I/GCSE Biology - The Production of Beer and Yoghurt (2024)

FAQs

How is beer made in GCSE biology? ›

The amylase breaks down the starch into maltose, producing a sweet liquid. This liquid is boiled to stop the enzymes and is filtered. Hops are added for taste and yeast is added to ferment sugars. The beer is centrifuged (rotated), filtered and sometimes pasteurised.

Lactobacillus bacteria is added to the milk. It is heated to 40°C and incubated in a fermenter. Lactic acid is produced as the bacteria ferment the lactose sugar in the milk. The lactic acid is what causes the milk to become solidified and clotted to form yoghurt.

Yogurt is a popular fermented dairy product produced by lactic acid bacteria, including Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus. During yogurt production, these bacteria produce lactic acid, decreasing pH and causing milk protein to coagulate.

Growing bacteria

Milk contains sugar called lactose. The Bacteria change the form from lactic acid. The lactic acid curdles the milk and lowers the pH which helps the milk to preserve the yogurt.

What are the steps in making beer? The beer brewing process involves malting, milling, mashing, extract separation, hop addition and boiling, removal of hops and precipitates, cooling and aeration, fermentation, separation of yeast from young beer, aging, and maturing.

Yeast cells multiply in the wort during fermentation breaking down sugars. The myriad of compounds produced at this stage is what gives the beer its unique flavor, aroma, and texture. Aldehydes, esters, and ketones are major contributors here.

The production of yoghurt is a relatively simple procedure. Milk, which can be fortified with milk powder to give a thicker product, is pasteurised, cooled and inoculated with starter bacteria, which ferment the milk, causing it to clot or gel.

Yogurt is made when heated milk is combined with bacteria, specifically Lactobacillus bulgaricus and Streptococcus thermophilus, and left to sit for several hours at a warm temperature (110-115°F). Additional types of lactobacilli and bifidobacteria may be added.

To turn milk into yogurt, these bacteria ferment the milk, turning the lactose sugars in the milk into lactic acid. The lactic acid is what causes the milk, as it ferments, to thicken and taste tart. Because the bacteria have partially broken down the milk already, it is thought to make yogurt easier for us to digest.

The yogurt quality is effected by different factors such as heat processing, incubation temperature, amount of culture inoculated and time of incubation.

What does pH have to do with yogurt? ›

The probiotic benefits, taste and shelf stability of yogurt samples, all depend on accurate pH measurements throughout manufacturing and quality control processes. Therefore, measuring the pH of yogurt becomes an important parameter during manufacturing and also while assessing the quality of the desired product.

Yogurt is traditionally produced from milk and/or cream through the action of two particular strains of LAB – Lactobacillus bulgaricus and Streptococcus thermophilus.

The bacteria in the starter culture work to change the milk sugar lactose into lactic acid. As acidity increases, milk begins the process of turning from a liquid into a solid. To continue the process of becoming a solid, coagulation begins by adding an enzyme called rennet.

Alcohols are produced industrially by hydration of alkenes in the presence of an acid catalyst. Ethanol is produced industrially by fermentation of glucose. The conditions for this process. Ethanol produced industrially by fermentation is separated by fractional distillation and can then be used as a biofuel.

Barley, water, hops and yeast, yes that's all it takes to create the world's most refreshing drink. The basic idea is to extract the sugars from grains (usually barley) so that the yeast can turn it into alcohol and CO2, creating beer. There are three main ways to brew– extract brewing, partial mash, and all-grain.