نشریه پژوهش های علوم و صنایع غذایی ایران
سال یازدهم شماره 2 (پیاپی 32، تابستان 1394)

Barberry is an agricultural product، which is cultivated in large amounts، only in Iran. Its popularity as an ingredient for many by-products has grown recently. It contains anthocyanins which can be used as natural food colorants. These compounds are useful for human health and have high economic value. Magnitude and duration of heating has a strong influence on anthocyanin stability. Temperature degrades the anthocyanins and the rates of degradation depend on the presence of oxygen، pH and their chemical structure. In this study the effect of temperature and solid content on degradation kinetic of anthocyanins in Berberis vulgaris var asperma were determined over a temperature range of 70-90◦C. Analysis of kinetic data suggested a first-order reaction for the degradation of barberry juice and concentrate anthocyanins. The half-life values were calculated 6. 02، 3. 32 and 1. 06h for juice، 3. 32، 1. 84 and 0. 76h for concentrate of 30 Brix and 3. 19، 1. 31 and 0. 49h for concentrate of 50 Brix between 70 and 90◦C، respectively. The temperature-dependent degradation was modeled using Arrhenius equation. By increasing solid content، the activation energy value was increased but D-value and Z-values were reduced. The results shows that the degradation of anthocyanins in concentrates occurred at a faster rate than in juice. By increasing the temperature degradation rates were increased both in juice and concentate.

In this study، dynamic rheological، structural and thermal properties of Alyssum homolocarpum seed gum (AHSG) were investigated as a function of concentration (1. 5، 2، 2. 5 and 3% w/v) and temperature (5–85 °C). The effects of heating/cooling rate on the rheology of AHSGs were studied using small amplitude dynamic oscillatory shear (SAOS). The LVE of this gum were observed at more than 1% strain. The elastic component was always higher than the viscous one. Mechanical spectra of these gum solutions were obtained by frequency sweep measurement classified into that of weak gels because G’ was larger than G” throughout the tested frequency range. The complex modulus has linear relationship with the frequency. The gums showed dependency behaviour as a function of temperature in the range of 5-85oC. The moduli were dependent on gum concentration. They were shown that strength of AHSG at cooling step was more than heating step. AHSG at concentrations above 2. 5% was formed gel and its gel was irreversible. Gel formation temperature increased with increasing concentration. FT-IR spectra to understanding their functional groups were recorded in the transmittance mode.

Antioxidant active packaging is one of the active packaging that prevents of lipid oxidation by releasing antioxidant during storage of food. In recent years the use of natural antioxidant instead of the synthetic variety in these packaging has been considered. The aim of this study was evaluating the performance of polymeric film coated with natural antioxidant (Rosemary Extract) to prevent lipid oxidation in butter. With three different concentrations (0. 1%، 0. 15%، 0. 2%)، the ethanolic extract of Rosemary was sprayed on the surface of low density polyethylene films (LDPE). Films without extract was used as control. Phenolic compounds migration from the surface of film to 95% ethanol (fatty food stimulant) was measured at 4ºc during 10 hours. With increasing time and extract concentration، migration to ethanol increased.

Kurdish cheese is semi-firm cheese which has been traditionally manufactured from whole raw cow or sheep milk، in the East of Iran. It is ripened in goat’s skin bags. The microbial diversity of kordish cheese originates from natural microbiota present in the raw milk and its unique organoleptic properties have made it excellent among other traditional cheeses in Iran. This study has been conducted to evaluate microbiological diversity during ripening of Kurdish cheese. Samples were taken from 6 batches of cheese on day 1، 20، 40 and 60. Sensory properties of Kurdish cheeses were determined at 60،120 and 180 days of ripening. Based on results، the diversity and microorganisms count of were mainly influenced by ripening time. Lactic acid bacteria and Enterobacteriaceae were the predominant families of micro-organisms during the first 20 days of ripening and lactobacilli was the most abundant lactic acid bacteria in cheese. Coliforms and E. coli decreased more rapidly in cheese، whereas mows and yeasts decreased gradually and then increased in ending days. At the end of ripening period، mo coliforms، salmonella and coagulase positive staphylococcus were detected in the samples. Changes in textural and chemical characteristics in relation to ripening time showed that; pH، Moisture، Total solid، aw and fat content of samples decreased during 40d and reached to 4. 69، 33. 9، 64. 07، 0. 927، 28. 1 at 60 days respectively. no significant variations observed in Protein values during ripening period. The values for sensory characteristics such as taste، aroma، colour and total acceptance of the full-ripened cheeses (120th days) increased as ripening progressed. According to our results، from a safety point of view، the optimum time for consuming Kurish cheese would be after passing ripening time of 60 days (during 1-2 months) due to decrease in pH، undesirable flora and increase in desirable LAB counts.

Spirulina platensis is a blue-green microalga with unique nutrient content and several therapeutic aspects which has been used for fortification of different foods. In this study، the effect of Spirulina platensis powder in different levels (0، 0. 5، 1 and 2 percent)، added in two stages (before pasteurization and at same time with starter culture) was studied on the microstructure and acidification characteristics of yogurt during fermentation time. The results showed that different levels of Spirulina biomass had significant effect on acidification kinetics parameters of yogurt samples.

Sepals and petals are byproducts from saffron production process that waste without any use in Iran. These byproducts containing a lot of anthocyanin and natural antioxidants. The aim of this study is determine efficiency of extraction and measurement of antioxidant activity and anthocyanin pigments of pollen and anther of saffron flower، using mixed solvent of ethanol and hydrochloridic acid 1. 5 N (85:15) by ultrasonic waves. Therefore، the time factors (5، 15، 25 minutes) and sound intensity (20، 60 and 100%) were usedThe results showed that the most efficient extraction of samples (54/48%) was extracted in 15 minute and 100% of sound intensity، and the maximum measure of anthocyanin compounds (48. 83 mg/ml)، total phenolic compounds (36. 54 mg/ml)، power of reviving the anti-radical DPPH activity of the extracts (335. 7 mg/ml) and the power of scavenging Fe III (431. 1µmol/lit Fe III)، the best sample in all of the exams was extracted in 10 minutes and 100% of sound intensity. So، the optimized situation for extraction of anthocyanin compounds by ultrasound waves was time 15 min and 100% about sound intensity.

Nisin has numerous applications as a natural preservative in foods، including dairy product، canned food، processed cheese and milk. Several studies demonstrated that proteolytic degradation and the interaction of nisin with food components might result in decreased its antimicrobial activity. Encapsulation of antimicrobial peptides into nanoliposomes may offer a potential alternative to protect antimicrobials، enhancing their efficacy and stability for food applications. In first stage of this research، Response Surface methodology was used for optimization of nanoliposomes produced by heating method. A central composite design (CCD) consisting of 18 experimental run with three independent variables: phospholipid concentration (2-30 mM)، stirring speed (500-1360 rpm) and processing time (30-90 min) were used and their effects on size of nanliposome were evaluated. In the next stages، stability of nanoliposomes was investigated during 2 month. The optimum operating conditions obtained from the quadratic form of RSM model for particle size were phospholipids 30 (mM)، stirring speed 930 (rpm) and process time 90 (min). The results of stability indicated that samples in the range of 400 to 500 nm were stable up to 2 month (P > 0/05) but samples larger than 500 nm were unstable during 2 month but stable up to 1 month (P> 0/05).

External and internal changes in fruits during storage time are affected by the various factors that some of them can by studied by measuring the qualitative parameters (physical and mechanical). The effects of storage time on some physical and mechanical properties of Valencia orange were investigated. The experiment was performed as factorial based on completely randomized design. Analysis of experimental results showed a significant effect of storage time on all the physical parameters of Valencia orange. With increasing time، the true density of oranges increased while other physical parameters decreased. Rind ratio and moisture content increased and true density decreased with increasing the size of fruit. Also the effect of storage time and fruit size on the rupture force and deformation was significant at the level 0. 01. The mean failure load for 2، 32 and 62 days storage were obtained 206. 05، 139. 64 and 221. 07 N، respectively. Rupture force and deformation values were followed by increasing fruit size.

In this study، ZnO nanoparicles and polymer nanocomposite were synthesized for film preparing of food packaging. The structural، physical and anti-microbial properties were then studied. ZnO nanoparticles were synthesized by sol- gel method. The Structural analysis by XRD verified the formation of zinc oxide phase. TEM images showed that the nanoparticles are spherical shape and their average size between 20 to 25nm. To prepare nanofilm، Zno nanoparticles were added at three concentration levels of 1،3 and 5%wt to the PVA matrix which prepared by solution processing method. SEM images of the film showed that in all samples the nanoparticles were distributed well in the polymer matrix. With using the Fourier Transmission Infrared (FTIR) at a wave length of 558cm- 1 Zn-0 band at all of nanoparticle concentrations were establish. The effect of inserting ZnO on the mechanical and antibacterial properties and moisture content of the PVA were also investigated. The increase of ZnO concentration in PVA from one to three percents causes the increase of tensile strength by 11%. The moisture content reduced up to 20%، when nanoparticles concentration increases from zero to five percents. Furthermore، by adding ZnO on PVA the antibacterial activity of the composite film was further improved.

This project was carried out in order to Study of possibity of uses from 4 hexyresorcinol for prevention of melanosis in cultured shrimp. Treatments including of samples processed with 0. 15% concentration of 4 hexylresorcinol and control samples. The samples were kept at -18oC. Bacterial، chemical and sensory examinations were carried out for a period of six months. Statistically significant difference was observed in peroxide value، free faty acids، thiobarbotouric acid and trimethylamin in test samples compared with the control samples during storage period.

Nisin، belonged to type-A lantibiotcs، is a well-known bacteriocin that applied as natural preservative in food productions such as milk and cheese. This peptide has an inhibitory effect on many of Gram-positive bacteria. Using of nisin alone and in combination with other hurdles may serves as an effective method to eliminate listeria monocytogenes and other pathogens in food industries. This study was undertaken to evaluate the effect of nisin against listeria monocytogenes in different temperatures (4، 9 and 14°C)، pH (5، 6 and 7) and NaCl concentrations (0، 1، 2 and 4). The minimum inhibitory concentration (MIC) of nisin was assessed using a broth micro-dilution method. Furthermore، for the effects of storage temperature، pH and sodium chloride concentration the Differences in Population (DP) assay were used. The MIC value of nisin was 320IU/ml. The effectiveness of nisin was pronounced at 14°C than at 9 and 4°C.

Plants derived products have been used for medicinal purposes for centuries because of antimicrobial activity. In this investigation Antibacterial effect of Hop (Humulus lupulus)، the pharmaceutical plant which has an important place in traditional medicine of Iran، was evaluated on some of food borne pathogens. This study conducted in order to evaluate antimicrobial effect of Hop water extract compared to Humulune from Hop against Staphylococcus aureus (PTTC1431)، Enterobacter aerogenes (PTCC1221)، Listeria monocytogenes (PTCC1298) and Salmonella enterica (PTCC1709) by agar disk diffusion and broth microdilution methods. The results indicated that gram positive bacteria were more sensitive to the extracts compared to gram negative bacteria. The minimum inhibitory concentration (MIC) of Humulune and water extract of Hop against Staphylococcus aureus were 0. 039 and 0. 625 mg/ml respectively. Findings indicate that Humulune had the most antibacterial activity in both methods. The most inhibitory effect was shown against staphylococcus aureus in disk diffusion method (inhibition zone of 17mm). The effect of Humulune were more than water extract of Hop. Results indicate that Hop extract has antibacterial effect and can be used in combinational therapy or as a food preservative.