How much Alcohol USP is required to preserve 1L of syrup containing 500 g sucrose?
Volume preserved by sucrose = 500 g x 0.53 ml/g = 265 ml Volume occupied by sucrose = 500 g x 0.647 ml/g = 324 ml Free water equivalent = 1000 ml – 265 ml – 324 ml = 411 ml Volume of alcohol required to preserve the product is 411 ml x 18% = 74 ml 74 ml Absolute alcohol รท 95% = 78 ml Alcohol USP If other dissolved solids are present, their volume (often estimated) is subtracted from the free water volume. If glycerin is present, its volume preserves an equal volume of free water. If propylene glycol is present, it is considered equivalent to ethanol.
