How to blanch mulberry leafs for freezing

I found this academic paper by some Japanese researchers that I think it's worth sharing.

https://www.jstage.jst.go.jp/article/kontyushigen1930/55/2/55_2_137/_pdf

ABSTRACT from paper

"Mulberry leaves blanched with hot water were put into polyethylene bags, and stored in a freezer
after as possible had been removed. Then, these mulberry leaves were fed to silkworms to
assess their feed value.
Blanching with hot water prevented mechanical damage to the cells and leakage of the content
of the cells during the freezing and thawing processes. It also inactivated the water soluble oxidase
that is activated by freezing and freezer storage. Blanching at 100oC for 30 seconds was the
optimum condition for blanching. Under this condition, the chlorophyll content of the leaf was
not decreased but about 20% of the carbohydrates were eluted into the hot water. Drying of
mulberry leaves by freezing was prevented by storage in polyethylene bags, and the water content
of the leaves was maintained at 70-75% even on the 120th day of storage. The parent silkworms
for hybridization reared on the stored mulberry leaves become mature and laid eggs."
{/quote]


Seems you only need to blanch each leaf for 30 seconds prior to patting dry and freezing in airtight bags or containers and the leafs are just as good afterwards ( the silkworms fed them are just as productive and nutritious as silkworms fed fresh mulberry leafs (or reconstituted chow)).

Worthwhile knowing how to do this as mulberry leafs are unable in winter and silkworm chow can be expensive to buy.
This way , if you are rearing your own silkworms and allowing some to go through their entire life cycle , you can , if you maintain adequately warm room temperatures, have silkworms on hand to use as feeders even in the off season (when they disappear off the market locally) and you wont be reliant on using expensive Silkworm Chow in winter when there are no mulberry trees with leafs on them.

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That's good info. Thanks for sharing it! I wonder if this would carry over to other kinds of greens too.

Don't know , can't see why not .

I also know of at least one keeper here who blanches and the freezers her silkworms to use in the offseason.

The other greens I use are available pretty much year round (our winters here are much more temperate than your's are).

Glad I saved the link here , as I now find I have 2.5 big freezer bags full of mulberry leaves that I received a week ago and have kept in the crisper (in sealed bags) that I don't want to waste (toss out) and would like to treat to preserve by freezing until my silkworm eggs hatch.

I'll let you guys know how the blanching and then freezing works out in a couple of days as I am planning of dealing with the left over "fresh" mulberry leaves on Thursday or Friday.

I've started taking my fresh greens and cutting them into hand sized bits then putting them into a big ziploc with a piece of paper towel. They go into the fridge and I've found they keep crisp and fresh for well over a week. They are by far outlasting the greens that I leave washed but otherwise untouched in the fridge. Not exactly on topic but similar thought.

Been putting off blanching the left over mulberry leaves (I have still got 2 and 1/2 big freezer bags of them) , they've kept extremely well ( 2 weeks old since I received the last batch from the silkworm lady in Sydney ) and when I checked them this morning , the crisper in the big fridge in spare room does a great job at keeping stuff fresh and crisp - no sign of any drying out or going off.

Took me 40 minutes once the big 10L saucepot of water came to a slow simmering boil to blanch them (a handful at a time (I had a timer handy but pointless being too obsessive about blanching each leaf for exactly 30seconds since the report says 30sec to 1min is fine and the blanched leafs should be fine for my purpose.
The most time consuming part of the job was draining and cooling (simply put a layer of paper towels on the side of the kitchen sink) and shook the fresh blanched leafs free of most of the water and pulled them on the sink, let the stand and drain and cool for 30mins and it then took me about an hour to pat each leaf dry between paper towelling (don't want to freeze them with water on them) and to bag them leafs = 8 medium freezer bags (2 of which were full of tender "new" soft leafs (best from baby silkworms).
I chose smaller bags as I don't want to have to thaw out and let come to room temperature a lot a leafs at a time (just enough to last a few days for medium silkworms or a day for large silkworms.)

Is blanching mulberry leafs less time consuming than mixing up and nuking silkworm chow ? no , BUT IT IS A LOT CHEAPER and there will be less wastage cf using chow.

The blanching water went brown looking , dust and dirt ? and maybe some chemical products from the blanching process, and the whole house now smells wonderful (my wife came home from shopping and wanted to know what yummy stuff I was cooking now .... smells kind of like blanched spinnage , she reckons it's making her feel hungry. LOL


I will find out how good the leaves are as silkworm food when I hatch my next batch of silkworm eggs.

CooperDragon":3j6y5pvl said:

I've started taking my fresh greens and cutting them into hand sized bits then putting them into a big ziploc with a piece of paper towel. They go into the fridge and I've found they keep crisp and fresh for well over a week. They are by far outlasting the greens that I leave washed but otherwise untouched in the fridge. Not exactly on topic but similar thought.

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I do that with leaks and spring onions ( I cut these into halves (white and greens in separate bags).
I cut the roots just the roots off.
Works a treat.

Started using blanched leaves in June (been frozen in the deep freeze since being blanched), found baby silkworms raised from hatched eggs (been chilled since February/March) are able to use the blanched leaves.

2 weeks and no yellow or white mould formation observed.

Latest batch of silkworms are feeding well on a mix of fresh mulberry leaves and blanched/frozen/thawed mulberry leaves. The worms are small and medium size and don't seem to care , eating both "qualities" of leaves equally well and growing well.

Do you run into problems with the silkworms getting soft, dying, and rotting? I've found that with several batches of silkworms they mostly die off like that. I remove the dead ones and move the live ones to new paper towel substrate with fresh food daily but it doesn't seem to help. I wonder if perhaps it's the chow mix and I should try to get some actual leaves instead.

CooperDragon":i8bwxp4t said:

Do you run into problems with the silkworms getting soft, dying, and rotting? I've found that with several batches of silkworms they mostly die off like that. I remove the dead ones and move the live ones to new paper towel substrate with fresh food daily but it doesn't seem to help. I wonder if perhaps it's the chow mix and I should try to get some actual leaves instead.

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No, not more than usual (for me), ie I've lost 2 small silkworms who were in shed when another silkworm crawled over then disrupting the shed (suffocating them) in 2 weeks.

I think I had the issues you mention when I was using chow only, not such a big problem with fresh or blanched leaves.

I think keeping them in a clean tub (at least daily cleanout of their poo and any remain food scraps - don't let any fungi (white or yellow) develop this will kill the worms) and making sure there is good air circulation between the leaves (toilet paper roll centres work a treat) is the key.

OK. It might be the chow or the way I'm offering the chow (in small rolled up balls, replaced every day). I'll see if I can track down a source for leaves and go that route the next time I order. I've never seen them locally.

CooperDragon":2iegw5wc said:

OK. It might be the chow or the way I'm offering the chow (in small rolled up balls, replaced every day). I'll see if I can track down a source for leaves and go that route the next time I order. I've never seen them locally.

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I think you'll be lots more successful with fresh or blanched (then frozen) mulberry leaves.

You could try squashing the balls of chow between two layers of plastic to about 2mm thick , kind off like a leaf and pealing the off the plastic onto a toilet paper roll core or bits of paper towelling roll core , I found that worked better than leaving chunks of chow which will force the worms to crawl overtop of each other to get to their food.

That's a good thought. I have PLENTY of those laying around due to housing for the roach colony. How big are the bins you use? I have bins that are 12''long by 7'' wide and 4'' tall. I've been keeping about 25-30 worms per bin. My other thought is perhaps overcrowding but as they die off they keep getting fresh food and paper towel substrate so more space as time goes on.

CooperDragon":3f5rqzjz said:

That's a good thought. I have PLENTY of those laying around due to housing for the roach colony. How big are the bins you use? I have bins that are 12''long by 7'' wide and 4'' tall. I've been keeping about 25-30 worms per bin. My other thought is perhaps overcrowding but as they die off they keep getting fresh food and paper towel substrate so more space as time goes on.

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I use these http://www.decor.com.au/product/tellfresh-oblong-4-0-l/ , all you need is an electric soldering iron to melt holes in the lid to give good air circulation.

Current about 100 medium silkworms on the go , have had up to 300 small - medium silkworms in the same size container.