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Essential oil distilled from Melaleuca alternifolialeaves, commonly known as tea tree oil, is well known for its biological activity, principally its antimicrobial properties. However, many samples are adulterated with other, cheaper essential oils such as eucalyptus oil. Current methods of detecting such adulteration are costly and time-consuming, making them unsuitable for rapid authentication screening. This study investigated the use of mid-infrared (MIR) spectroscopy for detecting and quantifying the level of eucalyptus oil adulteration in spiked samples of pure Australian tea tree oil. To confirm the authenticity of the tea tree oil samples, GC-MS analysis was used to profile 37 of the main volatile constituents present, demonstrating that the samples conformed to ISO specifications. Three chemometric regression techniques (PLSR, PCR and SVR) were trialled on the MIR spectra, along with a variety of pre-processing techniques. The best-performing full-wavelength PLSR model showed excellent prediction of eucalyptus oil content, with an R

Annual ryegrass is one of the most serious, costly weeds of winter cropping systems in Australia. To determine whether its competition-mediated plant defence mechanisms effect on wheat grain quality, wheat (cv. Yitpi) and annual ryegrass were grown under two levels of CO2 (400 ppm; (a[CO2]) vs 700 ppm; (e[CO2]), two levels of water (well-watered vs drought) and two types of competition (wheat only; (W), and wheat × annual ryegrass; (W × R) with four replicates. The competition × [CO2] interaction had a significant effect on wheat grain protein content, where it was increased in W × R under both e[CO2] (+17%) and a[CO2] (+21%). Grain yield, total grain reducing power and phenolic content were significantly affected by [CO2] × drought × competition. In a summary, annual ryegrass competition significantly altered the wheat grain quality under both [CO2] levels (depending on the soil water level), while also decreasing the grain yield.

Mid-infrared spectroscopy (MIRS) is a well-established technique in the field of chemical analysis. Although it has been applied to problems in the entomological field for over 65 years, MIRS typically remains underutilised in this discipline. Potential applications of MIRS include profiling of cuticular hydrocarbons, taxonomic discrimination between cryptic species, sex discrimination, age prediction, detection of endosymbionts such as Wolbachia, and characterisation of the surface chemistry of insect body parts and products. The number of potential applications is expected to continue rising rapidly as MIR technology advances and it is adopted by more members of the entomological community.

Mid-infrared spectroscopy is finding an increasing number of applications; however, many of its potential uses remain unexplored. In this study, mid-infrared spectroscopy is applied to predict total antioxidant capacity and phenolic contents of powdered matrices of 14 diverse plant species. In all instances, the optimum prediction models were found using standard normal variate smoothing as a pre-processing method. The results show high correlation between the FTIR predicted and chemically determined values, namely R2 values of 0.962 for total phenolics, 0.829 for cupric reducing antioxidant potential (CUPRAC) and 0.911 for ferric reducing antioxidant potential (FRAP). The relative RMSE found for validation indicated that total phenolic content could be predicted with higher accuracy than CUPRAC or FRAP. This pilot study highlights the promise of this technology for plant breeders and a range of industries where rapid screening of many samples for antioxidant and/or phenolic content is envisaged.

Graphical abstract, Highlights • Naturally derived compounds provide a potential wealth of antiviral agents. • We reviewed the literature on phytochemicals against different human and animal coronaviruses. • Compounds showing the greatest potential for drug development are highlighted. • All promising compounds contain a conjugated ring structure. • Most are polyphenols and/or contain a substituted fused ring., Coronaviruses are responsible for a growing economic, social and mortality burden, as the causative agent of diseases such as severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), avian infectious bronchitis virus (IBV) and COVID-19. However, there is a lack of effective antiviral agents for many coronavirus strains. Naturally existing compounds provide a wealth of chemical diversity, including antiviral activity, and thus may have utility as therapeutic agents against coronaviral infections. The PubMed database was searched for papers including the keywords coronavirus, SARS or MERS, as well as traditional medicine, herbal, remedy or plants, with 55 primary research articles identified. The overwhelming majority of publications focussed on polar compounds. Compounds that show promise for the inhibition of coronavirus in humans include scutellarein, silvestrol, tryptanthrin, saikosaponin B2, quercetin, myricetin, caffeic acid, psoralidin, isobavachalcone, and lectins such as griffithsin. Other compounds such as lycorine may be suitable if a therapeutic level of antiviral activity can be achieved without exceeding toxic plasma concentrations. It was noted that the most promising small molecules identified as coronavirus inhibitors contained a conjugated fused ring structure with the majority being classified as being polyphenols.

The finger lime (Citrus australasica) is endemic to Australia, attracting recent culinary interest due to its unique organoleptic profile. However, there is limited information available on the comparative chemical composition of current commercially available Australian cultivars. This study investigated the phytochemical composition of five Australian finger lime cultivars: Durhams Emerald, Chartreuse, Rhyne Red, Red Champagne and a hybrid cultivar (P1f2-10). The pulp ascorbic acid content ranged from 23 to 54 mg/100g (fresh weight basis), while the total phenolic content ranged from 144 to 197 mg/100g. In the pulp, flavonoids were more abundant than hydroxybenzoic and hydroxycinnamic acids, while phenolic acids were found at higher concentrations in the peel. The highest pulp antioxidant capacity and anthocyanin content were found in the Rhyne Red cultivar. The predominant volatile compounds present in peel were limonene, γ-terpinene, β-citronellol and citronellal, with distinct volatile chemotypes for each cultivar. Finger limes show promise for commercial development as a functional food.

Gingerols and their shogaol derivatives play an important role in determining the sensory and organoleptic properties of ginger. In this study, 6-gingerol, 8-gingerol, 10-gingerol and 6-shogaol were quantified in 98 samples of dried Australian processing-grade ginger using high performance liquid chromatography (HPLC). A significant level of variation was found in the gingerol and shogaol contents of ginger samples grown under different conditions. The level of variation found in 6-shogaol content was lower than that observed for 6-gingerol, 8-gingerol or 10-gingerol content. It is possible that zeroth-order reaction kinetics under mild dehydration conditions could be responsible for this observation. More detailed information on the kinetics of the gingerol-dehydration reaction could potentially be used to manipulate the gingerol and shogaol contents of ginger through differential heat treatments.

Chickpea is the second-most grown legume crop world-wide; however, most chickpea genotypes are susceptible to drought and heat stress, limiting expansion of this crop beyond current growing regions. Consequently, this study evaluated the agronomic performance and phyto-nutritional content of five new genotypes of desi chickpea, grown under rainfed conditions in central Queensland, Australia. Four of the new genotypes showed significantly improved yield over PBA Drummond, while two showed higher protein content. The chickpea hull byproduct typically contained a higher total phenolic content (56–150 mg gallic acid equivalents (GAE)/100 g) and ferric reducing antioxidant power (38–174 mg Trolox equivalents (TE)/100 g) compared to the kernel (TPC of 65–105 mg GAE/100 g and FRAP of 44–62 mg TE/100 g); however, this was not true for every variety. The husk also contained high levels of phenolics and antioxidant activity, highlighting the potential of chickpea hull and husk for use as value-added byproducts, rather than being discarded. This study highlights the difference in byproduct phyto-nutritional value that exists between chickpea genotypes, indicating that these parameters should also be considered when selecting genotypes in breeding programs. Furthermore, it presents several new genotypes of desi chickpea which may be suited to cropping in drier, warmer environments.