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  3. Comparison of the effect of packaging nano silver films and ordinary polyethylene on the growth of bread mushrooms

Comparison of the effect of packaging nano silver films and ordinary polyethylene on the growth of bread mushrooms

Number of pages: 101 File Format: word File Code: 31971
Year: 2014 University Degree: Master's degree Category: Health - Health
Tags/Keywords: baking industry - bread - bread mushroom - dough - mushroom - Nano films - Polyethylene covers - shelf life - Silver nano films
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  • Summary of Comparison of the effect of packaging nano silver films and ordinary polyethylene on the growth of bread mushrooms

    Dissertation for Master's Degree in Food Health and Safety

    Abstract

    Introduction: In this research, considering the antimicrobial property and resistance of packages containing silver nanoparticles based on titanium dioxide to the penetration of gases, including oxygen, the effect of these packages on the fungal flora of bread Consumption was compared with common polyethylene packages. This experimental study has been carried out in relation to increasing the shelf life of consumer bread. Materials and methods: First, 144 samples of bread loaves were randomly prepared from 6 types of bread produced by 12 bakeries in district 2 of Tehran. The bread samples were placed in 3%, 5%, 10% nano coatings and normal polyethylene (control) and were subjected to microbial control and tests on days 1, 3, 7, 14 and 28 in three repetitions based on the national standard of Iran.

    Findings: The results showed that the effect of film type and duration of storage as the main factors on the fungal flora of bread was significant. The lowest rate of mushroom growth with 14% is related to nano film and 10%, and the highest rate of mushroom growth with 42% is related to polyethylene coating (P<0.001). With the increase in the number of days of storage, the number of types of mushrooms increased, but in most cases, this increase was not the same in the type of bread and the type of mushroom, and there was a significant difference from each other (P=0.001).

    Conclusion: According to the results obtained, it can be said that the use of coatings containing silver nanoparticles based on titanium dioxide for bread packaging due to the increasing population and in the direction of improving food safety is more than polyethylene coatings. It is preferred and the use of this type of coating is recommended in the baking industry.

    Key words: shelf life, nano films, fungus, silver nanoparticles, bread

    Problem

    1-1-1 Research background

    1-1-1-1 Introduction

    Based on the fundamental changes predicted for the coming years, the global competition for dominance will no longer be the development of weapons and other factors, including food as the most formidable strategic weapon, will change the alignments and geographical lines of countries. The day after tomorrow, food and the set of possibilities to achieve it will be the main diagram of demarcation: rich and poor, advanced and backward, and the most basic link of global power and domination. On the other hand, food is an integral part of life and survival, among these grains and mainly wheat, which is considered the basic food of the country's people in various forms, is more important and bread as the main food consumed has a considerable priority (Rajbzadeh, 2007).

    1-1-1-2 Definition of bread

    In many countries, bread is a fermented product with Yeast is classified. Those products that are prepared on the basis of cereals and are non-bulky or bulked with sour dough or chemicals are not classified as bread. In some countries, non-bulky or bulky products with sour dough are used as daily bread. According to the American encyclopedia, bread is a food made from various plant materials that are turned into flour and then mixed with water to form a dough and baked in the form of a cake with tablets. This flour may be prepared from the seeds of grass plants such as wheat and rye, legumes and underground stems, and even from non-native materials such as artichokes (Kirimi, 2015).

    1-1-1-3 History Bread

    Wheat bread, which is one of the most common types of bread and constitutes the food of most nations of the world, reached the stage of production when wheat was identified by humans. This product is one of the oldest human achievements, so that the sources that exist about bread are even older than the people who lived around the Tigris and Euphrates. The first source of information dates back to five thousand years ago. In the city of Yuruk, where the Babylonians lived, documents have been found that describe their life, habits and traditions.Among these documents, important documents have been obtained about wheat, baking bread, moldiness and staleness of bread (Rajbzadeh, 2007). Wheat is one of the greatest signs of the greatness of creation and bread is one of the most pleasant and enjoyable food items consumed by humans in many civilized and traditional societies today. For us Muslims, wheat and bread have a special dignity and respect. In most religious ceremonies, holidays, and even people's daily meals, bread is used as a sign of Yemen and divine blessing (End, 2007). Before trade between ancient civilizations, there was cultivation of cereal grains in different parts of the world to prepare various types of flat breads as a main source of sustenance. Today, wheat and barley are used as essential ingredients in flat breads in Central and Western Asia, Southern Europe and North Africa. Flat bread is prepared from millet and sorghum flour in Africa. Corn and corn flour are the main ingredients of arepa [1] and tortilla [2] in America. In many Asian countries, bread is made from rice flour (Kirimi, 2005).

    1-1-1-4 Importance of bread

    According to the value and historical context, bread can be considered as the most important food known in different eras of human society. The average consumption of bread in Iran per capita is 413 grams per day in the city and 518 in the village, which is the total average of 450 and has the highest figure compared to other food groups. The percentage of bread in providing energy is on average 51.8, 53.6 protein, 5.0 fat, 68.7 carbohydrates, 33.9 calcium, 45.2 iron and 64.2 fiber (Nikozadeh, 1386). Danst, on the other hand, bread is important in terms of quality and nutritional value, because alone it can provide an important part of energy, protein and other nutrients for the body. In this regard, it should be said that the best bread for nutrition is bread made from whole wheat flour, and the bread made from such flour will have more protein, calcium, iron and vitamins. On the other hand, since wheat flour is mostly used to prepare bread, it can be said that this grain is the most important daily food item in our country (Kirimi, 2015).

    Bread, like other types of grain products, as the cheapest source of energy and protein, plays a vital role in feeding most of the world's people. According to the surveys conducted by the FAO organization, the people of Asian countries provide about 70% of their daily energy needs from bread and other foods made from wheat (FAO, 2013). It is a value that alone can provide many of the necessary needs of the body.

    1-1-1-5 types of bread

    Traditional Iranian breads are thin and flat breads that are prepared in the primitive and old way, that is, by mixing crushed wheat and water. The breads available in different parts of Iran have such a wide variety that it is difficult to describe and classify them (Payan, 2007). theses packaging with conventional polyethylene packages - on fungal flora of consuming bread. This experimental study was conducted to increase the shelf life storage of consuming bread.

    Method and material: One hundred forty four samples of 6 different types of loaf of bread randomly obtained from 12 bakeries in District 2 of Tehran. The samples were packaged with 3%, 5% and 10% nano coatings and also conventional polyethylene coatings as control group.

  • Contents & References of Comparison of the effect of packaging nano silver films and ordinary polyethylene on the growth of bread mushrooms

    List:

    Table of contents

    1- Chapter 1: Introduction and statement of the problem. 1

    1-1 statement of the problem. 2

    1-1-1 research context. 2

    1-1-2 reasons for choosing the topic. 30

    1-1-3 background. 31

    1-1-4 Inadequacies in the field of the subject. 32

    1-1-5 Necessity of doing work 32

    1-2 Goals. 33

    1-3 Assumptions. 33

    2- The second chapter: review of texts. 34

    2-1 Factors affecting the shelf life of bread. 35

    2-1-1 Microorganisms 35

    2-1-2 stale bread. 36

    2-2 A summary of bread packaging methods. 37

    2-3 traditional methods to increase the shelf life of bread. 37

    2-3-1 modified atmosphere packaging (MAP) 37

    2-3-2 antimicrobial additives. 38

    2-3-3 active packaging. 39

    2-4 Use of nanocomposites in packaging. 41

    2-5 The effect of nanocomposite on microorganisms: 42

    2-6 Using nanocomposites as antimicrobial agents in packaging. 45

    2-7 Risks of using nanocomposites in food packaging. 49

    3- The third chapter: research method. 52

    3-1 type of research. 53

    2-3 steps of research. 53

    3-2-1 Society and research environment. 53

    3-2-2 Sampling method and sample size. 53

    3-2-3 test principles. 54

    3-2-4 materials and tools. 54

    3-2-5 Test method. 55

    3-2-6 data analysis method 57

    3-3 Possibilities and limitations of research. 57

    3-3-1 Research possibilities. 57

    3-3-2 Research limitations. 57

    3-4 ethical considerations. 58

    3-5 Definition of words 58

    4- Chapter 4: Findings 59

    4-1 The effect of the type of film on the fungal flora of bread. 60

    4-2 The effect of storage time on the fungal flora of bread. 63

    4-3 Effect of type of bread on fungal flora. 64

    4-4 Effect of mushroom type on growth rate. 74

    5- Chapter Five: Discussion, conclusions and suggestions 76

    5-1 Discussion. 77

    5-2 Conclusions and suggestions. 82

    Resources..83

     

    Source:

     

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Comparison of the effect of packaging nano silver films and ordinary polyethylene on the growth of bread mushrooms
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