Food Biochemistry and Food Processing

14 Part I: Principles

Table 1.9.Changes in Lipids in Cheese Manufacturing

Enzyme or Actions Reaction

Lipolysis
Lipases, esterases Triglycerides →-keto acids, acetoacetate, fatty
acids
Acetoacetate decarboxylase (EC 4.1.1.4) Acetoacetate
H
→acetone
CO 2
Acetoacetate-CoA ligase (EC 6.2.1.16) Acetoacetate
ATP
CoA →acetyl CoA

AMP
diphosphate
Esterases Fatty acids →esters
Conversion of fatty acids
-oxidation and decarboxylation -Keto acids →methyl ketones
Sources:Schormuller 1968, Kilara and Shahani 1978, IUBMB-NC website (www.iubmb.org).

Table 1.10.Lipid Degradation in Seed Germination

Enzyme or Enzyme System Reaction

Lipase (oil body) Triacylglycerol →diacylglycerol
fatty acid
Triacylglycerol →monoacylglycerol
fatty acids
Diacylglycerol →monoacylglycerol
fatty acid
Fatty acid
CoA →acyl CoA
-oxidation (glyoxysome) Acyl CoA →acetyl CoA
Glyoxylate cycle (glyoxysome) Acetyl CoA →succinate
Mitochondrion Succinate →phosphoenol pyruvate
Reverse glycolysis (Cytosol) Phosphoenol pyruvate →hexoses →sucrose

Sources:Bewley and Black 1994, Murphy 1999.

Table 1.8.Enzymatic Lipid Oxidation in Food Systems

Enzyme Reaction

Arachidonate-5-lipoxygenase (5-lipoxygenase, Arachidonate 
O 2 →(6E, 8Z, 11Z, 14Z)-(5S)-

EC 1.13.11.34) 5-hydroperoxyicosa-6-8-11,14-tetraenoate

Arachidonate-8-lipoxygenase (8-lipoxygeanse, Arachidonate 
O 2 →(5Z, 9E, 11Z, 14Z)-(8R)-

EC 1.13.11.40) 8-hydroperoxyicosa-5,9,11,14-tetraenoate

Arachidonate 12-lipoxygenase (12-lipoxygenase, Arachidonate 
O 2 →(5Z, 8Z, 10E, 14Z)-(12S)-

EC 1.13.11.31) 12-hydroperoxyicosa-5,8,10,14-tetraenoate

Arachidonate 15-lipoxygenase (15-lipoxygenase, Arachidonate 
O 2 →(5Z, 8Z, 11Z, 13E)-(15S)-

EC 1.13.11.33) 15-hydroperoxyicosa-5,8,11,13-tetraenoate

Lipoxygenase (EC 1.13.11.12) Linoleate 
O 2 →(9Z, 11 E)-( 13 S)-13-

hydroperoxyoctadeca-9, 11-dienoate

Sources:Lopez-Amaya and Marangoni 2000a,b; Pan and Kuo 2000; Kolakowska 2003; IUBMB-NC website

(www.iubmb.org).