You forget that the sentence itself is stupid. Some sugar can be eaten, no one "eats sugar". Someone can "eats sugar" in case of hypoglycaemia, that - as anyone can understand except DL - is a medical term ( = "low blood sugar"= "when blood sugar decreases to below normal levels. This may result in a variety of symptoms including clumsiness, trouble talking, confusion, loss of consciousness, seizures or death" - see Wikipedia), NOT a sentence in a language course. And no one has a look to the 188 severe comments in SIX YEARS!
I guess (someone correct me if I am wrong), that you can say both "lo zucchero" and "zucchero" (without an article) interchangibly, the same way you would say in English "I eat sugar" or "I eat the sugar", unless you really want to specify that it is THE sugar (and not the salt) that you are eating. in which case it would be "tu mangi lo zucchero" and not "tu mangi zucchero". Correct? That is what I understand.
This is usually true. However, please keep in mind that Italian can vary greatly between regions and especially between North and South, so sometimes you can meet an Italian person who only uses "lo zucchero" and another who only says "zucchero". Strictly grammatically speaking though, you would be correct :)))
"There are several winemaking processes that see sugar added in order to improve or stylistically alter the finished wine (!!!), in addition to the natural sugars found in grapes.One such process is chaptalisation, named after its French originator Jean Antoine Chaptal." This is why Italian wines are the best: this trick, in Italy, is unknown (and, anyway, punished by law)
Only certain nouns have the quality of not being strict with article use; they are usually those nouns that rarely use a plural form, because the noun is something of an implied plural already. Nouns that would be awkward in English to use the indefinit article, for example, you wouldn't say "I eat a sugar". Sometimes these nouns get "de" or "di", or their respective plural form, in front of them instead.
As a beginner, I'm starting from the bottom without knowing any Italian word. How would I know the meaning of "zucchero" if I had never seen the word before? Besides, the course hasn't shown any previous explanation of the word like by a picture for instance. This one for me was hard to guess. I'd never know that haha