starch saccharification Flashcards
What happens to starch when it is suspended in water and heated?
Starch forms a paste and undergoes gelatinization, which allows enzymes like amylase to access the glycosidic bonds for hydrolysis.
How does amylase affect starch during hydrolysis?
Amylase cleaves the alpha (1→4) glycosidic bonds in starch, producing shorter chains known as dextrins, which decreases the viscosity of the solution.
What is Dextrose Equivalent (DE) and how is it calculated?
DE is a measure of the amount of reducing sugars present in a sugar product, expressed as a percentage on a dry basis relative to dextrose. It indicates the extent of hydrolysis of starch.
What DE ranges classify glucose syrups and maltodextrins?
DE > 55 is ‘high conversion’ glucose syrup, 35 < DE < 55 is ‘regular conversion,’ and DE < 20 classifies as maltodextrins.
What is the significance of glass transition temperature (Tg) in relation to DE?
Tg decreases as DE increases, affecting the physical properties of maltodextrins and influencing their behavior in food products. For example, DE 4 has a Tg of -5°C, while DE 20 has a Tg of -16°C.
Describe the role of pullulanase and isoamylase in starch hydrolysis.
These enzymes are added after alpha-amylase hydrolysis to cleave the alpha (1→6) glycosidic bonds, producing mono- and disaccharides such as maltose and glucose.
How is high fructose corn syrup produced from glucose syrup?
D-glucose keto isomerase converts glucose syrup to high fructose corn syrup to increase sweetness.
What are common applications of maltodextrins in food and pharmaceuticals?
Maltodextrins are used as bulking agents, thickeners, fillers, and in packets of sweeteners due to their functional properties.
How do higher DE glucose syrups compare to lower DE syrups in terms of sweetness and crystallization?
Higher DE glucose syrups are sweeter and less likely to crystallize compared to lower DE syrups, which have longer polymer chains.
