Journal of Food Research; Vol. 8, No. 2; 2019 ISSN 1927-0887 E-ISSN 1927-0895 Published by Canadian Center of Science and Education 48 A New Spectrophometric Method For The Analysis Of Fructose, Glucose And Sucrose, Using 2-Thiobarbituric Acid And Zero-Valent Iron Powder (ZVIP) Karine Assaker 1 & Jamil Rima 2 1 Platform of Research and Analysis in Environmental Sciences, PRASE, Doctoral School for Sciences and Technologies, Hadath Campus, Lebanese University, Lebanon 2 Laboratory of Physical chemistry and Environmental Engineering, Faculty of Science II., Lebanese University, Fanar, P.Q. BOX 26 11 02 17 Fanar Matn, Lebanon Correspondence: Jamil Rima, Laboratory of Physical chemistry and Environmental Engineering, Faculty of Science II. Lebanese University Fanar, P.Q. BOX 26 11 02 17 Fanar Matn, Lebanon. Tel: 961-332-1833. E-mail: jrima@ul.edu.lb Received: December 28, 2018 Accepted: January 24, 2019 Online Published: February 18, 2019 doi:10.5539/jfr.v8n2p48 URL: https://doi.org/10.5539/jfr.v8n2p48 Abstract A new spectrophotometric method has been developed for the determination of fructose, glucose and sucrose in fruit juices. The method is based on the oxidation of sugars with zero valent iron powder in acidic pH aqueous solution and bubbled with air. Oxidized by-products were complexed with 2-thiobarbituric and monitored by UV-Vis spectroscopy. The recorded spectra are specifically characteristic for fructose, glucose and sucrose respectively. Calibration curves were studied for each compound and the quantitative determination of carbohydrate concentrations was carried out using an internal standard addition method. The average relative standard deviation is 4% and recovery rate range from 98% to 103% for spiked concentrations of 0.05 – 4 mM carbohydrates. The detection limit are 13, 15 and 12 μM for fructose, glucose and sucrose respectively. The oxidation of carbohydrates gives rise to certain by-products, presents a new method of indirect measurement of carbohydrates. This method is applied in the determination of carbohydrates in juices and other foods in a precise, easy and inexpensive way. Keywords: oxidized by-products, carbohydrates, juices, analysis, and spectrophotometric method 1. Introduction The determination of individual sugar content in fresh fruits and vegetables and their juices is an important chemical analysis carried out to evaluate quality and to detect adulteration or contaminants. Analytical techniques such as high performance liquid chromatography (HPLC) using different separation mechanisms (adsorption, size exclusion, or ion exchange) and various detectors (refractive index, UV absorption, amperometric, etc.), thin-layer chromatography (TLC), and gas chromatography (GC) have been commonly used for qualitative and quantitative analyses of fruit juices (Stober et al., 1998; Arias et al., 2003; Weiß2017). While chromatographic techniques are very accurate, they are time-consuming and require tedious sample preparations. Sugar analyses carried out by enzymatic assays are specific, rapid and reproducible (Whitesides 1984; Matsumoto et al., 1990). However, the analyses require single determinations for each compound, which results in time-consuming procedures and high cost of analysis (Trifiròet al., 1997; Vodnar and Socaciu 2008). Lanza and Li (Lanza Li,B.W. 1984), Li et al. (Li et al., 1996) and Lorimor et al. (Ye et al., 2005) reported the application of Near Infrared (NIR) spectroscopy for the direct analysis of total sugar content in fruit juices (Suhandy et al., 2012). However, they concluded that it was not possible to determine individual sugars with acceptable accuracy or precision by using the transmission mode with a quartz cell path length of 2.2 mm. Giangiacomo and Dull (Giangiacomo and Dull 1986) and Ze’ev Schmilovitch et al. (Schmilovitch et al., 2000) developed NIR models based on transmittance measurements that predicted individual sugars (sucrose, glucose, and fructose) in aqueous mixtures with a standard error of prediction of 0.35-0.69. Improved sensitivity and accuracy for the quantitative analysis of individual sugars in juices have been accomplished by placing the liquid sample on a fiberglass support, eliminating the water and measuring the dry extract by diffuse reflectance