Original Research Article
Pasteurization of blackberry juice preserves polyphenol-dependent inhibition for lipid peroxidation and intracellular radicals
Highlights
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- The pasteurization effect on bioactive compounds in blackberry juices was evaluated.
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- Pasteurization decreased the concentration of anthocyanins but not of ellagitannins.
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- Pasteurized blackberry juice kept the ability to protect against lipid peroxidation.
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- Pasteurized blackberry juice maintained the ability to inhibit intracellular ROS.
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- The pasteurization of blackberry juices did not diminish their functional properties.
Abstract
Berries are commonly consumed as juice, and juice-processing conditions could affect their bioactive compounds. This study evaluated the effect of thermal treatments on the antioxidant capacity of blackberry juice polyphenols. Pasteurized blackberry juices were prepared at 75 °C for 15 s (JP75) and 92 °C for 10 s (JP92). Polyphenol analysis showed that for JP75 and JP92, anthocyanin concentrations decreased significantly, compared to non-pasteurized juice (NPJ), whereas ellagitannins were not significantly affected. The evaluation of the DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging capacity showed a significant decrease of 26% for JP75 and 27% for JP92, and, for the NO (nitric oxygen) scavenging capacity, the activity was reduced 15% for JP75 and 16% for JP92. There were no significant reductions observed for the peroxidation inhibitory capacity of the pasteurized juices for any of the oxidation substrates tested: liposomes, liver homogenates and erythrocytes. Furthermore, the intracellular antioxidant capacity showed no significant differences due to thermal treatments. The concentration of phenols necessary to scavenge 50% of the radical oxygen species was 204 ± 9 μg/mL for NPJ, 219 ± 10 μg/mL for JP75 and 220 ± 9 μg/mL for JP92. This study revealed that pasteurized blackberry juices maintained their biological properties related to inhibition of peroxidation and their capacity to scavenge intracellular radicals.
Keywords
- Blackberry juice;
- Rubus adenotrichos;
- Antioxidant activity;
- Lipid peroxidation;
- Pasteurization;
- Nutrient retention;
- Food processing;
- Bioactive non-nutrient;
- Food composition;
- Food analysis
1. Introduction
Research over the past few years has supported the health beneficial effects of berries. Different trials have demonstrated that berry consumption contributes to protect against cardiovascular disease (Basu et al., 2010) and metabolic syndrome (Basu and Lyons, 2012). Specifically, berry consumption lowers the oxidation of LDL (low density lipoproteins) and is associated with lowering blood pressure and improving insulin resistance (Basu and Lyons, 2012). In vitro and in vivo studies revealed that berry compounds have a potential for cancer prevention through the regulation of cancer cell proliferation, apoptosis and tumor angiogenesis signaling pathways ( Seeram, 2008). In addition, anti-inflammatory effects have been described for strawberries, mulberries and blackberries, mainly through immuno-modulatory mechanisms by the inhibition of cytokines ( Cuevas-Rodríguez et al., 2010 and Liu and Lin, 2013).
Blackberries are one of the most consumed tropical berries. This type of berry, which is from the Rubus spp. group, has a high level of polyphenolic compounds that contributes to its high antioxidant capacity. The total phenolics in blackberries range from 114 to 1056 mg/100 g FW (fresh weight) and this value is higher than other kinds of berries, such as cranberries (120–315 mg/100 g FW) or strawberries (43–443 mg/100 g FW) (Howard and Hager, 2007 and Szajdek and Borowska, 2008). The main polyphenols that are present in the blackberries are anthocyanins and ellagitannins ( Kaume et al., 2012).
Tropical highland blackberry (Rubus adenotrichos) is commonly processed as a juice or juice concentrate. In major producing countries (Colombia, Ecuador and Costa Rica), blackberry-based beverages are regularly produced by local industries ( Gancel et al., 2011). The juice-processing conditions, such as enzymatic reactions, thermal treatments or microfiltration steps, can affect the bioactive compounds and their subsequent antioxidant activity. Thermal decomposition is one of the main causes of bioactive compound loss ( D’Archivio et al., 2010 and Rawson et al., 2011). Studies evaluating the effect of thermal treatments on fruit phenolic compounds have been reported for mango (Santhirasegaram et al., 2013), grapefruit ( Igual et al., 2010), peach ( Oliveira et al., 2012), orange ( Lo Scalzo et al., 2004) and berries ( Aracibia-Avila et al., 2012, Gancel et al., 2011, Piasek et al., 2011 and Zhang et al., 2012). However, these studies focused on changes in the phenolic composition of the fruits after thermal treatments rather than on the changes in their potential beneficial activity. The impact on biological activities have also been evaluated for other industrial process, for example, a study on blackberries demonstrated that despite a reduction of polyphenol concentration by the microfiltration process, the capacity to inhibit lipid peroxidation was not affected ( Azofeifa et al., 2011).
The main objective of this study was to evaluate the effect of thermal treatments on the antioxidant capacity of blackberry polyphenols. We evaluated the antioxidant capacities for free radical-scavenging and inhibiting lipid peroxidation and intracellular reactive oxygen species (ROS). We believe that these capacities are close indicators of biological properties.
