Yoghurt is a popular dairy product enjoyed by millions of people in Nigeria. This delicious and nutritious food is made by fermenting milk with beneficial bacteria known as yoghurt cultures. One of the most important steps in making yoghurt is refrigerating it after it has been fermented. The refrigeration process helps to slow down the growth of bacteria, which can cause spoilage and make the yoghurt go bad. For many yoghurt vendors in Nigeria, the refrigeration process poses a bit of an issue due to unstable electricity supply preventing the supply of fresh batches to their customers. But what exactly happens when yoghurt is refrigerated and why is it an important part of the process? These are questions we sought to answer.
When yoghurt is refrigerated, several things happen that affect its taste, texture, and overall quality. There is a science behind refrigerating yoghurt that explains what happens to it over time.
Temperature and Bacteria Growth
Refrigeration is the process of keeping food at a low temperature to slow down the growth of bacteria and other microorganisms. The ideal temperature for refrigerating yoghurt is between 36-40°F (2-4°C). At this temperature range, the growth of bacteria is slowed down significantly, which helps to keep the yoghurt fresh and safe to eat for a longer period.
Yoghurt Culture Activity
Yoghurt cultures are living organisms that are responsible for fermenting the milk and turning it into yoghurt. These cultures are added to the milk before fermentation, and they continue to multiply and metabolise during the fermentation process. When yoghurt is refrigerated, the activity of these cultures slows down significantly, which can affect the taste, texture, and consistency of the yoghurt.
The longer yoghurt is refrigerated, the more the yoghurt cultures become inactive, and the yoghurt becomes thicker and tangier. However, if the yoghurt is left in the refrigerator for too long, the yoghurt cultures may die, and the yoghurt will become sour and unpalatable.
Another common issue that occurs when yoghurt is refrigerated is separation. This occurs when the yoghurt liquid (whey) separates from the yoghurt solids, resulting in a watery and less creamy texture. This separation occurs due to a process called syneresis, which happens when the yoghurt is stored at a low temperature for an extended period.
To prevent separation, it is important to store yoghurt properly. Make sure to store the yoghurt in an airtight container and avoid stirring it too much, as this can break down the yoghurt and cause separation. Also, try to consume the yoghurt within a week of opening the container to prevent separation from occurring.
Flavour and Texture Changes
When yoghurt is refrigerated, its flavour and texture can change significantly. As mentioned earlier, the longer yoghurt is refrigerated, the more sour and tangy it becomes. This change in taste is due to the activity of the yoghurt cultures, which continue to ferment the milk even after it has been refrigerated.
Additionally, refrigeration can cause the yoghurt to become thicker and more viscous, which can affect its texture. This change in texture occurs due to the separation of the yoghurt liquid (whey) from the yoghurt solids, which can make the yoghurt feel gritty and less smooth.
In conclusion, refrigeration is an essential step in storing yoghurt to maintain its quality and freshness. When yoghurt is refrigerated, the temperature slows down the growth of bacteria, which prevents spoilage and keeps the yoghurt safe to eat for a more extended period. Additionally, refrigeration affects the activity of the yoghurt cultures, causing the yoghurt to become tangier and thicker over time. Whether you’re a vendor or a consumer, refrigerating your yoghurt correctly is very important.
It is essential to store yoghurt correctly to prevent separation and maintain its taste and texture. Always store yoghurt in an airtight container, avoid stirring it too much, and consume it within a week of opening the container.