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

Abstract

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).

The influence of microwave cooking on the nutritional composition and antioxidant activity of the underutilized perah seed

“…The amounts of ash, crude protein, and fibre in MW roasted perah seed samples were found to be almost the same to those of the control sample (Table 1). The present results are in agreement with the results reported by Anjum et al (2006) for sunflower seeds. However, the ash, crude protein and fibre content were in the range of 3.33-3.39%, 29.18-29.33%, and 9.37-9.48% respectively.…”

Effect of Microwave Pretreatment on Extraction Yield and Quality of Catfish Oil in Northern Thailand

“…Acid value stayed relatively constant, as can be seen that untreated waste was 2.20% and microwave pretreatment waste was 2.35%. Increment in the acid value of oil may be attributed to hydrolysis of triacylglycerol by microwave to produce more amount free fatty acids [17]. Peroxide value is employed to measure the quantity of peroxides in the oil; these substances are important intermediate product of oxidative reactions since they decompose via transition metal irradiation and due to elevated temperatures to form free radicals.…”

Effect of pretreatment on the proximate composition, physicochemical characteristics and stability of <em>Moringa peregrina</em> oil

“…The peroxide value of the oil obtained from the roasted sample increased considerably (about 65% (p < 0.05)) compared to the raw one while the acid value decreased significantly (about 63% (p < 0.05)), (Table 1). With reference to the peroxide value, most studies (Anjum et al, 2006;Vujasinovic et al, 2012) reported a noticeable increase in the peroxide value with increasing roasting temperature and time whereas a few others (Abou-Gharbia et al, 2000) observed only a marginal decrease compared to unroasted samples. Generally, peroxide value does not correspond to the absolute state of oxidation of oil because hydroperoxides become unstable upon heating and decompose to secondary products (Choe and Min, 2006).…”