Mild concentration of ethanol in combination with ascorbic acid inhibits browning and maintains quality of fresh-cut lotus root

Authors: GAO, JIA - Sichuan Academy Of Agricultural Science; Luo, Yaguang - Sunny; Turner, Ellen; ZHU, YONGQING - Sichuan Academy Of Agricultural Science

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2016
Publication Date: 1/7/2017
Citation: Gao, J., Luo, Y., Turner, E.R., Zhu, Y. 2017. Mild concentration of ethanol in combination with ascorbic acid inhibits browning and maintains quality of fresh-cut lotus root. Postharvest Biology and Technology. 128:169-177.

Interpretive Summary: Ethanol is a well known antimicrobial agent that is used to sterilize surfaces and equipment. It is not well known that ethanol also is an effective browning inhibitor. Ascorbic acid is used to prevent browning of fresh-cut produce, but it is not compatible with most sanitizers. In this study low concentrations of ethanol were used together with ascorbic acid to discourage microbial growth and prevent browning on fresh-cut lotus root. Ethanol containing treatments were more effective than others at inhibiting browning and microbial growth. The addition of ascorbic acid improved the quality of lotus root slices beyond that achieved with ethanol alone. Various concentrations of ethanol with a set amount of ascorbic acid were also tested. Twenty to thirty percent ethanol plus ascorbic acid was able to inhibit browning and microbial growth, and maintain quality of fresh-cut lotus root for more than two weeks. Research outcome benefits the growers and processors of lotus roots by improving quality and reduce post-harvest loss.

Technical Abstract: Aqueous solutions of ethanol and ascorbic acid alone and in combination were compared to a commonly used sanitizer, sodium hypochlorite, and a leading commercial antibrowning agent containing calcium ascorbate (CA)for their efficacy to inhibit microbial growth and browning on fresh-cut lotus root. Fresh-cut lotus root slices were immersed in one of 7 treatment solutions including water (control), 30% ethanol, 30% ethanol plus 3% ascorbic acid, 30% ethanol plus 3% CA, 3% ascorbic acid , 3% CA and 100 mg/L sodium hypochlorite for 2 min, and then packaged in polyethylene bags and stored for 28 days at 4°C. Packages were monitored for headspace gas composition, color, texture, aerobic mesophilic bacteria, and yeast and mold populations, electrolyte leakage and sensory attributes. The results indicate that all ethanol treatments, with and without added ascorbic acid or CA not only inhibited microbial growth, but also delayed browning more effectively than either ascorbic acid or CA alone. The combined treatments of Ethanol 30% (v/v) along with 3% (v/v) ascorbic acid or 3% (v/v) CA were even more effective than ethanol alone in maintaining quality of fresh-cut lotus slices during cold storage. Increasing ethanol concentration within the range of 5% (v/v) to 30% (v/v) when accompanied by 3% ascorbic acid, decreased microbial populations and had little effect on quality maintenance of fresh-cut lotus root during cold storage. Ethanol concentrations of 20% (v/v) to 30% (v/v) in conjunction with 3% (v/v) ascorbic acid have the potential to inhibit browning and maintain quality of fresh-cut lotus root slices for more than 14 days during storage at 4°C. This is the first use of ethanol as a dual control for both browning and microbial growth in fresh-cut lotus root.