Drying treatment in the experiment
The sample for measurement, the extractor, and the organic solvent for extraction all require dehydration treatment. This is because: (1) If there is water in the extraction system, the water-soluble substance of the sample will be dissolved, resulting in a high measurement result; (2) if there is water in the extraction system, the extraction solvent is easily saturated with water ( In particular, diethyl ether can be saturated with about 2% water, which affects the extraction efficiency. (3) If there is water in the sample, the extraction solvent does not easily penetrate into the cell tissue, and as a result, it is difficult to extract the fat.
Precautions during the extraction process
The filter paper bag containing the sample was placed in a drawing cylinder with long tweezers, and 1.76 times of a petroleum siphon of a siphon amount was injected to completely immerse the sample bag in petroleum ether. Connect all parts of the extractor, turn on the condensate water flow, extract in a constant temperature water bath, adjust the water temperature between 70~80 °C, and make the ether under the condensation into a bead shape (120~150 drops/minor reflux) 7 times / h or more), extract the ether from the extraction cylinder and check the oil-free trace with a filter paper (about 6~12h). After the extraction is completed, the filter paper bag is taken out with long tweezers, and the ether is volatilized in a ventilated place (it is preferably 12 to 25 ° C at room temperature). The ether in the extraction bottle is separately recovered.
(1) It is too long to measure the maximum fat deficiency by Soxhlet extraction. If the sample can be refluxed for 1~2 times, then immersed in the solvent overnight, and then continue to extract the next day, the extraction can be significantly shortened. time.
(2) If there are more samples in the experiment, the YG-II type oil analyzer with larger capacity can be used to measure the fat content. The temperature is controlled at about 70 °C, and the extraction can be completed in 8 hours.