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王小啉

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专业: 食品加工技术

[求助] Activity of lipase in the hydr... 已有2人参与

Activity of lipase in the hydrolysis of emulsified olive oil
The hydrolytic activities of free and immobilized lipase were assayed by the olive oil–water emulsion method, according tothe modification proposed by Soares et al.22 The substrate was
prepared by mixing 50 mL of olive oil with 50 mL of gum arabic
solution (7% w/v). The reaction mixture containing 5 mL of
the oil emulsion, 4 mL of sodium phosphate buffer (0.1mol L?1,
pH 7.0) and either free (1.0mL, 0.1mgmL?1) or immobilized
(≈100 mg) lipase was incubated in a thermostated batch reactor
for either 5 min (free lipase) or 10 min (immobilized lipase) at
37 °C, pH 7.0 and agitation of 80 rpm. A blank titration was done
using a sample in which the enzyme was replaced with distilled
water. The reaction was stopped by the addition of 2mL of
acetone–ethanol–water solution (1:1:1). The liberated fatty acids
were titrated with potassium hydroxide solution (0.04 mol L?1)
in the presence of phenolphthalein as an indicator. All reactions
were carried out in triplicate. One unit (U) of enzyme activity was
defined as the amount of enzyme that liberated 1 μmol of free
fatty acid per min (μmolmin?1) under the assay conditions (37 °C,
pH 7.0, 80 rpm).
Analyses of hydrolytic activities performed on the free and
immobilized lipases were used to determine the total activity
recovery yield, Ya (%), according to Equation (1).
Ya =US÷U0× 100 (1)
where Us is the total enzymeactivity recovered on the support and
Uo is the enzyme units offered for immobilization

where Us is the total enzymeactivity recovered on the support andUo is the enzyme units offered for immobilization.
帮我解释公式的意思？？ @sugz

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