(Note! When I originally posted this response I may have mixed up my response with another question dealt with through Email- this is an updated response) 

 

There are several reasons for ice crean melting quickly apart from too much sugar. These include not ageing for long enough, very low fat mixes, not using the optimal emulsifier and low overrun. Use of stabilisers can also help reduce melting rate.

 

I will make a few suggestions.

 

1.  Check that the stabiliser has been correctly incorporated into the mix- make sure it is in solution.

 

2.  Double check your calculation and make sure the concentration is actually 0.65% and not 0.065%- sorry to say such an obvious thing!

 

3.Consider using another product, perhaps one that uses a blend of several stabilisers.

 

Pl let me know how you get on.

 

 

 

1. What is your mix composition?

 

2. How do you 'mix' your ingredients. What heat treatment do you use? Do you homogenize your mix and if so for how long and at what pressure. Single/double stage homogenization?

 

3. How long do you age the mix before freezing?

 

4. Does your freezer add air to the mix during freezing?

 

5. What overrun do you get?

 

6. What temperature does your mix come out of the freezer?

 

7. What temperature is your storage freezer set at?

 

8. How long do you hold the gelato in the storage freezer before you take it out to serve?

 

9. Is this a new problem?

 

10. If everything was OK before have you changed anything?

 

Some theory basic information for you to think about.

 

 

This is fairly easy to eliminate but first I will explain why it is important.

Pure water freezes at 0°C under standard conditions. Because of the high concentrations of substances, mainly sugars, in solution the freezing point of a typical ice cream mix is depressed and  freezing starts at around -2 to -3°C.  However this is only a partial freeze since the substances not frozen are now present at an even higher concentration in the unfrozen water, further depressing the freezing point. As the temperature drops, more water freezes and the freezing point of the unfrozen water gets lower and lower until a point is reached where the bulk of the water is frozen.

 

Many ice cream freezers discharge product at a temperature between -3 and -9°C and will have around 50-60% of the water unfrozen (fig. 1 below). It will take the temperature reduced to around -18°C before the bulk of the water is frozen. Unless you have commercial cooling facilities this can take many hours.

 

 

 

 

So you need to be quite certain that your temperatures are correct!

 

By the way properly produced commercial  ice cream properly conditioned can retain its shape in standardized melt tests for  30+ minutes.

 

Fat does have a role in melt resistance; hence the importance of emulsifiers! You might find the review by Professor Goff (1997) interesting.  He has explained that the optimal formation of fat structure in ice cream is responsible for many desirable ice cream quality characteristics including slowness of meltdown (Goff, 1997).

 

In conventional continuous ice cream freezing two unit operations have a major influence of  the  final ice cream product namely whipping (crudely mixing the air into the ice cream) and freezing. To obtain good melting behavior (and other characteristics!)  finely dispersed and narrowly distributed air bubbles and ice crystals have to be generated.

 

 

 

 

Goff, H.D (1997). Colloidal aspects of ice cream - a review. International Dairy Journal, 7,
363–373.

 

 

 

 

I have looked at my responses to you and have edited them a little.

 

Because your gelato lost its shape so quickly my immediate reaction was to question the temperature you held your ice cream at and whether you were using a stabiliser. I presumed because you were not using an emulsifier that this melting was  a new problem and not directly related to emulsifier use i.e. you were content with meltability in the past?

 

If temperature of the gelato and stabiliser use are not the cause of your problem then your mix composition and the use of an emulsifier need to be investigated.

 

I would be interested in hearing how your investigations are progressing?

 

 

So you have had this problem from the start!

 

Most ice cream problems are fairly easy to solve. However there is a good case for starting from the beginning!

 

What mix composition are you using? % fat, % MSNF etc

 

How do you prepare your ice cream mix e.g. how do you mix your ingredients? Do you have a homogeniser? Have you ever measured the % overrun?

 

By formulating your mix correctly (using stabilisers and emulsifiers) and adjusting the overrun to 100% you should be able quite quickly to get good resistance to melting.

 

Douglas Goff is an expert in ice cream microstructure and ice cream functional properties and you may find the summary of his work using the emulsifier https://www.uoguelph.ca/foodscience/book-page/ice-cream-ebook" rel="nofollow - polysorbate 80 helpful.

 

 

The calculators on this site take % MSNF, % Fat targets or specifications and tell you how much ingredient you need to get this % mix composition. If you do not work to a mix specification, then you need to take a step back and using your ingredients work out what MSNF etc they contribute to your mix, only takes a few minutes with  a spreadsheet.

 

The http://www.dairyscience.info/calculator1/index.php" rel="nofollow - subscription calculator can also be configured to work with whole milk powder (not currently enabled) but you need to make a small donation to use. This is not necessary for the moment.

 

BTW I have posted a free gelato recipe that should work well on this forum. You could test this out however it uses 6% fat and some gelato makers prefer 5%.

 

And  Professor https://www.uoguelph.ca/foodscience/book-page/ice-cream-ebook" rel="nofollow - Doug Goff's Ice cream Ebook is an excellent free ice cream manufacturing resource.

 

RE your PM:

 

1. The gelato recipe is at http://dairyscience.info/forum/5-low-fat-gelato-mix_topic223.html - http://dairyscience.info/forum/5-low-fat-gelato-mix_topic223.html  You put the specifications in to the free calculator- then add your ingredients. The calculator will tell you how much to add.

 

2.  I have put a calculator at

http://www.dairyscience.info/a1mixes.asp - www.dairyscience.info/a1mixes.asp to enable you to add the weights of your ingredients to the spreadsheet. Note this is set up for a 100 kg batch. You can use this to work out the MSNF and Fat concentrations in your mix. You can use this information to calculate if your mix is balanced

 

I have updated the On Line spreadsheet to enable the correct values of MSNF and fat to be calculated using cream of 27% fat. Have a go at doing the calculations.

 

I have looked at the new results.

 

As discussed your sugar concentration is too high. The fat concentration is now closer to what one would expect for the 'gelato' you make. We have already discussed emulsifier. Note that your MSNF is lower than optimum. But your mix adds up to more than 100 so caution is needed.

 

Happy to PM a screen shot of the calculations.

 

2. Please give me some information on the stabiliser used.

 

Your mix has a FPDF of around 25-assuming stabiliser does not contain sugars. This will give a  hard sorbet if served at -18C. With the amount of stabiliser added I would expect this to take some time to get soft!

 

Commercial sorbet stabilisers should reduce melting rate hence my query re the stabiliser used.

 

Your mix is also slightly too sweet! You need to reduce the sucrose a little and replace it with dextrose. This will also make the sorbet softer and may increase melting rate if the stabiliser is not changed.