پایان نامه بررسی اثر شرایط و زمان نگهداری سبزیجات منجمد بر میزان نمک های نیترات، نیتریت و اسید آسکوربیک

فهرست:

فهرست مطالب .............................................................................................................................................. ه

فهرست جداول ........................................................................................................................................... ح

فهرست شکل ها و نمودارها ....................................................................................................................... ط

چکیده .......................................................................................................................................................... 1

فصل اول: کلیات .............................................................................................................................. 2

مقدمه ........................................................................................................................................................... 3

اهداف پژوهش ............................................................................................................................................. 6

فرضیه پژوهش ............................................................................................................................................. 6

فصل دوم: ادبیات و پیشینه پژوهش ................................................................................................... 7

2-1- نیترات ................................................................................................................................................ 8

2-2- نیتریت ............................................................................................................................................... 9

2-3- مسیرهای ورود نیترات به بدن ......................................................................................................... 10

2-3-1- سبزیجات ................................................................................................................................................................ 10

2-4- عوامل موثر در تجمع نیترات ........................................................................................................... 11

2-4-1- عوامل محیطی – اقلیمی .......................................................................................................................................... 12

2-4-2- مواد غذایی خاک ..................................................................................................................................................... 12

2-5- توزیع نیترات در گیاه ....................................................................................................................... 13

2-6- مضرات نیترات ................................................................................................................................ 14

2-7- اثرات سودمند نیترات ...................................................................................................................... 15

2-8- اسید آسکوربیک .............................................................................................................................. 15

ه

2-9- سبزیهای مورد استفاده در پژوهش حاضر ........................................................................................ 19

2-9-1- هویج ....................................................................................................................................................................... 19

2-9-1-1- اهمیت مصرف .....................................................................................................................................................19

2-9-2- گوجه فرنگی ........................................................................................................................................................... 20

2-9-2-1- اهمیت مصرف .................................................................................................................................................... 20

2-9-3- اسفناج ..................................................................................................................................................................... 21

2-9-3-1- اهمیت مصرف .....................................................................................................................................................21

2-9-4- کرفس ...................................................................................................................................................................... 22

2-9-4-1- اهمیت مصرف .................................................................................................................................................... 22

2-9-5- بادنجان .................................................................................................................................................................... 23

2-9-5-1- اهمیت مصرف .................................................................................................................................................... 23

2-9-6- کدوسبز ................................................................................................................................................................... 24

2-10- وضعیت سبزیجات در کل کشور ................................................................................................... 25

2-10-1- سطح برداشت ....................................................................................................................................................... 25

2-10-2- میزان تولید ............................................................................................................................................................ 25

2-11- مروی بر پژوهش های پیشین ........................................................................................................ 28

فصل سوم: مواد و روش ها ............................................................................................................ 31

3-1- مواد شیمیایی ................................................................................................................................... 32

3-2-  تجهیزات مورد استفاده ................................................................................................................... 33

3-3- تهیه نمونه ها ................................................................................................................................... 33

3-3-1- آماده سازی نمونه ها ............................................................................................................................................... 34

3-4- اندازه گیری ماده خشک .................................................................................................................. 34

3-5- اندازه گیری نیترات .......................................................................................................................... 34

3-6- اندازه گیری نیتریت ......................................................................................................................... 35

و

3-7- اندازه گیری اسید آسکوربیک .......................................................................................................... 36

3-8- تجزیه و تحلیل آماری ..................................................................................................................... 36

فصل چهارم: نتایج و بحث ............................................................................................................. 37

4-1- نیترات ............................................................................................................................................  38

4-1-1- اثر گیاه ........................................................................................................................................... 38

4-1-2- اثر فرآیند ......................................................................................................................................... 39

4-1-3- اثر زمان نگهداری .............................................................................................................................. 41

4-2- نیتریت ............................................................................................................................................. 42

4-2-1- اثر گیاه .................................................................................................................................................................... 42

4-2-2- اثر فرآیند ................................................................................................................................................................. 43

4-2-3- اثر زمان نگهداری .................................................................................................................................................... 45

4-3- اسید آسکوربیک .............................................................................................................................. 47

4-3-1- اثر گیاه ..................................................................................................................................................................... 47

4-3-2- اثر فرآیند ................................................................................................................................................................. 48

4-3-3- اثر زمان ................................................................................................................................................................... 50

4-4- بررسی رابطه بین میزان نیترات، نیتریت و اسید آسکوربیک ............................................................ 52

فصل پنجم: نتیجه گیری و پیشنهادات .............................................................................................. 53

5-1- نتیجه گیری ...................................................................................................................................... 54

5-2- پیشنهادات ........................................................................................................................................ 54

منابع و مراجع ............................................................................................................................................ 55

پیوست ها .................................................................................................................................................. 66

English Abstract ……………………………………………………………………………...70

منبع:

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