Antioxidant capacity and mineral content of pulp and peel from commercial cultivars of citrus from Brazil
Highlights
► Brazilian citrus were analyzed in relation to antioxidants and minerals. ► Peels presented higher contents of minerals and phenolics than pulps. ► Pulps had higher concentrations of ascorbic acid. ► Ponkan peel presented the highest antioxidant capacity. ► Antioxidant capacity of citrus was correlated both to vitamin C and phenolic constituents.
Introduction
In recent years, clinical trials and epidemiological studies have established an inverse correlation between the intake of fruits and vegetables and the occurrence of chronic diseases, the most prevalent causes of death in the world. This protective effect has been attributed to the antioxidant properties, which coordinate and balance the body system to protect tissues and fluids from damage by reactive species or free radicals (Huang et al., 2005, Patil et al., 2009).
Citrus fruits (Rutaceae family) are an important source of antioxidants such as ascorbic acid, carotenoids, flavonoids, and other phenolic compounds (Abeysinghe et al., 2007, Ghasemi et al., 2009, Rapisarda et al., 2008), and also some essential minerals for human nutrition (Gorinstein et al., 2001, Topuz et al., 2005). Among the phenolic compounds, flavanones are the major group found in citrus. Studies have shown that intake of flavonones is associated with reduced risk of developing coronary heart disease, degenerative diseases and have received increasing attention as anti-carcinogenic compounds because of their anti-lipid peroxidation (Benavente-Garcia & Castillo, 2008).
Brazil is one of the major citrus producers, responsible for 20.5 million tons (MT) of citrus annually. Oranges (18.5 MT), mandarins (1 MT) and acid limes (1MT) are the major production (FAO, 2008). Approximately 2 MT are destined to the fresh fruits market, and according to data from IBGE – Brazilian Institute of Statistics Family Budget Surveys (IBGE, 2010), the citrus acquisition accounted for 25% of total fruits acquired by households in the country. The remaining production, about 90%, is destined to the juice industry (Ladaniya, 2008), generating a large amount of byproducts that account for 50% of the original whole fruit weight (Anagnostopoulou et al., 2006, Marín et al., 2007).
During citrus fruit processing to make juice, peels are the primary byproducts. If unused, they become waste and a possible source of environmental pollution. These byproducts have been traditionally used as molasses for animal feed, fibre (pectin) and for fuel production (Li, Smith, & Hossain, 2006). However, studies conducted on several fruits (citrus, apples, grapes and berries) have shown that peels are the major source of natural antioxidants. Therefore, phenolic compounds in peels and fruit byproducts can be used in food products as active ingredients or as substitutes for synthetic preservatives (Gorinstein et al., 2004, Ignat et al., 2011), and have been associated with health problems.
Citrus species of various origins have been studied due to their phenolic compounds and antioxidant capacity (Abeysinghe et al., 2007, Ghasemi et al., 2009, Gorinstein et al., 2001, Rapisarda et al., 2008). However, it is known that the chemical composition of fruits suffer variations according to climate, fertilisation applied, soil type, cultivar, fruit maturity, and even between parts of the same fruit. There are no studies comparing the potential health properties of pulp and peel of citrus from Brazil. Therefore, the aim of this study was to determine the antioxidant capacity, phenolic compounds, vitamin C and minerals of five commercial varieties of citrus from a Brazilian central region.
Section snippets
Plant materials
Four species of citrus: two cultivars of sweet oranges (Citrus sinensis cv. Pera and cv. Lima); two species of limes (C. latifolia Tanaka cv. Tahiti and C. limettioides Tanaka cv. Sweet lime) and one cultivar of mandarin (Citrus reticulata Blanco cv. Ponkan) were harvested at a local farm in the state of Goiás, Midwest of Brazil. For each variety, 100 fruits were picked from trees in the four quadrants (North, South, East and West), using a randomized design on June 2010. For the analyses
Physical characteristics
The quality parameters, including mean weight, juice yield, the peel/whole fruit ratio, pH, TSS, TA and TSS/TA ratio of citrus juices are shown in Table 1. The mean weight of fruits ranged from 109 ± 3 to 218 ± 13 g, with Pera and Lima varieties being the largest ones and Tahiti the smallest. The Lima orange had the highest juice yield (47.3%), and the Tahiti had the lowest (35.5%). The Ponkan mandarin and Pera orange had the highest peel/whole fruit ratio (29.1 ± 2.0 and 27.8 ± 0.8, respectively) and
Acknowledgments
Thanks to Fazenda Córrego Grande producer which provided the samples and CAPES (Coordenação de Aperfeicoamento de Pessoal de Nivel Superior) for the scholarship to H.R.M.B.
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