GRIT SANDIG, MARIETTA SEIFERT, THOMAS HERRLING, KATINKA JUNG*
*Corresponding author
Gematria Test Lab GmbH, Berlin, Germany

Abstract

Food product deterioration caused by radical chain reactions can lead to peroxidation processes, decomposition and rancidity. Electron Spin Resonance (ESR) Spectroscopy was used to detect both antioxidant activity and free radical reactions in raw materials and finished products. The Antioxidative Power (AP) of natural extracts, milk powders and tomato sauces decreased over time when oxidation processes occurred. On the other hand, the Radical Potential (RP) as an indicator of oxidation increased in foods like oils, nuts, meat and tomato sauces. Comparison of both parameters showed correlation between decreasing AP and increasing RP values as a result of peroxidation processes. Both methods are valid tools for the characterization and prediction of food and for the evaluation of strategies aimed to increase stability and shelf life.

INTRODUCTION

There are lots of factors in food and food products influencing the taste, colour and texture of a product like processing, storage time and conditions, harvest and growth variability, additives and quality of the raw materials used. Formation of free radicals inside the product is one of the major causes for food deterioration depending on the balance of pro-oxidant and antioxidant ingredients. Pro-oxidants such as singlet oxygen, lipoxygenases, transition metals, light and elevated temperatures are virtually found in all food and cause formation of free radicals, lipid hydroperoxides and further reactive decomposition products. The content of endogenous antioxidants in food products or the addition of known exogenous antioxidants to food preparations increase the oxidative stability of the product inactivating free radicals, pro-oxidants and oxidant intermediates (1). Antioxidants are defined as a heterogeneous class of molecules able to neutralize free radicals and terminate radical chain reactions (Figure 1A). The efficacy of an antioxidant is mainly driven by its oxidation state (1). Indeed, known antioxidants such as Vitamin C (ascorbic acid) ca ...