Pigmented rice oil: Changes in oxidative stability and bioactive compounds during storage of whole grains

Abstract

This study evaluated the effects of storage temperature on the oxidative stability and bioactive compounds present in oil extracted from whole rice grains. Whole rice grains (brown, black, and red pericarps) were stored at temperatures of 16, 24, 32, and 40 °C for 6 months. Oil extraction was carried out on samples at the beginning, and after 6 months, of storage. Oil acidity, extinction coefficients (K232 and K270), fatty acid profiles, γ‐oryzanol, carotenoid, and tocopherol contents were evaluated. Oil extracted from rice grains with black pericarps showed the highest concentrations of γ‐oryzanol, carotenoids, and tocopherols, followed by oil extracted from grains with brown and red pericarps. A storage temperature of 16 °C was effective for maintaining good oil quality and bioactive compounds extracted from the oil when stored for 6 months. Practical application The consumption of nutraceutical and bioactive foods has gained importance in recent years, highlighting the use of whole pigmented rice grains. A great amount of the rice grains used in the world's food industry are stored for periods up to 12 months prior to their use. This study presents the changes in the quality of oil and bioactive compounds present in the oil extracted from rice grain with brown, black and red pericarp as a function of storage conditions during long‐term and may help food industries to elucidate the differences in quality of oil and bioactive compounds in rice oil. The proper handling of post‐harvest rice grains is important to increase economic gains for the processing industries and maintain the quality of oil for human consumption and industrial use.

Exploiting the bioactive properties of γ-oryzanol from bran of different exotic rice varieties

“…NSICR9 exhibit higher predominance of 24-MCAF and Maçarico and Ceres present higher amounts of CampF when compared with the remaining varieties. The concentrations obtained for γoryzanol are within the range found in the literature (79.2 to 912 mg/100 g) 13,16,17,[33][34][35] . Lower concentrations obtained can be related with the extraction techniques and quantification with different temperatures and solvents, which may affect not only the lipid yield 36 but also the γ-oryzanol content 11,12,16,37 .…”

Nutraceutical Vegetable Oil Nanoformulations for Prevention and Management of Diseases

“…PO β-carotene elicits beneficial health effects, sustaining lower total cholesterol levels [ 9 ]. Notably, β-carotene contents in oil extracted from rice grain with brown, black and red pericarp are 12.54, 16.22, and 9.98 mg/100 g oil, respectively [ 33 ]. Franke et al [ 34 ] quantified by HPLC the carotenoid amount in rapeseed and sunflower marked oils, cold-pressed or refined, and in the oils of rape, sunflower, flax and safflower, including the respective seeds and press cakes from a local oil mill.…”

“…The most abundant FAs present in all analysed samples were as follows: (i) palmitic acid (C 16 :0) with concentrations from 5.76% (redcurrant oil) to 40.57% (PO); (ii) stearic acid (C 18 :0) from 0.46% (avocado oil) to 34.51% (cocoa butter); (iii) oleic acid (C 18 :1) from 7.66% (evening primrose oil) to 73.85% (olive oil); (iv) linoleic acid (C 18 :2) from 1.89% (cocoa butter) to 73.96% (safflower oil); and (v) arachidic acid (C 20 :0) from 0.03% (coconut oil) to 1.05% (cocoa butter) [ 23 ]. High amounts of oleic and linoleic acids have also been found in oil extracted from whole rice grains with brown, black, and red pericarp, ranging between 40.30–40.49 (oleic acid) % and 37.40–41.39 (linoleic acid) % [ 33 ], as well as in Oryza sativa L. ( O. sativa , rice bran) oil, with 38.4% and 34.4%, respectively [ 45 ]. Orsavova et al [ 37 ] investigated the FA composition of 14 vegetable oils, i.e., safflower, grape, Silybum marianum, hemp, sunflower, wheat germ, pumpkin seed, sesame, rice bran, almond, rapeseed, peanut, olive, and coconut oil, by using gas chromatography (GC).…”

“…Cycloartenol is structurally like cholesterol, and may compete with its binding sites and sequestrate it [ 45 ]. Recently, Ziegler et al [ 33 ] found 11.17, 18.48, and 7.92 mg of γ-oryzanol for every gram of oil extracted from rice grains, with brown, black, and red pericarps, respectively.…”

“…A notable difference in α-tocopherol concentration (mg/100 g fresh matter) was found among rapeseed and sunflower marketed oils, depending on whether they were overgone to refining or cold pressing: cold-pressed (63.5–72.2) vs. refined (45.7–60.8) sunflower oil > refined (27.7–29.9) vs. cold-pressed (26.2–27.0) rapeseed oil [ 34 ]; (ii) pericarp colour. Moreover, α-tocopherol had the highest concentrations in oil extracted from rice grains with black pericarp (37.48), followed by brown (18.25) and red pericarps (8.89) [ 33 ]; (iii) genetic manipulation. Oil from sunflower cultivars obtained by mutagenesis and genetic recombination also has high amounts of β- and δ-tocopherol than α-tocopherol [ 87 ].…”