Carbonated beverage off-flavors

Hi,

I am dealing with an off-flavor issue in a pasteurized carbonated beverage that contains 5% pineapple juice. I sent samples to a lab for testing, but I am not sure how to interpret the results.

I have looked on line to try and find a spec for similar products, but I haven't been able to find anything.

The result showed 

Lactobacillus Total Count: 210 CFU/ml

Lactic acid bacteria: 1600 CFU/ml

Everything else on the result was very low.

Could these levels cause significant off-flavors to develop in the product? 

Thank you!

Hi ttay,

That's certainly higher than I'd want to see in a soft drink, but that's as much because it's potentially going to continue growing and higher levels will create taint problems.

There are other bacteria that can be found in juices that can survive pasteurisation and cause off-flavours, and wouldn't necessarily be picked up on a standard TPC test or similar.

Some initial questions that may help with providing some further suggestions:

How would you describe the character of the taint?

What other micro have you done, what were the results and what methods were used?

What other ingredients are in there?

yes, lactic acid bacteria are good for kimchi and kosher dills................but are the #1 cause of spoilage in most everything else.

It sounds to me like your pasteurization and or pH process is off..........there is lots of good info online regarding LAB and spoilage

Are you absolutely sure the pasteurizer was at the correct temp the entire batch?

Ttay,

What other ingredients are in the product?  Lactic Acid bacteria can create diacetyl, which tastes like butter.    Lactic Acid bacteria and lactobacillus are nasty spoilers, it doesnt take a lot of colonies to start tainting the flavor.

What type of pasteurization do you perform, flash or tunnel?   If tunnel, what do your data loggers show?  If flash, are there any instances where the temperature requirement was not met and your system went into recirculation mode?   Was the timing pump set correctly to achieve the required contact time?

Do you retain pre pasteurized samples?  Did you send those samples for testing to determine the micro loading of the product before pasteurization?

Leo

Ttay,

There are other Bacillus that can survive traditional pasteurization and thrive in low pH applications like Alicyclobacillus. Which is also common in juices. I have clients who test for this organism specifically.

Lewis

For the character, some of the samples had an alcoholic odor of varying degrees. They were less sweet tasting than normal, maybe slightly sour.

The other tests performed were:

Aerobic plate count - 18

Anaerobic plate count - <LOD

Yeast - 66

Mold - <LOD

Bacillus cereus - <LOD

For the pH, the normal range is 3.5-3.9, pH in the sample tested it was 3.4.

I am working with a contract manufacturer, and that has made it more difficult to get answers about the process. 

I did not note any butter taste in the spoiled products.

There are also other flavors than pineapple, but none of them have had any issues with off flavors like this.

Hi ttay,

Ah, yes, resolving this type of issue with a contract packer can be very difficult - it's all too easy to be stuck between various parties who don't really want to do anything that may suggest it's their responsibility...

Nonetheless they should readily be able to give you a summary of the process parameters so I'd keep pushing them on this - if they're not prepared to do so then this in itself possibly tells you something ;)

What is the end product's intended shelf life / storage conditions?
If it's a longer life ambient/chilled product (i.e. shelf life in months) then the rest of the micro data also warrants some investigation, whereas for a short life chilled product it is less critical.

Nonetheless the survival of yeast suggests that the pasteurisation process may have achieved 5-log for pathogens but probably not for spoilage organisms, unless your starting count was ~10^6 cfu/ml yeast!

I think the FDA advises circa 71.1C for 6 seconds to achieve 5-log for salmonella/listeria in juices, but in practice most soft drinks processors I know who are making juice-based products are running at more like 85-90C for 15-30s largely due to spoilage generally being a greater challenge in this type of product.

Presume you've already reviewed samples of the raw materials? Ethanol presence in juices is expected at low levels (should be <3g/L) but higher levels are possible if fruit condition and/or process hygiene during initial processing have been poor. Certainly 66cfu/ml yeast shouldn't be giving you any problem immediately in this respect!

As Sweet_Lew noted, Alicyclobacillus can be a problem in juices, particularly cloudy ones as you can't filter to remove it, and killing it thermally requires a high level of heat to the point that it wrecks the flavour/colour of most juices. Taints from this vary, but "antiseptic"/TCP and "hammy" are two common descriptions so perhaps not relevant here unless the "alcoholic" element is perhaps the former?

It's moderately difficult to test for (won't show on your standard TPC or similar) so if this is a potential concern then you'll need to find an external lab who are familiar with it. You're on the wrong side of the Atlantic for me to make any specific recommendations there, but I'd suggest asking around to see if you can find one that is familiar with the IFU12 method for this.

Hi pHruit,

Yes it has a longer shelf life and is stored at room temperature. I am attempting to get more information on the raw materials but it has been difficult. 

Thank you for the information! I will look into finding an external lab who can test for Alicyclobacillus.

You're best bet for a lab in Canada is Maxxam.........they are not cheap, but they know their stuff

Hi ttay,

I'd be interested to know what process was used - is this aseptic fill / hot fill / bath pasteurised, is it preserved, what spec were they supposed to achieve etc?

Given the overall results and the intended ambient-stable nature of the product I'm leaning more towards the idea that something may have gone wrong with the processing/packing, rather than this being a case of a specific bacterial problem. ACB could be present, but it's perhaps academic given that there appears to be yeast and various other micro in an ambient product. If you'd said it was short life chilled then it'd not look untoward, but yeast *really* like juice and a comfy operating temperature so to me this looks like bottle/cartons that will ferment quite happily until they burst on the shelves!