Effects of caraway and juniper essential oils on aflatoxigenic fungi growth and aflatoxins secretion in polenta

Abstract

Inhibitory activity of caraway and juniper essential oils was tested against two aflatoxigenic strains (Aspergillus flavus—four isolates and Aspergillus parasiticus—one isolate) using the method of agar plates. A. flavus IKBT and A. flavus IKB isolated from corn flour, A. flavus IKT isolated from peanuts, and A. flavus IKK isolated from flint corn. A. parasiticus CBS 260.67 was obtained from the Centralbureau voor Schimmelcultures (CBS, Utrecht, The Netherlands). The inhibitory effect of essential oils on aflatoxins secretion by A. flavus (isolated from maize flour) was examined in the polenta. Growth of all fungi were completely inhibited at caraway essential oil concentration of 4.5 μl/g. At this concentration, aflatoxin secretion was completely inhibited in polenta. Juniper essential oil particularly inhibited growth of examined fungi at the applied concentration of 35 μl/g (from 42.4% to 79.7%). At concentration of 50.0 μl/g, this oil completely inhibited aflatoxin secretion in polenta. Practical applications The obtained results show that caraway essential oil had significantly better inhibitory effects against A. flavus, A. parasiticus, and aflatoxins production than juniper essential oil, in vitro and in polenta. Future research should point to the possible application of this oil in different types of food and the choice of an efficient method: adding them directly to the product, surface coating of the products, dispersing, applying them in the atmosphere of the package, coating the inner side of the packaging, applying in edible films, or in the form of nanocapsules. In the case of polenta, essential oils can be applied in the packaging atmosphere, by coating the inside of the package, or adding them directly to the polenta.

Edible and Functionalized Films/Coatings—Performances and Perspectives

“…Maillard compounds (hundreds of them) results from a sequence of non-enzymatic reactions (Figure 9), which start from sugars and an amino group (typically from an amino acid or protein) through room temperature to approximately 200 • C. These compounds are very good antioxidants, but they are usually associated with cooking processes (some of them) such as the flavors, aroma, and brown color released by baked food. Essential oil contains mainly terpenic compounds that are responsible for the antibacterial and antioxidant properties of films: monoterpenes (limonene, tricyclene, α-thujene, α-pinene, camphene, sabinene, β-pinene, β-myrcene, 3-carene, α-terpinene, α-phellandrene, p-cymene, υ-terpinene, α-terpinolene), oxigenated monoterpene (1,8-cineole (Z)-sabinenehydrate, linalool, d-fenchylalcohol, α-campholenal, camphor, borneol, 4-terpineol, α-terpineol, bornylacetate), sesquiterpene hydrocarbon (α-copaene, aromadendrene α, (E)-caryophyllene, alpha-amorphene, 7-cadinene, δ-cadinene), oxygenated sesquiterpene (caryophyllene oxide, α-eudesmol) [12,[117][118][119][120][121][122][123][124][125][126]. These molecules comply with the Code of Federal Regulations; they are GRAS, GRAS/FS, GMP, and are very effective, but their use is subject to controversy in the food industry, and replacements are needed (except for the natural product, and even for them, the use is allowed only after a careful evaluation of effects).…”

“…Total phenolic contents (TPC) (Folin-Ciocalteu reagent) data are expressed in equivalents of mg of gallic acid for 100 g of film (mg GAE/100 g film) [78,[118][119][120]155,156,[215][216][217][218][219][220][221][222][223][224][225][226][227][228].…”

The use of plant extracts and their phytochemicals for control of toxigenic fungi and mycotoxins

“…Furthermore, essential oils have been found to effectively modulate the growth of mycotoxigenic fungi such as A. favus, A. oryzae, A. niger, Alternaria alternata, F. moniliforme, F. graminearum, Penicillium citrinum and P. viridicatum , etc., and their associated mycotoxins ( da Cruz Cabral et al., 2013 ; Prakash et al., 2015 ; Powers et al, 2019 ). A study by Kocic-Tanackov et al. (2019) reported how essential oil of Carum carvi L applied at a concentration from 1.5 μl/g demonstrated complete inhibition of the growth of A. parasiticus , and likewise 4.5 μL/g exhibited complete inhibition of the growth of A. flavus as well as the secretion of aflatoxins by the same strain in polenta.…”

From laboratory to field: applying the Fo47 biocontrol strain in potato fields

“…cubense strains (Bai and Shaner 1996;Garcia-Bastidas et al 2019). Polenta was taken along as it has been used to propagate microbes (Kocic-Tanackov et al 2019).…”