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  3. Investigation and comparison of commercial baker's yeast strains to increase the quality and durability of industrial bread

Investigation and comparison of commercial baker's yeast strains to increase the quality and durability of industrial bread

Number of pages: 102 File Format: word File Code: 32418
Year: 2014 University Degree: Master's degree Category: Food and Packaging Industries
Tags/Keywords: Baked goods - Bread quality - Commercial strains - dry yeast - fermentation - Saccharomyces cerevisiae - Shelf life of industrial bread - tissue stiffness
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  • Summary of Investigation and comparison of commercial baker's yeast strains to increase the quality and durability of industrial bread

    Dissertation for receiving a master's degree (M.Sc.) in the field of food science and engineering engineering

    Food microbiology trend

    Abstract

    One ??of the effective ways to improve the quality of bread and baking products is to optimize the fermentation conditions of the product. In addition to increasing the nutritional value of bread, proper fermentation improves the rheological properties of the dough as well as the sensory characteristics and shelf life of the final product. In this regard, choosing the right yeast strain plays a very important role in improving the bread fermentation process. In this research, the effect of 4 types of dry yeast powder (3 domestic and 1 foreign) and one wild yeast strain was compared on the fermentation process and product characteristics. After purification, the yeast strains were analyzed in terms of parameters of growth factor and gas production. Also, the bread prepared from the studied yeasts were compared in terms of volume, percentage of moisture and sensory parameters (physical properties and bread crust, taste, color and texture). In addition, the shelf life of the prepared breads was measured by histometric method by Instron device up to 120 hours. According to the findings of this research, in most of the experiments, breads prepared from a type of domestic dry yeast as well as foreign sample showed the best results compared to other treatments (p<0.05).

    Key words: fermentation, sensory properties, Saccharomyces cerevisiae, firmness of texture, dry yeast

    Introduction

    The consumption of grains by humans has a history of 5000 years. In the beginning, humans consumed grains in roasted form. After mankind acquired the knowledge of milling, the use of grains in the form of dough and finally bread was developed. Early breads were often made flat. But later, with the progress of human knowledge, different types of semi-bulky and bulk bread were also prepared. Nowadays, in addition to the production of various types of bread, many other products are made from grains such as cakes and pastries, noodles and types of pasta, biscuits, etc. It is prepared (Rajbzadeh, 2006).

    Besides human nutrition, grains played an important role in the formation of the first human societies and the creation of villages and cities. Because the familiarity of early man with grains and their importance caused man to turn to agriculture and gradually to settlement and civilization. Later, with the discovery of fire, grains are roasted in clusters on the fire and consumed. Since the consumption of cereals in the mentioned way can sometimes cause digestive discomfort, humans started threshing and removing the covering of cereal grains. In this way, mankind gradually got acquainted with the mill and was able to prepare flour by grinding the dough and finally achieved the technology of bread production. The production of different types of bread, as well as the possibility of consuming other food items such as meat with it, caused nutritional diversity among humans (Payan, 1380). In addition, in the distant times when it was not possible to store bread for a long time, the resulting bread was dried in the sun to increase its shelf life. This type of bread is still produced in many rural areas (Rajbzadeh, 2016).

    1-2 statement of the problem

    Bread is the most important wheat product, which is prepared in various ways in different regions according to taste and facilities (Qaroni, 2015). The preparation of bread largely depends on the baking ability of the flour, which depends on the characteristics of the flour used, industrial factors and measures, preparation method and preparation steps (Rajbzadeh, 1386).

    Bread yeast (Saccharomyces cerevisiae [1]) is one of the main elements in the preparation and production of bread (Dobbes et al., 1982). Man has been using yeast to make bread since long ago. In ancient Egypt, lard obtained from beer, which contains yeast, was used to prepare high-quality bread.With the advancement of human knowledge, pure yeast strains were marketed as baker's yeast (Kurtzman and Fell, 1998; Querol and Fleet, 2006).

    There is an undeniable connection between the technological properties of flour and the fermentation power of yeast (Miric and Katarina, 2008). In general, the role of baker's yeast in improving the quality of bread can be categorized as follows (Paghambar Doost, 2008):

    helping to create a suitable structure in the dough, which is often done by producing gas and subsequently expanding the dough.

    Increasing the nutritional value of bread by producing nutritious compounds due to yeast activity Proper taste in bread

    Fermentation [2] is a series of physical, chemical and biochemical changes that occur in the dough after mixing flour, water and yeast before the baking process. As a result of these changes, new metabolites are produced which, along with other constituents, in addition to creating the final taste of bread, improve some of the quantitative and qualitative characteristics of bread (Qarouni, 2013).

    In the preparation of different breads, the fermentation stage often has the same necessity (Payan, 2015). The most important goal of the fermentation process in making bread is to increase the volume of the dough. In the bread production process, the final volume and structure of the product depends on the amount of carbon dioxide gas produced by the yeast. Also, the type of dough composition for the proper growth and activity of yeast, as well as the formation of a gluten network suitable for gas retention, are also very decisive in the quality of the resulting bread (Sahlstream et al., 2003). Van-Hoek et al., 2000). It should also be noted that some strains of Saccharomyces cerevisiae, which have the ability to withstand higher osmotic pressure, are also used in confectionery products. However, the use of this yeast in the confectionery industry and in the formulation of sweet products faces limitations (Nishida et al., 2004; Imura and Kawasaki, 2007).

    The different strains of Saccharomyces cerevisiae that are used as baker's yeast must have several characteristics (Spencer and Spencer, 1996; Donalies et al., 2008):

    have a high fermentation power so that it can more intensively consume the available carbohydrates and produce carbon dioxide gas.

    have a suitable respiratory metabolism and a high growth and reproduction speed so that it can produce high biomass [3] in a short period of time.

    Yeast side metabolites contain effective compounds in taste and aroma so that a higher quality bread can be produced.

    Therefore, it is necessary to isolate the appropriate strain in every industry and according to the desired performance. Also, choosing the ideal strain is very important from a commercial and economic point of view (Ando et al., 2003; Modige et al., 2007). Therefore, any research and study to improve the quality of produced breads can be practical and effective. In order to prepare high-quality bread and reduce the waste caused by it, it is necessary to have detailed information about the type of flour, the fermentation method, the way the dough is processed and also the correct baking (Yazdan Parast, 2017).

  • Contents & References of Investigation and comparison of commercial baker's yeast strains to increase the quality and durability of industrial bread

    List:

    Abstract 1

    The first chapter of the general research. 2

    1-1 Introduction. 3

    1-2 statement of the problem. 4

    1-3 Necessity of doing research. 6

    1-4 research objectives. 6

    1-5 research hypotheses. 7

    1-6 definitions of words 7

    Chapter Two: Literature and documents. 8

    2-1 Introduction of the genus Saccharomyces 9

    2-1-1 characteristics and characteristics of Saccharomyces 9

    2-1-2 Application of Saccharomyces in industry. 12

    2-1-3 bread yeast. 14

    2-2 technological stages of making industrial bread. 16

    2-2-1 Preparation of dough 16

    2-2-2 Development and formation of dough 17

    2-2-2-1 Mechanism of dough expansion 17

    2-2-2-2 Factors affecting dough expansion time 19

    2-2-3 Dough rest 20

    2-2-3-1 Primary fermentation. 20

    2-2-3-2 dough weight reduction 21

    2-2-3-3 protein changes during dough rest time 22

    2-2-3-4 the effect of fermentation on phytic acid decomposition and improving the nutritional value of bread. 24

    2-2-4 maturing the dough 26

    2-2-5 dividing the dough 29

    2-2-6 rounding the dough 30

    2-2-7 intermediate fermentation. 32

    2-2-7 shaping the dough 33

    2-2-8 final fermentation. 34

    2-2-8-1 wet fermentation. 34

    2-2-8-2 dry fermentation. 34

    2-2-9 bread baking process. 35

    2-3 bread staleness process. 38

    2-3-1 The mechanism of stale reactions. 38

    2-3-1-1 retrogradation of starch. 40

    2-3-1-2 rednaturation of protein. 42

    2-3-1-3 Bread crust changes in the stale process. 43

    2-3-2 Bread staleness measurement methods. 43

    2-3-2-1 Rheological methods. 44

    2-3-2-2 Chemical methods. 45

    2-3-2-3 sensory and organoleptic methods. 45

    2-3-2-4 enzyme methods. 45

    2-3-3 Methods of delaying bread staleness. 45

    2-3-3-1 Using different compounds in bread formulation. 46

    2-3-3-1-1 fats and lipids 46

    2-3-3-1-2 proteins 47

    2-3-3-1-3 gums 47

    2-3-3-1-4 enzymes 48

    2-3-3-1-5 emulsifiers 48

    2-3-3-1-6 Pentosans 49

    2-3-3-1-7 The role of other effective compounds in bread staleness. 49

    2-3-3-2 Applying technological measures in the preparation of bread. 50

    2-3-3-3 Improving storage and packaging conditions for bread. 51

    2-4 Review of the researches of other researchers. 52

    2-4-1 Researches carried out inside the country 52

    2-4-2 Researches carried out abroad 52

    Chapter 3 Materials and methods 55

    3-1 Place of experiments 56

    3-2 Materials and equipment used 56

    3-2-1 Yeasts used 56

    3-2-2 Devices and devices used in research. 56

    3-2-3 Chemicals used in research. 57

    3-2-4 solutions and media used 58

    3-2-4-1 physiological serum solution. 58

    3-2-4-2 medium used for freezing strains 59

    3-2-4-3 PDA culture medium. 59

    3-2-4-4 YPD Broth culture medium. 60

    3-2-4-5 YPD Agar culture medium 60

    3-2-4-7 ALP Agar culture medium 62

    3-3 Purification and measuring the characteristics of yeast strains. 62

    3-3-1 Examining the ability to consume sugar. 63

    3-3-2 Investigating the ability to consume ethanol. 63

    3-3-3 preparation of cell suspension. 63

    3-3-4 Examining the rate of growth and reproduction of yeast 63

    3-3-5 Measuring the amount of carbon dioxide gas produced by yeast 64

    3-4 Measuring the characteristics of the flour used 64

    3-4-1 Measuring wet gluten. 64

    3-4-2 Ash measurement 65

    3-4-3 Moisture measurement. 65

    3-4-4 Measurement of flour pH 65

    3-5 Measurement of bread characteristics. 66

    3-5-1 steps of preparing and baking bread. 66

    3-5-2 Measuring the volume of bread. 66

    3-5-3 How to test bread staleness. 67

    3-5-4 sensory tests. 67

    6-3 how to analyze the data 67

    Chapter 4 statement of results and discussion. 69

    4-1 Characteristics of yeast Saccharomyces cerevisiae. 70

    4-2 The results of measuring cell growth of Saccharomyces cerevisiae yeast. 72

    4-3 Gas measurement results in the investigated treatments. 75

    4-4 Measurement results of flour parameters 78

    4-5 Measurement results of prepared bread volume 78

    6-4 Measurement results75

    4-4 results of measuring flour parameters 78

    4-5 results of measuring the volume of prepared breads 78

    4-6 results of measuring staleness intensity of prepared breads 80

    4-7 sensory evaluations of prepared breads 83

    4-7-1 evaluation of physical and appearance characteristics of prepared breads 83

    4-7-2 Sensory evaluation of the texture of the prepared breads 84

    4-7-3 Sensory evaluation of the taste of the prepared breads 85

    4-7-4 Sensory evaluation of the color of the prepared breads 87

    4-7-5 General evaluation and degree of desirability of the prepared breads 88

    Chapter 5 Conclusion. 90

    5-1 General conclusion. 91

    5-2 suggestions. 91

    Resources and references. 93

    Persian sources. 93

    Foreign sources. 94

    Appendices Results of statistical analysis of data 107

    Appendix 1 - Results of specific growth factor of Saccharomyces cerevisiae yeast cells. 108

    Appendix 2 - Gas measurement results in the investigated treatments. 109

    Appendix 3 - The results of measuring the volume of the prepared breads 110

    Appendix 4 - The results of measuring the intensity of staleness of the prepared breads based on the firmness of the texture (Insteron test) 111

    Appendix 5 - The results of evaluating the physical and appearance characteristics of the prepared breads 112

    Appendix 6 - The results of the sensory evaluation of the texture of the prepared breads 113

    Appendix 7 - The results of the sensory evaluation of the taste of the prepared breads 114

    Appendix 8 - The results of the sensory evaluation of the color of the prepared breads 115

    Appendix 9 - The results of the overall evaluation and degree of desirability of the prepared breads 116

    Abstract. 117

     

    Source:

     

    Mr. Qolizadeh. R, M. H. Azizi and M. A. Sahari, 2013, investigation of lavash bread fermentation conditions, Food Science and Industry Quarterly, (1) 3:1-10

    End. R. 1380. An introduction to the technology of grain products, Novardazan Publishing House, Tehran

    Pighambarddoost. S.H. 1388, technology of grain products, first volume, Tabriz University of Medical Sciences and Health Care Services

    Jamalian. c and z Sheikh al-Islami, 1383, the effect of fermentation factors and the percentage of flour extraction on the amount of phytic acid in Sangak and machine lavash breads of Mashhad city, Agricultural sciences and techniques and natural resources, No. (1) 1: 192-183, Rajabzadeh. N. 1386. Bread technology, Tehran University Press, pages 68-70.

    Qaroni. J. 1383. Flat bread technology. Tehran-Andishmand, page 22-60.

    Kasai. Z, H. Prophet Dost, M.R. Dadpour, M.H. Mousavi and A. Shekoi Bonab, 2013, comparison of different methods of evaluating the power of gas production and fermentation activity of baker's yeast, Food Industry Research Journal, (4) 22: 442-431

    Kamali. H. 1381. The message of the chairman of the board of directors and the then managing director of the country's grain organization, the first international exhibition and bread production machinery. Published in the collection of articles called the second international exhibition of bread and bread production machinery. Country Grain Organization, Ministry of Commerce, Tehran

    Naghipour. F, B. Sahraian, M. Qaifeh Davoudi, M. Karimi and Z. Sheikh al-Islami, 2012, Comparison of the effect of initial, intermediate and final fermentation time on the quantitative and qualitative characteristics of Berberi bread, Quarterly Journal of Food Science and Industry, (1) 40: 55-47

    Vahedi. H, M.H. Azizi, F. Kabarfard, M. Barzegar, Z. Hamidi Esfahani and M. Hamedi, 2013, the effect of flour extraction degree and fermentation time on the reduction of free asparagine in Sangak bread dough, Food Science and Nutrition, (3) 4: 13-20, Yazdan Parast. c. 1377. Solutions to improve the production and supply of bread in the country. Ghele Venan Research Institute. Tehran. Publication No. 522.

    External sources

    AACC 07-09. Approved Methods of the American Association of Cereal Chemists. AACC 38-12. Approved Methods of the American Association of Cereal Chemists. AACC 44-16. Approved Methods of the American Association of Cereal Chemists. AACC 72-10. Approved Methods of the American Association of Cereal Chemists. AACC 74-09. Approved Methods of the American Association of Cereal Chemists. Ando. M, S. Nakamura and Y. Shinomiya. 2003. Sugar super tolerant yeast for confectionary and bakery. United state patent. No: US 6,521,272 B1.

     

    Ardent E.K, A.M.L. Ryan, F. Dal Bello. 2007. Impact of sourdough on the texture of bread. Food Microbiology, 24 (2): 165-174.

     

    Atlas. R.M. 2004. Handbook of microbiological media. Washington DC, USA. CRC Press, 1088p. Bartkiene. E., G. Schleining, G. razina Juodeikiene, D. Vidmantiene, V.

Investigation and comparison of commercial baker's yeast strains to increase the quality and durability of industrial bread
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