"1% 짜리 음료" is not an entirely clear phrase. 짜리 means a unit item, a representation, or a product as viewed in connection with its value. For example a $20 note is called 20불 짜리 지폐, a pair of pants that costs $100 would be a 100불 짜리 바지. 음료 means a beverage. The phrase may be interpreted as "a beverage diluted to 1%" (1 to 100 dilution). But we don't commonly say it like this. We may say "원액 1% (짜리) 음료" or maybe "농도 1% 음료" (원액 = original syrup, 농도 = concentration). Or "알코올 1% 짜리 음료" (1% alcohol content beverage). So it is hard to say what it exactly means without the context.

Maybe it was "2%". There is a beverage whose name is "2%부족할 때" in Korea. You can search for it.