Synthesis and Evaluation of Antimicrobial Biobased Waxes as Coating Materials.

The objective of this study was to synthesize and evaluate the efficacy of antimicrobial waxes to be used as both physical and biological protection to perishable fruits and vegetables. The existing wax materials used in postharvest coating applications do not provide this antimicrobial functionality. One class of such waxes was obtained by covalently linking quaternary ammonium compounds (QACs) featuring alkyl, benzyl, and stearyl ester hydrophobic side groups to the terminal position of a bromo stearyl ester. A second class was obtained by linking these QACs to the pendant hydroxyl group of an aliphatic diamide made of 12-hydroxystearic acid, stearic acid, and ethylene diamine. In total, six distinct structures having three different QAC groups were synthesized. Compounds containing QACs with C8 alkyl groups exhibited potent inhibition toward the growth of both bacteria and fungi. Notably, the complete inhibition of Penicillium italicum and Geotrichum candidum, two fungi detrimental to the postharvest quality of fruits, as well as the complete destruction of viable cells for Gram-positive and Gram-negative bacteria was observed when these organisms were incubated in contact with QAC waxes or dispersed in an aqueous system at a concentration of 1.0 mM. Comparatively, benzalkonium chloride with an alkyl chain length of 10 carbon can completely inhibit Staphylococcus aureus at a concentration of 1.44 mM. The properties of the attached hydrophobic groups appeared to exert a strong influence on antimicrobial activity presumably due to differences in molecular orientation, size, and differences among microbial cellular structures.

Nanoemulsions of terpene by-products from cannabidiol production have promising insecticidal effect on Callosobruchus maculatus.

Nanoemulsions of a terpene-rich by-product (TP) from commercial cannabidiol (CBD) production were successfully formulated and characterized. An enriched terpene distillate (DTP) was also obtained from steam distillation of TP and used for making nanoemulsions. The effects of formulation conditions including the hydrophilic lipophilic balance (HLB) value of the surfactant, TP and surfactant content, and sonication time on the properties of the emulsions were analyzed. The optimal formulation conditions were determined as surfactant HLB value of 13, TP content of 5 wt% in water, surfactant content of 2 times of TP, and sonication time of 1.5 min. A scaled-up production of the optimal nanoemulsion was also achieved using a microfluidizer and the effect of pressure and number of passes on emulsion properties was determined. The stability of the nanoemulsions was evaluated and the DTP nanoemulsion was determined to be the most stable. The nanoemulsions with desirable properties were then selected and evaluated for their insecticidal activity against the legume pest, Callosobruchus maculatus, with nanoemulsion of neem oil made under the same conditions as a control. Both TP and DTP nanoemulsions were found to exhibit excellent insecticidal activity, and the latter had the highest efficacy against the Callosobruchus maculatus.

Investigations into Determinants of Blueberry Coating Effectiveness.

Coatings have been investigated as a means of slowing weight loss and helping to preserve quality in blueberries but reported results have been inconsistent with the inadequate presentation of the impact of coatings on blueberry appearance. In this study, we compare the ability to limit weight loss, along with the effect on appearance, of several previously studied coatings for blueberries and attempt to identify reasons why coatings have not been more successful in limiting weight loss in blueberries. In a two-year study, coatings were applied either as a spray or a dip, depending on the nature of the coating, and included 1% chitosan (CH) with and without either 1% or 2% oleic acid (OA), 1% Semperfresh (SF), 2% sodium caseinate (SC), and carnauba wax (CAR). None of the coatings reduced weight loss in either year of the study and sometimes enhanced it. CH, CH + OA, CAR, and SF greatly altered the appearance of the berries by removing all or a part of the waxy bloom. SC also did this to some degree but was generally better at maintaining the natural appearance. It was found that coating application did not effectively limit weight loss through either the cuticle or stem end of the blueberries. Loss of the bloom on the blueberry surface, confirmed visually and by scanning electron microscopy, occurred during coating application, but was found to not influence coating effectiveness. Using CH + OA as an example, it was found that increasing the amount of handling during the drying process significantly increased subsequent weight loss relative to blueberries with minimal handling. This indicates that careful handling during the coating process is important for coating success.

Characterization of By-Products from Commercial Cannabidiol Production.

The chemical compositions of by-products from commercial cannabidiol (CBD) extraction were characterized and quantitated by employing gas chromatography mass spectrometry (GC-MS) and GC flame-ionization detection (GC-FID). The four major by-products included an ethanol-wax suspension (WAX), terpenoid distillate (DIST-A), tar-like residue (TAR), and red resin (RES). The composition of WAX consisted of ∼28 wt % n-alkanes and ∼33-38 wt % cannabidiolic acid and CBD combined. The DIST-A consisted of ∼40 wt % sesquiterpenoids and ∼58 wt % cannabinoids. The DIST-A terpenoid profile was compared to dried unprocessed inflorescences (HEMP) to observe changes in monoterpene content after the distillation process. The TAR was composed of ∼5-9 wt % higher n-alkanes and up to 91 wt % cannabinoids, while RES consisted of up to 99 wt % cannabinoids. Several impurities including cannabidibutol and dehydroabietic acid were identified in commercial CBD samples. Compositional information of these by-products may provide manufacturers with the opportunity to optimize processing conditions.