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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Food Quality Laboratory » Research » Publications at this Location » Publication #308654
Title: The mechanism of ethanol treatment on inhibiting lettuce enzymatic browning and microbial growth

Author
item YAN, SHOULEI - Huazhong Agricultural University
item Yang, Tianbao
item Luo, Yaguang - Sunny
item ZHOU, BIN - University Of Maryland

Submitted to: LWT - Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2015
Publication Date: 3/12/2015
Publication URL: https://handle.nal.usda.gov/10113/61213
Citation: Yan, S., Yang, T., Luo, Y., Zhou, B. 2015. The mechanism of ethanol treatment on inhibiting lettuce enzymatic browning and microbial growth. LWT - Food Science and Technology. 63:383-390.

Interpretive Summary: Tissue browning of fresh-cut lettuce greatly affects its quality and consumers’ appreciation. This study investigated the effects of ethanol treatment on tissue browning and natural microbe growth of cut lettuce stem discs. Cut lettuce stem discs were treated with 20% ethanol for 2 min and then packaged in Zip-bag and stored at 5 °C. Ethanol treatment can keep the stem discs in better appearance and quality with lower natural microbe loads compared to no treatment. And total phenols and quinone in the treated samples were reduced. The ethanol solution treatment stimulated the respiration of the lettuce stem discs and increase CO2 production which contributes to inhibit browning. Further antibrowning merit of the ethanol treatment was compared with that of other reported methods. The lettuce stem discs treated with ethanol were in the best sensory quality attributes. These results provide important information for reducing lettuce tissue browning and inhibiting microbial growth by industry so as to improve fresh cut lettuce quality and shelf-life.

Technical Abstract: Tissue browning of fresh-cut lettuce greatly affects its quality and consumers’ appreciation. This study investigated the effects of ethanol treatment on enzymatic browning and natural microflora growth of lettuce stem discs. After treated with 20% ethanol for 2 min and then drained by a spinner, lettuce stem discs were packaged in Zip-bag and stored at 5 °C. Ethanol treatment can keep the stem discs in better organoleptic characteristics with lower natural microbial loads compared to no treatment. Phenylalanine ammonia lyase mRNA level and enzymatic activities in the ethanol treated group were significantly repressed. And total phenols and quinone in the treated samples were reduced. The ethanol solution treatment stimulated the respiration of the lettuce stem discs and increase CO2 production which contributes to inhibit browning. Further antibrowning merit of the ethanol treatment was compared with that of other reported methods, such as heat shock, trans-cinnamaldehyde and salicylic acid immersion. The lettuce stem discs treated with ethanol were in the best sensory quality attributes. These results indicated that 20% ethanol treatment was an effective approach to inhibit enzymatic browning and control microbial growth in lettuce stem discs.