Degradation of β-carotene during fruit and vegetable processing or storage: reaction mechanisms and kinetic aspects: a review

Introduction. Food processing significantly lowers the quality of fruits and vegetables, which is a major concern for the food industry. Micronutrients are particularly affected, and among them beta-carotene, which exhibits very interesting sensory, nutritional and biological properties. The literature concerning beta-carotene degradation is extensive, but the conclusions are very different as a function of the biological, chemical and food transformation points of view. This paper proposes a synthesis of complementary approaches in the study of beta-carotene during food transformation and storage. Degradation reactions. Degradation compounds are numerous, including isomers, epoxides, apocarotenones, apocarotenals and short-chain cleavage products, among them some flavour compounds. A detailed reaction scheme of isomerisation and autoxidation of beta-carotene could be deduced from the literature data. The main pathways are well documented, but the global reaction scheme is still incomplete. Furthermore, most of the mechanistic studies are carried out in model systems, thus data may misrepresent beta-carotene behaviour in real food products. Kinetics during processing and storage. The determination of degradation kinetics permits the identification of the fastest reactions, i.e., generally those with the greatest impact, and also the quantification of the effect of the factors which can lower beta-carotene content. Temperature, occurrence of oxygen, food composition and food structure are shown to affect the beta-carotene loss rate significantly. However, the methodologies used to obtain the kinetic parameters are of major importance, and finally, most of the results found in the literature are specific to a study and difficult to generalise. Discussion and conclusion. Mechanistic and kinetic approaches each provide interesting data to improve understanding and monitoring of beta-carotene. The combination of all this data, together with thermodynamic and analytical considerations, permits the building of observable reaction schemes which can further be transcribed through mathematical models. By this multidisciplinary approach, scarcely used for the time being, knowledge could be capitalised and useful tools could be developed to improve beta-carotene retention during food processing and storage.