Does blanching cause loss of mass/weight in the vegetable?

Question

1. Let's say I am water-blanching 100g of green beans. After the blanching process will the resulting weight be less than 100g?

2. I aim to dehydrate the blanched 100 g of green beans. Will dehydrating 100g of blanched beans and 100g of unbalanced beans result in the same dried mass?

Answer 1

The weight is more likely to increase than decrease when blanching as some water or (condensed steam if you do it by steaming) will stay on the surface. With something like broccoli that has a lot of surface area that could be quite a lot. With beans less, unless you cut them up and immerse them so the water gets inside.

The dehydrated mass should be the same though. You're aiming to get the water content down to the same level. If you start the dehydrating process with extra water, it will take longer to reach the same point.

You may be concerned about the loss of things that dissolve in the blanching water, and thus losing weight that way. I really don't think you need to be. Most vegetables (including beans) are high in water to start with, and most of what's left is insoluble. This nutrition information table has fat+protein+carbs adding up to about 10%. Of that only the sugar (3.6% of the total weight) is soluble. But (i) blanching is brief and (ii) most of the sugar is trapped in the plant's cells so it won't dissolve out easily until cooked to mush.