I am teaching my students that meat must be koshered within 3 days or otherwise it can’t be koshered via salting only via broiling. I understand that soaking the meat extends the 3 day limit. How long does the meat have to be soaked for? Can rinsing it suffice? Can this be instead of the הדחה ראשונה- שרי’ה?
Ideally soaked well for a half hour. Many permit rinsing thoroughly as well. The meat needs to be rinsed again before salting.
The Geonim established that meat must be salted within seventy-two hours of its shechitah. They explain that after three days, blood inside the meat hardens and is no longer extractable through soaking and salting. Should meat not be soaked and salted within 72 hours, they ruled that only broiling successfully removes the blood.
Most authorities contend that one may extend the time if the meat is soaked thoroughly for a while during the 72 hours (Shulchan Aruch, Yoreh Deah 69:13, seeTaz ad loc.), although some permitted this only under extenuating circumstances (Toras Chatos, quoted by Shach 69:53).
Although most early authorities only mention ‘soaking’ meat, it became common practice to wash the meat instead, a practice that many authorities disputed (Pischei Teshuvah, Yoreh Deah 69:28; Darkei Teshuvah 69:231- 237). There are also many different opinions of what is called ‘washing’ the meat. Some hechsherim permit meat that was not salted within seventy-two hours of its shechitah by having the meat hosed down before the seventy-two hours has passed, and consider this washing as a renewal of the seventy-two hours. Thus, this meat is only permitted if it was washed within seventy-two hours of its shechitah or previous washing. If the meat was washed thoroughly, it is now has another 72 hours. If one is unable to kasher it by then, one can rewash it again to further extend its 72 hours. However, most authorities require that the meat be thoroughly wetted with a high-power hose so that the meat becomes moist even inside [not just spraying a light mist over the meat cf. Shu”t Masas Binyamin #108].