Iranian Food Science and Technology Research Journal
Year:2015 | Volume:11 | Issue:2|Papers Count:13

Barberry is an agricultural product, which is cultivated in large amounts, only in Iran. Its popularity as an ingredient 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 affect on anthocyanin stability. High temperatures degrade the anthocyanins and the rates of degradation depend on the presence of oxygen, pH and their chemical structures. In this study the effect of temperature and solid content on degradation kinetic of anthocyanins inBerberis vulgaris var asperma were determined over a temperature range of 70-90oC. 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 90oC, 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 (5-85oC). 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 Showed 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. It was shown that strength of AHSG at cooling step is 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 (P<0.05). Oxidative stability of pasteurized butter Components packaged with polyethylene film containing extract and without extract was evaluated in freezing (-18oc) and refrigeration (4oc) temperatures during 4 months and 45 days respectively. The index value of peroxide, free fatty acids (FFA) and sensory characteristics of the samples were investigated during storage. In both temperature, coating of extract on the surface of polyethylene film resulted in reduction of peroxide value and free fatty acids in butter samples (P<0.05). In both temperatures, increasing the extract concentration caused flavor changing of butter and consequently decreasing in public acceptability (P<0.05). Film coated with an extract concentration of 0.1% produced most desirable oxidative stability and sensory characteristics at both temperatures.

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 platensisis 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 (p<0.01). The interactive effect between different levels of biomass and stage of addition had significant impact on the time needed for reaching to the maximum acidification rate (p<0.05). Microstructure study of particles aggregation during fermentation time represented a slowdown trends in yogurt containing 2% of Spirulina compared to the control sample. SEM images of yogurt gel network in micrographs also demonstrated the positive effects of Spirulina biomass in the range of 0.5 and 1 percent on the strength of yogurts protein network.

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 used The 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 (431.1 mmol/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 Nano liposomes 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.

The effects of 4-hexylresorcinol for preventing black spots forming in whiteleg shrimps and checking chemical, bacterial and sensory qualities of cultured shrimps were evaluated. Two treatments containirg were inplemen ted immersed shrimp in a mixture of 4 - hexylresorcinol and citric acid (at a concentration of 0.15 % and 1%, respectively) for 10 minutes and without antioxidant shrimp. Qualities of samples had been evaluated by bacterial, chemical and sensory tests at a temperature of -18oC in frozen storage for 6 months. NoPseudomonas, Vibrio parahaemolyticus, Escherichia coli and hydrogen disulfide-producing bacteria were observed in experimental samples. Unlike the control samples, Coliform bacteria were hot observed in experimental samples. Peroxide value, thiobarbituric acid, free fatty acids, TVB-N and trimethylamine factors showed significant differences compared to control samples. TVB-N, trimethylamine, peroxide value, moisture, content total bacterial counts and Staphylococcus bacterial counts factors of experimental and control samples showed significant difference during the storage period (P<0.05). PH and moisture factors of experimental samples showed no significant difference compared to control samples (P>0.05), unlike total bacterial counts, s taphylococcus bacterial counts, C oliform bacterial counts, free fatty acids, peroxide value, thiobarbituric acid, TVB-N and trimethylamine factors. Sensory factors including color (melanosis) of experimental shrimp had better qualities than control samples. Sensory quality, melanosis and shelf life of experimental samples showed significant difference compared to control samples (P<0.05). black spot washot formed in the experimental treatments till the end of the storage period but melanosis was formed in the control samples in less than a month being kept in frozen storage.

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 monocytogenesand other pathogens in food industries. This study was undertaken to evaluate the effect of nisin againstlisteria monocytogenes in different temperatures (4, 9 and 14oC), 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, differences in population (DP) assay was used in order to analyze the effects of (storage) temperature, pH and sodium chloride concentration on Listeria monocytogenes survival in presence of nisin. The MIC value of nisin was 320IU/ml. The effectiveness of nisin was increased at 14oC better than at 9 and 4oC (P<0.016). Nisin activity increased in the presence of 2 and 4 g/100 ml of NaCl concentration (P<0.001). Also higher inactivation was observed after to pH 5 compared to pH 6 and 7 (P<0.001). Our results demonstrated that among different NaCl, pH, temperature and nisin values, the effect of NaCl was confounded than the effect of other factors at all prepared combinations (P<0.001).Our findings suggest the application of hurdle technology for achieving effective control in most in food industries.

Plants derived products have been used for medicinal purposes for centuries because of antimicrobial activity. In this research, antibacterial effect of Hop (Humulus lupulus), was evaluated on some of food borne pathogens. For this purpose, the effect of hop aqueous extract compared to Humulune from hop was analyzed against Staphylococcus aureus (PTTC1431), Enterobacter aerogene s (PTCC1221), Listeria monocytogenes (PTCC1298) and Salmonella enterica (PTCC1709) by agar disk diffusion and broth micro-dilution methods. Results showed 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 but no MBC was observed for the mentioned strains. Findings indicated that Humulune had more antibacterial activity than aqueous extract in both methods. The most inhibitory effect was found against Staphylococcus aure us in disk diffusion method (inhibition zone of 17mm). The effect of Humulune was more than aqueous extract of hop. Results indicated that hop extract had antibacterial effect which may be exploited in combinational therapy or as a food preservative.