is calculated from the specific gravity of the sake and indicates the sugar and alcohol content of the sake on an arbitrary scale. Typical values are between −3 (sweet) and +10 (dry), equivalent to specific gravities ranging between 1.007 and 0.998, though the maximum range of can go much beyond that. The must be considered together with to determine the overall perception of dryness-sweetness, richness-lightness characteristics of a sake (for example, a higher level of acidity can make a sweet sake taste drier than it actually is). () indicates the concentration of acid, which is determined by titration with sodium hydroxide solution. This number equals the milliliters of titrant required to neutralize the acid in of sake. () indicates a taste of umami or savoriness. As the proportion of amino acids rises, the sake tastes more savory. This number is determined by titration of the sake with a mixture of sodium hydroxide solution and formaldehyde and is equal to the milliliters of titrant required to neutralize the amino acids in 10 mL of sake. Sake can have many flavor notes, such as fruits, flowers, herbs, and spices. Many types of sake have notes of apple from ethyl caproate and banana from isoamyl acetate, particularly . In addition to apples and bananas, other fruits mentioned as flavor notes for fruity sake, especially ginjō-shu, include melons, grapes, peaches, pineapples, citrus, etc. Serving sake In Japan, sake is served chilled (), at room temperature (), or heated ( ), depending on the preference of the drinker, the characteristics of the sake, and the season. Typically, hot sake is a winter drink, and high-grade sake is not usually drunk hot because the flavors and aromas may be lost. Most lower-quality sake is served hot because that is the traditional way, and it often tastes better that way, not so that flaws are covered up. There are gradations of temperature both for chilling and heating, about every , with hot sake generally served around , and chilled sake around , like white wine. Hot sake that has cooled ( ) may be reheated. Sake is traditionally drunk from small cups called or () and poured into the from ceramic flasks called . This is very common for hot sake, where the flask is heated in hot water, and the small cups ensure that the sake does not get cold in the cup, but it may