Influence of the neutralization step on the oxidative and thermal stability of acid olive oil.
This study elucidate the modification on oxidative and thermal stability of acid olive oils during the neutralization step. The neutralization of an acidified olive oil, chosen as model, was carried out by substituting lime (calcium hydroxide) for soda (sodium hydroxide) as the neutralizing agent. Resulting olive oil preserved almost 95% of their alpha-tocopherol content and had higher temperatures of thermal decomposition than oils neutralized with soda. Oils neutralized with lime had better oxidative stability since the losses of their natural antioxidants, particularly tocopherols, were very limited. The neutralization with soda was accompanied by a passage of epoxides and hydroperoxides (products of first stage of oxidation) to alpha, beta-unsaturated aldehydes and ketones (products of second stage of oxidation). These purposes were confirmed by thermal spectrophotometric analyses and the increase of the carbonyl value after neutralization.
Essid
Kamel
K
Laboratory of applied chemistry: Heterocycles, Fats and Polymers Faculté des Sciences de Sfax, Tunisia.
Chtourou
Manef
M
Trabelsi
Mahmoud
M
Frikha
Mohamed Hédi
MH
D000975:Antioxidants / Q000737:chemistry; D002126:Calcium Hydroxide / Q000737:chemistry; D002627:Chemistry, Physical; D000069463:Olive Oil; D010084:Oxidation-Reduction; D010938:Plant Oils / Q000737:chemistry*; D012972:Sodium Hydroxide / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature
D000975:Antioxidants; D000069463:Olive Oil; D010938:Plant Oils; D012972:Sodium Hydroxide; D002126:Calcium Hydroxide