Studies On The Techniques To Inhibit The Browning Of Fresh-cut Sunchokes

Browning is the limiting factor in product quality and shelf-life of fresh-cut sunchoke. In this paper, we investigated the influences of ethanol treatment, gaseous mixture of N2 and CO2, pre-processing treatments including hot water dips plus a delay before cutting, warming up treatment on the browning of fresh-cut sunchoke, aimed to find an effective and safe method on this issue. The main conclusions are as follows:1. Ethanol treatment(5%, 3 min) effectively inhibited the browning of fresh-cut sunchoke and kept its better overall visual quality without causing damage. Fresh-cut slices stored at 5 °C, untreated control slices obviously browning on day 4, but those of ethanol dipping treatments still had good color till day 12.2. Pre-cutting gaseous mixture(N2 and CO2) treatment increased internal ethanol concentrations and inhibited browning of fresh-cut sunchoke. Fresh-cut slices stored at 5°C, untreated control slices were obviously browning on day 4, but those treated with gaseous mixture of N2 and CO2 for 16 d at 10 °C and then sealed 16 d treatments still had good color till day 12.3. Pre-processing treatments including hot water dips plus a decay before cutting could effectively inhibited browning of fresh-cut sunchoke. The use of brief heat treatments with 50°C water(HW) applied to sunchoke tubers for 6 min before cutting, after heat treatment, tubers were held 20°C for 1 d or 3 d before slicing. Fresh-cut slices stored at 5 °C, untreated control slices obviously browning on day 4, but those treated with 50 °C water(HW) for 6 min, then held 20 °C for 1 d still had good color till day 12. Pre-processing treatment inhibited phenylalanine aminolyase(PAL) activity, total phenolic content and the respiration rate, which is the main reason for delaying browning.4. Warming up treatment:tubers were packed in Ployethylene(PE) plastic bags and stored at 20 °C for 7 d and 14 d. Warming up treatment effectively inhibited browning. Fresh-cut slices stored at 5 °C, the slices with warming up treatment still had good color till day 8. The activity of phenylalanine aminolyase(PAL) and polyphenol oxidase(PPO),content of total phenols and the respiration rate were inhibited by warming up treatment.