[helene_t]

Another citrus fruit topic:

For new years dinner, I made a decorative desert: Orange sorbet put back into the empty orange halves, topped with wipped chream, a mynt leave, a strawberry and rasped chocolate.

Everything went well, but on the next day, when the left-over ice had been refrozen, it was full of ice crystals so you had to crunch it with a knife before you could eat it.

Sorbet ice from the supermarket can be refrozen without crystal forming. I see on the list of ingridients that they've added lecitine. It makes sense that lecitine prevents crystal forming in the precense of fat, but there's almost no fat in sorbet. Is the fat content in the oranges sufficient? I've never used lecitine myself, in fact I'm not sure where to buy it. Would adding a single egg to one litter of fruit juice be sufficient? Any tricks as to how to mix the thing?

Also, it's little weired that it makes crystals by the second freezing but not by the first. Would it help to defreeze it completely before refreezing? I can imagine that partial defreezing skews the sugar concentration between the part of the ice that was defrozen and the part that wasn't.

[hotShot]

Crystallization is a delicate process, the mix of temperature and purity has to fit. Additionally it depends on the forming of initial start crystals.

Stirring while freezing is usually very important, to prevent crystallization.
Lecitin is an emulgator and helps to disperse water in anything that does not mix well with water. Additionally any substance that solves in water lowers the freezing point of the water. The yolk contains lecitin and it can be used for that, but don't ask me how much you need. But if you made sorbet, you should have enough.

[Al_U_Card]

Sorbet, like milk or ice cream (or even hand cream) is an emulsion. Little particles of one material (liquid usually or finely divided solid) suspended in a medium of another immiscible liquid. Immiscible means like oil and water the two liquids do not mix together but separate into two disctinct parts (phases).

Lecithin in egg yolk (and casein as well as other emulsifying agents) acts to surround the fat particles so that they do not join up together (coalesce) that is why your hollondaise sauce gets creamy without lumps. If, however, you add the lemon juice (or improperly mix the yolk into the hot sauce base) the emulsion "breaks" and you get a lumpy or curdled or separated sauce.

Ice crystals form in any frozen liquid. The smaller the ice crystals, the "smoother" the resulting dessert. The presence of tiny fat (ice cream) or liquid (sorbet) particles that melt differentially to the base give these products their characteristic flavours and mouth "feel". Both of these products are "stirred" during freezing to retard and reduce crystal formation. This insures the smallest particle size crystals possible. During refreezing, if you do not stir, the crystals will form like ice on a lake.

Freeze-thaw cycles tend to break emulsions. Separate phases will freeze out and make the (ad)mixture even more inhomogenious.

You can buy food grade lecithin in most health food stores. It should be melted into the fatty or oil phase of the mixture PRIOR to agitation. The more and harder you agitate, the thicker and more stable will be the final emulsion. (Make your own mayonnaise by hand beating with a fork, a whisk,a Mixmaster or a Braun and see the difference that agitation makes.)

btw, supermarket products have been "homogenized" meaning the particle size of the "droplets" in the emulsion are micron size. They also contain stabilizers as well as very powerful emulsifying agents so the emulsion tends to resist "breaking" under freeze-thaw cycles.

[matmat]

vodka + sugar