A short-term carbon dioxide treatment inhibits the browning of fresh-cut burdock

Authors: DONG, TIANTIAN - Shandong Agricultural University; SHI, JINGYIN - Shandong Agricultural University; Jiang, Cai-Zhong; FENG, YANYAN - Shandong Agricultural University; CAO, YU - Shandong Agricultural University; WANG, QINGGUO - Shandong Agricultural University

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2015
Publication Date: 7/31/2015
Publication URL: http://dx.doi.org/10.1016/j.postharvbio.2015.07.014
Citation: Dong, T., Shi, J., Jiang, C., Feng, Y., Cao, Y., Wang, Q. 2015. A short-term carbon dioxide treatment inhibits the browning of fresh-cut burdock. Postharvest Biology and Technology. 110:96-102.

Interpretive Summary: Fresh-cut fruits and vegetables have been increasingly popular for their freshness and convenience during the current change of lifestyle. Burdock (Arctium lappa L.) is known for centuries in China and other Asian countries where it has been cultivated not only as the root vegetable but also as a medicinal plant. Burdock has high nutritional value, healthy effects, and other biological properties such as higher antibacterial activity, antioxidant activity and free radical scavenging activity. Therefore, fresh-cut burdock has been gradually recognized and may have high potential as a food crop. However, the white flesh of fresh-cut burdock root is very susceptible to browning which could limit the shelf life and decrease the nutritional value and visual quality. To control the browning of fresh-cut vegetables and fruits, various approaches including physical and chemical treatments, have been widely used. The reducing agents or preservatives including citric acid, ascorbic acid, and sulphites were used as the anti-browning additives in the general fresh-cut food industry. Although these chemicals could effectively inhibit the browning and maintain the quality of fresh-cut burdock, consumers nowadays tend to avoid the chemical additives due to the potential health concerns. Physical treatments, such as irradiation, heat-shock and controlled atmospheres (CA) have been found to inhibit the browning and extend shelf life of fresh-cut burdock roots. Heat shock combined with low temperature storage inhibited the browning of fresh-cut burdock. Hot water and ethanol treatments prevent the discoloration of fresh-cut sunchoke. However, some of these physical methods are not very suitable to industrial production because of expensive costs or safety issues. In addition, some processes may damage the nutrient content and incur organoleptic properties including off-odors, off-flavors and other sensory qualities. Recently, the utilization of non-toxic, cheap, residue-free and environmentally friendly gases to retard the browning, preserve the quality and extend the shelf life of fruits and vegetables has become the main focus of consumers and researchers. The use of CO2, a low-cost, odorless, tasteless and colorless gas, represents a novel approach to non-thermally inactivate undesirable enzymes and preserve the overall quality of fresh-cut produce. CO2 has been reported to decrease respiration rates, retard senescence, reduce or delay the overall enzymatic activity and alleviate physiological disorders showed that high CO2 concentration inhibits the activity of phenylalanine ammonia lyase (PAL), which is the catalyst in the first step of phenylpropanoids biosynthesis, and thus affects the synthesis of phenolic compounds. A high CO2 concentration was applied to persimmon cultivars in order to remove astringency prior to commercial sale. High CO2 levels could reduce postharvest rachis browning of table grape, which seemed to be related to the modulation of ethylene biosynthesis genes. However, there is no report yet on the application of high concentration of CO2 for controlling browning of fresh-cut burdock. The objective of this research was to determine the possible application of CO2 as an anti-browning method for the fresh-cut burdock by evaluating its effects on the changes in visual quality and the physiological parameters. Our results showed that the burdock slices treated with CO2 for 4 h, 6 h and 8 h exhibited better visual quality during 8 days storage, compared with the ones treated with air. CO2 treatment for 6 h on the fresh-cut burdock slices reduced the respiration rate, lowered the activity of PPO and PAL, and the content of total phenolic compounds. CO2 treatment also increased the content of H2O2, enhanced the antioxidative capability through DPPH inhibition and POD activity and decreased the content of MDA. The results indi

Technical Abstract: Fresh-cut burdock is susceptible to browning. The effect of short term carbon dioxide (CO2) treatment on inhibiting browning of fresh-cut burdock during storage at 2~4' was investigated. The results showed that the burdock slices treated with CO2 for 4 h, 6 h and 8 h exhibited better visual quality during 8 days storage, compared with the ones treated with air. CO2 treatment for 6 h on the fresh-cut burdock slices reduced the respiration rate, lowered the activity of PPO and PAL, and the content of total phenolic compounds. CO2 treatment also increased the content of H2O2, enhanced the antioxidative capability through DPPH inhibition and POD activity and decreased the content of MDA. The results indicate that the short-term pure CO2 treatment can extend the shelf life of fresh-cut burdock by inhibiting its browning and improving its quality.