<Tr> <Td> High temperature </Td> <Td> </Td> <Td> Heating </Td> </Tr> <Tr> <Td> Low temperature </Td> <Td> </Td> <Td> Chilling, freezing </Td> </Tr> <Tr> <Td> Reduced water activity </Td> <Td> </Td> <Td> Drying, curing, conserving </Td> </Tr> <Tr> <Td> Increased acidity </Td> <Td> pH </Td> <Td> Acid addition or formation </Td> </Tr>

Why is sugar or salt added to foods to preserve them