סימן פ סעיף יח
מַשְׁקֶה קַאפֶע שֶׁיֵּשׁ בְּתַחְתִּיתוֹ הַקָּאפֶע מַמָּשׁ שֶׁהוּא הַפְּסֹלֶת, וְכֵן שְׁאָר מַשְׁקֶה שֶׁיֵּשׁ בְּתַחְתִּיתוֹ שְׁמָרִים אוֹ שְׁאָר פְּסֹלֶת כְּשֶׁמְעִרִין אוֹתוֹ, צְרִיכִין לִזָּהֵר שֶׁלֹּא לְעָרוֹת כָּל הַצָּלוּל, אֶלָּא יַשְׁאִיר מְעַט אֵצֶל הַפְּסֹלֶת. וְחָלָב שֶׁהָעֳמַד אָסוּר לִקְלוֹט מַה שֶּׁלְּמַעְלָה הַנִּקְרָא סְמֶעטִין, רַק מַה שֶּׁצָּרִיךְ לֶאֱכוֹל עַתָּה וְגַם בָּזֶה יִזָּהֵר שֶׁלֹּא יִקַּח הַכֹּל, רַק יַשְׁאִיר קְצָת עַל הֶחָלָב הַתַּחְתּוֹן (שיט).
A coffee (beverage) which has coffee grounds on the bottom, which is pesoles, or any other beverage that has dregs on the bottom, or other pesoles, when you pour from it, care must be taken not to pour off all the clear liquid, but you must leave a little82When you pour off the clear liquid and leave the pesoles, some of the liquid remains mixed with the pesoles. Pouring out these drops constitutes boreir [Shulchan Aruch 319: 14]. It is not considered boreir when the other water is poured out because, according to the Chazon Ish 53, the other water was considered separate from the sediment and boreir applies only to the drops mixed in with the sediment. with the pesoles.83Mishnah Berurah 319: 55 and Eglei Tal rule that if you pour it off to drink immediately, you may even pour out the last drops. In the case of milk that has curdled, it is forbidden to remove the top which is called butterfat,84This is the halachah with regard to cream on top of milk. (See Magein Avraham 510: 13) unless it is needed for the immediate meal, and even in this case, you must be careful not to remove all of it,85You may take it all if you take some of the milk with it. (Acharonim, Mishnah Berurah 319: 62) rather leave some of it on the milk which is on the bottom.86You may remove the skin-like membrane that forms on boiled milk in order to drink the milk because it, too, is edible and is separate from the milk itself. Cream is different, for it is wet and not separate from the milk. (Rav Moshe Feinstein)
תנא דבי אליהו כל השונה הלכות בכל יום מובטח לו שהוא בן העולם הבא שנאמר הליכות עולם לו אל תקרי הליכות אלא הלכות (נדה ע"ג.)