Cooking Issues

The International Culinary Center's Tech 'N Stuff Blog

Cooking Issues header image 2

Enzymatic Peeling? Hell Yes!

March 23rd, 2010 · 40 Comments · Uncategorized

posted by Dave Arnold

Some assorted citrus: Red pomelo with peel, grapefruit, lime, lemon peel, lemon.


A few years ago, a number of chefs got a hold of Peelzym, an enzyme that can dissolve the white part of citrus (the albedo) while leaving the fruit segments and the colored part of the peel (flavedo) intact.  It can be used to automatically peel and supreme any citrus fruit without cutting the segments with a knife.  Pretty cool. 

Aw yeah.


Unfortunately, Novozymes, the company that made Peelzym, stopped production and has no more to sell (in this country at least).  Luckily, they suggested a substitute: a mixture of Pectinex Smash XXL (the enzyme we use to clarify apple juice), and Pectinex Ultra SP-L, a new enzyme we had never tried. 

Dynamic Duo: Pectinex Ultra SP-L and Pectinex Smash XXL

Here, our tests:

Here is the citrus we tested clockwise from upper left: California pink pomelo, Florida pomelo, grapefruit, orange, lemon, lime (kumquat not pictured).

The Procedure:

Make an enzyme solution with 2 grams of Pectinex Ultra SP-L and 1 gram of Pectinex Smash XXL per liter of ice water. The water has to be cold because you are going to vacuum it.  If you don’t have a vacuum the water can be warm, around 40-45°C. Either pre-peel the fruit or puncture the flavedo to allow the enzyme to penetrate. Vacuum-bag the fruit with the enzyme mix at full vacuum.  If you don’t have a vacuum, you can just soak the fruit in a Ziploc bag, but you won’t be able to use unpeeled fruit—you’ll have to peel it first.  Put the bags in 40°C water and allow the enzyme to work at 40°C for 25 minutes to 2 hours depending on results.  Rinse the fruits under cold water to remove the dissolved pectin. Enjoy.

The Steps in Pictures:

Step 1: Peel your citrus or...


... stab holes in the flavedo with needles. One of the best words in the English language: Flavedo–the very outside of a fruit–the colored part–the part with the delicious oils.


Step 2: Bag whole citrus or...


... bag the peels and peeled fruit.


Gratuitous close up of bagged grapefruit


Step 3: Circulate citrus at 40 degrees C


Step 4: Rinse under water. Peels should be lightly scrubbed with a toothbrush.

Results and Notes:

Originally, we tried to puncture the flavedo using a dog brush.  We had high hopes for the dog brush. We purchased one after we saw Chris Young and Nathan Myhrvold using them to puncture the skin of duck breasts at their Starchefs demo.  The dog brush works great on duck breasts–it helps the fat to render without letting the meat overcook the way traditional scoring does, but it was a bust on citrus.  The needles were too soft.  Instead we used a floral frog, or kenzan, the spikey thing used for ikebana (Japanese flower arranging).  You can get them at many Asian housewares stores.  The kenzan worked great.

Pet brushes don't work on citrus like they do on ducks.


Floral frog or kenzan

To get fully supremed segments, it worked better to pre-peel the fruit and split it in half since the enzyme tended not to penetrate fully to the center of the fruits.  The whole fruits we tested peeled amazingly well; but the membranes on the interior of the fruit were largely intact.

The most amazing products we obtained weren’t necessarily the fruits themselves, but perfect sections of peel.  Pure flavedo, baby.  We pre-sectioned the peel in large pieces, vacuumed them with enzyme and incubated them like the fruit.  We then carefully cooled the peels down and gently scrubbed off the goopy dissolved albedo with a toothbrush under water.  These peels would make a great garnish.  We haven’t candied one yet but I bet they’d be pretty good.

Notes on Individual Fruits:

Oranges worked great.

Orange segments and super peel

Peeling an orange

Grapefruits worked well but the segments were fragile and had to be handled with care.

Peeling a grapefruit

Lemons worked well.

Peeling a lemon

Limes were tricky.  We could get limes to peel nicely but the inner membrane never dissolved as well as the membranes in other fruits.

Peeling a lime

Pomelos were great.  We tried a white pomelo from Florida and a pink one from California.  Check out those pomelo segments! Check out those peels!  Pomelo segments are extremely fragile because their fruit vesicles are not tightly bound to each other.  Be gentle with them.

Cleaning a pomelo peel


Pomelo segments are pretty messy.


Purdy pink pomelo


Peeled Florida Pomelo. The flesh is still a little raggy. This one didn't work as well as the pink pomelo.

Kumquats are fantastic.  We really love what happens to kumquats.  If you pre-peel the kumquat in a star pattern (see picture) and incubate it with the enzyme you get kumquat-flower garnishes.  If you vacuum infuse the whole kumquat (there is no need to puncture the kumquat peel, just make sure it is ripped a little at the top where the stem was) you can easily remove the peel and divide the kumquat into perfect individual segments.  They look like miniature mandarin segments and taste like sour orange.  If you have access to seedless kumquats these would be great.

Kumquat flower

Other Stuff We Tried:

The enzyme mix doesn’t work on grapes.  The enzymes dissolve the insides of bell peppers, turning them to mush.  Tomatoes get softer and mushier when exposed to the enzyme. Blueberries were unaffected.

Pepper turned to mush

A Note on the Enzymes:

The original Peelzym was a mixture of enzymes obtained from Aspergillus Aculeatus, a fungus that attacks plants.  The data sheet says it is a mix of pectolytic enzymes (enzymes that break down pectin) but then says the main enzyme is a beta-glucanase. Beta-glucanases should break down cellulose, not pectin. Pectin is made up  galacturonic acid, not glucose.  I’ll have to get more information on this.  Pectinex Smash XXL is a pectin lyase (breaks down pectin) from Aspergillus niger, another plant-attacking fungus. Pectinex Ultra SP-L is primarily a polygalacturonase (breaks up polymerized galacturonic acid, like pectin) from Aspergillus Aculeatus, the same organism that was used to make Peelzym.  It makes sense that the SP-L and the Peelzym would have similar functionalities since they come from the same fungus and aren’t pure enzymes but mixes of several different enzymes.  Peelzym and Pectinex SP-L are probably slightly different mixes of the same components.

By the way, polygalacturonase enzymes are responsible for the softening of tomatoes, so it makes sense that Pectinex Ultra SP-L would soften them up.

Tags:

40 Comments so far ↓

  • Seth Caro

    That is aweeeeeesome.

    Are there any purveyors who carry the Pectin Smash products, or do I have to buy industrial buckets of the stuff direct?

    I instantly want to fry something in those little kumquat “stars”. Like a squash blossom.

    • nastassiar8se

      Hi Seth,

      We are selling the Pectinex Smash for $20 per 250 mL. You can buy it on Paypal using my email: nlopez@frenchculinary.com. Once we get your payment, I can send some out!

      Nastassia

  • Seth Caro

    …and more importantly than that, would it work with pomegranate?

  • mizz

    Is this procedure used in making canned mandarin oranges ?

  • Galen

    How does one get a hold of these enzymes. Novozymes has really tight sample restrictions. Do you have any pectinase smash xxl left?

    • nastassiar8se

      Hi Galen,

      Yes we do have Pectinex Smash XXL leftover if you’d like to buy some. Please go to http://www.paypal.com and use my email address: nlopez@frenchculinary.com. We’re going to buy some of the SP-L and sell it within the next few weeks.

      Nastassia

  • Mary Sanavia

    Excellent work!!! those segments look perfect.

  • Andy

    Now that was a funny post. I particularly like the gratuitous close up and the no pet brush pic. Does the albedo and flavedo leach any liquid into the bag after it poached at 40C and if so what does that taste like? Bitter? Does the peel once it has lost that layer of albedo taste less bitter?
    Oh and can peelzym be used as a topical to get rid of unsightly blemishes? You should get Cindy Crawford to endorse.
    Thanks for the entertainment.

    • davearnold

      Hey Andy,
      I haven’t tasted the water but it does have a citrus aroma. The peels are still bitter the way that straight citrus oil is bitter.

  • Tom Re

    How does the taste differ? Do the Ultra SP-L and Pectinex Smash XXL have a flavor or odor?

    • davearnold

      Hey Tom. I haven’t tasted the sp l, but the smash doesn’t taste good straight. You can’t taste it in the concentrations we are using.

  • Sean

    I do a lot of alcohol infusion with fruits like lemoncellos. This seems like it would be a great process to get the best flavor. Getting the Flavedo with out any of the albedo can be an issue when you have to do large amounts.

    I could see using an mechanical apple peeler to get longs strips that you could then remove the albedo from.

    Any thoughts on this use

  • Matt

    If it’s safe, why do you have to scrub it with a toothbrush? This stuff scares me a bit.

    • davearnold

      Hi Matt. The toothbrush is the most gentle way to get into all the nooks and crannies in the back side of the peel. It isn’t a safety thing.

  • Hanz Gueco

    We use to have a cheese course which had a slice of Roquefort and a thin layer of apple pectin jelly on top. Within minutes you would see the jelly start breaking down and turning back to liquid. I wonder if this is simular reaction to the enzyme used to breakdown the fruit.

    • davearnold

      Hi Hanz. That is really interesting. I’ll see if mcgee has heard anything about that.

  • Tzu-yen Wang

    This does remind me of canned oranges. Does the final product still taste like fresh fruit?

    • davearnold

      Hi Tzu-Yen. The fruit still tastes like fresh fruit when you are done. What is funny is that Nastassia, Harold McGee, and I just did a marathon citrus tasting (100 varieties), and one of the mandarins tasted like canned oranges right off the tree!

  • Seth Caro

    Neat. When you guys get the SP-1 in house, I’ll go ahead and order the two together. Thanks!

  • Jimmy DeCaff

    Because enzymes essentially act as catalysts and will keep working as long as there is substrate, do you think you could ultra-centrifuge the liquid to remove the solids and essentially recycle the enzyme solution? Might be useful for some of us on a budget…

    • davearnold

      Howdy Jimmy,
      I love the idea of ultra-centrifuge owners on a budget! Seriously though, I was also thinking of trying to use the water a couple of times just with ordinary filtration. We haven’t tried yet.

      • mellor

        Don’t see why that shouldn’t work, although to extend the lifetime of the enzymes i’d freeze the water after each use, and centrifuge at the lowest possible speeds that will still sediment the gunk…

  • mellor

    A quick note about the beta-glucanase content – the cell wall is a combination of pectin and cellulose. Cellulose is mainly responsible for rigidity and mechanical strength. I’d say it makes good sense to include a beta-glucanase in the mix to soften the pith.
    You mention they are a mix of enzymes – I would say yes, they probably include some of the same enzymes (SP-L and Peelzym), but due to functional considerations, not due to them being from the same fungus. They would probably express each enzyme separately and then mix them in the final buffer to sell.

    • davearnold

      Hi Mellor,
      I can’t seem to get a real breakdown on what is in those enzyme preparations, just what the primary enzyme is.

  • jeffje

    just got my enzymes in the mail today (thanks!) and am testing them now.
    my partner and i were discussing the process and i think we may have a method that’s a bit of a hybrid of the two you mention here – i’ll be testing it shortly:
    zest the citrus fruit, either with a microplane or veg peeler.
    pierce the “core” of the zested fruit with a cake tester (piano wire, etc) so that the enzyme may penetrate.
    (maybe inject some of the solution into the core with a syringe?)
    bag it up with the enzyme, circulate.

    also, i noticed that, from a botanical standpoint, the pith of a citrus fruit and the flesh of a tomato and bell pepper are all the same kind of tissue (albedo/mesocarp), whereas the skins of citrus, grapes, and blueberries are all flavedo/pericarp – looks like this enzyme mix targets pectin in the mesocarp of the fruit.

    • davearnold

      I agree. Tell us how the test works. BTW, if you like french fries, SPL helps makes some delicious fries (if you are interested see our second french fry post).

  • Pam

    hey dave, do you think this enzyme peeling can work with fruit outside citrous family? maybe peach or kiwifruit?

    • davearnold

      Hi Pam. Dunno about kiwi (I believe it has some proteolytic enzymes that might get in the way) or peach, but I know the flesh of the bell pepper itself gets eaten.

  • MarkD

    We peel tons of oranges and lemons for the dried peel market and prices of the fruit has rocketed, especially lemons. I am able to buy skins now from juice factories but am unable to remove any pith. Could this stuff work if i dumped the peels in large baths before cutting?

    • davearnold

      Howdy MarkD,
      I don’t see why not. What do you mean “before cutting?” The white should be exposed.

  • rich

    Hi there!

    Are you guys still selling any? I’d love to try it out. Thanks!

  • rich

    Great! I’ll keep checking in. Thanks for letting us know.

  • Chris Anderson

    For anyone that is looking, Pectinex Ultra SP-L is available at http://www.modernistpantry.com/pectinex-ultra-spl.html. Pectinex Smash XXL is no longer available from the manufacturer, but is not required. You can just use straight Pectinex Ultra SP-L.

  • Kyriako Tsamoglou

    How do the peels come out after the enzyme has removed the albedo?

    For example, could you get the skin of an orange, soak it in the solution and then just chop or blend up the remaining rind and use it as a zest?

    It seems that the answer is kind of yes from the above comments, but I’m not exactly sure.

    Also, I can only get the Enzyme Pectinex Ultra SPL here in Australia, would that work as well?

    Thanks! :D

    • davearnold

      Ultra SPL will work, but there is a lot of prep involved in the technique. You have to scrub the peels like crazy to remove the gummy albedo. From a visual standpoint, those peels are the best. I don’t know how they will compare with fresh zest because they will have soaked for a while and the oil pockets won’t have been cut the same way. I usually candy the peels, which are great.