4. DiscussionIn this work, no corre

4. Discussion
In this work, no correlation was found between the b-carotene
concentration of crude oil and thefinal color of the palm oil. On the
other hand, a high correlation was found between p-AnV after
bleaching with ABE and the palm oil color after deodorization/heat
bleaching. The same correlation was not observed when the
bleaching was done with NBE. It is also interesting to highlight that
heat bleaching was more efficient after bleaching with ABE, even
though NBE was capable of removing more efficiently the color
during bleaching. Oxidation of compounds such asb-carotenes may
be an explanation for those results as described hereafter.
Tonsil OPT 210 FF is an acid activated bleaching earth manufactured by acid activation of calcium bentonite. It has acidic and
catalytic activity, leading most importantly to hydroperoxide
decomposition, forming sub-products such as aldehydes, ketones
and conjugated polyenes (Zschau&Grp, 2001). Pure Flo B 80 is a
neutral bleaching earth with no catalytic activity. These properties
can be confirmed through oxidative state data (Fig. 1). Note, for
instance, a smaller amount of ABE is needed to reach zero peroxides
compared to NBE. Furthermore, the first point presenting a
maximum p-AnV value (secondary oxidation products) is correlated to the minimum PV value. Note also that ABE decreases p-AnV
until a constant value and NBE keeps it constant at the maximum.
Indeed, as suggested by Sarier&Guler (1988), b-carotene which
remains in solution with acid activated bleaching earth is rapidly
oxidized later on, even more than those submitted to oxygen for
48 h. Consequently, it may be said that acid activated bleaching
earth initiates the oxidation of unadsorbedb-carotene.
Carotenoids can react with radical species in three different
ways, including (1) radical addition, (2) electron transfer to the
radical or (3) allylic hydrogen abstraction (Bonnie&Choo, 1999).
Which mechanism will take place depends on the reaction conditions. For instance, by increasing the oxygen concentration, the
formation of secondary peroxyl radicals becomes important,
resulting in the loss of antioxidant behavior. With a sufficiently
high oxygen partial pressures (above 150 mmHg) (Burton&Ingold,
1984), b-carotene reactions have a pro-oxidant effect since they
could generate more radicals than they consume (Krinsky&Yeum,
2003). Electron transfer reactions have been reported either in
formation of a carotenoid cation CAR
þ
, anion CAR

or in the formation of an alkyl radical (Krinsky&Yeum, 2003), stable because of
its resonance structure (Kamal-Eldin, 2003). Finally, allylic
hydrogen abstraction by peroxyl radical occurs at an oxygen pressure of less than 760 mmHg, producing a carotene radical. Those
radicals undergo addition of oxygen producing dicarbonyls (KamalEldin, 2003). It is clear, that allylic hydrogen abstraction does not
occurs in bleaching conditions due to its moderate temperature and
pressures, being always lower than 50 mbar. Moreover,b-carotene
behaves differently in different oils and under different conditions,
i.e. temperature and lipid system composition (Zeb&Murkovic,
2013b).
BurtonandIngold(1984)suggested that b-carotene reacts
with peroxyl groups by addition, rather than by hydrogen
abstraction.Liebler&McClure (1996)identified radical adducts
formed during b-carotene oxidation, which then combines
with a second radical to form an addition product. The formation
of alkyl- and alkoxyl-containing addition products indicates
that both may add directly to b-carotene. In contrast, peroxyl
radical addition yields an unstable intermediate radical
adduct that collapses to an epoxide and releases an alkoxyl
radical.
The polarity of the medium determines the pathways thatbcarotene oxidation undergoes: in nonpolar solvents, only addition
radicals are formed, meanwhile in polar ones carotenoid radical
cations are formed. For both solvents, thefirst product is an addition radical formed between the acylperoxyl radical and the
carotenoid (Eq.(2), Fig. 3)(El-Agamey&McGarvey, 2003). In fact,
the Gibbs free energy presents similar negative values for both
system polarities, thus, the exergonicity of reactions depends
mostly on the nature of the free radical, being
OH radical the most
exergonic and peroxyl radicals the least one (Martinez, Vargas,&
Galano, 2010). Those radicals have no reactivity toward oxygen,
even at high oxygen pressures as 760 mmHg (Eq.(3))(El-Agamey&
McGarvey, 2003).
BCþROO/ROOBC
(2)
ROOBC þO2/✕ (3)
Subsequent steps of b-carotene oxidation follow different
pathways for polar and non-polar solvents (Fig. 4). In non-polar
solvents, the radicals decompose in epoxides and cyclic ethers,
therefore, with an acyloxyl radical elimination (Eq.(4))(El-Agamey
&McGarvey, 2003), leading to volatile products such as apocarotenals (Krinsky&Yeum, 2003). Note that this reaction releases a
radical, thus, showing no net consumption of radical, being an
autoxidation reaction (Liebler, 1993).
ROOBC þROO /“nonradical product” (4)
Nonetheless, in polar solvents, an ion-pair composed by a peroxyl anion (ROO) and a cation (CARþ) is formed, which absorbs
near-infrared radiation (El-Agamey&McGarvey, 2003) and after, it
is transformed to carotenoid radical cation. Even though vegetable
oil is nonpolar, BE negative sites may make a polar layer close to its

Hasil (Bahasa Indonesia) 1:

4. DiscussionIn this work, no correlation was found between the b-caroteneconcentration of crude oil and thefinal color of the palm oil. On theother hand, a high correlation was found between p-AnV afterbleaching with ABE and the palm oil color after deodorization/heatbleaching. The same correlation was not observed when thebleaching was done with NBE. It is also interesting to highlight thatheat bleaching was more efficient after bleaching with ABE, eventhough NBE was capable of removing more efficiently the colorduring bleaching. Oxidation of compounds such asb-carotenes maybe an explanation for those results as described hereafter.Tonsil OPT 210 FF is an acid activated bleaching earth manufactured by acid activation of calcium bentonite. It has acidic andcatalytic activity, leading most importantly to hydroperoxidedecomposition, forming sub-products such as aldehydes, ketonesand conjugated polyenes (Zschau&Grp, 2001). Pure Flo B 80 is aneutral bleaching earth with no catalytic activity. These propertiescan be confirmed through oxidative state data (Fig. 1). Note, forinstance, a smaller amount of ABE is needed to reach zero peroxidescompared to NBE. Furthermore, the first point presenting amaximum p-AnV value (secondary oxidation products) is correlated to the minimum PV value. Note also that ABE decreases p-AnVuntil a constant value and NBE keeps it constant at the maximum.Memang, seperti yang disarankan oleh Sarier & Guler (1988), b-karoten yangtetap dalam larutan dengan asam diaktifkan bleaching bumi adalah cepatteroksidasi kemudian bahkan lebih banyak daripada mereka diserahkan kepada oksigen untuk48 jam. Akibatnya, dapat dikatakan bahwa asam diaktifkan bleachingbumi memulai oksidasi unadsorbedb-karoten.Karotenoid dapat bereaksi dengan spesies yang radikal dalam tiga berbedacara, termasuk penambahan (1) radikal, transfer elektron (2)abstraksi radikal atau (3) allylic hidrogen (Bonnie & Choo, 1999).Mekanisme yang akan terjadi tergantung pada kondisi reaksi. Misalnya, dengan meningkatkan konsentrasi oksigen,pembentukan radikal peroxyl sekunder menjadi penting,mengakibatkan hilangnya antioksidan perilaku. Dengan cukuptekanan parsial oksigen yang tinggi (di atas 150 mmHg) (Burton & Ingold,1984), reaksi b-karoten memiliki efek Pro-oksidan karena merekadapat menghasilkan radikal lebih dari yang mereka konsumsi (Krinsky & Yeum,2003). elektron reaksi transfer telah dilaporkan baik dalampembentukan kation karotenoid mobilþ, anion mobilatau dalam pembentukan alkil radikal (Krinsky & Yeum, 2003), stabil karenastruktur resonansi (Kamal-Eldin, 2003). Akhirnya, allylichidrogen abstraksi oleh peroxyl radikal terjadi pada tekanan oksigen kurang dari 760 mmHg, menghasilkan radikal karoten. Orang-orangradikal mengalami penambahan oksigen yang memproduksi dicarbonyls (KamalEldin, 2003). Jelas, bahwa allylic hidrogen abstraksi tidakterjadi dalam pemutihan kondisi karena suhu moderat dantekanan, yang selalu lebih rendah daripada 50 mbar. Selain itu, b-karotenberperilaku berbeda dalam minyak yang berbeda dan di bawah kondisi yang berbeda,yaitu suhu dan lipid sistem komposisi (Zeb & Murkovic,2013b).BurtonandIngold (1984) menyarankan bahwa b-karoten bereaksidengan peroxyl grup oleh penambahan, bukan oleh hidrogenabstraksi.Adducts Liebler & McClure radikal diidentifikasi (1996)dibentuk selama b-karoten oksidasi, yang kemudian menggabungkandengan kedua radikal untuk membentuk produk tambahan. Pembentukanalkil dan alkoxyl-mengandung produk tambahan menunjukkanbahwa keduanya dapat menambahkan langsung ke b-karoten. Sebaliknya, peroxylSelain radikal menghasilkan radikal menengah tidak stabilAdisi itu runtuh ke epoxide dan rilis alkoxylradikal.Polaritas media menentukan jalur thatbcarotene oksidasi mengalami: dalam pelarut nonpolar, hanya penambahanradikal bebas yang terbentuk, sementara itu di kutub yang karotenoid radikalkation dibentuk. Untuk kedua pelarut, produk pertama adalah tambahan radikal dibentuk antara radikal acylperoxyl dankarotenoid (Eq.(2), Fig. 3) (El-Agamey & McGarvey, 2003). Sebenarnyaenergi bebas Gibbs menyajikan nilai-nilai negatif yang sama untuk keduapolaritas sistem, dengan demikian, exergonicity reaksi tergantungsebagian besar pada sifat dari radikal bebas, sedangOH radikal yang palingexergonic dan peroxyl radikal setidaknya satu (Martinez, Vargas, &Galano, 2010). Orang-orang radikal telah ada reaktifitas menuju oksigen,bahkan pada tekanan oksigen yang tinggi sebagai 760 mmHg (Eq.(3)) (El-Agamey &McGarvey, 2003).BCþ ROO/ROOBC(2)ROOBC þO2/✕ (3)Langkah berikutnya dari b-karoten oksidasi mengikuti berbedajalur untuk pelarut polar dan non-polar (gambar 4). Dalam non-polarpelarut, radikal membusuk di epoxides dan Eter siklik,oleh karena itu, dengan penghapusan radikal acyloxyl (Eq.(4)) (El-Agamey& McGarvey, 2003), terkemuka untuk produk volatil seperti apocarotenals (Krinsky & Yeum, 2003). Catatan bahwa reaksi ini rilisradikal, dengan demikian, menampilkan konsumsi radikal, yang tidak bersihautoksidasi reaksi (Liebler, 1993).ROOBC þROO / "nonradical Produk" (4)Meskipun demikian, dalam pelarut polar, ion-pasangan dikarang oleh peroxyl anion (ROO) dan kation (CARþ) dibentuk, yang menyerapradiasi Infra merah (El-Agamey & McGarvey, 2003) dan sesudahnya,ditransformasikan ke karotenoid kation radikal. Meskipun sayuranminyak nonpolar, situs akan negatif dapat membuat lapisan kutub dekat nya