Lactic acid as potential substitute of acetic acid for dissolution of chitosan: preharvest application to Butterhead lettuce
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Chitosan must be dissolved in acid solution to activate its antimicrobial properties. The objectives of present study were to determine whether acetic and lactic acids used to dissolve chitosan would influence its effectiveness to control the native microflora of Butterhead lettuce at harvest and during postharvest storage (7–8 °C, 5 days). Chitosan was applied as a SINGLE DOSE (14, 10, 7, 3 or 0 days previous to harvest) or in SUCCESSIVE DOSES (at 14 + 10 + 7+3 + 0 days prior to harvest). Although chitosan in acetic acid showed antimicrobial activity, treated plants showed dried brown stains which significantly reduced sensorial quality. Chitosan in lactic acid applied in a SINGLE DOSE at harvest or in SUCCESSIVE DOSES reduced microbial counts of all populations at harvest without affecting sensorial quality. After postharvest storage, lettuce treated with SUCCESSIVE APPLICATIONS of chitosan in lactic acid presented significant reductions in the microbial populations compared with untreated sample (−2.02 log in yeast and molds, −1.83 log in total coliforms, −1.4 log CFU g−1 in mesophilic bacteria and −1.1 log in psychrophilic bacteria). In conclusion, replacement of acetic by lactic acid did not affect the antimicrobial activity of chitosan, reducing microbial counts at harvest and after postharvest storage without affecting sensorial quality.
KeywordsBiopreservative Safety Greenhouse Organic Sensorial quality
This work was supported by Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Agencia Nacional de Promoción Científica y Tecnológica (ANCyT) and Universidad Nacional de Mar del Plata (UNMDP).
- Bautista-Baños S, Hernández-Lauzardo AN, Velázquez-del Valle MG, Hernández-López M, Ait Barka E, Bosquez-Molina E, Wilson CL (2006) Chitosan as a potential natural compound to control pre and postharvest diseases of horticultural commodities. Crop Prot 25:108–118. doi: 10.1016/j.cropro.2005.03.010 CrossRefGoogle Scholar
- Conner DE, Kotrola JS (1995) Growth and survival of Escherichia coli O157: H7 under acidic conditions. Appl Environ Microbiol 61:382–385Google Scholar
- Goñi M, Tomadoni B, Moreira M, Roura S (2013b) Application of tea tree and clove essential oil on late development stages of Butterhead lettuce: impact on microbiological quality LWT-Food. Sci Technol 54:107–113Google Scholar
- SAS INC (2002) SAS software, Version 9.0 of the SAS System for Windows. SAS Institute Inc., Cary, NC, USAGoogle Scholar