natural-products-in-plant-pest-management

Control of Mycotoxins and Mycotoxigenic Fungi 35NutsSalicylic acid, thymol, vanillyl acetate, vanillin and cinnamic acid completelyinhibited the germination of fungi contaminating walnut kernels. All fivecompounds showed somewhat similar activity in inhibiting the growth ofthe potentially mycotoxigenic A. niger, A. flavus and P. expansum at the concentrationstested (up to 25 mM), with thymol showing the highest activity(i.e. complete inhibition of growth at 5 mM) (Kim et al., 2006).Powders from the leaves of O. gratissimum and cloves of Syzgium aromaticumwere used as protectants at 3% in combination with various packagingmethods to store 3.5 kg groundnut kernel samples (9.3% moisture)artificially inoculated with A. parasiticus. Selected treatments were repeatedwith naturally infected kernels. A high level of protection was obtained withSyzygium powder at 3% concentration using 12% moisture kernels (Awuahand Ellis, 2002).Calori-Domingues and Fonseca (1995) found that treatment of unshelledpeanuts with grapefruit seed extract was not efficient in controlling aflatoxinproduction during storage. Peanuts treated with grapefruit seed extract at5,000 and 10,000 mg/kg had mean aflatoxin contamination in the range2,757–56,334 μg/kg and 688–5,092 μg/kg, respectively, while the control had3,362–108,333 μg/kg. Of all of the chemicals tested only propionic acid waseffective in controlling aflatoxin production. Treatments were consideredefficient when the aflatoxin content (B 1+ G 1) remained less than 30 μg/kg.Shelled groundnut samples with moisture contents between 7.5 and10.5% and inoculated with conidia of A. glaucus and A. parasiticus were storedfor 15–90 days at 25°C, and fumigated with synthetic food grade essential oilof mustard (Brassica rapa) (100 μl/l space). Deterioration of the samples wasassessed by estimating the percentage of kernels colonized by fungi, thenumber of CFUs/kernel, and the accumulation of ergosterol and free fattyacids. The values of these variables increased with the moisture content andstorage period, independent of the fumigation treatment; however, the rate ofincrease was significantly lower in fumigated samples (Dhingra et al., 2009).2.5 Use of Plant Products in Active PackagingActive packaging (AP) is an innovative food packaging concept that combinesadvances in food technology, food safety, and packaging and materialsciences in an effort to better meet consumer demands for fresh-like, safeproducts. One specific application is to incorporate essential oil(s) into thepackaging to prevent the growth of microorganisms.The use of preservative food-packaging films offers several advantagescompared to the direct addition of preservatives to food products, since thepreservative agents are applied to the packaging material in such a way thatonly low levels of the preservatives come into contact with the food. Eitherof two approaches can be used to give packaging materials antimicrobialactivities. In preservative-releasing or migrating approaches, preservatives