Science puzzle: what can make strawberries become intensely bitter?

[paulraphael]

Here's a head scratcher. Hoping someone with fruit science background has an idea.

 

I made a batch of strawberry ice cream to test a recipe. Calculated for 300g strawberries / 1000g mix. I was about 45g short on strawberries, so made up the difference with raspberries. Both kinds of berries were medium-quality ... from Whole Foods, pretty ripe, pretty fresh, tasted fine but unremarkable. 

 

Berries were added to the mix after pasteurization and homogenization. I washed, cored, thickly sliced, and froze them. Then blitzed them into the freshly homogenized mix with a vitamix for 30 seconds. Idea was to use the berries to start the mix cooling, and do so without cooking the flavor out of the berries. 

 

I chilled the mix down to about 13°C in an ice bath. At this point, my girlfriend and I both tasted it and thought it tasted good. LIke strawberries. My only concern was textural; the viscosity was higher than normal.

 

I refrigerated it down to 0.5°C overnight, and spun it today. It hasn't hardened yet. We both tasted it right out of the machine and almost had to spit it out. It's like when you try to hide a crushed pill in the cat food, but all you do is make the whole meal too bitter for the cat, and he's pretty sure you're trying to kill him. 

 

I've never experienced this before. Something introduced seriously bitter compounds into this brew while it chilled overnight.

 

ChatGPT thinks it could be polyphenol oxidase reactions, which I would have inadvertently allowed by keeping the berries out of the pasteurizing step. It also suggests that there can be polyphenol oxidase reactions that are affected by milk proteins. I'd never heard of this (or anything) turning berries into bad medicine overnight.

 

Thoughts? 

Edited 10 hours ago by Smithy
Adjusted title (log)

[oli]

I bet this would be great with Huckleberries.  

[paulraphael]

8 hours ago, oli said:

I bet this would be great with Huckleberries.  

 

Or to punish children.

[Duvel]

13 hours ago, paulraphael said:

Both kinds of berries were medium-quality ... from Whole Foods, pretty ripe, pretty fresh, tasted fine but unremarkable. 

Not sure where Whole Foods sources their berries, but at least in Europe the  sloe bug or hairy shieldbug (dolycoris baccarum) is known to impart a bitter, astringent flavor to the berries it infests. Unsually you can sort the spoiled berries out, but one “surviving” berry per batch is enough to render the product inedible. My mom makes raspberry marmalade very often and every once in a blue moon a batch of her marmalade tastes off …

[Katie Meadow]

18 hours ago, oli said:

I bet this would be great with Huckleberries.  

What isn't great with huckleberries? 

[paulraphael]

12 hours ago, Duvel said:

Not sure where Whole Foods sources their berries, but at least in Europe the  sloe bug or hairy shieldbug (dolycoris baccarum) is known to impart a bitter, astringent flavor to the berries it infests. Unsually you can sort the spoiled berries out, but one “surviving” berry per batch is enough to render the product inedible. My mom makes raspberry marmalade very often and every once in a blue moon a batch of her marmalade tastes off …

The thing is, the berries weren't bitter on their own. The ice cream mix wasn't bitter in the hour after the berries were added. The bitterness showed up the next day in the finished ice cream.

[TdeV]

Martians!

[AlaMoi]

I right regular fine dice fresh local strawberries as filling for crepes / toppings for x,y,z . . .

I make a point of macerating them over-night . . . and left overs go into 2-3 days.

operative words:  fresh local

 

I'm wondering if the 'forced red color but not really ripe' played a role?

[oli]

I usually mixed ground walnuts and almond jam in mine since my mom made them when I was a child and alternate the others with cottage cheese and powdered sugar for added protein. Not had them with strawberries but will make a point to do so with the next batch in a few weeks. A little chocolate drizzle would do the gilding.

Edited 3 hours ago by oli (log)

[gfweb]

I'm putting my money on an enzyme from one of them acting on the other to make bitterness.

 

It tasted OK initially, but after storage didn't.

 

You might argue that it was kept in the cold, but some enzymes work in surprisingly low and high temps, and bitter is one of t hose tastes where a little bit is very potent.