Effect of calcium and anti-browning agents on total phenols and antioxidant capability of 'Packham's Triumph' pears packed in modified atmosphere

Abstract

The effect of calcium propionate (PCa) 1% p/v, ethylenediaminetetraacetic acid (EDTA) 0.1% p/v, cysteine (CIS) 0.5% p/v and citric acid (AC) 0.5% p/v were evaluated on the total phenol content, antioxidant capability and respiration rate of 'Packham's Triumph' pear wedges, packed in modified atmosphere (MA, 8-11% O2 and 14-16% CO2 after 6 days of storage) and stored at 5°C for 8 days. The treatments were control (washed with water at 5°C, MA), PCa + EDTA + CIS + AC (MA), and PCa + EDTA + CIS (MA). The evaluations were performed on days 1, 3 and 8 after processing. The respiration rate of the control samples was 42% lower than the pear wedges treated with PCa and anti-browning agents (10-12 mg CO2 kg⁻¹ h⁻¹) during 8 days of storage. On days 3 and 8, the pear wedges treated with PCa + EDTA + CIS + AC and PCa + EDTA + CIS showed respiration rates 55% higher than the control samples. On the other hand, the total phenol content was preserved along the storage period, even though it was 27% lower than the content in peeled fresh fruit (265 mg 100 gfw-1). At the end of the storage period, the PCa + EDTA + CIS showed the highest phenolic content (214 mg 100 gfw-1), while it was lower in the other treatments (146 mg 100 gfw-1). According to the antioxidant capability, non-significantly statistical differences were shown throughout shelf-life, except those wedges treated with PCa + EDTA + CIS whose antioxidant capability was increased by 67%. After the minimally processing operations chemical agent immersions and MA packaging, the total phenol content was diminished compared to the initial fresh flesh fruit. In addition, MA could have a high impact on gas atmosphere inside the packages and preservation of the functional quality of 'Packham's Triumph' pear wedges because no differences were detected among treatments.