbar and Kazeroon, located in north and south of Iran respectively, with differences in pedoclimatic conditions, altitude and soil were investigated. To determine the physicochemical properties, acidity, peroxide value, spectrophotometric indexes at 232 and 270 nm, smoke point, specific gravity and refractive index as well as the total contents of phenolic compounds, alpha tocopherol, chlorophyll, carotenoid, and fatty acid composition were evaluated. To evaluate the oxidative stability, the effect of heat treatment at 180°C for 8 hours on indicators such as conjugated diene value, carbonyl value, polar compounds and oxidative stability index were tested. Results indicated the differences in the structural properties and oxidative stability of the oil obtained from two regions. As the oil from Roodbar region with lower altitude, lower average annual temperature, higher average annual rainfall, and specific geographical conditions, contain higher phenolic compounds, alpha tocopherol and oleic acid and also showed higher oxidative stability during heat treatment. But the oil of Kazeroon region with higher altitude, higher average annual temperature, and lower average annual rainfall, had higher linoleic and linolenic acids and exhibited lower oxidative stability during thermal treatment. Therefore the results of this study can be used as a description of physicochemical properties and oxidative stability of Roghani olive oil from two regions of Roodbar and Kazeroon.