posted by Dave Arnold
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.Â It can be used to automatically peel and supreme any citrus fruit without cutting the segments with a knife.Â Pretty cool.Â
Unfortunately, Novozymes, the company that made Peelzym, stopped production and has no more to sell (in this country at least).Â 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.Â
Here, our tests:
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.Â If you donâ€™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.Â If you donâ€™t have a vacuum, you can just soak the fruit in a Ziploc bag, but you wonâ€™t be able to use unpeeled fruit—youâ€™ll have to peel it first.Â 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.Â Rinse the fruits under cold water to remove the dissolved pectin. Enjoy.
The Steps in Pictures:
Results and Notes:
Originally, we tried to puncture the flavedo using a dog brush.Â 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.Â The dog brush works great on duck breastsâ€“it helps the fat to render without letting the meat overcook the way traditional scoring does, but it was a bust on citrus.Â The needles were too soft.Â Instead we used a floral frog, or kenzan, the spikey thing used for ikebana (Japanese flower arranging).Â You can get them at many Asian housewares stores.Â The kenzan worked great.
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.Â 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 werenâ€™t necessarily the fruits themselves, but perfect sections of peel.Â Pure flavedo, baby.Â We pre-sectioned the peel in large pieces, vacuumed them with enzyme and incubated them like the fruit.Â We then carefully cooled the peels down and gently scrubbed off the goopy dissolved albedo with a toothbrush under water.Â These peels would make a great garnish.Â We havenâ€™t candied one yet but I bet theyâ€™d be pretty good.
Notes on Individual Fruits:
Oranges worked great.
Grapefruits worked well but the segments were fragile and had to be handled with care.
Lemons worked well.
Limes were tricky.Â We could get limes to peel nicely but the inner membrane never dissolved as well as the membranes in other fruits.
Pomelos were great.Â We tried a white pomelo from Florida and a pink one from California.Â Check out those pomelo segments! Check out those peels!Â Pomelo segments are extremely fragile because their fruit vesicles are not tightly bound to each other.Â Be gentle with them.
Kumquats are fantastic.Â We really love what happens to kumquats.Â If you pre-peel the kumquat in a star pattern (see picture) and incubate it with the enzyme you get kumquat-flower garnishes.Â 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.Â They look like miniature mandarin segments and taste like sour orange.Â If you have access to seedless kumquats these would be great.
Other Stuff We Tried:
The enzyme mix doesnâ€™t work on grapes.Â The enzymes dissolve the insides of bell peppers, turning them to mush.Â Tomatoes get softer and mushier when exposed to the enzyme. Blueberries were unaffected.
A Note on the Enzymes:
The original Peelzym was a mixture of enzymes obtained from Aspergillus Aculeatus, a fungus that attacks plants.Â 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 Â galacturonic acid, not glucose.Â Iâ€™ll have to get more information on this.Â 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.Â It makes sense that the SP-L and the Peelzym would have similar functionalities since they come from the same fungus and arenâ€™t pure enzymes but mixes of several different enzymes.Â 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.