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_________________Purwiyatno Hariyadi
phariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
ITP503
ANALISIS SIFAT TERMAL PANGAN
Purwiyatno Hariyadiphariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
ITP503
ANALISIS SIFAT TERMAL PANGAN
• Konduktivitas panas• Difusivitas panas• Expansi panas• Panas jenis• Enthalpy
_________________Purwiyatno Hariyadi
phariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Penggunaan Model Pedugaan
Panas Jenis Pangan
Cp = f([H20], [protein], [lemak], [KH], [Abu])
Heldman (1975):Cp = 4.180XwH20 + 1.547X
wprot + 1.672X
wLemak + 1.42X
wKH + 0.836X
wAbu
Choi and Okos (1986), produk dengan n komponen:cp = ∑(X
wi . cpi )
Xwi = fraksi masa komponen i ,cpi = panas jenis komponen i (J/kg K).
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Penggunaan Model Pedugaan
Panas Jenis kentangContoh:
Berapa nilai Cp kentang dengan kadar air (bb) 85%?.Data:cpwater = 4186.80 J/kgKcpnonfat solids = 837.36 J/kgK
Choi and Okos (1986):cp = ∑(X
wi . cpi )
_________________Purwiyatno Hariyadi
phariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Penggunaan Model Pedugaan
Panas Jenis ApleContoh:
Berapa nilai Cp kentang dengan kadar air (bb) 85%?.Data:cpwater = 4186.80 J/kgKcpnonfat solids = 837.36 J/kgK
Choi and Okos (1986):cp = ∑(X
wi . cpi )
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Riegel,1992 :
Cp udara basah = cp dry air(1 + 0.837RH)
Penggunaan Model Pedugaan
Panas Jenis Udara = f(RH)
_________________Purwiyatno Hariyadi
phariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Choi and Okos (1986), Cp[=] J/kg◦C , sebagai berikut :
cpH2O = 4081.7 − 5.3062 T + 0.99516T2 (−40 0◦C)
cpH2O = 4176.2 − 0.0909 T + 5.4731 × 10−3 T 2 (0150◦C)
cpKH = 1548.8 + 1.9625 T − 5.9399 × 10−3 T 2 (−40 50◦C)cpprot = 2008.2 + 1.2089 T − 1.3129 × 10−3 T 2 (−40150◦C)cplemak = 1984.2 + 1.4373 T − 4.8008 × 10−3 T2 (−40 150◦C)cpabu = 1092.6 + 1.8896 T − 3.6817 × 10−3 T 2 (−40150◦C)cpes = 2062.3 + 6.0769 T
T [=] ◦C.
Penggunaan Model Pedugaan
Panas Jenis Pangan = f(T)
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
• Umumnya, Cp: hasil pengukuran > Hasil Pendugaan• ? interaksi komponen dengan airair terikat• Rahman (1993):
• excess specific heat, cex
• Fresh seafood (Rahman, 1993) :
Penggunaan Model Pedugaan Vs.Hasil Pengukuran ?
Panas Jenis Udara = f(RH)
_________________Purwiyatno Hariyadi
phariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Skema DSC
Differential Scanning Calorymetry (DSC)
- teknik untuk menganalisis perbedaan jumlah panasyang diperlukan untuk meningkatkan suhu “sampel”dan “baku” diukur sebagai fungsi suhu.
Tempat sampel (sample pan) danalat penutup secara hermetis
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Differential Scanning Calorymetry (DSC)
- teknik untuk menganalisis perbedaan jumlah panasyang diperlukan untuk meningkatkan suhu “sampel”dan “baku” diukur sebagai fungsi suhu.
_________________Purwiyatno Hariyadi
phariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Metal1
Metal2
Metal1
Metal2
Sample Empty
SampleTemperature
ReferenceTemperature
TemperatureDifference =Heat Flow
•A “linear” heating profile even for isothermal methods
Differential Scanning Calorymetry (DSC)
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Differential Scanning Calorymetry (DSC)
- Tiikal Kurva DSC
_________________Purwiyatno Hariyadi
phariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
• Glass transitions
• Melting and boiling points
• Crystallisation time and temperature
• Percent crystallinity
• Heats of fusion and reactions
• Specific heat capacity
• Oxidative/thermal stability
• Reaction kinetics
• Purity
Differential Scanning Calorymetry (DSC)Analisis ?
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
6
Temperature
Hea
t Flo
w- >
exo
ther
mic
GlassTransition
Crystallisation
Melting
Cross-Linking(Cure)
Oxidation
Differential Scanning Calorymetry (DSC)Analisis ?
_________________Purwiyatno Hariyadi
phariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Differential Scanning Calorymetry (DSC)Analisis ? Suhu Transisi Gelas
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Differential Scanning Calorymetry (DSC)Analisis ? Pelipatan proein (Protein Folding-unfolding)
_________________Purwiyatno Hariyadi
phariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Differential Scanning Calorymetry (DSC)Analisis ? Kristalisasi
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Suhu (oC)
Differential Scanning Calorymetry (DSC)Analisis ? Entalpi
_________________Purwiyatno Hariyadi
phariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
∆ = entalpi gelatinisasi pati (J/g)A = luas area kurva (cm2)TB = basis waktu (menit/cm)E = koefisien kalibrasi (mW/mV)∆qs = skala sensitifitas (mV/cm)m = massa sampel sagu (mg, berat kering)
Differential Scanning Calorymetry (DSC)Analisis ? Entalpi
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
670 Temperature (°C)150 152 154 156
0
-2
-4
-6
DSC
Hea
t Flo
w (
W/g
)
10mg
4.0mg
15mg
1.7mg
1.0mg0.6mg
Indium at10°C/minuteNormalized Data
158 160 162 164 166
Onset notinfluencedby mass
Differential Scanning Calorymetry (DSC)Analisis ? Entalpi perlu standar Indium
_________________Purwiyatno Hariyadi
phariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
∆H = panas peleburan indium (J/g)m = massa indium (mg)A = luas kurva (cm2)TB = basis waktu (menit/cm)∆ = skala sensitifitas (mV/cm)E = koefisien kalibrasi (mW/mV)
Differential Scanning Calorymetry (DSC)Analisis ? Entalpi perlu standar Indium
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Differential Scanning Calorymetry (DSC)Analisis ? Entalpi perlu standar atau Lainnya
_________________Purwiyatno Hariyadi
phariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Termogram DSC untuk patisagu segar. Nilai entalpigelatinisasi pati sagu (rasioair/pati 5/1) = 12.5 J/gatau 2.99 kal/g(Hariyadi, 1984)
Differential Scanning Calorymetry (DSC)Analisis ? Kemurnian?
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Termogram DSC untuk patisagu segar. Nilai entalpigelatinisasi pati sagu (rasioair/pati 5/1) = 12.5 J/gatau 2.99 kal/g(Hariyadi, 1984)
Differential Scanning Calorymetry (DSC)Analisis ? Kemurnian?
Termogram DSC untuksampel pati sagu yang lain(dianalisis dengan metodesama; rasio air/pati 5/1) =4.166 J/g atau 0.996 kal/g
ARTINYA?
_________________Purwiyatno Hariyadi
phariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Differential Scanning Calorymetry (DSC)Analisis ? Kinetika ?
Kurva standar, hubunganantara derajat gelatinisasi*)
pati sagu dengan nilaientalpi gelatinisasi
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Differential Scanning Calorymetry (DSC)Analisis ? Kinetika ?
Kurva standar, hubunganantara derajat gelatinisasi*)
pati sagu dengan nilai entalpigelatinisasi
Derajat gelatinisasi pati sagu sebagai fungsi waktu padaberbagai suhu pemanasan
_________________Purwiyatno Hariyadi
phariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
heating rate
timeHeat
=qt
= heat flow
Temperature increasetime
ΔTt
==
Differential Scanning Calorymetry (DSC)Analisis ? Cp
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
q
t
ΔT
t
=q
ΔT= Heatcapacity=
Cp
Differential Scanning Calorymetry (DSC)Analisis ? Cp
_________________Purwiyatno Hariyadi
phariyadi.staff.ipb.ac.id
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
Differential Scanning Calorymetry (DSC)Analisis ? Cp
Purwiyatno Hariyadi / phariyadi.staff.ipb.ac.id
HATUR NUHUN PISAN
phariyadi.staff.ipb.ac.idpurwiyatno_Hariyadi
@phariyadi