Effect of Gaseous Citral on Table Grapes Contaminated by Rhizopus oryzae ITEM 18876

Abstract

Rhizopus oryzae is responsible for rapidly producing a deliquescent appearance in grape berries, generally favoured by cold chain interruptions. To counteract fruit spoilage and to meet consumer acceptance, innovative strategies based on the application of natural compounds are ongoing. Due to their biological activities, including antimicrobial ones, natural flavour compounds extend the shelf life and improve the nutritional value as well as the organoleptic properties of foods. Thus, in this work, the application of the antimicrobial citral, a flavor component of monoterpenes identified in plant and fruit essential oils, was developed and validated against one spoiler of R. oryzae. Citral, as pure compound, was first investigated in vitro against R. oryzae ITEM 18876; then, concentrations equal to the minimal inhibitory concentration (MIC) and 4-fold MIC (4MIC) value were applied on the table grape cv Italia infected with this strain and stored. The MIC value was equal to 0.0125 μL/cm3; both citral concentrations (0.0125 and 0.05 µL/cm3) were effective in counteracting the microbial decay of infected table grapes over the storage period. The HS-SPME/GC-MS method showed citral persistence in the head space of plastic trays with the infected samples; as expected, a higher content of citral isomers was found in the sample treated with 4MIC value. In conclusion, citral revealed its efficacy to counteract the onset of soft rot by R. oryzae ITEM 18876 under storage conditions. Thus, it could be successfully exploited to develop an active packaging or natural preservatives to extend table grape shelf life without affecting its quality and sensory characteristics, whilst also satisfying the consumer demand for natural preservative agents.

Plant Antimicrobials for Food Quality and Safety: Recent Views and Future Challenges

“…Free citral showed a MIC value of 0.8 mg mL −1 against B. cereus and 2 mg mL −1 against E. coli and S. aureus [ 68 ]. However, the main application of citral is its use as an antifungal agent, as demonstrated against different fungal strains [ 69 , 70 , 71 ]. As regards cinnamaldehyde, it showed higher antibacterial activity than cinnamon oil against Gram-positive bacteria [ 72 ].…”

Process and Anti-Mildew Properties of Tea Polyphenol-Modified Citral-Treated Bamboo

“…In recent years, bamboo anti-mildew research has become a hot spot in which natural antimicrobial agent-related research has gradually gained attention. One of the natural antimicrobial agents is citral, which is primarily derived from the essential oil of the Chinese medicine Cyperus rotundus, which has the advantages of a broad spectrum of bacterial inhibition and being environmentally friendly and will have a greater outlook for applications in the anti-mildew of bamboo [ 9 , 10 , 11 , 12 , 13 ]. Currently, the study on the inhibition performance of citral against common bamboo molds carried out by the authors’ team [ 14 , 15 ] found that the inhibition rate of bamboo molds exceeded 100% when the concentration of citral was 75 mg mL −1 .…”

Advances in Postharvest Preservation and Quality of Fruits and Vegetables

“…Quintieri et al [10] investigated the effectiveness of citral, a flavour component found in plant and fruit essential oils, against Rhizopus oryzae ITEM 18876. In vitro tests showed that citral was effective against this spoilage microorganism at concentrations equal to the minimal inhibitory concentration (MIC) and 4-fold MIC.…”