Fruit Compression

Pardon my long absence, but I’ve been working on a cornbread recipe that is driving me down a dark and tortuously winding road. The cornbread’s flavor is perfect—barely sweet, corny, and buttery—but the texture leaves much to be desired. The bread is so moist that it’s almost gummy and sours in two days if left on the counter. So while I shelved this project out of sheer distaste for the volume of cornbread I’ve eaten during the last month, I’ve stumbled onto a new obsession: compressed fruit.

Although fruit compression is not a new technique, I haven’t been fortunate to work regularly in kitchens with equipment more advanced than a Kitchen-Aid mixer. While I had used a chamber-style vacuum sealer during my first kitchen job 15 years ago, it never occurred to me that it had culinary applications beyond portioning sauces. {Clearly, it didn’t occur to anyone else because when not in use (which was often) the vacuum sealer was a favored hiding spot for kitchen towels or used as extra table space when the kitchen became crowded.}

I saw the technique mentioned repeatedly in the Twitter feed of Antonio Bachour, Executive Pastry Chef of St. Regis Bal Harbour Resort, so I got access to a commercial vacuum sealer and decided to experiment for myself. A vacuum sealer takes air out of food and preserves it so it stays fresh and safe to eat for long periods of time—whether it will be frozen, refrigerated or sit on the shelf for a few months. This technology has been popular with food manufacturers for decades, especially within the meat and dairy industries where products are highly perishable. (Does “sealed for freshness” ring a bell?)

The question I wanted to answer:  “Why compress fruit?” The answer is: flavor, texture and color. These are all essential attributes of what makes fruit attractive and the experience is intensified by a quick round in the vacuum sealer (and the occasional dip in the immersion circulator… but more on that in another post.) Going back to biology 101, fruit is structured with tiny air pockets in between its cells that allow plants to take in carbon dioxide and expel oxygen during photosynthesis. When the air pressure outside of the fruit drops, the air pockets expand and air is forced out. When the pressure is released (i.e. the bag is heat sealed and the vacuum chamber is opened), the air doesn’t return to the fruit. Instead the liquid released from ruptured cells fills the void once occupied by air. The fruit feels softened as if it was cooked or frozen once, but it is still raw. When I first tasted a compressed peach, my first thought was, “It’s like canned fruit. Except that it tastes fresh and really peachy.” But the fruit itself is not more flavorful; it’s just that the perception of the fruit’s flavor is more intense.

With conventional cooking methods like poaching and confit, flavor often comes at the expense of textural integrity. Poached pears have an intense pear flavor but can often feel mushy. The reverse can also be true as in the case of fruit confit: great texture, but cloyingly sweet. Porous, airy fruit like watermelon and apples respond well to fruit compression. Additionally, when the fruit is vacuum-sealed with liquid, the liquid is pushed into the space once occupied by air and infuses the fruit with its flavor. Infusing fruit with flavor, without having to apply heat, reveals the true power of fruit compression. Using this technique, you can infuse fruit with the flavors of fresh herbs, spices, or liqueurs without using the heat that would destroy their appealing fragility: blueberries with lemon verbena, strawberries with chartreuse, or pineapple with yuzu. Besides the practical applications of extended shelf life, fruit compression is a fun technique that allows you to experience an altered state of fruit existence. In other words, it’s an LSD trip for fruit geeks. Buckle up and enjoy the ride!

Compressed Peaches

Peaches, ripe (sliced ½ inch thick)

Elderflower cordial

Toss peaches with elder flower syrup just until coated. Pack into bags and vacuum seal. Compress for 24 hours. Because the fruit has not been heat treated, the fruit should remain in liquid until service, otherwise it will brown when exposed to air.  (Peaches that are very firm can be cooked sous-vide (80C for 6-8minutes) immediately after compression and cooled overnight in an ice bath.)

Poached Rhubarb

Rhubarb, peeled and trimmed into ½ inch thick batons

Granulated sugar

Rose geranium, rough chopped

Toss the rhubarb with sugar and rose geranium. Macerate for 20 minutes. Pack into bags with the syrup (but do not add any additional liquid) and vacuum seal. Cook sous vide (80C for 8 minutes) and cool in an ice bath.) Even though it is compressed, rhubarb will still turn mushy if overcooked.

***Special thanks to Joe the Baker and Shane Cook

for igniting my obsession with fruit compression.***