Table 2.

Some examples of strategies undertaken to improve the performance of enzymes with applications in food and feed.

Enzyme	Role	Targeted improvement	Strategy/comments	Reference
α-amylase	Starch liquefaction	Thermostability	Protein engineering through site-directed mutagenesis. Mutant displayed increased half-life from 15 min to about 70 min (100°C).	[70]
	Starch liquefaction	Activity	Directed evolution. After 3 rounds the mutant enzyme from S. cerevisiae displayed a 20-fold increase in the specific activity when compared to the wild-type enzyme.	[71]
	Baking	pH-activity profile	Protein engineering through site-directed mutagenesis	[72]
l-arabinose isomerase	Tagatose production	pH-activity profile	Protein engineering through directed evolution	[73]
Glucoamylase	Starch saccharification	Substrate specificity, thermostability and pH optimum	Protein engineering through site-directed mutagenesis	[74]
Lactase	Lactose hydrolysis	Thermostability	Immobilization	[75]
Pullulanase	Starch debranching	Activity	Protein engineering through directed evolution	[76]
Phytase	Animal feed	pH-activity profile	Protein engineering through site-directed mutagenesis	[77]
Xylose (glucose) isomerase	Isomerization/epimerization of hexoses, pentoses and tetroses	pH-activity profile	Protein engineering through directed evolution. The turnover number on D-glucose in some mutants was increased by 30%–40% when compared to the wild type at pH 7.3. Enhanced activities are maintained between pH 6.0 and 7.5.	[78]
		Substrate specificity	Protein engineering through site-directed mutagenesis. The resulting mutant displayed a 3-fold increase in catalytic efficiency with L-arabinose as substrate.	[79]