ANTIOXIDANTIVE ACTIVITY OF DRY AND GERMINATED SEEDS OF AGRICULTURAL CULTURES - Biochemistry and Biotechnology: Research and Development - page 156

The concentration of analyzed antioxidant [InH] 0 is calculated from expression (1) using
the experimentally determined induction period and the known initiation rate W i . The
inhibiting rate constant k 7 , determining the anti-radical activity of the antioxidant and
constituting its quality characteristic, is found from relation (2) using the known constant of
the chain continuation rate k 3 , hydrocarbon concentration [RH], experimentally determined
induction period and the quantity of absorbed oxygen O 2 . The greater the amount of AO in

the sample the greater the period of induction .
A detailed description of the method can be found in [1-4].

R ESULTS AND D ISCUSSION

Experimental data enabled to obtain the total AO content of the examined samples. As an
example, the figure shows the kinetic dependence of absorbed oxygen in a reaction of cumene
initiated oxidation (straight line 1) and the presence of dry seeds of sesame, wheat, “Nut”
peas and milk thistle (curves 2-5). It can be seen from the figure that, in the absence of the
additive, hydrocarbon oxidation proceeds at constant rate (straight line 1). Upon introducing
seeds, the oxidation rate at the initial instant is greatly retarded and begins to increase after
some time, which indicates that there is AO in the additive. The growth of the reaction rate is
due to the expenditure of AO. After its expenditure, the reaction reaches a constant non-
inhibitor reaction rate. The time of AO expenditure (τ) is determined graphically on the
kinetic curve by the point of intersection of two straight lines, one of which is the straight-line
portion of the kinetic curve after AO has been used up. The other is the tangent to the kinetic
curve whose inclination angle is one-half the tangent angle of the first. Data on analysis of
AO are present in the Table 2.

Figure 1. Kinetic Dependences of Oxygen Absorption. 1 - hydrocarbon (cumene) + initiator (AZO-bis-
ISOBUTYRONITRILE, 2 mg), 2 - with sesame added (15.3 mg), τ = 24.5 min, 3 - with wheat added
(91 mg), τ = 51 min. 4 - with “Nut” peas added (33 mg), τ = 63 min. 5 - with milk thistle added (78
mg), τ = 167 min. Hydrocarbon 1 ml, t = 60 0 С.