Cooking For Engineers

[gogomama]

Hope this post is appropriate to this forum.

As a non-engineer, I would be interested to learn what is the effect of boiling a vegetable (say, potatoes) in non-water fluids such as stock, juice, wine, or a mixture of one of these plus water. Are viscosity, salinity, or acidity significant factors in boil time needed to soften the vegetable? (I know that the boiling _point_ is affected, but I am curious about the boiling time to soften the vegetable.)

This question arises today as I make a squash soup for Thanksgiving. I sauteed some aromatic vegetables (onion, celery, carrot) in olive oil, and added a few spices (ground coriander, red chili, turmeric) after the aromatics had softened. To this I added 4 potatoes (1/2 " dice of usual wisconsin russets) and 4 cups of pasteurised apple cider and some salt. My intention was to boil the potatoes for approximately 20 minutes to soften them. However, it took about 60 minutes of boiling to soften them! Furthermore, the starch from the potatoes seemed to combine with the slightly reduced cider to increase its viscosity. Dag!
So what do you think happened?

Not that it matters, but I completed the soup by adding to the above concoction the pulp of 2 oven-roasted acorn squash, and then processed in batches in a blender, adding additional cider to get smooth consistency.

Thank you for considering what factors can increase boil time.

[GaryProtein]

Stock is a water based material, but it can contain materials that alter vegetable softening time. Things like enzymes that may be released from some vegetables may cause others to soften faster or release other compounds into the mixture that can change the viscosity of a soup or stock.

[gogomama]

Thank you for your reply... Now you've got me thinking. . .
I thought the cider was pasteurized and free of pectin, but now I am guessing that there must have been some pectin there. This would coat the potatos and then denature with heat. Pectin is what separates juice from jelly, as I should have known. Duh.

After further reading, I gather that most pectin is removed before flash pastuerization using other enzymes, but the "natural" ciders may still contain some pectin.

Thanks again.