This is a quote from Stanley Marianski’s Book “The Art of Making Fermented Sausages:
Sugar is mainly added to dry sausage to provide food for starter cultures. The pH drop in sausage depends on the type and amount of sugar utilized. Introduction of more sugar generally leads to lower pH and stronger acidification. What is notable is that lactic bacteria process different sugars differently. Only dextrose (glucose) can be fermented directly into lactic acid and by all lactic bacteria. Other sugars molecular structure must be broken down until monosaccharides are produced and this takes time and some lactic bacteria are more effective than others. Sugar introduction also helps to offset the sourly and tangy flavor of fastand medium-fermented sausages and acts as a minor hurdle in lowering water activity. The types of sugar which may be used in making fermented sausages are listed in order of their importance on producing lactic acid by lactic acid bacteria:
glucose – “dextrose” is glucose sugar refined from corn starch which is approximately 70% as sweet as sucrose but it has an advantage of being directly fermented into lactic acid and is the fasted acting sugar for lowering pH. As lowering pH is the main hurdle against bacteria growth in fast-fermented sausages, dextrose is obviously the sugar of choice. It can be easily obtained from all sausage equipment and supplies companies.
sucrose – common sugar (also colled saccharose) made from sugar cane and sugar beets but also appears in fruit, honey, sugar maple and in many other sources. It is the second fastest acting sugar. It can be used with GDL in medium-fermented sausages. In slow-fermented sausages common sugar should be chosen as it has been used for hundreds of years. There is no need to lower fast pH and sugar contributes better to a strong curing color and better flavor.
maltose – malt sugar is made from germinating cereals such as barley, is an important part of the brewing process. It’s added mainly to offset sour flavor and to lower water activity.
actose – also referred to as milk sugar is found most notably in milk. Lactose makes up around 2-8% of milk (by weight). Maltose and lactose are less important as primary fermenting sugars but may be used in combinations with common sugar to bring extra flavor.
About 1 g (0.1%) of dextrose per 1 kg of meat lowers pH of meat by 0.1 pH. This means that 10 g of dextrose added to meat with initial pH value of 5.9 will lower pH by one full unit to 4.9. Sugar levels of 0.5% – 0.7% are usually added for reducing pH levels to just under 5.0.
When using acidification as a main safety hurdle, salami is microbiologically stable when pH is 5.2 or lower and this normally requires about 48 hrs fermentation time for fast-fermented product and 72 – 96 hours for medium-fermented type. In slow-fermented salami pH does not drop lower than 5.5 but the sausage is microbiologically stable due to its low moisture level (prolonged drying).