ISO 19660:2018 pdf free

ISO 19660:2018 pdf free.Cream – Determination of fat content – Acido-butyrometric method
Weigh into the previously tared weighing system (6.2) 5 g±0,005 g of the sample taken using the syringe (6.2). Place the system inside the butyrometer. Using the automatic system (6.4), introduce 10 ml of sulphuric acid (5.1) taking care not to wet the neck of the butyrometer and allowing the reagent to flow down along the wall of the butyrometer tube.
Using the automatic system (6.5), introduce 1 ml of amyl alcohol (5.2) into the butyrometer, without wetting the butyrometer neck nor mixing the liquids, allowing the alcohol to flow down along the wall of the butyrometer tube.
Using a pipette, add water without mixing the liquids allowing adjustment to the level to graduation 45 by means of the bottom stopper (in general around 6,5 ml to 7,0 ml is enough).
Stopper the top part of the butyrometer.
Shake and invert the butyrometer, the operator being suitably protected against the risk of breakage,until its contents are thoroughly mixed, and until the proteins are completely dissolved. Place the butyrometer in the water bath (6.2) and keep it there for 5 min.
Place the butyrometer in the centrifuge (6.6). Centrifuge for 5 min at room temperature as soon as the required rotational speed is reached.
Remove the butyrometer from the centrifuge and place it, wide stopper downwards, in the water bath (6.7) for 10 min; the water level shall be above the top of the fat column.
Remove the butyrometer from the water bath, stopper still downwards, and carefully adjust the stopper by pulling on it in order to bring the bottom of the fat column, with minimum column movement, in line with the nearest mark, preferably a main graduation line. (It is recommended to choose the 0 graduation line of the butyrometer as mark A.)
Note the graduation line (A) corresponding to the bottom of the fat column, then, taking care not to move the latter, note, as quickly as possible, the graduation line (B) coincident with the lowest point of the meniscus at the top of the fat column.
While reading, the butyrometer shall be held and moved verticall, in order to obtain the reading point at eye level and avoid parallax error. (Do not move the head.)
No more than 10 s shall elapse between the removal of the butyrometer and the end of the reading.
If it is necessary to verify the obtained result, replace the butyrometer in the water bath for approximately 5 min, then remove it and take the readings as indicated in the previous paragraph.
If the fat is turbid or dark coloured, or if there is a black or white deposit at the bottom of the fat column,the value obtained for the fat content will not be reliable.
Do not centrifuge a second time. The result obtained risks being excessively false.ISO 19660 pdf download.