Morteza Khomeiri

Production of pectin-whey protein nano-complexes as carriers of orange peel oil

Orange peel oil is one of the most common flavorings used in the food industry which is volatile under environmental conditions. Encapsulation is the best way to protect it and control its release. One of the nanoencapsulation systems for food bioactive ingredients is complexation method, which entraps the core materials in a complex of two different biopolymers. In this study, orange peel oil was nanoencapsulated by pectin-whey protein nanocomplexes. After determining the optimum nanocomplex suspensions containing orange peel oil based on the stability, viscosity, and color, they were formulated in three different pH values (3, 6 and 9) and converted into powdered forms by freeze drying. The analysis of size and zeta potential of nanocomplexes revealed that the smallest particles formed in pH=6. The encapsulation efficiency of the powders at pH=3, 6 and 9 were 88, 84, and 70%, respectively and there was a reverse linear correlation between encapsulation efficiency and the color index (b*). The microstructure and the morphology of the nanocomplex powders was investigated by SEM and AFM and the results showed that more spherical particles are formed in pH=3. FTIR analysis determined that there was a chemical reaction and bond formation between whey proteins and pectin as a sharp band was appeared in 991cm-1.

Isolation and Identification of Yeasts and Lactic Acid Bacteria from LocalTraditional Fermented Camel Milk, Chal

The yeasts and lactic acid bacteria in samples of the Iranian traditional fermented camel milk, Chal were identified on the basis of physiological and morphological properties. Yeast species were identified including Pichia. anamala, Pichia. jadinii, Debaryomyces. hansenii, Pichia. guilliermondii, Kluyvermyces. marxianus, Candida. fermentati, Pichia. ciferrii, Torulospora. delbrueckii, Candida. versatilis, Kluyvermyces. lactis, Candida. kefir, Saccharomyces. pastorianus, Saccharomyces. serevisiae, Candida. friedrichii, Kluyvermyces. polysporus, Rhodotorula. musilaginosa, Candida. lipolytica and Candida. lusitaniae. All of them could assimilate the glucose and liquefacted the gelatin, but could not production starch, tolerated 1% acetic acid, growth in the presence of Nacl 16% (except Debaryomyces. hansenii), anassimilateed the nitrat (except Rhodotorula. musilaginosa). Within the yeasts species, Kluyvermyces. lactis (8.57%) and Kluyvermyces. marxianus (8.57%) were the predominant. Also 93 different lactic acid bacteria species were identified including 64 bacilli as lactobicallus and wieselia, 8 cocci, leuconostoc, 11 coccobacili, leuconostoc, lactococcus and wieselia, 2 streptococci, streptoccus and 8 tetrad cocci shapes, pediococci. All isolates fermented galactose, except Lactobacillus delbrueckii subsp. Bulgaricus, Lactobacillus kefir, Lactobacillus viridescens. All the isolates could growth at 37°C, only Leuconostoc mesenteroides subsp. Cremoris and Leuconostoc paramesenteroides could not growth at 30°C. This study revealed Chal contained a wide variety of yeasts and lactic acid bacteria.

Production of Kefiran in Kefir Grains and its Effects on the RheologicalProperties Low Protein Wheat Dough and Quality of France Bulky Bread

Kefiran is an exogenous microbial metabolite which is produced principally by lactic acid bacteria and fungi and molds throughout growth. Exo polysaccharide of kefiran was extracted from kefir grains and in status of gel was added at 1, 2, 3% concentrations (w/w flour basis) to wheat flour to evaluate its effects on rheological properties of weak wheat dough. The rheological measurements of the dough were investigated using Farinograph and Extensograph instruments. Results of Farinograph evaluation of dough showed that adding of kefiran and increase in its levels leads to increase in the water absorption capacity, dough development time and departure time, while the dough degree of softening after 20 min and mixing tolerance index were decreased in comparison with the control sample. The study on Extensograph behavior of the dough containing kefiran showed that resistance to extension at 45 and 90 min resting times was increased by increasing the percentage of the added kefiran. Longer fermentation time for each level of kefiran led to decrease of resistance to extension. Significant difference was observed in the resistance to extension of the dough containing different levels of kefiran and the control sample. Addition of kefiran to the dough after 45, 90 and 135 min resting times significantly decreased the extensibility, also with an increase in resting time from 45 to 135 min, the extensibility decreased for both the control and kefiran samples. Generally, addition kefiran at 45, 90 and 135 min resting times led to a significantly increase in resistance to extension ratio. Energy input increased at 45 and 90 min resting times, whereas chaotic effect was shown at time of 135 min restig time. Therefore, kefiran can be used to playing an important role in improving of rheological properties of weak dough and its processing conditions.

Incorporating Zataria multiflora Boiss. essential oil and sodium bentonite nano-clay open a new perspective to use zein films as bioactive packaging materials

Active zein films with different levels of Zataria multiflora Boiss. essential oil were produced successfully. To enhance properties of this biopolymer for food packaging applications, sodium bentonite clay was used at two levels (2 and 4%). The results indicated that the addition of Z. multiflora Boiss. essential oil caused a reduction in tensile strength and Young’s modulus and slight increase in the percent of elongation at break of the films. Maximum solubility in water and water vapor permeability was observed by incorporation of 10% Z. multiflora Boiss. essential oil in the zein matrix. Transmission electron microscopy micrographs of zein film were verified by the exfoliation of the layers of sodium bentonite clay in the zein matrix. Stronger films with lower water vapor permeability and water solubility were evident of good distribution of sodium bentonite clay in the zein matrix. According to the results, 2% sodium bentonite clay was selected for evaluation of nano active film properties. Water vapor permeability, UV light barrier, tensile strength, and Young’s modulus values of active films were improved by incorporation of 2% sodium bentonite clay. The antibacterial activity of different contents of Z. multiflora Boiss. essential oil in vapor phase demonstrated that use of Z. multiflora Boiss. essential oil in the liquid phase was more effective than in vapor phase. The antibacterial zein-based films showed that active zein film with 5 and 10% Z. multiflora Boiss. essential oil had reductions of 1.68 log and 2.99 log, respectively, against Listeria monocytogenes and 1.39 and 3.07 log against Escherichia coli. Nano active zein film containing 10% Z. multiflora Boiss. essential oil and 2% sodium bentonite clay showed better antibacterial properties against L. monocytogenes (3.23 log) and E. coli (3.17 log).

Optimization of the new formulation of ice cream with native Iranian seed gums (Lepidium perfoliatum and Lepidium sativum) using response surface methodology (RSM)

In this study, effect of Qodume shahri (Lepidium perfoliatum) and cress (Lepidium sativum) on rheological properties of ice cream were investigated. The gums were added to the ice cream formulation and different quality attributes including pH, acidity, melting characteristics, viscosity, overrun, texture analysis and sensory evaluation were determined. Results showed that ice cream formulations containing both the gums had improved overrun, melting rate, first dripping time, viscosity, hardness and adhesiveness. The gum concentrations beyond 0.2% level led to a negative effect on gumminess and chewiness of ice cream. Both the gums addition to improved quality attributes and textural properties of ice cream.

Response surface optimization of low-fat ice cream production by using resistant starch and maltodextrin as a fat replacing agent

In this research, maltodextrin (0, 1 and 2% w/w) and resistant starch (0, 1 and 2% w/w) were used in the formulation of low-fat ice cream (4% fat) and their effects on the physicochemical and sensory properties were investigated. The optimum levels of maltodextrin and resistant starch were determined by response surface methodology. Increment of maltodextrin and resistant starch increased acidity, viscosity, melting rate, time of dripping and overrun but decreased melting rate of ice cream. Results showed that the incorporation of maltodextrin and resistant starch at 0 and 2% w/w respectively, resulted into ice cream with suitable viscosity, melting rate, first dripping time, overrun and acidity.

Steady and dynamic rheological behaviour of frozen soy yogurt mix affected by resistant starch and β-glucan

ABSTRACT The present study investigated the effect of resistant starch (0, 1%, 2%) and β-glucan (0, 1%, 2%) on the steady and dynamic rheological properties of frozen soy yogurt mixes. The results showed that addition of fibres to the mix caused an enhancement of pseudoplasticity. The power law model was the best model to fit with data. The lowest and the highest of hysteresis loop area belonged to sample containing 1% β-glucan and 2% resistant starch, respectively. Dynamic rheology results showed that storage modulus (G’) and loss modulus (G”) increased within the frequency range of 0.01–100 Hz. The loss tangent (tan δ) of all samples was above 1, indicating liquid viscoelastic behaviour. Resistant starch at concentration of 2% as compared to β-glucan was a better choice to modify the rheological properties of frozen soy yogurt mixes.

Biodiversity and origin of the microbial populations isolated from Masske, a traditional Iranian dairy product made from fermented Ewe’s milk

Masske is a traditional Iranian dairy product containing 50% butterfat made from fermented ewes milk. Overall, 672 bacterial isolates were collected from ewes milk, fermented milk (FM) and Masske samples that were produced in households located in southern regions of the Khorasan Province in Iran. To identify lactic acid bacteria in these samples, a total of 79 Gram-positive and catalase-negative isolates were analysed. The identification of isolates was achieved by phenotypic and sequential analysis of the 16S rRNA gene. Enterococcus faecium and Aerococcus viridans were the most frequently isolated species in the samples, but the most commonly present bacteria in Masske were Streptococcus thermophilus.

ویژگی های فیزیکوشیمیایی، بافتی، حسی و رئولوژیکی سس مایونز کم کالری بر پایه لبنیات

Introduction Traditional mayonnaise is probably one of the oldest and most widely used sauces in all over the world. Mayonnaise is a product with particular consistency and is classified as a type of oil in water emulsions. Vegetable oil, acetic acid, and egg yolk are main components of mayonnaise. In addition, mayonnaise may contain salt, sweeteners, spices, effective flavor materials, preservatives and stabilizers. It must contain at least 78.5 % of total fat and 6 % pureegg yolk. Due tohigh levels of oil present in mayonnaise, continuous usageof this product may result in diseases such as obesity,arteriosclerosis, hypertension and cardiovascular diseases.Therefore, consumers tend to consume low-fat products. Yoghurt is a very useful fermented milk products in terms of lactic acid bacteria that have beneficial effects on human health and Because of the similarity between this productand mayonnaise in terms of rheological properties, Yoghurt have been selected as a fat mimetic in mayonnaise.Therefore, the objective of present study was to investigate the effects of partial fat substitutionby yoghurt on physicochemical, rheological and sensory properties of low fat mayonnaise. Materials and methods Mayonnaise preparation One kilogram of each mayonnaise sample was prepared.Different recipes of mayonnaise contained yoghurt asfat mimetic (as % of oil and yoghurt) including (49.5 % & 25%), (33% & 50%), (16.5% & 75%). All formulations contained 13 % Egg yolk, 10 % Vinegar, 1 %Mustard, 1 % common salt ,4 % sugar , sodium benzoate 0.07 % , Xanthan gum 0.2%.Mayonnaise preparation procedure was as follows; firstlyegg and vinegar were mixed together and then all otherIngredients(including Yoghurt for the low fatmayonnaise recipes) except oil were added and mixed well. The oil was finally poured insidethe mixer very slowly and homogenized for 1 min. Subsamples (250 g) of mayonnaise were aseptically transferredto sterile 250 ml, Duran glass bottles withpolypropylenescrew caps and left for one-day at 5 °C. Proximate composition analysis Moisture, protein, and ash contents were determined accordingto AOAC (2005) official methods. Fat content wasmeasured by Bligh and Dyer (1959) method, and totalcarbohydrate content was calculated by difference. Rheological measurements Rheological measurements were performed after 24 hstorage using a Brookfield viscometer Model RVDV-IIwith aspindle no.6 at 5 °C and 25 °C. Shear stress data wereplotted versus shear rate for each mayonnaise sample ata range of spindle speed (10–200 rpm). Plots of Lnshear stress versus Ln shear rate (for each sample) werethen used to calculate values including flow behaviorindex (n) andconsistency coefficient (K). Texture analysis Mayonnaise samples were stored in refrigerator for 24 huntil texture analysis. The measurements were carriedout using a Brookfield texture analyzer (BrookfieldLFRA texture analyzer model number 4500 texture prolite) equipped with a 38 mm diameter cylindrical probeat 25 °C. The condition of the analysis was as follows; one cyclewas applied, at a constant crosshead velocity of 1 mm/s to asample depth of 30 mm, and then returned. From the resultingforce-time curve, the values for texture attributes, i.e.firmness, adhesiveness, and consistency were obtained usingtexture pro lit software. pH measurement and stability test pH was determined using AOAC standard method at 25 °C. The samples were assessed for the stability test after 24 h storage at 35 °C. Mayonnaise stability wasdetermined after centrifugation (10 min, 2,500 rpm), andwas expressed as the volume of separated phase to the totalemulsion volume. Color measurement Mayonnaise samples were measured for color in the L*, a*,b* system using a Lovibond Colorimeter. Sensory analysis After 1 day storage Sensory characteristics including appearance,color, odor, texture, taste, and overall acceptabilitywere evaluated by 14 semi-trained panel on 5-point hedonicscale (1 = the least or the lowest; 5 = the most or thehighest). Statistical analysis All the tests were performed in triplicate. The data collectedwere analyzed by one-way analysis of variance (ANOVA),and significant differences of means were compared usingDuncan test at 5 % significance level using SAS softwareprogram. Results and Discussion: In present study, physicochemical, texture, sensory and rheological properties were evaluated in mayonnaise formulation with dairy-based. Fat was partially substituted by yoghurt at levels of 25, 50 and 75% which were referred respectively as SM1 (25% fat substitution level), SM2 (50% fat substitution level) and SM3 (75% fat substitution level) and the full fat mayonnaise (S) with 66 % oil was used as control sample. Results indicated that low-fat mayonnaise samples had considerably lower energy content compared with control sample, but higher water content than it. In terms of texture, SM3 had lower hardness compared with control sample. The samples exhibited thixotropic and shear thinning behavior through rheological studies and all samples were classified in the group of solid viscoelastic materials because, in all samples, storage modulus was greater than loss modulus. Also, the loss tangent of low-fat mayonnaise samples were higher than the control sample which reflects the tendency of these samples behavior to pseudo-liquid behavior. Results of sensory evaluation demonstrated that SM2 and SM3samples, were more acceptable. It was concluded that yoghurt can be used as a suitable fat replacer in mayonnaise formulation.

Evaluation of the effect of Aspergillus flavus inoculation on fatty acids, proxide value and aflatoxin production in four common varieties of peanut cultivated in Golestan province

Introduction:Toxigenic fungi such as A. flavus grow widely in peanut and produce aflatoxins, a group of carcinogenic metabolites. Aflatoxin produced in peanut differed from the genetic variety of plant. The high humidity and moderate temperatures in the subtropical Caspian littoral of northern Iran could increase the growth of A. flavus and the production of aflatoxin. The objectives of this study were 1) to determine the chemical composition of peanut cultivars grown in Golestan Province, Iran, 2)to select resistant variety of peanut to aflaoxigenic A. flavus growth and 3) to evaluate relationship between A. flavus growth and changes in oleic and linoleic acid content and peroxide value. Materials and method: Peanut samples were used from four important varieties of peanut, Goli, Mahalli, China and India. those have been harvested from farms in Golestan province, Iran. Fat, protein, ash, moisture, reducing sugar, AFB1 content and peroxide value in each sample were measured by the standard method of AOAC. Fatty acids of the peanut seed oil were analyzed using gas chromatography (GC, Varian CP-3800 model) with a flame ionization detector (FID) and a DB-WAX column (50 m × 0.32 mm ×0.2 µm). To study the effects of A. flavus on peanut varieties, they were sterilized with 0.5% NaClO solution and then one ml of A. flavus spore suspension was added to every 20gr disinfected peanut and was placed in the incubator for eight days at 26°C. After incubation, the number of seeds colonized by fungi, spore production, AFB1 production, the association between colonization rate of hydrolysis of fatty acids and peroxide value were determined. Results and Discussion: The results showed that there were significant differences (P<0.05) in the oil, moisture, protein, ash, reducing sugar, oleic acid and linoleic acid content between peanut varieties. Average values for the main constituents of peanuts are the following: (oil: 44.77-51.26% , moisture: 3.33-3.56%, protein: 20.02-24.28%, Ash: 1.98-2.43%, reducing sugar: 3.56-4.53%, oleic acid: 43.16-59.33% and linoleic acid: 25.19-36.84%). In order to study the susceptibility of peanut varieties to aflatoxigenic, A.flavus growth, colonization rate, aflatoxin B1 and spore production on peanut kernels were evaluated at the end of 8 days of incubation. The results showed that there were also significant differences (P<0.05) between the colonization rates for different peanut varieties at the eighth day of inoculation. The India and China varieties had the highest colonization rates, at 100 and 95.21%, respectively. The Goli and Mahali varieties had the lowest colonization rates, at 81.61 and 89.6%, respectively. Furthermore, at the end of the eighth day of inoculation, A. flavus had covered the India and China varieties completely, but had covered the Goli and Mahali varieties only slightly. For this reason, additional experiments evaluated the content of spore production with a haemocytometer. It was observed that the Goli variety had the minimum spore production, and the India variety had the maximum spore production. Therefore, it can be said that the India variety was most susceptible to the A. flavus, followed by (in descending order) the China, Goli and Mahali varieties. Dissimilarity in host resistance to aflatoxigenic A. flavus is due to difference in host genotype. One of the strategies to decrease the risk of aflatoxin contamination is the cultivation of genotypes with resistance to Aspergillus infection. Some factors found to be associated with resistance to seed colonization by aflatoxigenic A. flavus are cell structure, cell arrangement, permeability, wax layer and tannin content, fatty acid and amino-acid peanut components. In another part of the study, the production of aflatoxin was assessed. Results indicated that the India (highest sensitivity to mold) and Goli (least sensitivity to mold) varieties were contained the maximum and minimum aflatoxin content, respectively. Results also showed that growth of A. flavus on peanut increased the proxide value whereas decreased oleic and linoleic acid content. A. flavus hydrolyzes oil when grown on the oil medium and produces free fatty acid. Aspergillus uses of free fatty acid (oleic and linoleic acid) in form of hydroperoxy for production of sexual and asexual bodies. Therefore with production of hydroperoxy molecules increase proxide value and decreased oleic and linoleic acid content in the oil peanut that extracted of peanut with mycelium. Conclusion: Linoleic acid and fat content had significant relationship with A. flavus growth and AFB1 production. it seems, it is possible to control the A. flavus growth and AFB1 production by Choosing varieties that have less acid linoleic and fat content.