Available online at www.japt.tpa.usab-tm.ro Journal of Agroalimentary Processes and Technologies 2009, 15 (4), 511-514 Journal of Agroalimentary Processes and Technologies ______________________________________________________ * Corresponding author: e-mail address: glevitzky.mirel-ab@ansvsa.ro Studies Regarding Non-enzymatic Browning of Orange and Apple Juices during Storage M. Glevitzky a* , Gabriela-Alina Dumitrel b , Maria Popa c a Alba Sanitary-Veterinary and Food Safety Directorate, 510217 – Lalelelor Street 7A, Alba Iulia, Romania b “Politehnica” University of Timisoara, Faculty of Industrial Chemistry and Environmental Engineering, 300006 – Victoriei Square 2, Timisoara, Romania c University “1 Decembrie 1918” of Alba Iulia, Faculty of Sciences, 510009 – Nicolae Iorga Street 11-13, Alba Iulia, Romania Received: 14 Octomber 2009; Accepted: 12 November 2009 Abstract The aim of this paper was to evaluate the quality of two juices with or without antioxidants added. The quality of juices was assessed during storage by measuring the rate of non-enzymatic browning and by microbiological analysis. The non-enzymatic browning was monitored by spectrophotometric measurements at 420 nm (A 420 ) for apple juice and at 640 nm (A 640 ) for orange juice. The results demonstrated that the quality of juices during storage could efficiently be improved by adding antioxidants. Keywords: non-enzymatic browning, orange and apple juice, antioxidant, storage 1. Introduction The need to ensure food safety and a higher quality level for food requires the development of some strategies that allows the monitoring of possible microbiological, chemical and physical risks. Such a risk is browning, a phenomenon frequently encountered during food processing and storage, being due to oxidative or non-oxidative reactions [1]. Non-oxidative or non-enzymatic browning is a reaction involving the caramelization phenomenon, the degradation of ascorbic acid and / or the interaction of proteins or amines with carbohydrates [2,3]. The non-enzymatic browning reactions affect the organoleptic characteristics and are responsible for the most important qualitative changes in food during storage, leading to decrease of their shelf life [4]. The microbial spoilage of juices can lead to changes in flavor, odor, turbidity and carbon dioxide formation [5]. In general, browning causes destruction of nutrients and formation of undesirable intermediate compounds, like furfural and 5- hydroxymethylfurfural [6]. Apple and orange juices are the most consumed soft drinks in the world. The nutritional value of orange juice is primarily related to the content of vitamin C. Two of the biggest changes occurring during storage of orange juice are flavor degradation and browning. The ascorbic acid is an antioxidant with the role to slow down the browning reaction. However, the ascorbic acid is easily oxidized and decomposes at high temperatures contributing to the food’s browning. The decomposition of ascorbic acid together with the non-enzymatic browning is the main degradation reaction occurring during storage of orange juice, in particular. Factors influencing the degradation of vitamin C are: oxygen, ascorbic acid concentration, temperature, light, metals, citric acid, etc [7]. The addition of synthetic or natural compounds provides rich resources of antioxidants in pharmaceuticals, cosmetics, including food products [8]. Most often, people add preservatives, antioxidants or conservation methods without knowing how they protect food against spoilage. Benzoic acid, the presence of antioxidants, carbon dioxide, and the lack of oxygen contributes to microbial inhibition [9]. The purpose of the present work was to examine the influence of several natural and synthetic antioxidants on the degree of nonenzimatic browning of two juices varieties (apple juice and orange juice) during storage.