Pengaruh Suhu dan Penyimpanan Terhadap Kadar Nitrat dan Nitrit Dalam Brokoli (Brassica Oleracea. L)
PENGARUH SUHU DAN LAMA PENYIMPANAN TERHADAP
KADAR NITRAT DAN NITRIT DALAM BROKOLI
(Brassica oleracea. L)
ABSTRAK
Sayuran merupakan sumber utama paparan nitrat dalam makanan. Nitrat
terbentuk secara alami di dalam tumbuhan melalui daur nitrogen. Nitrat memiliki
efek racun yang rendah bagi tubuh manusia, namun nitrat dapat berubah menjadi
nitrit dimana nitrit memiliki tingkat berbahaya yang lebih tinggi dibanding nitrat.
Akumulasi nitrat dan nitrit didalam tubuh dapat menyebabkan kanker usus serta
methaemoglobinaemia pada bayi berumur kurang dari 6 bulan. Faktor suhu dan
lama penyimpanan dapat menyebabkan perubahan kadar nitrat dan nitrit. Tujuan
penelitian ini adalah untuk mengetahui pengaruh suhu dan lama penyimpanan
terhadap kadar nitrat dan nitrit pada brokoli.
Dalam penelitian ini sampel yang dianalisis adalah brokoli yang berasal
dari pasar induk lau cih, Medan tuntungan. Sampel disimpan selama 0 jam, 6 jam,
12 jam, 24 jam, 30 jam dan 36 jam pada dua suhu penyimpanan yaitu suhu lemari
pendingin (± 10°C) dan suhu kamar (± 30°C). Sampel dihaluskan, ditimbang,
dipanaskan dan dilakukan metode analisis kualitatif dan kuantitatif. Analisis
kualitatif nitrit dilakukan dengan menggunakan pereaksi asam sulfanilat dan N-(1naftil) etilendiamin dihidroklorida dan dengan menggunakan pereaksi KMnO4 dan
H2SO4 (p). Analisis kualitatif nitrat dilakukan dengan menggunakan pereaksi
Serbuk Zn dan NaOH(e) dan dengan menggunakan pereaksi KI dan Asam Asetat.
Penentuan kadar nitrit dilakukan secara spektrofotometri sinar tampak dengan
menggunakan pereaksi asam sulfanilat dan pereaksi N-(1-naftil) etilendiamin
dihidroklorida pada panjang gelombang maksimum 540 nm. Penentuan kadar
nitrat dilakukan dengan cara mereduksi nitrat terlebih dahulu menjadi nitrit
dengan menggunakan serbuk Zn kemudian diukur menggunakan spektrofotometri
sinar tampak.
Hasil Penelitian menunjukan bahwa pada suhu kamar selama
penyimpanan 0 jam sampai 36 jam, kadar nitrit meningkat dari kadar awal 1,53
mg/kg menjadi 1,75 mg/kg dan kadar nitrat dari penyimpanan 0 jam sampai 36
jam meningkat dari kadar awal 64,19 mg/kg menjadi 154,51 mg/kg. kadar nitrit
suhu lemari pendingin selama penyimpanan 0 jam sampai 36 jam meningkat dari
kadar awal 1,53 mg/kg menjadi 2,09 mg/kg dan kadar nitrat dari penyimpanan 0
jam sampai 36 jam meningkat dari kadar awal 64,19 mg/kg menjadi 113,06
mg/kg.
Kata Kunci : Brokoli, Nitrat, Nitrit, Spektrofotometri Sinar Tampak, Suhu dan
lama penyimpanan
vi
Universitas Sumatera Utara
THE EFFECT OF TEMPERATURE AND STORAGE TIME
AGAINTS NITRATE AND NITRITE IN
BROCCOLI (Brassica oleracea. L)
ABSTRACT
Vegetables are the major source of nitrates in human intake. Nitrate occurs
naturally in plant by nitrogen cycle. Nitrate has low level of acute toxicity, but it
can be transformed into nitrite, which has much higher acute toxicity.
Accumulation of nitrate and nitrite in the body can increase risk of colon cancer
and methaemoglobinaemia in infants under 6 months of age. Temperature and
storage time might changes in nitrate and nitrite level in vegetable. The purpose of
this research is to investigate the effect of temperature and storage time againts
nitrate and nitrite level in broccoli.
The sample were analyzed was broccoli which were obtained from Lau cih
market, Medan Tuntungan. Samples were stored for 0 hours, 6 hours, 12 hours, 24
hours, 30 hours and 36 hours in separated storage condition, that is refrigerated (±
10° C) and room temperature (± 30° C). Sample which has been mashed, weighed
and heated were subjected to qualitative and quantitative analysis. Qualitative
analysis of nitrite was performed by using sulfanilic acid and N- (1-naphthyl)
ethylenediamine dihydrochloride and using KMnO4 and concentrated H2SO4.
Qualitative analysis of nitrate was performed using Zn powder and NaOH 0.2N
solution and by using KI and Acetic Acid. Determination of nitrite level was
conducted by using visible spectrophotometry method at maximum wavelength of
540 nm with addition of sulfanilic acid and N-(1-naphthyl) ethylenediamine
dihydrochloride prior to analysis. Determination level of nitrate was conducted by
reducing nitrate to nitrite first by using Zn powder, and then determination level
of nitrite were performed as in the step of determining the reduced nitrite level.
The results show that nitrite level of broccoli stored in room temperature
during 0 to 36 hours of storage increased from 1.53 mg / kg to 1.75 mg / kg and
nitrate levels during 0 to 36 hours storage increased from 64.19 mg / kg to 154.51
mg / kg. Nitrite levels of broccoli storage from refrigerator temperature during 0
to 36 hours of storage increased from 1.53 mg / kg to 2.09 mg / kg and nitrate
levels increased from 64.19 mg / kg to 113.06 mg / kg.
Key Words: Broccoli, Nitrate, Nitrite, Visible Spectrophotometry, temperature
and storage time
vii
Universitas Sumatera Utara
KADAR NITRAT DAN NITRIT DALAM BROKOLI
(Brassica oleracea. L)
ABSTRAK
Sayuran merupakan sumber utama paparan nitrat dalam makanan. Nitrat
terbentuk secara alami di dalam tumbuhan melalui daur nitrogen. Nitrat memiliki
efek racun yang rendah bagi tubuh manusia, namun nitrat dapat berubah menjadi
nitrit dimana nitrit memiliki tingkat berbahaya yang lebih tinggi dibanding nitrat.
Akumulasi nitrat dan nitrit didalam tubuh dapat menyebabkan kanker usus serta
methaemoglobinaemia pada bayi berumur kurang dari 6 bulan. Faktor suhu dan
lama penyimpanan dapat menyebabkan perubahan kadar nitrat dan nitrit. Tujuan
penelitian ini adalah untuk mengetahui pengaruh suhu dan lama penyimpanan
terhadap kadar nitrat dan nitrit pada brokoli.
Dalam penelitian ini sampel yang dianalisis adalah brokoli yang berasal
dari pasar induk lau cih, Medan tuntungan. Sampel disimpan selama 0 jam, 6 jam,
12 jam, 24 jam, 30 jam dan 36 jam pada dua suhu penyimpanan yaitu suhu lemari
pendingin (± 10°C) dan suhu kamar (± 30°C). Sampel dihaluskan, ditimbang,
dipanaskan dan dilakukan metode analisis kualitatif dan kuantitatif. Analisis
kualitatif nitrit dilakukan dengan menggunakan pereaksi asam sulfanilat dan N-(1naftil) etilendiamin dihidroklorida dan dengan menggunakan pereaksi KMnO4 dan
H2SO4 (p). Analisis kualitatif nitrat dilakukan dengan menggunakan pereaksi
Serbuk Zn dan NaOH(e) dan dengan menggunakan pereaksi KI dan Asam Asetat.
Penentuan kadar nitrit dilakukan secara spektrofotometri sinar tampak dengan
menggunakan pereaksi asam sulfanilat dan pereaksi N-(1-naftil) etilendiamin
dihidroklorida pada panjang gelombang maksimum 540 nm. Penentuan kadar
nitrat dilakukan dengan cara mereduksi nitrat terlebih dahulu menjadi nitrit
dengan menggunakan serbuk Zn kemudian diukur menggunakan spektrofotometri
sinar tampak.
Hasil Penelitian menunjukan bahwa pada suhu kamar selama
penyimpanan 0 jam sampai 36 jam, kadar nitrit meningkat dari kadar awal 1,53
mg/kg menjadi 1,75 mg/kg dan kadar nitrat dari penyimpanan 0 jam sampai 36
jam meningkat dari kadar awal 64,19 mg/kg menjadi 154,51 mg/kg. kadar nitrit
suhu lemari pendingin selama penyimpanan 0 jam sampai 36 jam meningkat dari
kadar awal 1,53 mg/kg menjadi 2,09 mg/kg dan kadar nitrat dari penyimpanan 0
jam sampai 36 jam meningkat dari kadar awal 64,19 mg/kg menjadi 113,06
mg/kg.
Kata Kunci : Brokoli, Nitrat, Nitrit, Spektrofotometri Sinar Tampak, Suhu dan
lama penyimpanan
vi
Universitas Sumatera Utara
THE EFFECT OF TEMPERATURE AND STORAGE TIME
AGAINTS NITRATE AND NITRITE IN
BROCCOLI (Brassica oleracea. L)
ABSTRACT
Vegetables are the major source of nitrates in human intake. Nitrate occurs
naturally in plant by nitrogen cycle. Nitrate has low level of acute toxicity, but it
can be transformed into nitrite, which has much higher acute toxicity.
Accumulation of nitrate and nitrite in the body can increase risk of colon cancer
and methaemoglobinaemia in infants under 6 months of age. Temperature and
storage time might changes in nitrate and nitrite level in vegetable. The purpose of
this research is to investigate the effect of temperature and storage time againts
nitrate and nitrite level in broccoli.
The sample were analyzed was broccoli which were obtained from Lau cih
market, Medan Tuntungan. Samples were stored for 0 hours, 6 hours, 12 hours, 24
hours, 30 hours and 36 hours in separated storage condition, that is refrigerated (±
10° C) and room temperature (± 30° C). Sample which has been mashed, weighed
and heated were subjected to qualitative and quantitative analysis. Qualitative
analysis of nitrite was performed by using sulfanilic acid and N- (1-naphthyl)
ethylenediamine dihydrochloride and using KMnO4 and concentrated H2SO4.
Qualitative analysis of nitrate was performed using Zn powder and NaOH 0.2N
solution and by using KI and Acetic Acid. Determination of nitrite level was
conducted by using visible spectrophotometry method at maximum wavelength of
540 nm with addition of sulfanilic acid and N-(1-naphthyl) ethylenediamine
dihydrochloride prior to analysis. Determination level of nitrate was conducted by
reducing nitrate to nitrite first by using Zn powder, and then determination level
of nitrite were performed as in the step of determining the reduced nitrite level.
The results show that nitrite level of broccoli stored in room temperature
during 0 to 36 hours of storage increased from 1.53 mg / kg to 1.75 mg / kg and
nitrate levels during 0 to 36 hours storage increased from 64.19 mg / kg to 154.51
mg / kg. Nitrite levels of broccoli storage from refrigerator temperature during 0
to 36 hours of storage increased from 1.53 mg / kg to 2.09 mg / kg and nitrate
levels increased from 64.19 mg / kg to 113.06 mg / kg.
Key Words: Broccoli, Nitrate, Nitrite, Visible Spectrophotometry, temperature
and storage time
vii
Universitas Sumatera Utara