831 Research Article Received: 16 February 2011 Revised: 17 June 2011 Accepted: 12 August 2011 Published online in Wiley Online Library: 12 October 2011 (wileyonlinelibrary.com) DOI 10.1002/jsfa.4654 Variations in antioxidant properties of strawberries grown in Brazilian savannah and harvested in different seasons L´ ıvia de L de O Pineli, a* Celso L Moretti, b Juliana SQ Rodrigues, a Danielle B Ferreira c and Marileusa D Chiarello d Abstract BACKGROUND: Strawberries are nutritive fruits and a source of antioxidants. We evaluated antioxidant properties of ‘Camino Real’ strawberries grown in the Brazilian savannah, harvested in different seasons. Analytical and meteorological data were analyzed by partial least squares regression. RESULTS: Fruits from May showed the lowest contents of total phenolics (1789.78 mg kg -1 fresh weight (FW)), catechin (21.37 mg kg -1 FW), quercetins (4.89 mg kg -1 FW) and total ellagic acid (208.68 mg kg -1 FW) and the lowest antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) (11.39 mg Butylated hydroxytoluene (BHT) eq. g -1 FW) and ferric reducing antioxidant power (FRAP) (22.01 mg ferrous sulfate eq. g -1 FW) assays. Strawberries harvested in July presented the lowest concentrations of total (190.61 mg kg -1 FW) and individual anthocyanins (73.88 mg kg -1 FW and 5.96 mg kg -1 FW for pelargonidin-3-glucoside and cyanidin-3-glucoside, respectively), but the highest contents of vitamin C (685.47 mg kg -1 FW), DPPH (18.87 mg BHT eq. g -1 FW) and FRAP (39.30 mg ferrous sulfate eq. g -1 FW). The highest contents of free ellagic acid (26.11 mg kg -1 FW), pelargonidin-3-glucoside (291.82 mg kg -1 FW) and cyanidin-3-glucoside (11.84 mg kg -1 FW) were found in strawberries from September. Rain in the previous 30 days to harvest influenced negatively many phenolics and antioxidant activity of strawberries harvested in May. In July, longer photoperiod and lower temperature at 30 days previous to harvest probably led to higher antioxidant activity and vitamin C. Increased photoperiod and temperature at the final stage of maturation seem to raise pigments and free ellagic acid in strawberries. CONCLUSION: It was possible to observe significant relationships among meteorological and antioxidant variables for strawberries grown in the Brazilian savannah. c  2011 Society of Chemical Industry Keywords: strawberry; antioxidants; seasonality; meteorological variables; partial least squares regression (PLS) INTRODUCTION Antioxidants from fruits and vegetables are considered an important protection factor against oxidative stress and its deleterious consequences to human health. Strawberry (Fragaria × ananassa Duch.), a very popular berry with high visual appeal and desirable flavor, is also considered a good source of antioxidants, mainly due to its high vitamin C and phenolic contents. Phenolic classes commonly found in strawberries are hydroxybenzoic acids (gallic and ellagic acids), hydroxycinnamic acids (p-coumaric), hydrolysable tannins (ellagitannins), flavonols (quercetin, kaempferol and myricetin), flavan-3-ols (catequins), and anthocyanins, with pelargonidin-3-glycoside as the most important flavonoid pigment. 1 In vivo 2 and in vitro 3 studies have been recently carried out to establish the effects of strawberries on free radical scavenging and on the prevention of cardiovascular diseases. However, it is important to consider that the protective effect of antioxidants can be dose dependent and that antioxidant contents in strawberries can vary due to many factors, given that phenolic compounds are products of secondary metabolism. 4 Genotype and environmental conditions can influence physical and chemical characteristics of strawberries. 5–8 A complex interaction between temperature, rain, day duration, background radiation and humidity determines yields and quality of strawberry cultivars in a given region. 9 Therefore, when a cultivar is selected for a certain environmental condition, but is grown in another one, changes in yield and fruit quality are expected. Differences can be also observed among seasons for a given region. In Brazil, strawberries are grown in tropical, subtropical and temperate climates. Over the last few years, production has expanded to places varying from mild to hot tropical wet – dry climates, such as ∗ Correspondence to: L´ ı via de L de O Pineli, College of Health Sciences, University of Brasilia, Brasilia, DF, 70910-900, Brazil. E-mail: liviapineli@unb.br a College of Health Sciences, University of Brasilia, Brasilia, DF, 70910-900, Brazil b Postharvest Laboratory, Embrapa Vegetables, Brasilia, DF, 70359-970, Brazil c National Meteorology Institute, Development and Research Coordina- tion – CDP, Brasilia, DF, CEP 70680-900, Brazil d Catholic University of Brasilia, Brasilia, DF, 71966-700, Brazil J Sci Food Agric 2012; 92: 831–838 www.soci.org c  2011 Society of Chemical Industry