PEREZ Ethel Erminia
capítulos de libros
Effects of Pretreatments on the Yield and Quality of Sunflower and Rapeseed Oils
Seed Oil and Co-Products: Biological Properties, Health Benefits and Commercial Applications
Nova Science Publishers
Lugar: NY; Año: 2015; p. 50 - 66
Rapeseed oil contains high amounts of bioactive compounds, such as polyphenols, phytosterols, tocopherols and other antioxidants, which play an important role in the prevention and treatment of some chronic diseases and improve immune function. In addition to its use as a food, this oilseed is also a viable option for the production of alternative fuels (biodiesel) due to its high oil content and yield per hectare, as well as the good quality of the extracted oil. Sunflower oil is used as a food and as an emollient in ointments and creams. Sunflower oil is essentially free of linolenic acid compared to soybean and rapeseed oils (3-10%). This provides some increased oxidative stability, but does not furnish valuable omega-3 acids that are necessary for health. Tocopherols are the main compounds with antioxidant properties present in sunflower seeds. In the oil extraction process, the seeds undergo a series of unit operations such as drying, storage, crushing, cleaning, flaking, conditioning, mechanical pressing and extrusion followed by solvent extraction. These processing stages may affect the quality and quantity of the oil extracted. First it is necessary to reduce the moisture content of the seeds for safe storage. The literature shows divergent data on the effect of the process temperature on the oil quality (measured in terms of the acidity value, peroxide index and tocopherol content) of different seeds. Conditioning of the seeds prior to extraction is required to make the oil inside the membranes more accessible to the solvent. Pretreatments such as crushing, hydrothermal treatments and the novel microwave technology are applied to seeds in order to modify or break their structure so as to facilitate the release of the oil. These pretreatments could also affect the release of other minor compounds, such as tocopherols. Another method used to make the release of the oil easier is by enzymatic degradation of the cell wall before and/or during extraction, but the release of bioactive compounds is also affected.