Heat stability of RIKEN NATURAL TOCOPHEROLS


NATURAL TOCOPHEROL:

RIKEN E-Oil, having excellent heat stability and resistance to volatilization, exerts a reliable antioxidant activity on deep fried food products.

When TOCOPHEROL is added to frying oils, the TOCOPHEROL content may gradually decrease in heating procedure. This is interpreted not as TOCOPHEROL decomposition but as TOCOPHEROL being consumed to suppress oxidation of frying oils.

Heat Stability of RIKEN E-oil

Heating conditions	Residual amount
Heated at 40°C for 6 month	95.9%
Heated at 140°C for 2 hours	No change
Heated in rape seed oil at 200°C for 1 hour	97.0%
Heated in rape seed oil at 200°C for 3 hours	90.0%

From Antioxidant Effect to Food Freshness Retention

1) Mechanism of oxidation of fats and oils and function of TOCOPHEROL as an antioxidant:
The formation of peroxides by auto-oxidation of fats and oils occurs by the following mechanism:

Initiation	RH -> R' + H'
Propagation	R´ + O2 -> ROO
	ROO´ + RH -> R'+ ROOH
Termination	R' + R' -> R - R
	R' + ROO´ -> ROOR
	ROO´ + ROO´ -> ROOR + O2
RH : oxidizable substance R' : fatty radical ROO´. : peroxyl radical ROOH : hydroperoxide

In general, edible fats and oils consist of unsaturated fatty acids. The radicals R' and ROO' play an important role in oxidation of unsaturated fatty acids which contain double bonds. Oxidation is inhibited if these radicals are scavenged.

This mechanism of action is the same as that of phenol antioxidants like BHA and BHT. Ascorbic acid (vitamin C) in the figure acts as a synergist and is useful for the reactivation of TOCOPHEROL.

The following substances are also known to act synergistically with TOCOPHEROL: citric acid and EDTA which chelate metals, in particular Cu and Fe, from the reaction system; phospholipids; amino acids; peptides; and melanoidin. To obtain a better effect as an antioxidant it is suggested to use TOCOPHEROL along with a synergist. The amount of TOCOPHEROL and the choice of synergist can be selected according to the application,

TOCOPHEROL scavenges radicals in the following manner:

2) Function of TOCOPHEROL as a food freshness retainer.

TOCOPHEROL is recommended to be used as antioxidants for not only edible fats and oils but also for foods containing fats and oils regardless of the amount.

A rancid odor is generated by the oxidation of lipids and it is emitted independently of lipid content. Even a small quantity of lipid contained in foods materials such as grain is known to be oxidized and causes in unfavorable odor. TOCOPHEROL exhibits an antioxidant effect on such lipids.

Color fading caused by oxidation decreases the commodity value of foods containing carotenoids which exist in shrimps, prawns, salmon and yellow-green colored vegetables such as carrots, sweet potatoes, pumpkins, etc. This problem can also be solved by the antioxidant effect of TOCOPHEROL.
Lipid peroxides formed by oxidation may become associated with proteins in food and cause an unpleasant mouthful. This problem is, of course, solved by TOCOPHEROL.

Consequently, TOCOPHEROL is not only utilized as antioxidant for fats and oils but are also expected to give a freshness retaining effect on foods.