Oregano Essential Oil versus Conventional Disinfectants against Salmonella Typhimurium and Escherichia coli O157:H7 Biofilms and Damage to Stainless-Steel Surfaces.

This study compared the effect of oregano essential oil versus sodium hypochlorite, hydrogen peroxide, and benzalkonium chloride against the viability of adhered Salmonella Typhimurium and Escherichia coli O157:H7 on 304 stainless steel. Oregano essential oil was effective in disrupting the biofilms of both bacteria at concentrations ranging from 0.15 to 0.52 mg mL-1. In addition, damage to stainless-steel surfaces following disinfection treatments was assessed by weight loss analysis and via visual inspection using light microscopy. Compared to the other treatments, oregano oil caused the least damage to stainless steel (~0.001% weight loss), whereas sodium hypochlorite caused the most severe damage (0.00817% weight loss) when applied at 0.5 mg mL-1. Moreover, oregano oil also had an apparent protective impact on the stainless steel as weight losses were less than for the control surfaces (distilled water only). On the other hand, sodium hypochlorite caused the most severe damage to stainless steel (0.00817% weight loss). In conclusion, oregano oil eliminated monoculture biofilms of two important foodborne pathogens on 304 stainless-steel surfaces, while at the same time minimizing damage to the surfaces compared with conventional disinfectant treatments.

Antioxidants in Oak (Quercus sp.): Potential Application to Reduce Oxidative Rancidity in Foods.

This review explores the antioxidant properties of oak (Quercus sp.) extracts and their potential application in preventing oxidative rancidity in food products. Oxidative rancidity negatively impacts food quality, causing changes in color, odor, and flavor and reducing the shelf life of products. The use of natural antioxidants from plant sources, such as oak extracts, has gained increasing interest due to potential health concerns associated with synthetic antioxidants. Oak extracts contain various antioxidant compounds, including phenolic acids, flavonoids, and tannins, which contribute to their antioxidative capacity. This review discusses the chemical composition of oak extracts, their antioxidative activity in different food systems, and the safety and potential challenges related to their application in food preservation. The potential benefits and limitations of using oak extracts as an alternative to synthetic antioxidants are highlighted, and future research directions to optimize their application and determine their safety for human consumption are suggested.

Facing Resistant Bacteria with Plant Essential Oils: Reviewing the Oregano Case.

Antibiotic resistance is a serious global threat, and the misuse of antibiotics is considered its main cause. It is characterized by the expression of bacterial defense mechanisms, e.g., ß-lactamases, expulsion pumps, and biofilm development. Acinetobacter baumannii and Pseudomonas aeruginosa are antibiotic-resistant species that cause high morbidity and mortality. Several alternatives are proposed to defeat antibiotic resistance, including antimicrobial peptides, bacteriophages, and plant compounds. Terpenes from different plant essential oils have proven antimicrobial action against pathogenic bacteria, and evidence is being generated about their effect against antibiotic-resistant species. That is the case for oregano essential oil (Lippia graveolens), whose antibacterial effect is widely attributed to carvacrol, its main component; however, minor constituents could have an important contribution. The analyzed evidence reveals that most antibacterial evaluations have been performed on single species; however, it is necessary to analyze their activity against multispecies systems. Hence, another alternative is using plant compounds to inactivate hydrolytic enzymes and biofilms to potentiate antibiotics' effects. Despite the promising results of plant terpenes, more extensive and deep mechanistic studies are needed involving antibiotic-resistant multispecies to understand their full potential against this problem.

Plant-Derived Substances with Antibacterial, Antioxidant, and Flavoring Potential to Formulate Oral Health Care Products.

Bacterial diseases and reactive oxygen species can cause dental caries and oral cancer. Therefore, the present review analyzes and discusses the antibacterial and antioxidant properties of synthetic and plant-derived substances and their current and future patents to formulate dental products. The reviewed evidence indicates that chlorhexidine, fluorides, and hydrogen peroxide have adverse effects on the sensory acceptability of oral care products. As an alternative, plant-derived substances have antimicrobial and antioxidant properties that can be used in their formulation. Also, adding plant metabolites favors the sensory acceptability of dental products compared with synthetic compounds. Therefore, plant-derived substances have antibacterial, antioxidant, and flavoring activity with the potential to be used in the formulation of toothpaste, mouth rinses, dentures cleansers-fixatives, and saliva substitutes.

Contribution of Bioactive Compounds to the Antioxidant Capacity of the Edible Mushroom Neolentinus lepideus.

Neolentinus lepideus is a fungus consumed by rural communities in Central America and Asia due to its rich flavor; however, little information on its chemical composition is available. With this in mind, the objective of this work was to determine the content of vitamin E and C, ergosterol, and phenolic compounds of this fungus, as well as its antioxidant capacity. The quantified bioactive compounds were two isoforms of vitamin E, highlighting α-tocopherol (3370.35 mg/100 g dry weight, DW) and ergosterol (11.70 mg/100 g DW). The total phenolic content was 164.80 mg gallic acid equivalents/100 g, and nine phenolic compounds were identified (protocatechuic, p-hydroxybenzoic, caffeic, vanillic, ferulic, salicylic, p-anisic, trans-cinnamic acids, and scopoletin). The highest antioxidant capacity was detected in the lipophilic extract with TEAC (27688 µmoles Trolox equivalents/100 g). These results suggest that lipophilic compounds are among the main bioactive compounds in N. lepideus, and they might exhibit the highest radical scavenging properties in non-polar extracts.

Antioxidant Properties and Industrial Uses of Edible Polyporales.

The content of antioxidant compounds varies within fungal species, and the Polyporales order has been recognized for this property. Numerous antioxidant compounds have been identified in Polyporales fungi, including phenolic compounds, ß-glucans, ergosterol, ergothioneine, vitamin C, and tocopherols. Each compound contributes differently to the antioxidant potential of fungi. Besides the health benefits for rural communities caused by fungi consumption, their antioxidant composition attracts the food, cosmetic, and pharmaceutical industries' interest. In this context, the present review compiles, analyzes, and discusses the bioactive composition of edible fungi of the Polyporales order and its contribution to total antioxidant capacity.

Using Sensory Evaluation to Determine the Highest Acceptable Concentration of Mango Seed Extract as Antibacterial and Antioxidant Agent in Fresh-Cut Mango.

Plant extracts have the potential to be used as food additives; however, their use have been limited by causing undesirable changes in the sensory attributes of foods. We characterized the mango seed extract as a preserving agent for fresh-cut mangoes. We established the maximum concentration of extract that, while increasing the antioxidant activity, and limiting microbial contamination of the fruit, did not negatively affect fruit sensory acceptability. The extract contained 277.4 g gallic acid equivalent (GAE)/kg dw (dry weight) of polyphenols and 143.7 g quercetin equivalent (QE)/kg dw of flavonoids. Antioxidant capacity values were 2034.1 and 4205.7 µmol Trolox equivalent (TE)/g against 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radicals, respectively. Chromatographic analysis revealed the presence of gallic and chlorogenic acids. The extract (16 g/L) inhibited the growth of Escherichia coli, Salmonella Typhimurium, Staphylococcus aureus and Listeria monocytogenes. The highest concentration with sensory acceptability was 6.25 g/L. At such concentration, the extract preserved fresh-cut fruits, increasing polyphenols (0.427 g GAE/kg fw (fresh weight)), flavonoid content (0.234 g QE/kg fw) and antioxidant activity (DPPH = 2.814 and ABTS = 0.551 mol TE/kg fw). It also reduced inoculated bacteria (range: 5.50 × 10³ to 1.44 × 105 colony forming units (CFU)/g). These results showed the importance of considering consumer acceptability to determine the effective concentration of plant extracts as additives.

Combination of Cymbopogon citratus and Allium cepa essential oils increased antibacterial activity in leafy vegetables.

BACKGROUND: Cymbopogon citratus and Allium cepa essential oils (EOs) are rich in terpenes and sulfur compounds respectively, both with antibacterial activity and different cell targets, supporting the idea that their combination can increase their efficacy. RESULTS: Major constituents of C. citratus were geranial and neral, while A. cepa presented dipropyl disulfide and dipropyl trisulfide. Cymbopogon citratus and A. cepa EOs inhibited the in vitro growth of Escherichia coli O157:H7 (minimal inhibitory concentrations of 2.21 and 5.13 g L-1 respectively), Salmonella Choleraesuis (3.04 and 1.28 g L-1 ), Listeria monocytogenes (1.33 and 2.56 g L-1 ) and Staphylococcus aureus (0.44 and 5.26 g L-1 ). Application of the EO combination to spinach caused a greater reduction in E. coli (2.34 log colony-forming units (CFU) g-1 ), S. Choleraesuis (2.94 log CFU g-1 ), L. monocytogenes (2.06 log CFU g-1 ) and S. aureus (1.37 log CFU g-1 ) compared with higher doses of individual EOs; a similar effect was observed for romaine lettuce. Individual and combined EOs caused a reduction in flavor acceptability level; however, no significant differences were found among odor acceptability of control vegetables and those treated with the EO combination and C. citratus EO. CONCLUSION: Leafy vegetables treated with the EO combination showed higher antibacterial protection and odor acceptability compared with individual EO treatments. © 2016 Society of Chemical Industry.

Oregano (Lippia graveolens) essential oil added within pectin edible coatings prevents fungal decay and increases the antioxidant capacity of treated tomatoes.

BACKGROUND: Tomato is a fruit widely consumed due to its flavor and nutritional value; however, it is susceptible to fungi contamination. Oregano essential oil (OEO) is a fungicide whose constituents are volatile; therefore, their incorporation within edible coatings can protect them and maintain their efficacy. In this context, this study evaluated the effect of OEO applied within pectin coatings on the inhibition of Alternaria alternata growth, antioxidant content and sensorial acceptability of tomatoes. RESULTS: The major volatile compounds of OEO were carvacrol (47.41%), p-cymene (26.44%) and thymol (3.02%). All the applied OEO concentrations (15.7, 25.9 and 36.1 g L(-1) ) inhibited the in vitro growth of A. alternata, whereas the in vivo effective concentrations were 25.9 and 36.1 g L(-1) . Additionally, there was an increment of total phenols and antioxidant activity in coated tomatoes compared to controls. Aroma acceptability of tomatoes was not affected by the pectin-OEO coating; additionally, the pectin, pectin-OEO 15.7 g L(-1) treatments and control tomatoes showed higher flavor acceptability than those coated with pectin-OEO 25.9 and 36.1 g L(-1) . CONCLUSION: Pectin-OEO coatings showed antifungal effect and increased the antioxidant activity without negative effects on the sensorial acceptability of tomatoes. © 2015 Society of Chemical Industry.