Food Biochemistry and Food Processing (2 edition)

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14 Seafood Enzymes: Biochemical Properties and Their Impact on Quality 279

(A) Hydrolysis:

RCOOR′+H 2 O ↔ RCOOH + R′OH

(B) Synthesis:

Reactions under this category can be further separated:

(a) Esterification

RCOOH + R′OH ↔ RCOOR′+H 2 O

(b) Interesterification

RCOOR′+R′′COOR• ↔ RCOOR•+R′′COOR′

(c) Alcoholysis

RCOOR′+R′′OH ↔ RCOOR′′+R′OH

(d) Acidolysis

RCOOR′+R′′COOH ↔ R′′COOR′+ RCOOH

Figure 14.8.Lipase reactions.

37 ◦C. The enzyme was stable up to 45◦C for 15 minutes and in

the pH range 5–9.5 after a 1-hour incubation period. A lipase

from the hepatopancreas of red sea bream was purified and char-

acterized by Iijima et al. (1998). The enzyme was extracted by

a combination of anion exchange, hydrophobic interaction, and

gel filtration. The MW of the lipase was 64 kDa and the enzyme

exhibited the maximal activity at pH 7–9. The lipolytic activity

of the red sea bream enzyme is Ca^2 +independent. Lipase was

purified from tilapia intestine using ion exchange, chromatofo-

cusing, and gel filtration chromatography techniques (Taniguchi

et al. 2001). The temperature optimum was 35◦C and it was sta-

ble below 40◦C. The pH stability fell within the relatively narrow

range of 6.5–8.5 and the highest activity was at pH 7.5, typical

of corresponding mammalian lipases and those from other fish

species. The inclusion of bile salts caused an approximate 9-fold

increase in the enzyme activity. The tilapia lipase’s MW of 46

kDa, pH of 4.9 and efficient hydrolysis of soybean and coconut

oils are characteristics similar to mammalian lipase. A lipase

was partially purified from the viscera of grey mullet by ammo-

nium sulfate fractionation, ultrafiltration, and cholate-Sepharose

affinity chromatography (Aryee et al. 2007). Optimum activity

againstp-nitrophenyl palmitate was displayed at pH 8. The tem-

perature optimum was 50◦C. Grey mullet lipase is completely

stable in several water-immiscible organic solvents, suggesting

that it may have potential applications for synthesis reactions in

organic media.

Recently, Cherif and Gargouri (2009) purified crab di-

gestive lipase from crab hepatopancreas by heat treat-

ment, DEAE–cellulose, ammonium sulfate precipitation, S-200,

Mono-Q, and S-200. The enzyme had a molecular mass of 65

kDa. The maximum activity of crab lipase appeared at pH 8.

Lipase activity was compatible with the presence of organic sol-

vents, except for butanol. Furthermore, the hydrolysis was found

to be specifically dependent on the presence of Ca^2 +to trigger

the hydrolysis of tributyrin emulsion.

Fish Lipase Applications

Lipases have been widely used for biotechnological applica-

tions in detergents, and dairy and textile industries, production

of surfactants and oil processing. Recently, lipases have received

considerable attention with regard to the preparation of enan-

tiomerically pure pharmaceuticals, since they have a number of

unique characteristics: substrate specificity, regiospecificity, and

chiral selectivity (Cherif and Gargouri 2009). Because of their

high affinity for long chain fatty acids, specificity for particu-

lar fatty acids and regiospecificity (Kurtovic et al. 2009), fish

digestive lipases may find applications in the synthesis of struc-

tured lipids. Using lipases, TGs could be enriched with certain

beneficial fatty acids, like eicosapentaenoic acid or docosahex-

aenoic acid at a specific position along the glycerol backbone.

Enzymatic synthesis of modified lipids using lipases could be

economically more attractive than chemical synthesis because

of the lower energy requirements and specificity. In addition,

long-chain PUFAs are highly labile and lipase-catalyzed lipid

modifications could prevent detrimental oxidation andcis-trans

isomerization processes. Lipases have the important physiolog-

ical role of preparing the fatty acids of water-insoluble triacyl-

glycerols (TAG) for absorption into and transport through mem-

branes by converting the TAG to the more polar diacylglycerols,

monoacylglycerols, free-fatty acids, and glycerol (Shahidi and

Kamil 2001). Marine lipases are likely to have advantages over

their microbial or mammalian counterparts because they may

operate more efficiently at lower temperatures. Termination of

enzymatic reactions could be achieved by smaller changes in

temperature as marine lipases often have lower temperature op-

tima and stabilities than lipases from other sources. The lipases

do not require potentially hazardous high or low pH media in

contrast to the requirements of many chemically driven reac-

tions. Fish digestive lipases could also carry out lipid inter-

esterification reactions (e.g., transesterification) with minimal

or no by-products, a problem often encountered in chemical