Fresh basil pesto recipe: To process or pestle? That is the question

11 Aug

By Tom Havran

Traditional pesto, that quintessential culinary expression of summer-fresh sweet basil leaves, was originally created using a stone mortar and wooden pestle. Pesto required a lot of time, effort and arm strength before the swirling blades of electric food processors sliced their way onto the culinary scene. While technological advancements now let us quickly chop bushels of basil into a full winter’s supply of flash-frozen pesto, many purists contend electric processing destroys the true aroma, texture and flavor of pesto.

fresh-basil-pesto-recipe-mortar-pestle-2

Fresh basil pesto made the old-fashioned way, with a mortar and pestle.

The differences

So, I set out to find what aspects of sweet basil pesto preparation might create the perceived differences.

Heat: The high-speed electric motor and blade friction of a powerful food processor can produce a lot of heat, while the stone mortar and wooden pestle remain cool during the slow grinding action used in traditional pesto. Heat can change the delicate oils in the basil — and possibly alter the flavor of the pine nuts, olive oil, cheese and garlic as well. Heat and over-processing will partially “cook” the ingredients in your fresh pesto before it even hits your pasta. Pesto is at its best when not cooked at all, but rather applied as a dressing or fresh sauce at the time food is consumed.

Air: The whirring blades of a food processor suck air into the pesto mixture while the mortar and pestle does not. Besides altering the appearance, texture and consistency of the pesto, air in your pesto might be carrying away the volatile aromatic oils. The mortar and pestle effectively crush the submerged ingredients into the oil without incorporating any air, therefore capturing the full flavor in a silky, oily, emerald-green pesto, rather than one that’s light green and frothy because it’s puffed up with air.

Steel blades vs. wooden pestle: Most food processor blades are made of stainless steel which will chemically neutralize some of the flavor compounds in fresh garlic. Mortar and pestles are crafted of inert non-reactive materials that shouldn’t alter the flavor of the pesto ingredients during the slow, gentle grinding process.

Crushing vs. emulsification: A mortar and pestle will crush and smear the ingredients into a paste, while a food processor will chop and slice them into a microscopic mince. Besides the textural difference produced by the two methods, a partial emulsification of the water-based constituents into the olive oil occurs with the food processor. Emulsified pesto from a processor will be very different from the flavored oil that the mortar and pestle creates.

The Test

Theoretically, it would seem that the traditional mortar and pestle method is superior to a food processor, but I’ve had pesto that’s been prepared both ways, and I’ve thoroughly enjoyed both results. But then again, I’ve never objectively compared them side by side. Since I have a great crop of basil in my garden this summer and work with a group of enthusiastic co-workers who are all in for any kind of fresh-food sampling opportunity, we decided to conduct a test taste that attempted to objectively quantify the differences.

Ingredients:

  • 2 cups fresh sweet basil leaves (variety: Sweet Genovese)
  • ½ cup extra virgin olive oil (from 1st cold pressing)
  • 3 tablespoon pine nuts
  • 2 garlic cloves
  • 3 tablespoons freshly grated Parmesan (Italian Parmigiano Reggiano) cheese
  • ¼ teaspoon salt

Mortar and Pestle Method:

  • Toast pine nuts in heavy bottom pan on medium heat until fragrant, remove from pan and allow nuts to cool.
  • Peel garlic cloves and place in mortar with a pinch of salt. Crush garlic into a chunky paste with pestle.
  • Add a drizzle of olive oil, several basil leaves and another pinch of salt. Crush with pestle in a grinding, circular motion. It will help to rotate the mortar in the opposite direction periodically. Continue adding oil, basil and salt in manageable increments until all of the leaves, oil and salt are crushed and incorporated.
  • Add the toasted pine nuts and crush them to desired consistency.
  • Finally, incorporate the grated Parmesan cheese.
fresh basil pesto recipe

Mortar and pestle method

Food Processor Method:

  • Toast pine nuts in heavy bottom pan on medium heat until fragrant, remove from pan and allow nuts to cool.
  • Peel garlic and place in food processor with salt and process until well-chopped.
  • Add olive oil, basil leaves and salt, process until all the basil leaves are broken down.
  • Add pine nuts and process until you achieve desired consistency.
  • Finally, incorporate the grated Parmesan cheese.
fresh basil pesto recipe

Food processor method

Results

Eight of us sampled the unlabeled pestos side by side on French baguette and recorded our preferences and impressions of each.

Appearance: Five people preferred the appearance of the pesto from the food processor, while three preferred the pesto from the mortar and pestle. The food processor pesto was brighter green with a uniform appearance, while the mortar and pestle pesto was a darker, inky green with a mix of larger and smaller leaf, pine nut and garlic fragments.

Aroma: Two people preferred the aroma of the pesto from the food processor. Three people preferred the pesto from the mortar and pestle, while three had no preference for the aroma of either. Two people noted that the aroma of garlic was sharper and more distinct in the mortar and pestle pesto.

Texture: Five people preferred the texture of the pesto from the food processor. Two people preferred the pesto from the mortar and pestle, while one person had no preference for the texture of either. Most liked the fine, uniform texture of the pesto from the food processor, while a few objected to the larger bits of leaf material in the mortar and pestle pesto.

Flavor: Three people preferred the flavor of the pesto from the food processor, while five preferred the flavor of the pesto from the mortar and pestle — with some noting a contrast between the pungent garlic and sweet, fresh basil. The pesto from the food processor seemed to have a richer, nuttier flavor that just slightly subsumed the fresh nuances of the basil leaves.

fresh basil pesto

The good news: Processor or pestle, fresh basil pesto is delicious!

Conclusions

The pesto from the food processor got high marks for appearance and texture, while the pesto from the mortar and pestle got the highest marks for flavor. My impressions square with the overall results except for one detail: I made the stuff, and after spending 5 minutes with the food processor and 20 minutes with the mortar and pestle (which gave me a nasty blister), I can say that pestled pesto is literally a pain. I will likely go with the food processor to deal with the glut of basil I have.

But first I’m off to the bank to take out a loan for all the pine nuts and Parmigiana Reggiano cheese I’ll need.

Process or pestle: How do you make pesto?

Tom-HavranAbout the author: Tom is communicator of natural living for Frontier, Simply Organic and Aura Cacia brands. In other words, he’s a very imaginative copywriter. A local boy, raised on a farm just down the road from the company’s headquarters in Norway, Tom enjoys drawing, plant hoarding, cooking and living the simple life in the beautiful state of Iowa.

One Response to “Fresh basil pesto recipe: To process or pestle? That is the question”

  1. Mary Pat August 12, 2013 at 10:38 am #

    Read with interest. Thank you! Just wish I could grow enough basil to have your problem! Here in my CA home garden, the butterflies are attracted to all my herbs…they lay their little eggs and before you know it, caterpillars devour the plants! The only thing I manage to grow in any quantity is mint and thyme. Basil and tarragon are favorites of the butterflies!

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