10 replies to this topic

[J Young]

Hi All
New member!
I work in the food industry but am currently doing a dissertation on 'the effects of cream shelf life and its butterfat' at fat levels 18% single, 48% double and 56% clotted. I will be carrying out sensory analysis and micro analysis, just APC and enteros. I will be looking at trends in fat content a acceptability along with the effects of heat treatment levels, within the pasteurisation ranges. I will also look into the effects of homogenisation, used in single cream and any effects this may have.

hopefully i will be able to produce a guide for the shelf life prediction from APC taken from production date, with view of either reducing or extending dates.

Please if anybody has any information on cream shelf life, sensory analysis and the science behind them, i would be most thankful.
regards J

[Charles.C]

Dear JYoung,

Welcome to the forum !

Interesting subject area (not mine unfortunately). May I enquire what the dissertation is being done for ? It has some influence on the necessary depths of study from my experience. My first reaction was that this is a pretty multivariable investigation. Looks like an ANOVA analysis coming up somewhere.

I presume you hv already defined the criteria / limits for shelflife acceptability ? Or are you at the “gathering info.” stage ?

There should be people here with experience in this area.

Rgds / Charles.C

[SaRaRa]

Hello,

Even though I don't have any work experience on this I made a small search online. I hope that something of the following will prove to be useful...

Control of the quality of short shelf-life products

Factors affecting shelf-life - Cream

Shelf-life of Cream liqueur

Cream Products

Nicin extending the shelf-life of pausterised double cream

Complex example - Investigation of a cream that contains 2 active compounds

Pure butterfat as ingridient in fabricated foods

Sterilized UHT processed milks and creams

HACCP - Case study: Fresh cream and jam gateau

Extented Shelf-life Refrigerated Foods: Microbiological Quality and Safety

Sensory-directed Flavor Analysis

Applied Sensory Analysis of Foods


Good luck!

[GMO]

Not my area I'm afraid (Caz is the woman who knows all about dairy). One thing which popped into my head that I'd look into is the size of any fat globules in the cream / homogeneity. I'm sure it will have an effect but I'm toying with myself on which way round that correlation will be! One one hand, smaller fat globules will give a higher surface area / volume ratio for oxidation of that fat. On the other hand, poor homogeneity could lead to splitting out of the cream and a lot of fat on the surface in contact with the air leading to rancidity. That said, the fat layer which is deliberately on the top of clotted cream may protect the product underneath?

I've said this to people before but if you or someone you know has an Athens password, you can use web of knowledge to search academic literature. Although it looks like it's not as good as it used to be. Not sure if that's because Athens passwords were routinely passed around... However, I've just found "Google Scholar". It's only in its beta version but probably worth a try:

http://scholar.google.co.uk/

If you're doing a dissertation, I assume you have access to a college or university? You should be able to get copies of the papers you find there. It's also worth talking to the Librarian about searching for academic papers because you will have IP address authenticated searches from Uni computers that we won't be able to access and may have some electronic access to papers.

Here are a couple of papers which might be useful:

http://www3.intersci...l...=1&SRETRY=0

http://www.sciencedi...977c4131acbafb7

http://www3.intersci...580318/abstract

Remember if you access American papers, I think they call double cream "heavy cream" but it's worth checking fat contents as they may not be exactly the same.

You might find on all of this that the fat content is almost immaterial because the effect of poor hygiene practices is more impactful and more common! Maybe I'm just getting jaded in my old age...

[J Young]

Hi All

Many thanks for all your time, some very valid help. The dissertation is for my (HONS)Bsc in Food Management. I am looking into the current base specifications for micro and shelflife criterias (12 days life) and trying to look if the life could be evaluated and worked out by fat volume and not just fresh cream in general. I will also be looking into effects of homogenisation, mainly for single cream and how the clotted cream density and fat seal on the crust protects the product.
I will run sensory analysis alongside the micro analysis, finding it difficult to obtain info on cream as much research is on milk and milk products in general.

Thanks all again, let me know if anybody has any further thoughts!

regards justin

[J Young]

Great links to some books, but is there any way i can print them? All i seem to get is a blank page, am i being stupid or is it a copyright thing?
J

[GMO]

If it's a book page from a google search, I think they deliberately prevent you from printing them. It's worth taking the title though and seeing if you can get it from your uni library. If you only want one paragraph, you could always click on the "print screen" button and then open a word file and press ctrl v but it's better to get hold of the original source material if you can, you should have copies of all references you cite in a thesis.

It sounds like you're doing some sensible trials. Maybe the absence of other work is a good thing! I just had a thought as well. Although it doesn't give you the basis for these limits, Tesco (and other supermarkets) produce guidance on what the maximum limits for different bacteria and Y&M. Although these don't give guidance on shelf life, it does provide a target for microbiological loading at the start of life meaning that if the supplier isn't meeting this, they will work on the hygiene standards to improve it and by doing that they will (probably) normally achieve a decent shelf life.

It might also be worth looking at any retailer standards on how to conduct a shelf life trial. Anyone got any copies they can attach? From memory, the protocol suggests keeping at a higher temperature (8 - 10 degrees) during the last 2 days before testing to ensure you're replicating the (usually) dodgy fridges in peoples homes. Also consider cream is a product which may be opened on one day and consumers may abuse the "eat within 48 hours of opening" (or whatever it is).

To ensure your results are valid, I'm sure you've already considered this but not all tasters can taste certain 'off' flavours, particularly in dairy products so you may need to do some fairly extensive screening before you start to ensure the results are valid.

It might even be worth phoning up the CCFRA and asking for some basic information and whether they've done any research on this. The worst thing they'll do is say "we can't discuss it" but when I've contacted them in the past, they've normally been really helpful. They may even let you come to one of their panels if you ask *very* nicely!

Attached Files

•  F30_F31_F32__F38_F39_Chilled_Foods_Micro_Limits.doc   126.5KB   56 downloads

Edited by GMO, 18 May 2009 - 11:25 AM.

[J Young]

Thanks again GMO

[Charles.C]

Dear JYoung,

There are some well-known shareware solutions which improve on the printscreen function if you try googling for something like " copying pages on the computer screen" however their effectiveness is not 100% I believe.

Rgds / Charles.C

[cazyncymru]

Not my area I'm afraid (Caz is the woman who knows all about dairy). One thing which popped into my head that I'd look into is the size of any fat globules in the cream / homogeneity. I'm sure it will have an effect but I'm toying with myself on which way round that correlation will be! One one hand, smaller fat globules will give a higher surface area / volume ratio for oxidation of that fat. On the other hand, poor homogeneity could lead to splitting out of the cream and a lot of fat on the surface in contact with the air leading to rancidity. That said, the fat layer which is deliberately on the top of clotted cream may protect the product underneath?

I've said this to people before but if you or someone you know has an Athens password, you can use web of knowledge to search academic literature. Although it looks like it's not as good as it used to be. Not sure if that's because Athens passwords were routinely passed around... However, I've just found "Google Scholar". It's only in its beta version but probably worth a try:

http://scholar.google.co.uk/

If you're doing a dissertation, I assume you have access to a college or university? You should be able to get copies of the papers you find there. It's also worth talking to the Librarian about searching for academic papers because you will have IP address authenticated searches from Uni computers that we won't be able to access and may have some electronic access to papers.

Here are a couple of papers which might be useful:

http://www3.intersci...l...=1&SRETRY=0

http://www.sciencedi...977c4131acbafb7

http://www3.intersci...580318/abstract

Remember if you access American papers, I think they call double cream "heavy cream" but it's worth checking fat contents as they may not be exactly the same.

You might find on all of this that the fat content is almost immaterial because the effect of poor hygiene practices is more impactful and more common! Maybe I'm just getting jaded in my old age...

The biggest problem with cream is that due to the high levels of fat content (from 18 to 48%) is that it can go rancid very quickly.
You have to ensure that it is pasteurised completely (most places use flash at 80 degrees) and that it is adequately cooled and stored.

Another issue is the hygiene of the potting machine. it really does have to be clean.

The best book i could recommend is "Cream Processing Manual" edited by J Rothwell (Society of Dairy Technology)
ISBN 0-900681-08-X

Hope this helps

Caz x

[J Young]

Thank you CAZ, you've all been very helpful.
Thanks again
Justin