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How the pH of Lime Juice Changes as it Ages

This post is part of a mini-project looking at sweet and sour elements in cocktails, sponsored by PAMA Pomegranate Liqueur.

In recent years, bartenders have discovered that lime juice for cocktails tastes best not when it is first squeezed, but several hours afterward, typically something like 4-6 hours old. 

Sweet vs sour copyI believe it was Dave Arnold who first discovered this. He was testing whether limes juiced in a machine versus hand-squeezed were better (hand-squeezed won), and also found that 4-hour-old juice from both squeezing methods tasted better than fresh lime juice from either method; a fascinating and completely non-intuitive bonus. Since then, I've heard of other people testing and confirming this. 

One observation Arnold made was, "Some tasters commented that  that the aged juices not only tasted better, but had more of an acid bite."

So I thought I'd see what happens to the pH of lime juice as it ages. 

Testing the pH of Lime Juice as it Ages

I started with two batches of limes. The Good limes I purchased that day. These were large, plump, and relatively good-looking limes purchased in California. (Not sure where they originated.) They tasted bright, sour, and floral. 

The Janky limes I had purchased about 5 days earlier. They were small and in bad shape when I bought them, and only got worse while waiting to start the experiment. They had lots of high notes, were not nearly as aromatic/floral, not a full round flavor; just a simple acid/lime flavor. 

Good and janky limes
Good limes on left, Janky on the right

 Then I squeezed both limes in a hand squeezer, filtered them through a fine strainer to get the large bits out, and measured their pH values over the course of two days.

I'd say my pH meter readings are only accurate to around .03 or so. 

Time Good Limes pH Janky Limes pHes pH
0.0 2.32 2.23
0.5 2.2 2.18
1.0 2.2 2.17
1.5 2.21 2.18
2.0 2.19 2.17
3.0 2.2 2.14
4.0 2.19 2.13
5.0 2.16 2.13
6.0 2.14 2.11
7.0 2.16 2.12
8.0 2.16 2.13
9.0 2.13 2.1
10.0 2.16 2.14
20.5 2.2 2.15
22.0 2.2 2.15
28.0 2.25 2.23
29.0 2.26 2.23
30.5 2.23 2.18
40.5 2.2 2.15
41.5 2.2 2.18
53.0 2.18 2.14
     

Looking at that as a chart, we have:

Book1_29870_image001

Click to pop out the chart or launch it in a new window. 

Note that our scale is only from a pH of 2 to 2.5, so this isn't a big change in pH over time. I wouldn't be confident in saying that we could make any firm conclusions, so we'll just call them observations from this one experiment. 

  • Unless I measured incorrectly, the largest change appears to be in the first half hour; the pH drops a bit, then remains about the same for a few hours

Now if we blow up the first 10 hours of measurement:

 

Book1_29870_image001

  • Maybe it's wishful thinking, but it appears that after around 3 hours (janky limes) or 4 hours (good limes) they settle down into a pH level where they'll stay for the next 6 hours.
  • That would agree with the taste data that Dave Arnold and other people have found, in as far as there is a change around then. I did not taste the lime juice separately or in cocktails as it aged. 

Overall, it appears in this experiment the lime juice became slightly more acidic after the limes were juiced, which agress with the quoted observation from Dave Arnold.

From a cocktail perspective, it seems your palate would still be a much more finely tuned instrument to measure the perceived or correct acidity of lime juice over time than a pH meter. 

Other factors known or suspected to impact the flavor of lime juice as it ages include:

  • Oxidation
  • Interaction of pith and oils with the juice
  • Temperature (refrigerated or not)

 

Pama imageThis post about sweet and sour is sponsored by PAMA,  a pomegranate liqueur with a unique balance of sweet-to-tart you can read more about on the PAMAPros.com website. Follow @PAMAPros on Twitter!

 

 

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