5 replies to this topic

[idquest]

I started to make smoothies recently with leafy greens like red leaf lettuce, other kinds of lettuce, some spinach-like chinese leaves (forgot the name). What I've noticed is that when I wash the leaves they become sort of slimy as if their surface produces some kind of mucus. I remember watching/reading Dr. Mercola blog that this kind of mucus is a preservative put by farmers to keep the leaves fresh. But I felt Dr. Mercola wasn't sure himself this is a correct explanation.

What's your take on this? What is this mucus, is it dangerous? Is it related somehow to oxalates? To preservatives?

[niner]

The only time I've ever seen sliminess in leafy greens has been when they were starting to rot, which they will do pretty quickly when injured. Maybe it's not so much rot as some sort of reaction to bruising; I dunno. I don't think it has anything to do with preservatives, since I've seen it with greens that I picked up at an organic farm that I know isn't using anything on them. It's possible that it has something to do with oxalates, since spinach seems to be particularly susceptible, if the thing I'm thinking of is what you're describing. At any rate, I've always tossed out the parts with the slime. I don't know if it's safe to eat or not, but it's gross at the very least.

[rwac]

Slime is usually some sort of biofilm. Whether its generated by the leaf itself or bacteria, i cannot say.

[InVeritate]

It could be the Chinese spinach you are using. There are several plants commonly sold as Chinese spinach. One is Malabar spinach which has succulent leaves that produce a mucilaginous substance. It is frequently used in soups as a type of "thickener." The scientific name is Basella Alba. I do not know about its health benefits, but personally I find it unappetizing; especially if over cooked. Like okra, it can be slimy. Are you breaking the leaves while washing them? The few times I have bought it I do not remember it getting greasy when washed. But putting it in a smoothie would certainly produce a mucal substance.

[idquest]

The leaves that turn slimy are fresh and of good quality, without any damage. I first noticed that with Chinese spinach were the amount of mucus was the biggest. But the same kind of mucus is produced by red leaf lettuce and green leaf lettuce. I'm personally more concerned with possible oxalates in the leaves but I'm lacking knowledge to make a guess as to how oxalates would behave when leaves are washed. In fact, if those are oxalates being washed away, that would be not so bad. The mucus itself can be washed away pretty easily; that just takes too much time to rinse each single leaf.

[niner]

The oxalates in spinach are not washed away. Some oxalates are soluble in water, others not; I don't know what form is in spinach, but it's locked up in the leaves and won't come out with washing. If oxalates are involved, the leaf would need to be crushed or digested in some way. Is there a significant amount of oxalate in lettuce? (I think not much, if any, but didn't look it up.)