Effect of continuous high thermal processing on physico-chemical and nutritional alterations in cold-pressed and refined edible oils
- 1Food Chemistry Division, ICMR-National Institute of Nutrition, Hyderabad, India
- 2Clinical Epidemiology, ICMR-National Institute of Nutrition, Hyderabad, India
Abstract
BackgroundContinuous high thermal processing of edible oils induces significant physicochemical and nutritional alterations, influence their safety, stability, and consumer acceptability. Cold-pressed oils are generally perceived as nutritionally superior, but their oxidative stability under continuous heating remains less understand compared to the refined oils.MethodsTwelve edible oils (7 cold-pressed and 5 refined oils) were collected and subjected to the continuous high thermal processing at 230 ± 5 °C for 0, 1, 2, and 4 h. Fatty acid composition, peroxide value, saponification value, free fatty acid percentage, acid value, iodine value, conjugated dienes, conjugated trienes, refractive index and colour were analysed.ResultsAmong the oils available in the both cold-pressed and refined types, cold-pressed groundnut, sunflower, rice bran and palm oil retained more polyunsaturated fatty acids at 1 h, but showed greater losses after 4 h then their refined types. Soybean oil exhibited a sharp rise in trans fatty acids (0.76 to 5.88%), whereas, coconut oil remained lowest (0.38%) at 4 h. Peroxide value increased in refined sunflower oil (7.60 to 15.81 mEq O2/kg), but refined and cold-pressed rice bran oil declined to 0.01 mEq O2/kg in after 2 h. Free fatty acid and acid values decreased variably across oils. Iodine value reduction was highest in coconut oil and minimal in soybean oil (6.72%). Saponification peaked in coconut oil (321 ± 0.68 mg KOH/g) and lowest in cold-pressed sunflower oil (213 ± 0.83 mg KOH/g). Conjugated triene rose steadily but remained below diene, while progressive darkening (L* reduction) was observed in all oils. Heating for 1 to 2 h impacted the saturation of fatty acids, while 4 h can increase the risk of trans fatty acid and dienes/trienes formation.ConclusionContinuous high thermal processing compromises the nutritional and oxidative stability of edible oils. Coconut oil showed minimal alterations, while soybean oil and sesame oil were highly susceptible. These findings highlight the need for cautious thermal application in cooking practices to preserve oil quality.
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BibTeX
@article{nandipeta2026effect,
title = {{Effect of continuous high thermal processing on physico-chemical and nutritional alterations in cold-pressed and refined edible oils}},
author = {Venkatesh Nandipeta and Sai Lakshmi Chava and Nagaraju Mergu and Ananthan Rajendran},
journal = {Frontiers in Nutrition},
year = {2026},
month = oct,
doi = {10.3389/fnut.2026.1949768},
url = {https://doi.org/10.3389/fnut.2026.1949768},
note = {CC BY},
}
RIS
TY - JOUR
TI - Effect of continuous high thermal processing on physico-chemical and nutritional alterations in cold-pressed and refined edible oils
AU - Venkatesh Nandipeta
AU - Sai Lakshmi Chava
AU - Nagaraju Mergu
AU - Ananthan Rajendran
PY - 2026
DA - 2026/10/23
JO - Frontiers in Nutrition
DO - 10.3389/fnut.2026.1949768
UR - https://doi.org/10.3389/fnut.2026.1949768
AB - BackgroundContinuous high thermal processing of edible oils induces significant physicochemical and nutritional alterations, influence their safety, stability, and consumer acceptability. Cold-pressed oils are generally perceived as nutritionally superior, but their oxidative stability under continuous heating remains less understand compared to the refined oils.MethodsTwelve edible oils (7 cold-pressed and 5 refined oils) were collected and subjected to the continuous high thermal processing at 230 ± 5 °C for 0, 1, 2, and 4 h. Fatty acid composition, peroxide value, saponification value, free fatty acid percentage, acid value, iodine value, conjugated dienes, conjugated trienes, refractive index and colour were analysed.ResultsAmong the oils available in the both cold-pressed and refined types, cold-pressed groundnut, sunflower, rice bran and palm oil retained more polyunsaturated fatty acids at 1 h, but showed greater losses after 4 h then their refined types. Soybean oil exhibited a sharp rise in trans fatty acids (0.76 to 5.88%), whereas, coconut oil remained lowest (0.38%) at 4 h. Peroxide value increased in refined sunflower oil (7.60 to 15.81 mEq O2/kg), but refined and cold-pressed rice bran oil declined to 0.01 mEq O2/kg in after 2 h. Free fatty acid and acid values decreased variably across oils. Iodine value reduction was highest in coconut oil and minimal in soybean oil (6.72%). Saponification peaked in coconut oil (321 ± 0.68 mg KOH/g) and lowest in cold-pressed sunflower oil (213 ± 0.83 mg KOH/g). Conjugated triene rose steadily but remained below diene, while progressive darkening (L* reduction) was observed in all oils. Heating for 1 to 2 h impacted the saturation of fatty acids, while 4 h can increase the risk of trans fatty acid and dienes/trienes formation.ConclusionContinuous high thermal processing compromises the nutritional and oxidative stability of edible oils. Coconut oil showed minimal alterations, while soybean oil and sesame oil were highly susceptible. These findings highlight the need for cautious thermal application in cooking practices to preserve oil quality.
SN - 2296-861X
ER -