Hard scalding has been the most common scalding method in the US poultry industry and is desirable for products with retained skin that are to be batter coated). Hard-scald or full-scald systems typically use water temperatures from 60 to 66°C (140–150°F) and immersion time of 45 to 90 s .

 A soft scald, or semiscald uses the lowest water temperatures from 51 to 54°C (124–130°F) and the longest immersion times for 120 to 210 s.

You can check the following websites for detailed information:

1. http://www.foodtechinfo.com/FoodPro/GasTechnologies/Scalding_-_Poultry.htm

2. http://www.worldpoultry.net/Broilers/Processing/2011/4/Scalding-and-plucking-for-optimum-carcass-quality-and-yield-WP008731W/

Soft scald: 53.35 ° C for 120 seconds; no damage to the cuticle, important in LA where pigment is required.

Hard Scalding: 62-64 ° C for 45 seconds, removing the pen is easier

Multistage scalding: In order to ensure food safety, is made from a dirty to a less dirty, in order to keep the bacterial load and increase performance low water. (Castañeda, 2009; Quintana et al, 2011 Avitecnia)

In industrial processes, is more or less standardized scalding from 3 to 3 ½ minutes at a temperature between 50 - 52 Celsius for yellow chicken (Cervantes, 2008)

Another: http://www.scielo.org.co/scielo.php?pid=S1692-35612011000100009&script=sci_arttext

Sorry for my english, but its clear to catch de general idea.

Best Regards

http://www.scielo.org.co/scielo.php?pid=S1692-35612011000100009&script=sci_arttext