Kinetics of the cis-trans isomerization of linoleic acid in the deodorization and/or physical refining of edible fats

Abstract

The cis‐trans isomerizations undergone by linoleic acid during industrial deodorization and/or physical refining of edible fats were studied in an experimental discontinuous pilot plant of 250 kg using nitrogen as stripping gas in place of steam. For each oil, the expression of the analytical results has been made as molar fraction, which is kinetically equivalent to making an abstraction from the other components in the reaction bulk and assumes they do not take part in the isomerization. The kinetic constants for the formation of the acids C18:2(9c,12t), C18:2(9t,12c) and C18:2(9t,12t) were determined. The equations and values obtained justify that the reaction orders studied are zero (or can be considered zero) for the time taken in an industrial deodorization and/or physical refining of edible fats. The analytical method used is appropriate for direct application of the results in industry.

Trans Polyunsaturated Fatty Acid Contents in Brazilian Refined Soybean Oil

“…Fatty acid 18:2 9c, 12t was found in concentrations larger than that of acid 18:2 9t, 12c in all brands, which represents a mean of 55% for this group. The predominance of this fatty acid has been confirmed by other authors 16 in studies of the isomerization kinetics of linoleic acid during soybean oil deodorization. The authors concluded that the formation of 18:2 9c, 12t is about 10% higher than that of 18:2 9t, 12c at 240˚C, and increases to 35% at 260˚C.…”

Trans Polyunsaturated Fatty Acid Contents in Brazilian Refined Soybean Oil

“…Fatty acid 18:2 9c, 12t was found in concentrations larger than that of acid 18:2 9t, 12c in all brands, which represents a mean of 55% for this group. The predominance of this fatty acid has been confirmed by other authors 16 in studies of the isomerization kinetics of linoleic acid during soybean oil deodorization. The authors concluded that the formation of 18:2 9c, 12t is about 10% higher than that of 18:2 9t, 12c at 240˚C, and increases to 35% at 260˚C.…”

Fatty acid profiling of 75 Indian snack samples highlights overall low trans fatty acid content with high polyunsaturated fatty acid content in some samples

“…Such high proportions of TFA as well as SFA in the bakery products are likely to be derived from the usage of margarine or bakery shortenings, both of which are partially hydrogenated vegetable oils (PHVO) [15]. The process of deodorization as well as repeated heating and frying of edible oils, especially those rich in PUFA, has also been reported to produce trans fatty acid isomers of oleic, linoleic and linolenic acids [3,16,17]. This might explain the significantly higher proportion ( p < 0.05) of TFA in the perishable deep-fried samples which also contain significantly higher amounts of PUFA (38%) as compared to the non-perishable food samples (19.7%) and bakery foods (10.2%) (Fig 2).…”

Determination of Thermally Induced trans-Fatty Acids in Soybean Oil by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy and Gas Chromatography Analysis

“…These trans fatty acids were probably produced during the oil refining process because of the high temperature. The heating during deodorization and physical refining causes the formation of TFAs. , …”

“…The heating during deodorization and physical refining causes the formation of TFAs. 14,15 A range of trans isomers was detected in the thermally treated samples, and trans-linoleic and trans-linolenic acids were observed as the major trans-fatty acids in soybean oil heated at 240 °C. The amount of each TFA increased with heating time as shown in the graph.…”

Trans Polyunsaturated Fatty Acid Contents in Brazilian Refined Soybean Oil

“…Fatty acid 18:2 9c, 12t was found in concentrations larger than that of acid 18:2 9t, 12c in all brands, which represents a mean of 55% for this group. The predominance of this fatty acid has been confirmed by other authors 16 in studies of the isomerization kinetics of linoleic acid during soybean oil deodorization. The authors concluded that the formation of 18:2 9c, 12t is about 10% higher than that of 18:2 9t, 12c at 240˚C, and increases to 35% at 260˚C.…”

Fatty acid profiling of 75 Indian snack samples highlights overall low trans fatty acid content with high polyunsaturated fatty acid content in some samples

“…Such high proportions of TFA as well as SFA in the bakery products are likely to be derived from the usage of margarine or bakery shortenings, both of which are partially hydrogenated vegetable oils (PHVO) [15]. The process of deodorization as well as repeated heating and frying of edible oils, especially those rich in PUFA, has also been reported to produce trans fatty acid isomers of oleic, linoleic and linolenic acids [3,16,17]. This might explain the significantly higher proportion ( p < 0.05) of TFA in the perishable deep-fried samples which also contain significantly higher amounts of PUFA (38%) as compared to the non-perishable food samples (19.7%) and bakery foods (10.2%) (Fig 2).…”

Determination of Thermally Induced trans-Fatty Acids in Soybean Oil by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy and Gas Chromatography Analysis

“…These trans fatty acids were probably produced during the oil refining process because of the high temperature. The heating during deodorization and physical refining causes the formation of TFAs. , …”

“…The heating during deodorization and physical refining causes the formation of TFAs. 14,15 A range of trans isomers was detected in the thermally treated samples, and trans-linoleic and trans-linolenic acids were observed as the major trans-fatty acids in soybean oil heated at 240 °C. The amount of each TFA increased with heating time as shown in the graph.…”

Trans Polyunsaturated Fatty Acid Contents in Brazilian Refined Soybean Oil

“…Fatty acid 18:2 9c, 12t was found in concentrations larger than that of acid 18:2 9t, 12c in all brands, which represents a mean of 55% for this group. The predominance of this fatty acid has been confirmed by other authors 16 in studies of the isomerization kinetics of linoleic acid during soybean oil deodorization. The authors concluded that the formation of 18:2 9c, 12t is about 10% higher than that of 18:2 9t, 12c at 240˚C, and increases to 35% at 260˚C.…”

Fatty acid profiling of 75 Indian snack samples highlights overall low trans fatty acid content with high polyunsaturated fatty acid content in some samples

“…Such high proportions of TFA as well as SFA in the bakery products are likely to be derived from the usage of margarine or bakery shortenings, both of which are partially hydrogenated vegetable oils (PHVO) [15]. The process of deodorization as well as repeated heating and frying of edible oils, especially those rich in PUFA, has also been reported to produce trans fatty acid isomers of oleic, linoleic and linolenic acids [3,16,17]. This might explain the significantly higher proportion ( p < 0.05) of TFA in the perishable deep-fried samples which also contain significantly higher amounts of PUFA (38%) as compared to the non-perishable food samples (19.7%) and bakery foods (10.2%) (Fig 2).…”

Determination of Thermally Induced trans-Fatty Acids in Soybean Oil by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy and Gas Chromatography Analysis

“…These trans fatty acids were probably produced during the oil refining process because of the high temperature. The heating during deodorization and physical refining causes the formation of TFAs. , …”

“…The heating during deodorization and physical refining causes the formation of TFAs. 14,15 A range of trans isomers was detected in the thermally treated samples, and trans-linoleic and trans-linolenic acids were observed as the major trans-fatty acids in soybean oil heated at 240 °C. The amount of each TFA increased with heating time as shown in the graph.…”