Sada je: 29 ožu 2024, 10:20.
Moderatori/ce: Diami, nevenera
silki je napisao/la:koliko sam ja pokopčala do sad, rođena dalmošica, dinstanjem i prženjem samo gubi na kvaliteti. ništa više.
Myth. Heating olive oil will evaporate the alcohols and esters which
make up the delicate taste and fragrance of olive oil. Heating olive
oil will not change its health aspects appreciably. All oils will
oxidize if repeatedly heated to high temperatures. Olive Oil seems to
be more resistant to this. Heating olive oil will not change it from a
monosaturated fat which is considered far healthier than the
polyunsaturated fats in margarine or the cholesterol in butter. When
olive oil and other vegetable oils are subjected to heating a lower
amount of undesirable TRANS fatty acids are formed in olive oil than
in the other oils. Use a cheaper, less flavorful pure oil for frying
and a more flavorful extra virgin olive oil on salads and as a
condiment at the table."
The Facts: As far as making a saturated fat, according to Dr. A.
Kiritsakis, a world renowned oil chemist in Athens, (Book - OLIVE OIL
FROM THE TREE TO THE TABLE -Second edition 1998), all oils will
oxidize and hydrogenate to a tiny degree if repeatedly heated to very
high temperatures such as is done in commercial frying operations.
Olive pomace oil and virgin olive oil are both highly monounsaturated
oils and therefore resistant to oxidation and hydrogenation. Studies
have shown oxidation and hydrogenation occurs to a lesser degree in
olive oil than in other oils. But in any case, the amount of trans
fat formed is miniscule and no home cook would ever experience this
problem.
The large refinery-like factories which take unsaturated vegetable oil
and turn it into margarine or vegetable lard do so by bubbling
hydrogen gas through 250 to 400 degree hot vegetable oil in the
presence of a metal catalyst, usually nickel or platinum. The process
can take several hours. You cannot make a saturated product like
margarine at home by heating olive oil or any other vegetable oil in a
pan. We don't know where this weird notion has come from. For more
see our olive oil chemistry page
Changing a cis-fat to a trans-fat does not occur on a home stove.
Oils that are best to use for high heat cooking include those with higher smoke points. These would include high-oleic safflower oil (smoke point: 450ºF/232ºC), high-oleic sunflower oil (smoke point: 450ºF/232ºC), avocado oil (smoke point: 520ºF/271ºC), or refined coconut oil (smoke point: 450ºF/232ºC). Also, you may consider ghee, which has a smoke point of 400˚-500˚F (204˚-260˚C).
As you'll note, the only oil we include on our website is extra virgin olive oil. At the heart of the Mediterranean diet, extra virgin olive oil is rich in monounsaturated fats and polyphenol antioxidants and has found to be heart healthy. Yet, we don't like to cook with extra virgin olive oil (the highest we'll cook with it is up to 250˚F121˚C, which is fine for making sauces or heating up a dish but not high enough for sautéing).
The reason we don't like to heat extra virgin olive oil to higher temperatures is because it has a lower smoke point than the other oils mentioned. All vegetable oils are susceptible to heat damage-much more so than the whole foods from which they were pressed or extracted. But in the case of extra virgin olive oil, the susceptibility is especially great, notably in the destruction of its polyphenolic phytonutrients. Extra virgin olive oil has such a great flavor let alone an amazingly rich nutrient profile that we want to preserve so we don't like to cook with it but rather enjoy it as a salad dressing or drizzled on foods after they have been cooked.
Masha je napisao/la:frižiš uvijek na laganoj vatri. kad dinstaš npr. luk, čim se zastakli podliješ s malo vode.
meni nikad nema tog dimnjenja.
super ako je tako, jesi mozda mjerila?
2008: Napolitano Aurora; Morales Francisco; Sacchi Raffaele; Fogliano Vincenzo
Relationship between virgin olive oil phenolic compounds and acrylamide formation in fried crisps.
Journal of agricultural and food chemistry 2008;56(6):2034-40.
In this paper the relationship between virgin olive oil (VOO) phenol compounds and the formation of acrylamide in potato crisps was investigated. The phenol compositions of 20 VOO samples were screened by LC-MS, and 4 oils, characterized by different phenol compound patterns, were selected for frying experiments. Slices of potatoes were fried at 180 degrees C for 5, 10, and 15 min, and acrylamide content was determined by LC-MS. Results demonstrated that VOO phenolic compounds are not degraded during frying, and crisp color was not significantly different among the four VOOs. Acrylamide concentration in crisps increased during frying time, but the formation was faster in the oil having the lowest concentration of phenolic compounds. Moreover, the VOO having the highest concentration of ortho-diphenolic compounds is able to efficiently inhibit acrylamide formation in crisps from mild to moderate frying conditions. It was concluded that the use of ortho-diphenolic-rich VOOs can be proposed as a reliable mitigation strategy to reduce acrylamide formation in domestic deep-frying.
Deterioration of olive, corn and soybean oils due to air, light,heat and deep-frying
Shahina Naz *, Rahmanullah Siddiqi, Hina Sheikh, Syed Asad Sayeed
Department of Food Science and Technology, University of Karachi, Karachi 75270, Pakistan
Abstract
To follow the relative rate of oxidative deterioration of edible oils, refined olive, corn and soybean oils were analyzed periodically
for their peroxide value (PV), p-anisidine value (p-AV) and iodine value (IV) following exposure to air and air–light for 30 days.
Changes in the above values of the oils were also examined and after being used for deep frying of French fries at 180 °C for varying
periods of time i.e. 30, 60 and 90 min PV and p-AV values increased in the order, deep frying > air–light exposure > air exposure,
while the values with respect to the oils increased as soybean > corn > olive. Decreases in IV followed the same pattern, i.e. deep
frying > air–light > air and soybean > corn > olive. %Free fatty acid increased with increase in time of deep-frying. Deep-frying
of French fries in corn oil was also carried out in presence of caffeic, ferulic, vanillic acid and crude tea extract as antioxidants.
All antioxidants effectively reduced the oxidation rate in the oil as detected by decreases in PVs and p-AVs and relatively low reduc-
tion rates in IVs for all the frying times. The order of antioxidative activity was caffeic acid > vanillic acid > ferulic acid > tea
extract. Variation in %FFA of corn oil due to variation in nature of fried food was also analyzed. %FFA of the oil used for deep
frying of chicken drum sticks were higher than the values of the oil used for deep-frying of French fries.
Ó 2004 Elsevier Ltd. All rights reserved.
Olive oil stability under deep-frying conditions
Susana Casal a, Ricardo Malheiro b, Artur Sendas a,b, Beatriz P.P. Oliveira a, José Alberto Pereira b,*
a
REQUIMTE/Serviço de Bromatologia, Faculdade de Farmácia da Universidade do Porto, Rua Aníbal Cunha 164, 4050-047 Porto, Portugal
b
CIMO/School of Agriculture, Polytechnic Institute of Bragança Apartado 1172, 5301-854 Bragança, Portugal
a b s t r a c t
The suitability of different commercial olive oil categories for domestic frying was investigated. Oil samples were taken every 3 h of frying and evaluated for free acidity, peroxide and p-anisidine values, specific extinction coefficients, oxidative stability, fatty acids, vitamin E, b-carotene and total phenols, until the total polar compounds achieved the maximum legal value (25%). All olive oils were fried during more time than the commercial vegetable oil blend taken for comparison (from 24 to 27 h, against 15 h.The extra-virgin Protected Designation of Origin (PDO) olive oil was characterized by reduced levels oxidation and hydrolysis, and superior amounts of minor antioxidant compounds. The ‘‘olive oil” commercial category behaves similarly, but ‘‘Cobrançosa” olive oils performance was slightly worse, and clearly different between years, highlighting the importance of blending different cultivars. The vegetable oil, despite containing significantly higher amounts of vitamin E, was highly susceptible to oxidation under frying conditions when compared to all olive oils.
The results also show that the chemical composition of olive oils, particularly the amount of natural antioxidants, are important parameters in their predictive behavior along the frying process, but mostly that olive oil is clearly resistant to frying conditions, independently to the commercial category chosen.
Retention and distribution of natural antioxidants (a-tocopherol, polyphenols and terpenic acids) after shallow frying of vegetables in virgin olive oil
Nick KalogeropoulosÃ, Anastasia Mylona, Antonia Chiou, Maria S. Ioannou, Nikolaos K. Andrikopoulos
a
Laboratory of Food Chemistry-Biochemistry-Physical Chemistry, Department of Science of Dietetics-Nutrition, Harokopio University,
70 El. Venizelou Av., 176 71 Kallithea, Athens, Greece (2006.)
Abstract
Potatoes, green peppers, zucchinis and eggplants were shallow fried in virgin olive oil (VOO) according to the Mediterranean
traditional culinary practice. Zucchinis and eggplants were also blanketed with wheat flour or batter prior to frying. Polyphenols and hydroxy pentacyclic triterpene acids (HPTAs) were determined by GC/MS, while a-tocopherol was determined by high-performance liquid chromatography. Among 12 polyphenols determined, tyrosol predominated in frying oils and zucchini samples, while chlorogenic acid was the major phenolic species in the other vegetable samples. The triterpene acids maslinic, oleanolic and ursolic were determined in frying oils and fried vegetables, while a-tocopherol was present in all samples. Besides water loss and oil absorption, shallow frying resulted in partial loss of all the antioxidants studied in frying oils and enrichment of fried vegetables with olive oil antioxidants, which was in some extent affected by the type of vegetable fried and the culinary practice followed. The overall retention of the antioxidants in oil and food ranged from 32% to 64% for a-tocopherol, 25% to 70% for polyphenols and 35% to 83% for HPTA. It appears that vegetables fried in VOO provide an additional intake of a-tocopherol, terpenic acids and polyphenols as tyrosol and chlorogenic acid.
r 2006 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.
Sanika je napisao/la:dimi se kao dinstanja, ma na koliko slaboj vatri radila, i ma koliko polako
nije to onaj smrdljivi dim, ali se dimi, blagi dim se vidi..smoke point dosegnut...
nemrem bas vjerovati da vam se ali ama bas ni malo ne zadimi, onda to nije dinstanje vec umakanje u mlakom ulju
Ina66 je napisao/la: ovo što opisuješ nije dimljenje ulja.
Trenutno korisnika/ca: / i 3 gostiju.