Effects of different roasting conditions on the nutritional value and oxidative stability of high-oleic and yellow-seeded <em>Brassica napus</em> oils

Abstract

SUMMARY:This study was conducted to evaluate the possibility of enhancing the nutritional value and oxidative stability of rapeseed oil obtained from seeds subjected to thermal treatment prior to pressing. The yellowseeded and high-oleic B. napus lines, harvested in Poland, were roasted prior to pressing for 1 h at 100 and 150 °C. This study highlighted how rapeseed breeding lines affect the quality profile of the oils obtained both before and after the roasting process. In principle, the high-oleic B. napus was accompanied by a nearly 2-fold increase in oxidative stability compared to the yellow-seeded B. napus, most likely due to a higher content of oxidation-resistant oleic fatty acids (~74.24% vs. ~60.76%) and a decreased concentration of oxidizable PUFAs (~16.32% vs. ~31.09%). Similar to the case of roasting black-seeded rapeseed, the thermal pre-treatment of yellow-seeded and high-oleic B. napus prior to pressing did not alter the composition of their fatty acids. Based on the results obtained in this study, it can be concluded that roasting seeds prior to pressing does not reduce the amount of tocopherols in the oil; moreover, a slight increase in γ-tocopherol content was observed.KEYWORDS: Fatty acids; High-oleic B. napus; Rapeseed oil oxidative stability; Roasting conditions; Tocopherols; Yellow-seeded B. napus RESUMEN: Efecto de diferentes condiciones de tostado sobre el valor nutritivo y la estabilidad oxidativa de aceites de semillas de Brassica napus alto oleico y semillas amarillas. Este estudio se realizó para evaluar la posibilidad de aumentar el valor nutritivo y la estabilidad oxidativa del aceite de colza obtenido a partir de semillas sometidas a tratamiento térmico antes del prensado. Las líneas de B. napus sembrados amarillos y alto oleico, cosechadas en Polonia, fueron tostadas antes de ser prensadas durante 1 hora a 100 y 150 °C. Este estudio pone de relieve cómo las líneas de colza mejoradas ven afectado el perfil de calidad de los aceites obtenidos antes y después del proceso de tostado. En principio, el alto oleico B. napus aumenta casi 2 veces la estabilidad a la oxidación en comparación con semilla amarilla B. napus, muy probablemente debido a un mayor contenido de ácido graso oleico resistente a la oxidación (~74,24% vs. ~60,76%) y una concentración menor de PUFAs oxidables (~16,32% frente a ~31,09%). Similar al caso de tostar semillas de colza-negro, las semillas amarillas y las alto oleico de B. napus antes tratadas térmicamente antes del prensado no alteran su composición de ácidos grasos. También Basándonos en los resultados obtenidos en este estudio, se puede concluir que el tostado semillas antes del prensado no reduce la cantidad de tocoferol en aceite; Además, se observó ligero aumento en el contenido de γ-tocoferol.

Effects of Roasting Temperature and Time on the Chemical Composition of Argan Oil

“…The maximum values (0.28-0.3) were recorded for the temperature of 175°C. This result is consistent with previous works on pine nuts, colza, and sesame oils [ 16 – 18 ]. The increase in acidity could be explained by the release of FA following the hydrolysis of the triglycerides which constitute the major components of vegetable oils.…”

Microwave radiation and conventional roasting in conjunction with hulling on the oxidative state and physicochemical properties of rapeseed oil

“…Thus, the seeds thermal pretreatment under the harshest conditions (10 min of microwave radiation, roasting for 100 min at 165°C) increased IP twofold, when compared to the control oils. Favorable effect of rapeseed thermal pre-treatment on the oxidative stability of oil was confirmed both in a studies investigating the effect of microwaving [6,8,10] and roasting [24]. These studies emphasized a significant effect of the canolol (4-vinylphenol), formed under elevated temperatures, in addition to improved extractability of compounds possessing antioxidative properties, such as tocopherols and carotenoids as a major factors responsible for an enhancement of the oxidative stability of the oils pressed from thermally pre-treated rapeseeds.…”

“…Anjum et al found p ‐AnV to be the most sensitive of the parameters describing oxidative state of oil to changes in the chemical properties of oils pressed from microwave treated sunflower seeds (5–10 min, 500 W). Rękas et al reported a gradual increase of p ‐AnV with higher roasting temperature of rapeseed (100 and 150°C). Cai et al found that the increase of roasting time (10–60 min at 150°C) resulted in the higher accumulation of p ‐AnV in pine nut oil.…”

“…The highest total carotenoids content was achieved following microwaving for 8 min and roasting for 80 min, where the amount of these compounds increased by 77 and 47%, in the NHROs and the HROs. While studies on rapeseeds and mustard seeds roasting indicate significant effect of heating on the content of chlorophyll and carotenoid pigments in the oil, degradation of these compounds during roasting of pumpkin seeds [26], and pine nuts was observed.…”

Evaluation of the Oxidative Stability of Cold‐Pressed Rapeseed Oil by Rancimat and Pressure Differential Scanning Calorimetry Measurements

“…[36,37] The composition of fatty acids can [31] Rapeseed oil is characterized by lower Cox value than linseed (12.62-13.97), camelina (8.76-9.94), or poppy seed oil (6.31, 9.54) which translates into its higher oxidative stability. The fatty acid composition of analyzed oils was comparable to the results available in the literature.…”