Posted by Sam Sears, CEC on October 09, 19100 at 21:12:03 :
In Reply to: Broccoli Cheddar Soup \ curdeling posted by Nancy Shadomy on October 06, 19100 at 21:16:37 :
: This really is a delima... I made 17 gallons of soup the other day.Usually I make it with whole milk.I am at a new job and someone suggested I make it with 15 gallons of half and half , so I did...The following day it began to curdle... What happened... any chemistry lessons in this? Thanks Nancy S
Here begins the science lesson: natural acids such as those found in fruits & veggies (such as broccoli) can cause curdling because they interfere with the distribution of the proteins in the dairy product,,, here are some tips to help prevent curdling, but by no means foolproof, and by the way, since you are using 1/2 & 1/2, which by some chefs idea is a little less stable than whole milk, since there is much more protein in 1/2 & 1/2 to curdle....always heat & thicken your milk before adding to your soup base, this will form a thin bechamel, which is relativley stable...whenever possible sweat your veggies in butter to remove & release the natural acids found in the veggies/fruits OR blanch in lightly salted water first instead.. after blending the base veg & the bechamel or veloute', would be advisable to pass thru a food mill or processor or VCM &/or thru a fine china cap, this can help keep the solids in suspension (or emulsion, if you will)....and remember to reheat slowly over a bain marie with simmering water....you can repair the soup w/ a little cold heavy cream added to warm soup,,,,,and remember most cream based soups are not meant to prepare, chill & reheat, without some adverse reactions.....another note...if you use arrowroot or waxy maise the soup will be less likely to break, but will not have the rounded out flavor of a Blond Butter Roux.......hope this helps......Sam Sears, Certified Executive Chef, American Culinary Federation