فصلنامه پژوهش های صنایع غذایی
سال بیست و چهارم شماره 3 (پاییز 1393)

Olive leaf is a source of natural polyphenolic compounds that have antioxidant activity and enrichment of oils with olive leaf extract which contains high amounts of polyphenols and tocopherol can increase its oxidative stability. In this study, the total amount of methanolic extracts of polyphenols of olive leaf (Oleaeurpopeae) in four Iranian varieties of olive was determined and the leaf antioxidant effect on thermal stability of rapeseed oil was studied by rancimat (P<0.05). The amount of tocopherols, fatty acids and polyphenols were determined before and after heating at 180°C. Maximum amount of polyphenols was 80 mg (acid galic in 100 grams of dry leaf) in Taram variety and minimum amount was 52.5mg in Moghan variety. The results showed tocopherols amount were decreased after heating at 180°C. Rancimat results showed that oil fortified with Taram variety extract with induction time of 11.3 hr was stable in comparison with control samples without antioxidants. According to the obtained results, adding olive leaf as a natural and valuable antioxidant to increase stability of oil can be recommended.

Water losing and fungal decay are the main limiting factors of grape berries during storage. In this study, the effects of plastic film covered with titanium dioxide nanoparticles were investigated on the controlling of postharvest decay and increasing the shelf-life of three table grape cultivars (BidaneSefid, Gezel Ozom, and Rish Baba). The results showed that grape packed in plastic film covered with titanium dioxide nanoparticles considerably decrease berries shedding, decay incidence and weight loss. In addition to, this treatment suppresses decreasing color hue during the storage time. There was no significant difference between treated and untreated samples for berry firmness. Table grape CV. Gezel Ozom showed the best shelf life than two other cultivars. Overall, grapes packed in plastic film coated with titanium dioxide nanoparticles showed better taste, flavor, marketability and general appearance than the control because of lower decay incidence and weight loss.

Blueberries are full of antioxidants and phenolic acid compounds that play an important role to prevent cancer, delay Alzheimer, and prevent the growth of pathogens such as salmonella. In this study, inulin and β-cyclodextrin were used as wall materials at 5 ratios (100, 75, 50, 25, 0 w/w) and blueberry as core at a ratio of 1:5 to produce nanoemulsion by ultrasound with 24 KHz ultrasound intensity for 130 seconds. Nanoemulsion diameter were measured by particle sizer and then dried through spray dryer. Dried powder was stored at 4˚C in refrigerator for determining encapsulation efficiency, surface oil content and morphology properties of encapsulated powders by scanning electron microscope. The results showed that different ratios of wall materials had very significant difference (P<0.01) with emulsion droplet size, surface oil content and encapsulation efficiency. Among all of samples, sample containing 75% of inulin and 25% of β-cyclodextrin had the highest encapsulation efficiency. Because, it had the smallest emulsion droplet size and least surface oil content. Based on Pearson’s value, there is a direct relation between emulsion droplet size and surface blueberry content; on the other hand, there is a reverse relation between the surface blueberry content and encapsulation efficiency with emulsion droplet size. Based on results, Inulin had the best covering power compared with β-cyclodextrin at a ratio of 1:5 and prevented from leaking core material to surface of capsules more and more.

The aim of this study was to isolate and identify the probiotic bacteria from microbial flora of buffalo milk and its traditional yogurt in Khoi city. To achieve this goal, the lactic acid bacteria were isolated by phenotypic methods (cellular morphology, Gram staining, catalase test, biochemical tests including growth in different temperatures, various concentrations of salt and fermentation of different types of sugar) and their probiotic potential (resistant to stomach acid and bile salts) were evaluated. Then, to identify more accurately, the 16S rRNA gene of bacteria were replicated with pairs of specific primers and then the purified PCR product was sent for gene sequencing. At the end, 13 strains of Lactobacilli and 6 strains of Enterococci were reported as the natural microbial flora with probiotic potential in Khoi city. These bacteria provide the good quality of the dairy products in those areas and can be used in industrial manufacture of dairy products.

Iran has first place producing and exportation of the saffron in the world and more than 65% of the word production of this expensive product is related to Iran. This expensive product of our country, because of the contact with soil, has a high microbial contamination that especially at the beginning of the season its amount is higher than permitted standard. In addition to that, existence of larvae in saffron causes difficulties in exporting of this worthy product. In this research, ozone was used as a disinfectant for the saffron which was attacked by the pest and microorganisms. For the purpose of inactivating of microbiological contamination of saffron, 4 levels of ozones include (0, 0.5, 1 and 2 ppm) and contact times include (0, 1, 2 and 3 hours) were used. After using these conditions microbiological tests were done including total count of bacteria, coliform, mold and yeast and chemical analyses of main characteristic of saffron. The results of this research showed that at level 2 ppm of ozone and during 3 hours contact time of saffron with ozone, decrease in the total count of bacteria, coliforms, mold and yeast were found to be 93.3%, 99.8%, 96.9% and 84.5%, respectively. At this condition, results of measurement of crocine, saffranal and picrocrocine also showed a decrease of 14.9%, 10.46% and 13.85%, respectively. The results of investigation for the presence of the living larvae, after using 2 ppm dosage of ozone, showed after 20 minutes annihilated almost 84% of larvae and by continuing ozonation for 40 minutes nearly no larvae remained alive.

In this study, the effects of potato puree obtained from two varieties (Ageria and Sante) each at five levels of 1, 2, 4, 8 and 10 % (w/w flour basis) on quality of Barbari bread were investigated. Different properties of bread characteristic including specific volume, oven spring and shape regularity, crumb porosity, moisture content of crumb, crumb firmness, crumb microstructure using scanning electron microscopy (SEM) and sensory evaluation were evaluated. By increasing the amount of potato paste, quality of bread improved and the most effect was observed by 10% of two varieties of potato. According to the results of bread texture, microstructure and porosity and hardness decreased with the increase of potato paste and bread crumb showed a finer and more uniform overall structure. In sensory properties of samples only 10% of both cultivars had significant differences in the overall score of the other samples. In most cases Sante cultivar variety had significant impact on quality of breads (P<0.05). In conclusion, 10 % of potato paste in the Barbari bread formulation improved quality properties.

Natural antioxidants have gained considerable interest in recent years not only for their role in preventing the autoxidation of fat, oils and fat-containing food products, but also for their consumer health benefits. In the present study, phenolic extracts obtained from the leaves of two plants, namely, mint (Mentha spicata) and mulberry (Morus indica) at three different concentrations (0.5%, 1% and 1.5%; w/w) were used as sources of natural antioxidants in biscuit. Total phenol content of mint and mulberry extract were 130.5 and 158.7 (mg galic acid in gram of extract, respectively). The extract of mint (1% w/w), and that of mulberry (1.5% w/w) were acceptable in terms of sensory attributes and colour characteristics in biscuits. The biscuits containing selected extracts had lower peroxide and thiobarbituric acid-reactive substances (TBARS) values than control (biscuit without addition of any antioxidant/extract) during storage of 90 days at room temperature. Biscuits treated with the extracts were well acceptable in terms of sensory parameters during storage period. The antioxidant efficiency of the extracts in biscuit was comparable to that of a synthetic antioxidant, butylated hydroxyanisole. Therefore, phenolic extracts of mulberry and mint leaves may be used as natural antioxidants to extend the shelf life of lipid-containing foods such as biscuits.

Flaxseed has high content of essential fatty acids, tocopherols, fiber and antioxidant compounds. Therefore using flaxseed powder in different food products can have useful role in diet. In this research, flaxseed powder at 4 levels (4%, 8%, 12%, and 16%) added to fat-reduced mayonnaise and during three months of storage was compared with blank sample in properties such as water content, ash content, protein, oil, pH, acidity, microbial content, heat stability and organoleptic properties. When amount of flaxseed powder increased, oil and protein content of mayonnaise samples were increased. Stability and heat stability of samples were decreased when flaxseed powder were used at higher level (>8%). All samples were at standard range in pH, acidity and microbial content. Sensory evaluation indicated that mayonnaise with 8% of powder in some properties such as odor, flavour, texture, total acceptability has the highest value. Results of this study showed that flaxseed powder can be used in formulation of low fat mayonnaise and it can be as a new functional product in the food market.

Toxicogenic potential of Aspergillus tubingensis isolates occurring on grape and raisin in southern regions of East Azerbaijan province were evaluated using of ammonia vapor, UV photography and high performance liquid chromatography (HPLC) methods. For this purpose, fungal isolates were grown on Capek Yeast Autolysate Agar (CYA) and Coconut Cream Agar (CCA) media and Ochratoxin A (OTA) production was evaluated. The results of this study showed that toxin production was detectable on 69%, 41% and 65% of the isolates using ammonia vapor, UV photography and HPLC methods, respectively. The compatibility of ammonia vapor vs. HPLC, HPLC vs. UV, ammonia vapor vs. UV and three mentioned methods was 50%, 69%, 62% and 42%, respectively. According to the results of this study, UV photography method appeared to be more efficient for detection of toxigenic isolates of A. tubingensis in comparison to ammonia vapor. The amount of OTA produced by isolates was determined 29-1089 μg/kg using HPLC.

Lighvan cheese has large market acceptability due to its excellent sensory atributes. Since Lighvan cheese is made of raw sheep milk that was always warring for health with respect of pathogenic bacteria such as brucella, Listeria monocytogenes and others pathogens. The present research was done to, produced cheese from pasteurized sheep milk by adding microbial starter culture of lactobacillus casei and lactobacillus plantarum isolated from Lighvan cheese were used as starter in cheese for producing Lighvan special aroma and taste. In this reaserch the physicochemical and sensory properties of the white brine cheese made of pasteurized sheep milk using lactobacillus and plantarum was studied. Results revealed type of that treatment, ripening time and their interactions had significant (P < 0.05) increase and decrease effects on the physicochemical properties such as ash, dry matter, pH, acidity, fat, protein, lipolysis content. Pasteurization for cheese samples on day 60 ripening 41% had less dry matter than control samples had not been pasteurized. The rate of lipolysis pasteurized treatments cheese was 15 meq/100g oil. Ash samples pasteurized at about % 0/5, most of the samples had not been pasteurized. Pasteurization treatment with Lactobacillus plantarum strains have the highest of soluble nitrogen to total nitrogen was among treatments. Sensory assessment of cheese samples showed the highest sensory scores obtained from pasteurized cheese made with starter lactobacillus plantarum at the end of 60 day of ripening. It can be concluded that, while reducing the amount of chemical properties of pasteurized cheeses such as dry matter, but the risk of pathogenic bacteria were eliminated. According to sensory evaluation and physicochemical results obtained can be said of Lactobacillus plantarum strains isolated from Lighvan cheese capable of can be used as a starter in the pasteurized cheeses for flavor and desirability to consumers than Lactobacillus casei strain.

Commercial exploitation of black mouth croaker stocks in the Oman Sea is currently in progress. Gelling properties of surimi has a direct correlation with the quality of the products made from it. Due to limited information on surimi gel properties of this fish species and effects of different hydrocolloids, this study was conducted. Kamabako gel samples with the addition of Iranian tragacanth gum (TG), xanthan gum (XG), chitosan (CS) and whey protein concentrate (WPC) in 1% (w/w) were prepared. Textural characteristics of the samples were carried out by texture analyzer device and the microstructure features were determined using electronic scanning electron microscope and ImageJ software. TG treatment (555.50 g) and WPC (503.00 g) showed the highest breaking force among other surimi gels, respectively (P≤0.05). Most parameters of texture profile analysis were higher than control treatment (P≤0.05). However, all parameters of texture profile analysis in XG treatment was reduced (P≤0.05). Maximum and minimum number of polygonal in the microstructure surimi gels were observed in TG (13371 per mm2) and XG treatments (7247 per mm2) (P≤0.05).Best result in enhancing of the textural and microstructural properties of surimi gels were achieved in TG treatment. However, weakest protein network and gel strength were obtained in XG treatment. Breaking force, deformation, hardness parameters and microstructure attributes of the surimi gel showed that this fish species is an appropriate raw material for the production of high quality surimi.

In the recent years, considerable attention has been allocated in the area of using natural preservatives (essential oils) in foods. This study was designed to evaluate the use of starch foam containing essential oil to prevent mold growth and improve packaged bread Shelf life. For this purpose, first cinnamon essential oil was extracted with water by distillation method and its minimum inhibitory concentration was determined, then 250 grams samples of bread within polypropylene plastic bags was prepared. Various amounts of cinnamon essential oil (500, 750, 1000 and 1500ppm) with 1g of starch foam powder inside sterilized filter paper were placed in these packages. The control samples also were parcels containing starch and without adding essential oil. Then control and treated samples were evaluated three times each three days for 15 days form old contamination, and sensory characteristics. The obtained results of multi way and intergroup repeated tests indicated that significant difference (P <0/05) exists between the control groups and various groups containing cinnamon essential oil in terms of microbial content. In the samples containing essential oils, less increase was observed for microbial load content and with increasing concentrations of cinnamon essential oil. It can be concluded that by using starch foam containing cinnamon essential oil in bulky bread packing at normal temperature (25 °C), the corruption process of bread can be postponed of 3 day to 6 days and it can be used as an appropriate natural and antifungal preservative in packaging of bread.