ELECTRONIC JOURNAL OF FOOD PROCESSING AND PRESERVATION
Year:2017 | Volume:8 | Issue:1 |Papers Count:7

Background and objectives: Sourdough is a complex biological system based on synergistic interaction between wheat microflora and Lactobacilli used as specific starter culture. These starter cultures are used to improve aroma, taste, nutritional value, shelf life, as well as exerting health-promoting effects in fermented bread. Most of beneficial properties of sourdough are characterized by acidifying activity of dominant Lactobacillus plantarum. Sourdough improve nutritional value of the final product by decreasing glycemic and harmful compounds, increasing the amount and stability of bioactive compounds, enhancing mineral absorbtion and increasing digestibility. Using sourdough in cereal whole flour which are rich in dietary fiber would result in uniform distribution of air bubles, improved rheology, increase in loaf volume, more suitable texture and finally enhancing product acceptance.Materials and methods: The aim of this study was to evaluate the effect of controlled fermentation of Lactobacillus plantarum on sensory properties and staling of semi-loaf wheat bread. For this purpose, the effect of fermentation time (8, 16, 24 h) and sugar content (0.5, 1, 1.5%) on the activity of mentioned starter culture in the sourdough from wheat flour (with 76% extraction rate) in a split plot design were examined. After processing of semi-loaf breads with sourdough treatments, the stalling of these breads were evaluated during 96 h after baking, based on their specific volume, crumb hardness (texture analysis) and amount of porosity (Image j method).Results: According to the results, different fermentation times and sugar contents had a significant effect (P≤0.05) on sourdough total titratable acidity. Among the produced samples, the lowest specific volume and the maximum amount of crumb firmness were also observed in bread produced with sourdough after 16 h fermentation and 1% sugar content, after 96 h. The maximum amount of specific volume and the lowest crumb firmness were also observed in sample produced with sourdough after 8 h fermentation and 0.5% sugar content, after 2 h storage. Furthermore, the maximum amounts of porosity and the best sensory properties were obtained after 16 and 24 h fermentation with 1.5% sugar content, respectively.Conclusion: According to these results, to produce sourdough bread with longer shelf life and better sensory properties, the effective control of microbial starter activity and influencing parameters on its fermentation is necessary.

Backgrounds and objectives: In the recent years, food manufacturers have tried to decrease the energy density of food products due to the ascending rate of obesity together with the negative outcomes of consuming high-caloric food products. Despite the advantages and considerable functional properties of sucrose as a natural sweetener, it may induce some health complications, such as high blood pressure, obesity, cardiovascular diseases, tooth decay and the increase in blood glucose level. Currently, several studies are being conducted in order to replace sucrose with different sweeteners. In this study, the possibility of replacing sucrose with a sucralose-maltodextrin blend at 25, 50, 75 and 100% replacement levels was evaluated in whipped cream.Materials and methods: 35% fat cream (obtained from Pegah dairy company) was diluted to 30% fat with skim milk and heated at 60oC. Then, sucrose, commercial stabilizer (Robertete 1185, France) and sucralose-maltodextrin blend were added to the cream and mixed. Sucralose-maltodextrin blend was used to replace the sucrose content at 25, 50, 75 and 100 % levels (W/W). After preparation, rheological, physico-chemical and sensory tests were done for each sample. Finally, means were compared using the Duncan test (p<0.05) in SPSS v. 22.Results: Results: Considering the overrun tests, 25 and 50% sucralosemaltodextrin blends had the best results. Moreover, there was no evidence of drainage in the entire samples (P˃0.05). Regarding the complex viscosity, the highest complex viscosity belonged to 50 and 100% sucralose-maltodextrin blends. These samples showed desirable textural characteristics. In the rheological tests, 100 % sucralose-maltodextrin blend was significantly different from the others, according to storage, loss and complex moduli (P<0.05). Moreover, all the samples exhibited no significant differences considering the loss tangent values (P˃0.05). Finally, the results of the sensory evaluations suggested that the best sample was 50% sucralose-maltodextrin blend.Conclusion: The sucrose content can be completely replaced with the sucralosemaltodextrin concentrate. All in all, the 50% sucralose-maltodextrin sample was considered as the best alternative considering all the measured properties.

Background: Donut, a popular fried bakery product, is susceptible to acrylamide formation during processing. Acrylamide is a compound produced in starchy foods which are processed at temperatures higher than 120oC. Acrylamide is known as a carcinogenic compound and therefore controlling the factors affecting its formation during food processing is of great importance. The aim of this study was to investigate the effect of dried milk powder (at the levels of 0, 1.5 and 2.5 % w/w) and sweeteners type (stevia and sucrose at different ratios 0:100, 30:70, 50:50 and 100:0) on the amount of acrylamide produced in donuts. Materials and Methods: A completely randomized design based on factorial experiments was used to evaluate the effect of milk powder and sweetener on physic-chemical properties and the amount of acrylamide in the product (donut). Samples from different treatments were analyzed in terms of chemical properties (moisture, pH, acidity, total sugar and protein) and the product color. A gas chromatography  with mass spectrometry detector (GC-MS) was used to investigate the effect of treatments on the formation of acrylamide in the end product. The mean values were compared using Duncan test (p≤0.05) by Minitab software (version 16) and the graphs were drawn in Microsoft Excel.Results: The results showed that by incorporating milk powder into donut formulation, the levels of moisture, protein, total sugar, reducing sugar and acrylamide increased and non-reducing sugar and darkness decreased in the product. The concentration of milk powder had no significant effect on pH and acidity. The results showed that by replacing sugar with stevia in the formulation of donut, moisture content, acidity, color appearance and concentration of acrylamide decreased and the levels of protein, total sugar and reducing sugar increased. The results also showed that the type of sweetener was an important factor in acrylamide formation and by replacing sugar with stevia, the final content of acrylamide decreased. It was also found that by increasing the amount of milk powder in the formulation, the amount of acrylamide in the final product increased. Therefore, acrylamide formation in and chemical properties of the final product can be controlled by optimizing the formulation.Conclusion: By using this information, we can optimize the conditions so that acrylamide is formed at the least concentration and therefore improve the public health.

Background and objectives: Nowadays, due to the environmental problems raised by synthetic packagings, considerable attention to biodegradable and edible food packagings is increased. Edible coatings are thin layers of materials coated on the surface of food products extending the shelf life of food by providing a moisture and oxygen barrier. Edible coatings might be used as carriers of various substances, including antioxidants. Edible pine seeds are susceptible to oxidation due to high levels of unsaturated fatty acids. Antioxidants are additives added to food for preventing oxidation. Due to the harmful effects of synthetic antioxidants, attention to plant extracts has been increased .The objective of this study was to evaluate the effects of carboxy methyl cellulose (CMC) edible coatings containing natural and synthetic antioxidants on oxidative stability of Persian pine nut.Materials and methods: Carboxy methyl cellulose coating (1% W/V) containing natural antioxidant valerian extract (1% W/V) and synthetic alpha tocopherol (0.5 W/V) were prepared. After coating, nuts were stored for 91 days in an incubator at 35oC with 35% relative humidity. The seeds were coated by theimmersion method. Moisture content, peroxide and thiobarbituric acid index of samples were determined at 7 days interval.Results: During storage, moisture content of all samples was increased. Average moisture content of control samples, seeds coated with carboxymethyl cellulose, seeds coated with carboxymethyl cellulose and alphatocopherol and samples coated with carboxymethyl cellulose containing valerian extract were 3.58, 3.25, 3.17 and 3.17% respectively. At the end of storage period moisture content of coated samples containing valerian extract (3.47%) was lower than uncoated samples (4.37%). Peroxide value in all of samples had increasing trend and the highest and the least peroxide value during storage were observed in uncoated samples (26.34 meq O2/kg Oil) and coated samples containing valerian extract (15.07 meq O2/kg Oil) respectively. Thiobarbituric acid values increased during storage time and coated samples containing valerian extract had the least TBA value (1 mg MA/kg Oil) during storage.Conclusion: The use of edible coating containing valerian extract could decrease the rate of oxidation and increase the shelf life of pine nut as a natural antioxidant. According the standard amount of peroxide value and TBA index in different samples, the best time for pine nut storage were 42, 63, 77 and 91 days for samples without antioxidant , carboxy methyl cellulose with alphatocopherol and carboxy methyl cellulose with Valeriam, respectively.

Background and objectives: Cheese is a dairy product that has a special position in the diet of many nations due to its high nutritional value. Production of cheese (with reasonable properties) with simpler process results in increased production yield and reduced production cost. The aim of this work was to produce whey less feta cheese with acceptable textural and sensory properties but comparable with ultrafiltration feta cheese by adding whey protein (WPC) and milk protein concentrate (MPC), without ultrafiltration processing.Materials and methods: In this study, produced wheyless cheese (a kind of feta cheese) was considered as a substitution for UF cheese. In this method, by mixing whey protein concentrate or milk protein concentrate in cream, a retentate similar to that which is used in UF cheese, was obtained. Then, the process was followed similar to that of UF cheese production. Two experimental samples with different whey protein / casein ratio were produced: treatment 1 was produced by mixing whey protein concentrate and milk protein concentrate (whey protein to casein ratio of 30: 70) and treatment 2 was produced by mixing milk protein concentrate (with the whey protein to casein ratio of 20:80). Then, free amino acid profile at 30th day of ripening, textural properties at 1th, 30th and 60th days of ripening and sensory property at days 30 and 60 of ripening were evaluated in the produced cheeses.Results: The concentration of free amino acids in the control cheese was significantly more than treatment 1 (containing MPC and WPC) and treatment 2 (containing MPC). Results of statistical analysis showed that the interaction effect of treatment and storage had significant effects on textural and sensory properties (P<0.05). Considering texture and sensory properties, treatment containing MPC and WPC was acceptable and competitive with control cheese.Conclusion: Based on these results, total free amino acids concentration (micromoles per liter) in the control cheese, was significantly higher than treatment containing MPC and WPC and treatment containing MPC, because of the high proteinase activity. Considering texture, up to 30th day of ripening, treatment containing MPC and WPC had the highest hardness, but the control cheese had the highest hardness at the end of storage period (day 60). Regarding sensory properties, treatment 1 had the highest level and treatment 2 containing MPC had the lowest level of overall acceptability at 30th and 60th days of ripening. In overall, according to textural and sensory results and low cost of production, treatment containing MPC and WPC can be selected as suitable replacement with ultrafiltration cheese.

Background and Objectives: Pomegranate is native to subtropical regions of Iran. Losses of horticultural products are a major problem in the postharvest chain. Although, many researchers tried to find suitable storing treatments and their effects on physicochemical properties, but due to the genetic potential of different cultivars, finding the best treatments for each region is necessary. This study aimed to investigate the influence of some wrapping, chemical and thermal treatments on storage life and fruit quality in the pomegranate cv. Shirin Kolbad. Materials and Methods: In this experiment, pomegranate fruits cultivar Shirin Kolbad were harvested at suitable maturing stage from Kolbad region, north of Iran and were under different storing treatments in a completely randomized design with factorial arrangement including three replications each containing three fruits. The first factor was the storage treatment, including two wrapping treatments (polyethylene and paper covering), two chemical treatments (calcium chloride and wax) and two thermal treatments (4°C and outdoor). The second factor was the storage time, including two and four month storage period and control at harvesting time. In control fruits at harvest time and in the treated fruits two and four months after storage some physicochemical properties were measured.Results: The study showed that different treatments did not have any significant influence on phenol and flavonoid, but they increased after four months of storage. Control fruits showed the highest amounts of total soluble solids (20.01 °Brix), acidity (0.35 mg/100 ml fruit juice) and vitamin C (31.81 mg/100 ml fruit juice), but the lowest amount of PH (2.47). In contrast, calcium chloride had the lowest amount of total soluble solids (16.40 °Brix) and the percentage of fruit juice (30.50%). The highest amount of glucose was observed in treatments polyethylene and paper covering (0.98 and 0.84 g/100 ml fruit juice, respectively) and after four months of storage (1.46 g/100 ml fruit juice). Conversely, the lowest amount of glucose was observed in control fruits (0.02 g/100 ml fruit juice) at harvesting time. The highest amount of fructose (22.89 g/100 ml fruit juice) was seen in fruits stored in 4oC. The results also showed that after four months of storage uncovered fruits had the highest amount of anthocyanin, which can be due to the higher concentration of CO2 under the coverage. The results also showed that different treatments and storage periods had a significant influence on weight loss of fruits. Polyethylene covering showed the lowest weight loss in fruits.Conclusion: Wax and polyethylene refrigerator temperature could preserve total sugar, glucose and fructose, but the amount of phenol and flavonoid did not change. After four months of storage, polyethylene and wax had the best effect on preventing the weight loss and on the keeping the properties of pomegranate fruits.

Background and objectives: Scolymus is one of the most abundant plants of mountainous regions of Iran, which has attracted the attention of consumers. In Iran, more than 17 percent of the food produced is lost during various stages of the supply chain. Its prevention requires the knowledge of physical, mechanical and hydrodynamic properties of agricultural products. Information on physical, mechanical and hydrodynamic properties of Scolymus can be helpfull in designing machines, transferring, separation, hydraulic grading, washing, quality inspection, preservation and processing which in turn reduce crop losses and increase efficiency of operations during processing. Materials and methods: In this study, some physical, mechanical and hydrodynamic properties of Scolymus were measured in three replications under standard conditions. The physical properties including length, width, thickness, geometric and arithmetic mean diameter, mass, volume, density, sphericity, surface area, aspect ratio and moisture content on a wet basis were measured. The mechanical properties of the samples during shear and bending (break) of Scolymus from the middle of its length were measured by Instron machine Zwick/Roell under required standards. The hydrodynamic properties for scolymus transferring, sorting and grading were carried out by water.Results: I terms of physical properties, length, width, thickness, mass, volume and geometric mean diameter had a direct relationship while density had inverse relation with the size of the Scolymus. Shape, size, volume, surface and density are important physical properties determining the design of a specific machine or in analysis of obtaining behaviors in transporting materials. For mechanical properties in bending test, elastic modulus, maximum force needed to bending Scolymus, work done to achieve maximum force needed to bending and deformation in order to apply maximum force were 0.00341 GPa, 41.5 N, 444.29 N.mm and 18.91 mm, respectively. In shear test, shear modulus, the maximum force needed to shear Scolymus, shear strength and shear deformation when applying maximum force were calculated as 0.002 N/mm2, 82.9 N, 0.0207 N/mm2, 19.15 mm, respectively. Information obtained from the mechanical properties of Scolymus in shear and bending tests can be used by Scolymus processing factories. Hydrodynamic properties of Scolymus including the rising time in the water column, average limit speed and average flotation force exerted on Scolymus in the water column was obtained as 4.67 s, 0.02 m/s and 0.93 N, respectively. The density of Scolymus was lower than water and as a result, it can be graded and transmitted hydraulically without any damage.Conclusion: The data obtained from this study can be applied for designing and optimization of process equipments, transport, sorting and packing of Scolymus.