Vitamin E and Oxidative Stability of Soya Bean Oil Prepared with Beans at Various Moisture Contents Roasted in a Microwave Oven

Yoshida, Hiromi; Takagi, Shun

doi:10.1002/(sici)1097-0010(199609)72:1<111::aid-jsfa645>3.0.co;2-q

Cited by 17 publications

(14 citation statements)

References 11 publications

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“…However non-stripped oil showed higher value (174.62) of color index after the same period of heating time. The higher values recorded for non-stripped oil may be due to interaction of tocopherols components with unsaturated fatty acid to give toco-red compound similar to that reported in soybean oil (23)(24)(25).…”

Section: Resultsmentioning

confidence: 53%

Effect of microwave heating of linseed oil on the formation of primary and secondary oxidation products

Megahed¹

2011

ABJNA

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The purpose of the present study was to explore the influence of microwave heating for different periods on the primary and secondary oxidation, total oxidation as well as conjugation of stripped and non-stripped linseed oils. Color index of the oil samples was also evaluated to show changes of color during periodical heating. It was generally found that a significant increase in peroxide value, p-anisidine, total oxidation, conjugated diene and conjugated triene for microwave heating periods of 1,2,3,4 and 5 min. Two samples (stripped and non-stripped) of linseed oil (microwave treated) were analyzed individually in triplicate, and the results were reported as mean ±SD. Statistical significance of the differences between mean values was assessed by one-way ANOVA. It was found that stripped linseed oil (absence of antioxidants) is prone to heat effect than the non-stripped oil (with antioxidants). Generally, it is recommended that polyunsaturated oils have to be prevented from heat treatment for cooking purposes (e.g. soybean and linseed oils), since they contain linoleic and linolenic acids which are sensitive to oxidation.

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Section: Resultsmentioning

confidence: 53%

Effect of microwave heating of linseed oil on the formation of primary and secondary oxidation products

Megahed¹

2011

ABJNA

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“…Our results were comparable with those of Yoshida et al (6,10,37). Yoshida and Takagi (38) reported that >80% tocopherol of the original level in soaked soybean oils still remained after 20 min of microwave roasting. Barrera-Arellano et al (39) found that α-tocopherol losses were very rapid and independent of the unsaturation of the TAG system under their conditions.…”

Section: Resultsmentioning

confidence: 97%

“…According to Yen (23), the level of tocopherol in sesame oils prepared by electric oven heating increased with roasting temperature up to 200°C but decreased up to 260°C. Yoshida et al (38) also reported that the tocopherol concentration gradually decreased at a similar rate in oils prepared from soybeans roasted in a microwave oven and that percentages of the losses increased significantly after 12 min of exposure time. Moreau et al (40) showed that a significant amount of γ-tocopherol in corn hull was bound to proteins or linked to phosphates or phospholipids and that heat broke these bonds.…”

Section: Resultsmentioning

confidence: 99%

“…The results of the FA analysis showed no formation of any trans FA during microwave roasting. Yoshida et al (10,38) observed a decrease in the amount of PUFA in soybean oil. The composition was generally characterized by relatively higher percentages of saturated FA (palmitic or stearic acids) and relatively lower percentages of unsaturated FA such as oleic or linoleic acid.…”

Section: Resultsmentioning

confidence: 99%

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Microwave roasting effects on the physico‐chemical composition and oxidative stability of sunflower seed oil

Anjum

Anwar

Jamil

et al. 2006

J Americ Oil Chem Soc

166

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The purpose of the present study was to explore the influences of microwave heating on the composition of sunflower seeds and to extend our knowledge concerning the changes in oxidative stability, distribution of FA, and contents of tocopherols of sunflower seed oil. Microwaved sunflower seeds (Helianthus annuus L.) of two varieties, KL-39 and FH-330, were extracted using n-hexane. Roasting decreased the oil content of the seeds significantly (P < 0.05). The oilseed residue analysis revealed no changes in the contents of fiber, ash, and protein that were attributable to the roasting. Analysis of the extracted oils demonstrated a significant increase in FFA, p-anisidine, saponification, conjugated diene, conjugated triene, density, and color values for roasting periods of 10 and 15 min. The iodine values of the oils were remarkably decreased. A significant (P < 0.05) decrease in the amounts of tocopherol constituents of the microwaved sunflower oils also was found. However, after 15 min of roasting, the amount of α-tocopherol homologs was still over 76 and 81% of the original levels for the KL-39 and FH-330 varieties, respectively. In the same time period, the level of δ-tocopherol fell to zero. Regarding the FA composition of the extracted oils, microwave heating increased oleic acid 16-42% and decreased linoleic acid 17-19%, but palmitic and stearic acid contents were not affected significantly (P > 0.05).

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“…But the longer the roasting time, the greater were the relative percentages of palmitic, stearic and oleic acids, and the less were those of linoleic and linolenic acids. However, these trends were not so pronounced as the results obtained from whole soybeans (3). Tocopherols are predominantly detected in the hypocotyl, followed by the cotyledons and the seed coat (8).…”

Section: Figmentioning

confidence: 99%

Tocopherol distribution and oxidative stability of oils prepared from the hypocotyl of soybeans roasted in a microwave oven

Yoshida

Takagi

Mitsuhashi

1999

J Americ Oil Chem Soc

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Whole soybeans (Glycin max L.) were roasted by exposure to microwaves at a frequency of 2,450 MHz, and their hypocotyls were separated from other tissues (seed coat and cotyledons). The quality characteristics and composition in the hypocotyl oils were studied in relation to their tocopherol distributions and were evaluated as compared to an unroasted oil sample. Only minor increases (P < 0.05) in chemical and physical changes of the oils, such as carbonyl value, anisidine value and color development, occurred with increased roasting time. Significant decreases (P < 0.05) were observed in the amounts of phospholipids in the oils after microwave roasting. Nevertheless, compared to the original level, more than 80% tocopherols still remained after 20 min of roasting. These results suggest that the exposure of soybeans to microwaves for 6 to 8 min caused no significant loss or changes in the content of tocopherols and polyunsaturated fatty acids in the hypocotyls. Therefore, a domestic microwave oven would be useful as a simple and quick means for preparing hypocotyl oil of good quality.Paper no. J8997 in JAOCS 76, 915-920 (August 1999). KEY WORDS:Anisidine value, carbonyl value, hypocotyl, microwave roasting, oxidative stability, peroxide value, soybeans, TBARS (thiobarbituric acid-reactive substances), vitamin E homologs.Microwave ovens are found in the majority of homes in Japan, and today more people use microwaves for cooking and reheating than ever before. Microwave heating is considered to be the interaction of polar molecules with the electric component of the electromagnetic field, heat being generated by friction as the molecules attempt to orient themselves within the oscillating field. However, the differential heating behavior of food components can result in severely uneven heating of certain foods rich in fats and proteins (1). Consumers are concerned by reports that noxious compounds are produced in microwaved food (2). Little investigation has been conducted concerning the effects of microwave roasting on the oxidative stability of the oils in relation to tocopherol distribution in whole soybeans. We demonstrated the effects of microwave energy on the oxidative stability of the oils (3) or the fatty acid distribution (4) in whole soybeans. The distribution of lipoxygenase activity in whole soybeans is remarkable in the hypocotyl, followed by the cotyledons, and the seed coat (5). Therefore, Snyder and Kwon (6) reported that the hypocotyl is the source of beany off-flavors, and some processors of soymilk have tried to remove the hypocotyl to avoid off-flavors in soymilk. Microwaves were also applied to inactivate soybean lipoxygenase to prevent the formation of undesirable off-flavors (7). This work showed the interrelationship treatment time, enzyme inactivation, and protein extractability. However, no research has been reported on how microwave roasting affects not only the distribution of tocopherols but also the oxidative stability of the lipids, especially within each structural part (seed coat,...

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Vitamin E and Oxidative Stability of Soya Bean Oil Prepared with Beans at Various Moisture Contents Roasted in a Microwave Oven

Cited by 17 publications

References 11 publications

Effect of microwave heating of linseed oil on the formation of primary and secondary oxidation products

Effect of microwave heating of linseed oil on the formation of primary and secondary oxidation products

Microwave roasting effects on the physico‐chemical composition and oxidative stability of sunflower seed oil

Tocopherol distribution and oxidative stability of oils prepared from the hypocotyl of soybeans roasted in a microwave oven

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