Investigation of the Influence of Packaging Film Type and Indoor Atmosphere on the Characteristics of Sangak Bread Enriched with Carrot Powder

Because of its good flavor, Sangak bread is one of the most widely used kinds of flat bread in Iran. Dietary fiber has been the focus of attention in recent years due to its beneficial physiological and metabolic effects. Most studies have focused on reducing and delaying bread staling using bread improvers. There are many ways to reduce bread staling today, such as the use of fiber in bread formulation. One of the abundant and inexpensive sources for enrichment of foods with fibers is waste from the processing plants including fruits and vegetable powder. Some high-fiber wastes include tomato, beet, apple, and carrot powders, which are often wasted. Carrot contains large amounts of fiber, protein, fat, and carbohydrates. Carrots have been used in foods such as bread, cakes, pickles, enriched wheat bread, and biscuit to enhance the fiber content of these products. In our country, the consumption of flat breads such as Lavash, Sangak, Barbary, and Taftoon is high. Sangak bread has the highest amount of insoluble fiber among traditional bread types in the country, and adding soluble fiber to it, due to differences in physiological responses of these fibers, seems desirable. This study aims to use carrot powder waste and extract its fiber to increase the nutritional value of Sangak bread and to prevent bread waste by using new and cost-effective packaging.

In this research, wheat flour with a 90% extraction rate, was supplied from the Maryanaj-kar Co in Hamedan. Carrot powder was collected as a juice waste from the local fruit juice shops. Wheat flour (1 kg), salt (45 g), and water were used to prepare the dough. Carrot powder was added to the dough at different percentages of 3, 5, and 7 % (w/w based on flour) at the mixing stage. The dough was then rested at 25 ± 2°C for 1 to 2 hours to complete fermentation. Wheat flour (3 kg), salt (45 g), and water (as needed) were used to prepare the dough. Then, the sourdough (20%) was added, and the dough stirred for half an hour with the stirrer. The fiber was added to the dough at various levels during the mixing process. It was then baked in the oven for 4 min at about 400°C. For the packaging of bread, silicon Nano-polymer film and lightweight polyethylene film were prepared from Tehran Aitak Nano-polymer and Tehran Plast companies, respectively. The mechanical properties, qualitative and microbial properties of enriched Sangak bread and control under modified atmosphere (80% carbon dioxide, 20% nitrogen) and ambient atmosphere at 4 and 20°C and two kinds of silicon nano-polymer film and light polyethylene film were studied. Puncher test is a destructive test in which a sample is studied under uniaxial tension until failure. Puncher test was done using food testing device (Bbt-Fro. 5 th.D, model: Zowick/roell 14, made in Germany) equipped with a load cell (X Force Hp nominal Force: 500 N Capacity) in the laboratory of biosystem group at Bu-Ali Sina University. The color model of L* a* b* and the Chinese colorimeter (model HP Hanter Lab) were used to evaluate the color and determine the colorimetric factors. To evaluate the concentrations of O2 and Co2 gases, three packages of coated and uncoated treatments stored at 4 and 25℃ were provided and their concentrations were measured every other day using gas analyzer machine (WITT- GASTECTHNIK OXybaby 6i; made in Germany). The control and enriched breads during the storage period were examined for appearance of microbial load. The present study was designed in the form of a completely randomized design in factorial with 3 replications. The data were normalized via Minitab14 software and analyzed by SPSS software at the probability level 5% and 1%.

As the storage time increases, the bread becomes stiff and the amount of force required for the punching test increases. The results of tissue and puncher test showed that by adding carrot powder to bread, the bread staling process decreased, and Silicon nano-polymer film had a better process in staling the bread than light polyethylene film. Colorimetric results also showed that the amount of L* was reduced but increased by a* due to the presence of colored ingredients in Sangak bread, which made the bread maker more attractive. The results showed that the enriched bread with nano-film had the highest b* factor compared to the control bread. Changes in oxygen and nitrogen at modified atmospheric conditions during storage showed that the oxygen content of the nano-films at modified atmospheric conditions was gradually increasing. It can be concluded that silicon nano-polymer films have less permeability for oxygen inlet and outlet. This process caused the samples in the silicon nano-film film to die later due to the oxygen control properties of the films in the polyethylene film. The results of polyethylene film showed that this film had high permeability for inlet and outlet gases so that carbon dioxide content varied between 3% and 80%, which was a significant difference in polyethylene film. The highest color difference was observed in the bread sample enriched with nano-film and the lowest color difference was observed in the control bread sample with polyethylene film. The lowest color difference was observed in the samples using nano-film. The microbial load of enriched and control Sangak bread was significantly influenced by all three factors of time, temperature, and atmosphere in the package, so that by reducing carbon dioxide concentration and increasing storage time, mold in the samples seen. Microbial results of the samples kept at 4°C for up to 20 days did not show any mold, but samples kept at 20°C for 6 days.

The overall results showed that with the addition of carrot powder to flour, the protein, fat, and fiber contents increased but the carbohydrate content decreased. Thus, the carrot powder had a significant effect on Sangak bread. The results of the films showed that silicon nano-polymer film prevented the staling process during the storage period compared to the light polyethylene film. Results of storage temperature showed that 4°C for 20 days prevented bread molding but 20°C only prevented bread spoilage for 9 days. In-package gas results showed that at 4°C the modified atmosphere had a better tendency to preserve bread than the ambient atmosphere.