Antioxidant activity characterization of a commercial juice (apple, strawberry and lemon thyme infusion) and comparison with its manufactured equivalent

Abstract

Background: Natural juices are nowadays related with healthy food choices due to their antioxidant properties [1]. Yet processing fruit may alter some of its antioxidant properties [2]. It is, therefore, relevant to compare the total phenol content (TPC) and antioxidant activity (AA), of a commercial fruit juice with its manufactured equivalent. Methods: Ten independent samples of commercial juice (CJ) and ten samples of this equivalent manufactured juice (MJ) were analyzed. The TPC were determinate through the Folin-Ciocalteau test [3], and AA through FRAP and DPPH tests [4]. The t-Student test was applied to compare the TPC of the two juices, the two-way ANOVA was used to compare the AA of the two juices for the two tests and the Spearman coefficient to verify the correlation between TPC and AA. Results: Regarding comparison of the juices for TPC, the results revealed a significant difference between juices. A strong interaction between the 2 factors, juice and method was found, which influences the AA. The AA results revealed no significant difference between methods for MJ in spite of a difference for CJ, Table 1. The Spearman Correlation Coefficient obtained for the association between TPC and AA for FRAP and DPPH tests revealed a strong correlation (R = 0.891 and 0,891, respectively) with statistical significance (p < 0.01), for MJ. Regarding CJ, a weak correlation was found between TPC and AA in both methods (R = 0.479 for FRAP and R = 0.467 for DPPH), without statistical significance (p = 0.162 and p = 0.174 respectively). Conclusion: The results revealed significant differences between the commercial and manufactured juices, which is in accordance to the literature [5]. These results suggest an advantage for commercial juice in which concerns the antioxidant properties.