Antimicrobial effects of chitosan and garlic against Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes in hummus during storage at various temperatures

Abstract

The study aimed to evaluate the antimicrobial activity of 0.5 or 1% (w/w) chitosan and 1% (w/w) garlic against Salmonella spp., Escherichia coli O157:H7 and Listeria monocytogenes in hummus dip stored at 4, 10, or 25°C for 28, 21, or 7 days, respectively. In hummus without garlic, at all storage temperatures and storage periods, 0.5% chitosan decreased Salmonella spp., E. coli O157:H7, and L. monocytogenes by 0.9–2.3, 0.6–2.3, and 0.9–1.3 log CFU/g, respectively. In comparison, 1% chitosan decreased the numbers by 1.6–2.9, 1.4–2.7, and 1.3–1.8 log CFU/g, respectively. In hummus with 1% garlic, 0.5% chitosan decreased Salmonella spp., E. coli O157:H7, and L. monocytogenes by 0.7–2.5, 0.6–2.2, and 1.0–1.5 log CFU/g, respectively. Furthermore, 1% chitosan decreased the numbers by 1.6–2.8, 1.2–2.7, and 1.5–1.6 log CFU/g, respectively. With few exceptions, adding 1% garlic to hummus did not result in any significant reduction (at p < 0.05) in microbial numbers. The greatest decreases of Salmonella spp., E. coli O157:H7, and L. monocytogenes were 3.1, 3.6, and 2.9 log CFU/g with 1% chitosan held at 4°C for 28 days. The highest overall acceptability was for hummus with 0.5% chitosan + 1% garlic. Commercial use of chitosan is expected to help producers improve hummus safety. Practical Application Hummus is consumed worldwide as a dip due to its taste and health benefits. Microbial safety of hummus can be enhanced by incorporating chitosan, derived from the natural polymer chitin, into the formulation. This enhanced recipe would be a bonus for producers and consumers alike.

Beyond Chemical Preservatives: Enhancing the Shelf-Life and Sensory Quality of Ready-to-Eat (RTE) Hummus with Vinegar and Other Natural Antimicrobials

“…It can be concluded that garlic addition reduced the sensorial acceptability of the hummus samples probably due its strong and sharp flavor and odor, but its combination with other antimicrobials, mainly vinegar or both vinegar and natamycin, helped reduce or mask the effect of garlic and improved its acceptability. This result agrees with another study that showed that when minced fresh garlic was added to hummus, a lower level of acceptance regarding the flavor was noted compared to the control [44]. Moreover, Khoshtinat et al (2022) concluded that garlic cannot be used directly in salad dressing production due to its intense odor [89].…”

“…Overall, the lowest TAC count or highest log reduction was mainly recorded for GVN compared to all the other treatments during the test days. Several studies showed that combining antimicrobials has more effect against different types of microorganisms in hummus and ready-to-eat food due to the wider spectrum of activity and synergistic activity of antimicrobials such as the combination of potassium sorbate and sodium metabisulfite [10], natamycin, and chitosan-based films [15], natamycin and chitosan [43], garlic and chitosan [44], citric acid and garlic [9]. When the same thymol and carvacrol mixture was used at a higher concentration of 0.8%, a higher effectiveness was achieved in controlling TAC counts in marinated beef (1.1-1.3 logs reduction) [17] and marinated chicken (2.9-3 logs reduction) [18].…”

“…It was also shown that using 0.17% and 0.35% thyme oil had a great effect in controlling E. coli when added to soft cheese [76]. Another study showed that the combination of antimicrobials like 1% garlic and 0.5% chitosan in hummus was able to reduce Salmonella, E. coli O157:H7, and L. monocytogenes by 0.7-2.5, 0.6-2.2, and 1.0-1.5 log CFU/g, respectively [44]. This shows the interest of using essential oils, garlic, and similar antimicrobial combinations for the control of both spoilage and safety, especially for pathogens such as Salmomella and Listeria Monocytogenes known to be significant hazards in hummus [77].…”

“…Yeasts and molds were only detected in the control samples after day 10 at low levels of around 4 log CFU/g, showing the efficiency of the antimicrobials used in controlling fungal growth [44] and the poor competition of yeasts and molds with bacteria like TAC, Pseudomonas spp., and LAB that dominated the microbiota of the hummus samples [17].…”