Why invert sugar is useful in jelly making ?!
Answers: answr elaborately
I won't give you an overly elaborate answer because that would be a full lesson in chemistry.
If you are referring to candy jelly such as gummi bears and gum drops, then invert sugar is used because it will not become hard when cooked. Corn syrup behaves similar to invert sugar when cooked and sometimes can be substituted for invert sugar or glucose when making things like nougat candies or gummy candies.
If you are referring to the jelly, used on breakfast toast or peanut butter and jelly sandwiches, that is made with high methoxyl pectin, then invert sugar or corn syrup is used with regular sugar to get a softer set to the jelly. But it is used sparingly because too much will cause the jelly to be more like a thick syrup. Note: High methoxyl pectin requires sugar and acid (lemon or lime juice usually) for it to set.
There is a low methoxyl pectin that is used extensively in commercial kitchens and is recently available to the home consumer. This pectin does not require sugar to set but does require acid plus a calcium compound to set. With low methoxyl pectin you can use no sugar, regular sugar, invert sugar, maple sugar, honey or Splenda. The only low methoxyl pectin I am aware of that is available to the home consumer is Pomona brand pectin. It is readily available in the USA and the UK, and probably other countries as well, where home canning supplies are sold..