Food & Vac Series Part 4: Science of Vacuum, Marinades & Brines

Marinades and brines have been reliable techniques in food preparation since the dawn of civilization. The ancient Egyptians practiced these methods to enhance flavor, improve tenderness, and preserve food. Although they are frequently used, some complaints arise. They require advanced planning and can take a long time, with some even arguing that they don’t penetrate well. In an attempt to improve penetration by extending the marinating or brining time, the texture of the meat can sometimes suffer. I don’t know about the critics, but I have to believe King Tut would be pleased to know that I’m refining these processes and using a vacuum chamber setup to penetrate foods more quickly and deeply.

Millions of meals are cooked across the world every day, and even though the collision of physics and chemistry make the culinary arts possible, it rarely requires anyone to write a model as depicted in the cover image here to create lemon herb marinade under vacuum at -20 inHg for 15 minutes,. In the kitchen, we are masters of the sciences, expressing equations with flavor and love instead of a pencil. To present this to you, I couldn’t rely solely on flavor and anecdotes alone. I had to seek credible information and scientific evidence to explain what I believed I was observing in my ad hoc kitchen vacuum experiments. The kitchen truly is the coolest lab, and now I have to find a pencil.

While searching the internet for anyone already working with vacuum chambers and food, the first content I found was a video by Nate From the Internet titled “Does a Vacuum HURT Marinade?”. It was exactly what I needed! Nate set out to examine the effects of marinating flank steak and chicken in a vacuum chamber. He started with marshmallows, just like me, so I felt I was in the right place. Ultimately, with the help of blue food coloring, he demonstrated that the vacuum didn’t improve marinating much, if at all, and went as far as saying that it rendered the chicken’s texture inedible. This wasn’t great news, but he credited Adam Ragusea’s video “Does Marinating Do Anything?” for the blue food coloring concept. This was a fantastic discovery and an excellent video that offers a wealth of information about marinades, along with insightful comments from a food industry expert. I’d definitely recommend watching it. 

The blue dye trick for visually observing the extent of marinade penetration seems ingenious, and I, probably like everyone who watched these videos, bought into it. However, knowing vacuum applications well, I found several issues in Nate’s video that left me doubtful about his conclusions. Adam’s video was much better, but a few inconsistencies prompted me to dig deeper until the doors of science opened and Greg Blonder’s article “Dyeing To Get In” guided me toward the promised land. Greg explained that the size of the molecules and their atomic charge make blue food dye a poor choice for determining how marinade components are absorbed, using an impressive visual representation of comparative atomic size to illustrate how large the blue dye molecule is compared to other components. 

(image from “Dyeing To Get In” via chemspider.com)

 

The blue dye experiments misrepresented how marinades are absorbed and didn’t show the failure of marinades to penetrate as they believed it did. It makes sense that smaller particles, like salt and sugar, move more easily and deeper into a protein than larger compounds. That’s precisely how liquid chromatography functions, except it doesn’t use food proteins as the stationary phase. 

I was encouraged that the blue dye idea was debunked, but I was still struggling to make the connections I needed. Then, I finally found someone who spoke my language in the “Magical Marinades” article from Meat + Poultry: 

“In this process, vacuum pulls the air out of meat, opening it up to better absorb the topically applied marinade.” 

I’ve observed proteins opening up under vacuum as described and assumed this was how moisture, lubricity, and flavors could penetrate the protein deeper, but it was just a guess. I know it’s not rocket science, but this confirmation that vacuum is already being used as I’d hoped was perfect and made me twerk a little. The remaining question was how this could be accomplished without ruining the protein’s texture and making it unpleasant to eat. 

The progress was happening slowly until, BINGO, a three-word term burst into my life and forever won my heart. An article from Food Quality and Safety titled “Marination Ingredients on Meat Quality and Safety - a Review " noted,

“Recently, physical marinades with biological or chemical marinades have gained popularity in the meat industry to surpass the traditional method and accelerate their performance. Emerging technologies, called physical marinades include pulsed vacuum impregnation, CO2 micro-perforation, ultrasound treatment, and high-pressure treatment.”

Pulsed Vacuum Impregnation (PVI)! The heavens opened and an idea had a real name.  Be sure to check out the article because it’s outstanding and contains an ungodly amount of knowledge on the science of marinades.

Stalking PVI led me to another fantastic article, “Recent advances in vacuum impregnation of fruits and vegetables processing: A concise review (March 28, 2024), that provided the ultimate technical terms and explanations of the exact mechanisms involved. The Deformation-Relaxation Phenomenon (DPR) describes how the tissues of an object behave under a vacuum, while the Hydrodynamic Mechanism (HDM) explains how fluids can interact with the variant tissue behavior.  You know I was already excited, but this took it to a whole new level:

“DRP dominates the first stage while HDM dominates the second stage of the process when the impregnating solution penetrates the material's structure. This is backed by deformation and compression of material [21]. From a practical perspective, the relaxation phase is crucial because only tissue impregnation occurs at this moment. Quick vacuum removal should be avoided because too rapid pressure equalization may cause capillary channel closure and hinder the hydrodynamic mechanism.”

And then another.  “Vacuum impregnation: Effect on food quality, application and use of novel techniques for improving its efficiency.”

“VI is based on capillary flow and mass transfer, when a food product with porous structure is immersed in a solution the mass transfer rate is faster due to inflow of solution through capillary pores which is being monitored by compression or expansion of internal gas.”

 

There it was! Pulse Vacuum Impregnation lets us utilize the Hydrodynamic Mechanism to exploit the Deformation-Relaxation Phenomenon. It had been on the tip of my tongue the whole time!  This was jiving perfectly with my observations and experiences so far.

 

Balance in Working Together

To pull all of this together successfully in a delicious way, vacuum application, marinades/brines, and individual proteins must be well considered together, in balance, to work together for the best outcome.  Marinades and brines utilize the chemical denaturing powers of acids and salt to tenderize meats.

Those powers, paired with the intense tenderizing effect of the vacuum pulling protein fibers apart can quickly overwhelm the weak structure of a protein. The process must be approached with careful consideration to ensure that all tenderizing components aren’t over-applied in terms of power or time.  What marinade or brine and how much vacuum to use all depends on the prepared protein.  The density and structure of a protein determine how easily a marinade can penetrate.  Fish requires less vacuum than chicken, chicken less than pork, pork less than beef (kind of), and smaller proteins need less than larger ones.

To achieve this balance, applying varying vacuum levels and times to different proteins requires fine control. Additionally, as noted in the passage shared above, not only is a controlled application of vacuum crucial, “Quick vacuum removal should be avoided because too rapid pressure equalization may cause capillary channel closure and hinder the hydrodynamic mechanism.” 

 

A slow, controlled vacuum release, followed by the protein resting and climatizing slowly, allows for the best absorption. If balanced correctly, the vacuum chamber, with the marinades and brines, will perform its function before compromising the texture of the protein.

Vacuum sealers are more of a wild card, with less control than a bull stung on the balls by a hornet.  The rapid pressure changes programmed into them make achieving the ideal balance almost impossible.  Fortunately, for those using sealers, that doesn’t always matter.  Quick marinading in a vacuum-sealed bag is effective and yields great results in many instances.  However, I think most marinade penetration occurs at one specific moment in the process—rapidly and violently, when the vacuum releases and seals the bag. Once sealed, the protein becomes compressed, limiting further absorption of limited liquid. The video of the wet sponge undergoing the vacuum sealing process demonstrates this remarkably. 

 

The speed of transition from vacuum in the sealer to regular ambient pressure is shocking.  The process demonstrates DRP and HDM in action as the water is expelled, gas escapes, and is then drawn back in when ambient pressure is restored to the sealed bag. The condition of the flattened sponge inside the bag makes it unlikely that DRP, HDM, or PVI can be easily exercised. While the bag could be opened and the contents transferred to a new bag for repeated processing a few times, it is cumbersome, wasteful, and uncontrolled.

Ultimately, a chamber set or a vacuum sealer will accomplish the task to varying degrees, but the chamber set will do so better, more affordably, sustainably, and with greater ease. It’s finally time to move on to the final part of the series to apply what we’ve learned into practical methods for creating delicious brined and marinated food!