Ascorbic acid determination at low concentrations and in coloured sample is

possible by high performance liquid chromatography, for example, although very expensive equipment and chemicals are necessary (Xi & Masanori, 1995). Ion chromatographic and gas chromatographic methods are lengthier and also very expensive for the determination of ascorbic acid (Mura et al., 1995 and Silva, 2005). The enzymatic method is known to be a very sensitive, specific, simple and useful method, in which the immobilised form of the enzyme is generally used (Akyilmaz & Dinçkaya, 1999). Authors would like to thank FAPEMIG (Fundação de Amparo à Pesquisa do Estado de Minas Gerais), CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) and PROPESQ/UFJF RG 7204 (Pró-Reitoria de Pesquisa e Pós-Graduação da Universidade Federal de Juiz de Fora) for financial

support and grants. “
“The authors regret that in Fig. 1 the labels ‘A’ and ‘B’ which are mentioned in the caption were omitted in the printed figure. The corrected figure appears below, and the authors would like to apologise for any inconvenience caused. “
“Hydrogen peroxide (H2O2) is widely used in food industry for sterilization of equipment related to mixing, transporting, bottling and packing. During sterilization, H2O2 may become incorporated into the surface of bottles and packages check details and thereafter an additional process is required to decompose or remove the residual H2O2 (Hsu, Chang, & Kuo, 2008). Additionally, H2O2 has been widely used for preservation of raw milk due to its bactericidal properties (Haddadin, Ibrahim, & Robinson, 1996). However, excess of H2O2 can bring deleterious effects on the nutritional value of milk such as the degradation of folic acid, which is an essential vitamin to Etofibrate human body (Taher & Lashmaiah, 1992). Moreover, the ingestion of H2O2 at high levels can cause severe gastrointestinal

problems. The addition of H2O2 in milk at any concentration is not allowed in Brazil in such a way that the product containing H2O2 is considered adulterated (Brasil, 2002). In September 2007 Brazilian producers adulterated pure milk sold to manufacturing companies and end users by adding H2O2 due to its low-cost in order to increase the shelf-life of the product (Paixao & Bertotti, 2009). Nevertheless, the presence of adulterants (including H2O2) in Brazilian ultra-high temperature (UHT) processed milks from different regions of the country was recently reported (Souza et al., 2011). There are a few analytical methods for determining H2O2 in milk. A highly sensitive fluorimetric method was described for the determination of H2O2 in milk (Abbas, Luo, Zou, & Tang, 2010). A limitation of this method for routine applications is its prior sample preparation step, which involved a 9-min reaction before measurements. Electrochemical biosensors were also presented for milk analysis (Alpat et al., 2010, Campuzano et al.