Comparison of Generally Recognized as Safe Organic Acids for Disinfecting Fresh-cut Lettuce

Abstract

14In this study, we aimed to determine the organic acids (acetic, lactic, citric, malic, 15 propionic, succinic, and tartaric acids; 1% and 0.5%, w/w or v/v) that were most 16 effective for fresh-cut lettuce disinfection based on analysis of quality (i.e., color, 17 electrolyte leakage, and sensory quality) and microbial examination. The results 18 showed that these acids did not negatively affect the color quality (i.e., L * , a * , b * , 19 whiteness index, and sensory color). Additionally, 0.5% lactic acid led to the lowest 20 electrolyte leakage (0.83%), which was not significantly different (p > 0.05) from that 21 of distilled water (0.46%). Lactic acid (1%) did not affect the sensory quality and led 22 to the highest microbial reduction (1.45 log reduction in aerobic plate counts [APCs]; 23 2.31 log reduction in molds and yeasts [M&Y]) and was therefore recommended as 24 the primary choice for lettuce disinfection. Malic acid (0.5%), with a 1.07% 25 electrolyte leakage rate, 0.73 log reduction in APCs, and 1.40 log reduction in M&Y, 26 was better than the other six acids (0.5%) and was recommended as a pH regulator 27 and a potential synergistic agent for oxidizing sanitizers. Acetic acid (1%) negatively 28 affected the sensory quality and led to the highest electrolyte leakage (2.90%). 29Microbial analysis showed that propionic acid (0.5% and 1%) was ineffective for 30 disinfection of lettuce (p > 0.05); thus, acetic and propionic acids were not 31 recommended. Our results provide insights into the choice of sanitizers and formula 32 design in food safety. 33 IMPORTANCE 34Since chlorine is forbidden in several countries, generally recognized as safe 35 organic acids are used in minimal processing industries and in household sanitizers. 36The disinfection efficacy of organic acids has been studied when used alone or with 37 oxidizing sanitizers. However, since different antibacterial mechanisms, contact time, 38 fresh produce, and concentration have been reported, the acids most effective for 39 single fresh produce disinfection, especially that of lettuce, an important salad 40 vegetable, are not known. Moreover, in developing countries, because of 41 imperfections in field management, cold chain transportation, and minimal processing 42 industry development, the demand for low-cost household sanitizers is greater than 43 that for minimally processed fresh produce. In this work, microbial load in lettuce was 44 determined after disinfecting with seven GRAS organic acids. The changes in quality 45 were also determined. These results provide insights into the choice of minimal 46 processing sanitizers and a formula design for household sanitizers. 47 48

Disinfection of Ready-to-Eat Lettuce Using Polyhexamethylene Guanidine Hydrochloride

“…As the AA concentration was increased to 1.9% and the washing time was increased to 10 min, the sensory qualities including overall acceptability, odor and texture were negatively affected [25]. Wang et al [30] showed that washing with 1% AA for 2 min did not negatively affect the sensory color and texture of ready-to-eat lettuce, indicating that the washing time and concentration of AA were the major factors influencing the quality of lettuce. Moreover, a loss of color quality was observed after storage for several days.…”

The Effect of Nitrogen Fertilizer and Water Supply Levels on the Growth, Antioxidant Compounds, and Organic Acids of Baby Lettuce

“…Organic acids are used as an active ingredient in anti-browning agents applied on lettuce post-harvest [4]. Application of solutions with various organic acids has been widely demonstrated as an effective disinfectant agent on lettuce [5,6]. The effectiveness of organic acids is associated with their activity when applied on the leaves externally.…”