This article is from the Food Preserving FAQ, by Eric Decker firstname.lastname@example.org with numerous contributions by others.
A. Begin with the procedures. The tomato skins are removed, the rest
of the tomato is blended, the onions and peppers are chopped, added to the
tomatoes, and the mixture is simmered until thick. It is not sieved. Of the
USDA tomato recipes used in the previous section, the Blender ketchup is again
the most similar in procedures.
B. Look at the proportions.
sweet-sour 2.6 C veg : 10 C tom : 2 C acid
or to reduce it to lowest common denominator (divide all by 2.6):
sweet-sour 1 C veg : 4 C tom : 0.75 C acid
Blender 1 C veg : 3 C tom : 0.75 C acid
So, this is an almost perfect match. The sweet-sour sauce has more
tomatoes than necessary for minimum safety, the acid and vegetable are
balanced correctly. The long boiling times match, the final processing
C. What recommendations are necessary?
The only thing that could be said would be "Be sure the vegetables are chopped
finely, to approximate the blending used in the Blender ketchup." Most people
wouldn't mind using a blender to chop the vegetables, so it is a minor change.
Remember, if there is no similar USDA recipe, the only recommendation can be
to freeze or refrigerate the product.
Prepared by Mary A. Keith, Foods and Nutrition, September, 1991
Revised by M. Susan Brewer, Foods and Nutrition, June, 1992