Answer
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
Maltose is a sugar made out of two glucose molecules bound together. There is nothing in maltose to consider it as unlawful for Muslims.
Responding to your question, Sheikh Ahmad Kutty, a senior lecturer and an Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states;
This is what I found about maltose on the internet:
“Maltose is a sugar made out of two glucose molecules bound together. It’s created in seeds and other parts of plants as they break down their stored energy in order to sprout. Thus, foods like cereals, certain fruits and sweet potatoes contain naturally high amounts of this sugar.
Even though maltose is less sweet than table sugar and fructose, it has long been used in hard candy and frozen desserts because of its unique tolerance to heat and cold.
Thanks to growing public awareness about the negative health effects of high-fructose corn syrup and other sweeteners containing fructose, many food companies are switching to maltose, which contains no fructose.”
In conclusion, “Maltose is found in starchy grains, vegetables and fruits. It is useful as a low-cost sugar source in the form of high-maltose corn syrup.” (Maltose: Good or Bad?)
Based on the above information, I find nothing in maltose to consider it as unlawful for Muslims.
For more, see these fatwas:
Is It Halal to Eat Food Cooked with Wine?
Are Monoglycerides and Diglycerides Halal?
Is Eating Non-Halal Meat Allowed?
Is Food Coloring Derived from Cochineal Insect Halal?
Almighty Allah knows best.