Effect of Gamma Irradiation on Fat Content, Fatty Acids, Antioxidants and Oxidative Stability of Almonds, and Electron Paramagnetic Resonance (EPR) Study of Treated Nuts
Gamma irradiation has been applied as an efficient and inexpensive method for the sterilization of nuts for years. However, along with the benefits of such treatment, negative effects are possible because of the formation of reactive oxygen species with a toxic effect on important biologically activ...
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MDPI AG
2023-02-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/28/3/1439 |
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| author | Svetlana Momchilova Adriana Kazakova Sabina Taneva Katerina Aleksieva Ralitsa Mladenova Yordanka Karakirova Zhanina Petkova Mariana Kamenova-Nacheva Desislava Teneva Petko Denev |
| author_facet | Svetlana Momchilova Adriana Kazakova Sabina Taneva Katerina Aleksieva Ralitsa Mladenova Yordanka Karakirova Zhanina Petkova Mariana Kamenova-Nacheva Desislava Teneva Petko Denev |
| author_sort | Svetlana Momchilova |
| collection | DOAJ |
| description | Gamma irradiation has been applied as an efficient and inexpensive method for the sterilization of nuts for years. However, along with the benefits of such treatment, negative effects are possible because of the formation of reactive oxygen species with a toxic effect on important biologically active substances. Because of the scarce and contradictory information in the literature about gamma-irradiated almonds, the aim of our work was the examination of the lipid changes, antioxidant activity, and oxidative stability of almonds treated by 10 and 25 kGy gamma rays, as well as changes in intensity of the EPR spectra as an indicator for the stability of radiation-induced free radicals. The results revealed no significant differences in the EPR spectra of almonds treated at 10 and 25 kGy doses, neither in their intensity nor in kinetic behaviour. The EPR signals decayed exponentially over 250 days, with a decreasing of central line by 90%, with satellite lines by about 73%. No significant changes in the fat content, fatty acids composition, and acid value of irradiated almonds were observed. However, the amount of (alpha)tocopherols decreased from 292 to 175 mg/kg, whereas the conjugated dienes and trienes increased, K<sub>232</sub> from 1.3 to 3 and K<sub>268</sub> from 0.04 to 0.15, respectively, with the increasing of irradiation dose. The same was observed for total polyphenols in defatted almonds (1374 to 1520 mg/100 g), where in vitro antioxidant activity determined by ORAC and HORAC methods increased from 100 to 156 µmol TE/g and from 61 to 86 µmol GAE/g, respectively. The oxidative stability of oil decreased from 6 to 4 h at 120 °C and from 24.6 to 18.6 h at 100 °C (measured by Rancimat equipment). The kinetic parameters characterizing the oxidative stability of oil from 10 kGy irradiated almonds were studied before and after addition of different concentrations of ascorbyl palmitate as a synergist of tocopherols. Its effectiveness was concentration-dependent, and 0.75 mM ensured the same induction period as that of non-irradiated nut oil. Further enrichment with alpha-tocopherol in equimolar ratio with palmitate did not improve the oil stability. In conclusion, gamma irradiation is an appropriate method for the treatment of almonds without significant changes in fat content and fatty acids composition. The decreasing of oxidative stability after higher irradiation could be prevented by the addition of ascorbyl palmitate. |
| first_indexed | 2024-03-11T09:32:52Z |
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| last_indexed | 2024-03-11T09:32:52Z |
| publishDate | 2023-02-01 |
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| spelling | doaj.art-e423dbefe4ae4b268ef25ceae819ff572023-11-16T17:32:31ZengMDPI AGMolecules1420-30492023-02-01283143910.3390/molecules28031439Effect of Gamma Irradiation on Fat Content, Fatty Acids, Antioxidants and Oxidative Stability of Almonds, and Electron Paramagnetic Resonance (EPR) Study of Treated NutsSvetlana Momchilova0Adriana Kazakova1Sabina Taneva2Katerina Aleksieva3Ralitsa Mladenova4Yordanka Karakirova5Zhanina Petkova6Mariana Kamenova-Nacheva7Desislava Teneva8Petko Denev9Laboratory of Lipid Chemistry, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., bl. 9, 1113 Sofia, BulgariaLaboratory of Lipid Chemistry, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., bl. 9, 1113 Sofia, BulgariaLaboratory of Lipid Chemistry, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., bl. 9, 1113 Sofia, BulgariaCentre of EPR spectroscopy, Institute of Catalysis, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., bl. 11, 1113 Sofia, BulgariaCentre of EPR spectroscopy, Institute of Catalysis, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., bl. 11, 1113 Sofia, BulgariaCentre of EPR spectroscopy, Institute of Catalysis, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., bl. 11, 1113 Sofia, BulgariaLaboratory of Organic Synthesis and Stereochemistry, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., bl. 9, 1113 Sofia, BulgariaLaboratory of Organic Synthesis and Stereochemistry, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., bl. 9, 1113 Sofia, BulgariaLaboratory of Biologically Active Substances, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 139 Ruski Blvd., 4000 Plovdiv, BulgariaLaboratory of Biologically Active Substances, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 139 Ruski Blvd., 4000 Plovdiv, BulgariaGamma irradiation has been applied as an efficient and inexpensive method for the sterilization of nuts for years. However, along with the benefits of such treatment, negative effects are possible because of the formation of reactive oxygen species with a toxic effect on important biologically active substances. Because of the scarce and contradictory information in the literature about gamma-irradiated almonds, the aim of our work was the examination of the lipid changes, antioxidant activity, and oxidative stability of almonds treated by 10 and 25 kGy gamma rays, as well as changes in intensity of the EPR spectra as an indicator for the stability of radiation-induced free radicals. The results revealed no significant differences in the EPR spectra of almonds treated at 10 and 25 kGy doses, neither in their intensity nor in kinetic behaviour. The EPR signals decayed exponentially over 250 days, with a decreasing of central line by 90%, with satellite lines by about 73%. No significant changes in the fat content, fatty acids composition, and acid value of irradiated almonds were observed. However, the amount of (alpha)tocopherols decreased from 292 to 175 mg/kg, whereas the conjugated dienes and trienes increased, K<sub>232</sub> from 1.3 to 3 and K<sub>268</sub> from 0.04 to 0.15, respectively, with the increasing of irradiation dose. The same was observed for total polyphenols in defatted almonds (1374 to 1520 mg/100 g), where in vitro antioxidant activity determined by ORAC and HORAC methods increased from 100 to 156 µmol TE/g and from 61 to 86 µmol GAE/g, respectively. The oxidative stability of oil decreased from 6 to 4 h at 120 °C and from 24.6 to 18.6 h at 100 °C (measured by Rancimat equipment). The kinetic parameters characterizing the oxidative stability of oil from 10 kGy irradiated almonds were studied before and after addition of different concentrations of ascorbyl palmitate as a synergist of tocopherols. Its effectiveness was concentration-dependent, and 0.75 mM ensured the same induction period as that of non-irradiated nut oil. Further enrichment with alpha-tocopherol in equimolar ratio with palmitate did not improve the oil stability. In conclusion, gamma irradiation is an appropriate method for the treatment of almonds without significant changes in fat content and fatty acids composition. The decreasing of oxidative stability after higher irradiation could be prevented by the addition of ascorbyl palmitate.https://www.mdpi.com/1420-3049/28/3/1439gamma irradiationalmondsnut oilfatty acidsantioxidantsoxidative stability |
| spellingShingle | Svetlana Momchilova Adriana Kazakova Sabina Taneva Katerina Aleksieva Ralitsa Mladenova Yordanka Karakirova Zhanina Petkova Mariana Kamenova-Nacheva Desislava Teneva Petko Denev Effect of Gamma Irradiation on Fat Content, Fatty Acids, Antioxidants and Oxidative Stability of Almonds, and Electron Paramagnetic Resonance (EPR) Study of Treated Nuts Molecules gamma irradiation almonds nut oil fatty acids antioxidants oxidative stability |
| title | Effect of Gamma Irradiation on Fat Content, Fatty Acids, Antioxidants and Oxidative Stability of Almonds, and Electron Paramagnetic Resonance (EPR) Study of Treated Nuts |
| title_full | Effect of Gamma Irradiation on Fat Content, Fatty Acids, Antioxidants and Oxidative Stability of Almonds, and Electron Paramagnetic Resonance (EPR) Study of Treated Nuts |
| title_fullStr | Effect of Gamma Irradiation on Fat Content, Fatty Acids, Antioxidants and Oxidative Stability of Almonds, and Electron Paramagnetic Resonance (EPR) Study of Treated Nuts |
| title_full_unstemmed | Effect of Gamma Irradiation on Fat Content, Fatty Acids, Antioxidants and Oxidative Stability of Almonds, and Electron Paramagnetic Resonance (EPR) Study of Treated Nuts |
| title_short | Effect of Gamma Irradiation on Fat Content, Fatty Acids, Antioxidants and Oxidative Stability of Almonds, and Electron Paramagnetic Resonance (EPR) Study of Treated Nuts |
| title_sort | effect of gamma irradiation on fat content fatty acids antioxidants and oxidative stability of almonds and electron paramagnetic resonance epr study of treated nuts |
| topic | gamma irradiation almonds nut oil fatty acids antioxidants oxidative stability |
| url | https://www.mdpi.com/1420-3049/28/3/1439 |
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