Lesson 3 - Mashing Biochemistry SAQ
This lesson provides the opportunity for you to test yourself on the material covered in Lesson 2, Mashing Biochemistry and determine the level to which you have attained the expected outcomes.
SAQ Suggested Response - Q2
* Indicate whether the following statements are true or false. Explain your answers.
a) The function of α-amylase and β-amylase is to degrade two types of protein.
b) β-amylase catalyses the hydrolysis of starch from the non-reducing end.
c) α-amylase has a higher optimum temperature than β-amylase.
d) Maize starch granules have a lower gelatinisation temperature than the large starch granules of barley.
e) A condensation reaction is the opposite of hydrolysis.
f) Enzymes are proteins that speed up reactions.
Response
a) False. Both α-amylase and β-amylase are starch degrading enzymes. Enzymes only work on specific substrates, so they would not be able to form a complex with proteins and catalyse their hydrolysis.
b) True. β-Amylase is an exoenzyme that can only catalyse the production of disaccharides (maltose) from the non-reducing end of starch.
c) True. α-Amylase is more heat stable than β-amylase The optimum operating temperature for α-amylase is 70-75°C compared to 63-65°C for β-amylase.
d) False. The gelatinisation temperature range of maize starch granules (70-80°C) is higher than that of barley large starch granules (61-62°C). Barley small starch granules gelatinise at a similar range of temperatures to that of maize. Fortunately, most of these are broken down during malting.
e) True. Condensation reactions involve joining molecules together with the loss of water molecules, while hydrolysis reactions involve breaking them apart with the addition of water.
f) True. They are biological catalysts that speed up chemical reactions. Being proteins means they can be denatured above certain temperatures and outside of a specific range of pH.