Michigan State University Extension
Preserving Food Safely - 01600629
One or more of the following may cause cloudy jelly:
-Pouring jelly mixture into glasses too slowly.
-Allowing jelly mixture to stand before it is poured.
-Juice was not properly strained and contains pulp. (The clearest jelly comes from juice that has dripped through a jelly bag without pressing. But a greater yield of juice can be obtained by twisting the bag of fruit tightly and squeezing or pressing, or by using a fruit press. Pressed juice should be re- strained through a double thickness of damp cheesecloth or a damp jelly bag; the cloth or bag should not be squeezed).
-Jelly set too fast, usually the result of using too- green fruit, which is extremely high in pectin. (If jelly sets too fast, air bubbles are trapped in it, giving it a cloudy appearance. With a slow-setting jelly, air bubbles are allowed to rise, resulting in improved clarity).