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TitleBaker Yeast
TagsCellular Respiration Saccharomyces Cerevisiae Yeast Pyruvic Acid Breads
File Size877.1 KB
Total Pages28
Document Text Contents
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Table of Contents

1. Introduction ................................................................................................................ 3

2. Role of yeast in bread-making ................................................................................. 4

2.1. Carbon dioxide evolution in doughs ..................................................................... 5

2.2. Changes in dough structure and texture ................................................................ 5

2.3. Contribution to bread flavor .................................................................................. 6

3. Raw materials ............................................................................................................ 6

3.1. Baker yeast ............................................................................................................ 6

3.2. Factors Affecting Yeast Growth ......................................................................... 10

3.2.1. Sugar feed (media composition): .................................................................. 10

3.2.2. Aeration ........................................................................................................ 10

3.2.3. Temperature .................................................................................................. 11

3.2.4. pH .................................................................................................................. 11

3.3. Medium ............................................................................................................... 11

4. Manufacture of dried Baker's yeast ....................................................................... 14

4.1. Dried Baker’s yeast production process.............................................................. 14

4.1.1. Medium preparation. ..................................................................................... 15

4.1.2. Inoculum prepagation ................................................................................... 15

4.1.3. Main Fermentation Stages ............................................................................ 16

4.1.4. Centrifugation ............................................................................................... 18

4.1.5. Filtration........................................................................................................ 19

4.1.6. Extrusion ....................................................................................................... 20

4.1.7. Drying ........................................................................................................... 21

4.1.8. Packing.......................................................................................................... 22

4.2. Contaminations ................................................................................................... 22

4.2.1. Wild yeasts and moulds ................................................................................ 23

4.2.2. Bacteria ......................................................................................................... 23

5. Standard of dried yeast’s product .......................................................................... 25

5.1. Metabolites activities .......................................................................................... 25

5.2. Microbiological characteristics ........................................................................... 25

5.3. Physico-chemical characteristics ........................................................................ 26

5.4. Others .................................................................................................................. 27

References ..................................................................................................................... 28

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Table of figures

Figure 1.1. Classification of yeast ................................................................................... 6

Figure 1.2. life cycle of yeast .......................................................................................... 7

Figure 3.1. Batch fermenter ........................................................................................... 16

Figure 3.2. Fed-batch fermenter .................................................................................... 17

Figure 3.3. Yeast centrifuge .......................................................................................... 19

Figure 3.5. Rotary vacuum filter ................................................................................... 20

Figure 3.6. Yeast extruder ............................................................................................. 20

Figure 3.7. Fluidized bed dryer ..................................................................................... 21

Figure 3.8. Automatic vertical packaging machine ....................................................... 22

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