Research Article Received: 14 November 2013 Revised: 7 March 2014 Accepted article published: 14 March 2014 Published online in Wiley Online Library: (wileyonlinelibrary.com) DOI 10.1002/jsfa.6654 Phenolic content and ferric reducing–antioxidant power of cow’s milk produced in different pasture-based production systems in southern Brazil Shirley Kuhnen, a* Juliana R Moacyr, a Jaqueline K Mayer, a Bruno B Navarro, a Rafael Trevisan, b Luciana A Honorato, c Marcelo Maraschin d and Luiz C Pinheiro Machado Filho c Abstract BACKGROUND: Phenolic compounds are widely present in forage. However, few studies have been carried out to investigate the presence of these compounds in animal products such as milk. In this study, the total phenolic content (TPC) and ferric reducing–antioxidant power (FRAP) of milk produced under agroecological and conventional management systems in southern Brazil were determined. Three systems were compared: (a) agroecological, with intensive rotational grazing, also known as Voisin grazing (ECO); (b) semi-intensive conventional (SIC); and (c) conventional grazing (CGR) (n = 8 per group). Pastures with distinct and more diverse botanical composition were observed on the ECO farms. RESULTS: Significantly (P < 0.05) lower amounts of TPC were found in agroecologically produced milk in autumn and summer and the CGR system showed the highest FRAP value (P < 0.05) for the samples collected in autumn. Positive correlations where found between the TPC and FRAP values obtained for the milk samples (0.198, P < 0.05), milk FRAP and forage TPC values (0.344, P < 0.05), and the TPC and FRAP values obtained for the forage (0.70, p < 0.01). PCA applied to the UV spectra dataset (200 – 350 nm) clearly distinguished the samples collected from the ECO system in the winter. CONCLUSION: Our results revealed that, under the conditions prevalent in southern Brazil, since the cows were allowed to graze in all of the systems, the TPC and antioxidant capacity of the milk samples showed minimal variation. However, since the forage TPC and FRAP values for the milk were correlated, TPC appears to be a promising variable for the purpose of monitoring forage prior to its selection aimed at enhancing the antioxidant activity of milk. © 2014 Society of Chemical Industry Keywords: agroecological milk; phenolic compounds; sustainable livestock; antioxidant activity INTRODUCTION Plant phenolics are aromatic compounds which possess one or more hydroxyl groups attached to a phenyl ring. They are biosyn- thesized via the phenylpropanoid pathway and act in a broad range of physiological process in plants, such as growth, develop- ment and reproduction. Furthermore, they are frequently involved in plant adaptation to their environment acting, for instance, as phytoalexins, attractants for pollinators, pigmentation contribu- tors and protective agents against damage by UV light. Phenolic compounds in nature can range from simple molecules, such as phenolic acid and flavonoids, to highly polymerized compounds such as tannins and lignins. 1 – 3 There is an increasing interest in phenolics due to their antioxidant properties, which seem to be more effective than vitamin E or C. 4 An adequate daily intake of phenolics is considered to be of great importance for the protec- tion of macromolecules against oxidative damage in cells and thus in the prevention of the development of several health problems, mainly some forms of cancer and coronary heart disease. 5,6 Milk is considered to be a good source of antioxidant com- pounds, including vitamins C and E, carotenoids and phenolics, the ∗ Correspondence to: Shirley Kuhnen, Laboratório de Bioquímica e Morfofisiolo- gia Animal, CCA, Departmento de Zootecnia e Desenvolvimento Rural, Univer- sidade Federal de Santa Catarina, Rod. Admar Gonzaga, 1346, Florianópolis, SC 88034–001, Brazil. E-mail: shirley.kuhnen@ufsc.br a Laboratório de Bioquímica e Morfofisiologia Animal, CCA, Departmento de Zootecnia e Desenvolvimento Rural, Universidade Federal de Santa Catarina, Florianópolis, SC 88034-001, Brazil b Departmento de Botânica, CCB, Universidade Federal de Santa Catarina, Flori- anopolis, SC 88040-970, Brazil c Laboratório de Etologia Aplicada, CCA, Departmento de Zootecnia e Desen- volvimento Rural, Universidade Federal de Santa Catarina, Florianópolis, SC 88034-001, Brazil d Laboratório de Morfogênese e Bioquímica Vegetal, CCA, Universidade Federal de Santa Catarina, Florianopolis, SC 88034-001, Brazil J Sci Food Agric (2014) www.soci.org © 2014 Society of Chemical Industry