Raisins are simply dried sweet grapes, of course. Until medieval times, raisins were the second in choice as a sweetener, honey being the top choice. At one time in ancient Rome, raisins were considered so valuable that two jars could buy a slave. Most raisins are dried naturally by the sun right in the vineyards, although some are mechanically dehydrated. Once sun-dried, a process taking two to four weeks, they are then graded, cleaned, and packed. Some raisins are kept golden in color by the use of sulfur dioxide (sulfites). These are convenient, high energy low fat snack; they are easy to pack, easy to eat and almost never go bad.