How Does The Ph Affect The Fermentation Of Milk

Abstract- This experiment is to determine at what point in the fermentation process milk becomes spoiled. If milk becomes spoiled it will have a terrible smell and usually taste sour but the sour taste does not necessarily mean it is spoiled as cheese and yoghurt are made from slightly fermented milk. Milk spoils and ferments at the same time but at a certain point, the milk will no longer be a good form of fermentation and it will then go on to spoil which means it is unhealthy and potentially dangerous to ingest. This will be experimented by simply measuring the pH levels of four different milk types which are being stored in a refrigerator over a two week period.
Aim- The aim of this investigation is to determine which out of four different

The pH will also show quantitative data of how much the milk has spoiled because the lower the pH gets, the more spoiled/fermented it will become and therefore the worse the spoilage/fermentation will be at the end of the experiment. It will be able to prove the milk is spoiled as the milk will begin to produce a filmy, chunky or possible yellow look to it and the pH level will become lower or the same as what they use to produce cheeses (approx. 5.1-5.9). If it gets to this point, the milk has been spoiled.
Hypothesis- It is hypothesized that the milk with the highest sugar content (trim) will end up with a lower pH than the other milks experimented on. This is because milk with a low sugar content lasts longer than milk with a high sugar content as bacteria grow slower in substances with lower amounts of sugar (EatByDate, 2017). Fermentation is a process in which food is exposed to bacteria and yeasts, naturally through the air. In some cases it is good and is used to make cheese and other dairy products but when it gets to a certain stage it just causes illness and is not healthy to consume. It converts sugar into acids, gases and alcohol. Lactic acid is one of a few causes of creating fermentation. Therefore the more sugar present, the more acid created, the lower the pH level will get and the worse the

, 2017). Although fermentation is good in some cases for the production of cheese and yoghurt, if it gets to a certain point it will only cause illnesses and have a completely opposite effect on the body. The pH level of cheese ranges from 5.1-5.9 with a few exceptions. If the pH of the milk being experimented on gets to a pH level of around 5.1-5.9 it will be clear that the milk has spoiled. During the process of making cheese and yoghurt they use an ingestible range of fermented milk and mix it with a certain bacterial culture which then stops the ‘bad’ fermentation from occurring and makes it safe to consume. If you were to drink the milk being used to make the cheese/yoghurt without it being mixed with a culture then you will most likely become sick. Starter cultures are used early in the cheese making process to assist with the curdling by lowering the pH prior to rennet addition. The bacterial cultures help to prevent the growth of spoilage organisms and pathogens (Kosikowski,