You should crush the olives under inert gas (nitrogen or argon)

You should crush the olives under inert gas (nitrogen or argon)

Sorry, the question was not correct. I mean to inactivate the enzymes just AFTER the crushing, sampling the pastes during the malaxation and inactivating the enzymes in the sample picked up. Now it's amended.

Before crushing, you do blanching in alkaline condition (o.o5%) so you can preserve color as well as inactivate blanching. If the sample size is small you can use microwave otherwise you use hot water.

The enzyme lypoxigenase can best be inactivated by heat treatment. We have observed that in case of rice bran the enzyme could be inactivated by elevating its temperature to about 100 degree centigarte.

DVKSamuel

Lipoxygenase is commonly inactivated by heat treatments. temperatures above 60 degrees C will do. steam or microwave can be used as heat source.

Thank you for the answers, but i cannot use heat. I'll explain what the experiment is meant for more deeply: i'll pick up samples of olive pastes from the malaxer at regular intervals in order to create a kynetic model of the evolution of volatile compounds during the malaxation. To stop the lipoxygenase cascade, that lead to the production of volatiles, i need a chemical agent inside the vial that will be filled with some grams of olive paste. That will stop the reactions and freeze the volatile composition at the time the sample was picked up. The vials with sample and inhibitor will be stored in freezer until analyses. I've found some indications in the literature about Calcium cloride saturated solution as an inhibitor, if you know of more and/or better inhibitors i'll be grateful if you could share. Thank you in advance.

I think the best method foe deactivation of lipoxygenase is in your case is by adding inhibitor

You may try the inactivation of lipoxygenase by changing the pH.

http://lib3.dss.go.th/fulltext/Journal/J.AOCS/J.AOCS/1999/no.10/oct1999,vol76,no10,p1163-1168.pdf

You might consider to use tannic acid. Tannic acid forms complexes with proteins in general and also might inactivate enzymes as these are only a special form of proteins. We know from our activities in the brewing industry that barley-LOX activity can be reduced by the addition of tannic acid at mashing-in.

To all contributors, Thank you very much for your advices.

You have the same problem with the soymilk. I have worke on the acceptability of the soymilk in the past as you might know, ther is that so called beany flavor due to the action of lypoxygenase. what we did was just, immediately pouring the grounded soybean in hot water ( 80 degree C) to inactivate the enzyme. There is a work that has been done at Cornell University in ithaca new york that you can refer to. and that method is called cornell Method...

My experience is with LOX from tomato, not olive, however we do use saturated calcium chloride, or diatomaceous earth (hydromatrixTM), and this does inactivate LOX at room temp, advantageous for extraction of volatiles (with the diatomaceous earth we obtain a thick paste and this can be used for extraction of the volatiles by accelerated solvent extraction).

Flavonoids are known to inhibit lipoxygenases. The cheapest source, probably green tea (epicatechin) may be able to provide the inhibition required for your assay. Non-flavonoid polyphenols such as caffeic acid and resveratrol may also be potent inhibitors in your system.

If the LOX enzymes are still membrane/substrate bound in your system small molecules like epicatechin might have an advantage compared to tannic acid due to their smaller size and easier access to sterically hindered access points on the enzyme especially when it is still attached to membranes or other substrates. However, in the brewing application the native beer polyphenols, similar in structure to tea flavonoids, are not capable of deactivation the barley LOX enzymes in the malt. You need the higher molecular weight, more reactive tannic acid to do that.

Hello, in the extraction process off soy oil happens something similar, when you crush de grains, the LOX activates and produce oxidation reactions. The way to prevent this, is cook the grains or submerge them in aqueous alcohol. The disadvantage of this process is the reduction of the nutritional value and the high cost. Maybe you can try this, in olives.

Check this reference: http://www.sanutricion.org.ar/pdf/soja.pdf

Pilar Fallas. Costa Rica.