Daniel Patrick Killeen

Plant and Food Research

Type V' natural deep eutectic solvents (TV NADES) are a novel class of solvent media with many potential ‘green chemistry’ applications. Here, we assess the potential of two TV NADES: menthol:carvacrol (M:C) and menthol:thymol (M:T), and a single terpenoid extraction media carvacrol (C), as media from total lipid extraction of three compositionally...

Raman and infrared spectroscopy, used as individual and low-level fused datasets, were evaluated to identify and quantify the presence of adulterants (palm oil, PO; ω-3 concentrates in ethyl ester, O3C and fish oil, FO) in krill oil. These datasets were qualitatively analysed with principal component analysis (PCA) and classified as adulterated or...

The concentrations and pro-oxidative effects of free fatty acids in commercial krill oil are not well defined. We now report that krill oil free fatty acids account for 2–13% of total lipids in commercial krill oil (n = 8) that these compounds are enriched in eicosapentaenoic acid (+7.1%) and docosahexaenoic acid (+6.3%) relative to whole oils; and...

Improving the lipid composition of feed‐rotifers enhances the survival and growth rates of juvenile fish in aquaculture, but monitoring enrichment profiles using gas chromatography (GC) is slow, labour‐intensive and requires expensive instrumentation. Here, we describe the potential of Raman spectroscopy as an alternative, more rapid tool for quant...

This study uses Raman and IR spectroscopic methods for the detection of adulterants in marine oils. These techniques are used individually and as low-level fused spectroscopic data sets. We used cod liver oil (CLO) and salmon oil (SO) as the valuable marine oils mixed with common adulterants, such as palm oil (PO), omega-3 concentrates in ethyl est...

Vibrational spectroscopy can be used for rapid nutrient assessment of horticultural produce as a means of quality control. Most commonly, spectral data are calibrated against chemical reference data, which are acquired through resource-intensive analytical methods, using partial least squares regression (PLSR). Recently, genetic algorithms (GAs) ha...

Krill oil contains eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), long chain omega-3 polyunsaturated fatty acids with essential roles in human health, and astaxanthin, a naturally occurring keto-carotenoid that protects EPA+DHA against oxidation. Here, we assess Raman and IR spectroscopy (as stand-alone techniques and paired using thre...

The concentrations and pro‐oxidative effects of free fatty acids in commercial krill oil are not well defined. We now report that krill oil free fatty acids account for 2–13% of total lipids in commercial krill oil (n = 8) that these compounds are enriched in eicosapentaenoic acid (+7.1%) and docosahexaenoic acid (+6.3%) relative to whole oils; and...

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are commercially important omega-3 fatty acids found in fish oils. Here we demonstrate that a handheld Raman spectrometer can be used to quantitate these compounds in intact fish oil capsules, avoiding oxidizing risk. Partial least squares regression models were prepared by relating Raman s...

The surface chemistry of graphene oxide (GO) can be modified by the chemical reduction of oxygen-containing groups using L-ascorbic acid (L-AA). Being able to “tune” the surface hydrophobicity of GO in a controlled manner, with a well-defined level of reduction, provides a valuable tool for understanding and controlling interactions with hydrophobi...

The absolute concentration of phospholipids (PL) (μmol g−1, wet tissue) in five marine tissues was determined using quantitative phosphorous nuclear magnetic resonance spectroscopy (31P NMR). Hoki (Macruronus novaezelandiae) roe was identified as a “high‐PL” seafood, containing 15.97 ± 4.72 μmol g−1 (wet tissue) of these compounds. This was 2–4× hi...

Fish oils are the primary dietary source of ω-3 polyunsaturated fatty acids (PUFA), but these compounds are prone to oxidation, and commercial fish oil supplements sometimes contain less PUFA than claimed. These supplements are predominantly sold in softgel capsules. In this work we show that Fourier-Transform (FT)-Raman spectra of fish oils (n=5)...

Introduction: The valuable secondary metabolites in hops (bitter acids, xanthohumol, volatile monoterpenes and sesquiterpenes) are sequestered in lupulin glands (extracellular trichomes) which can be collected and analysed with little or no sample preparation. Objectives: To determine whether high throughput screening of lupulin glands compositi...

Four trimethylated acylphloroglucinols (5-8) have been isolated from ma̅nuka (Leptospermum scoparium) foliage. Apart from myrigalone A (8), which has previously been isolated from European bog myrtle (Myrica gale), these compounds have not been characterized before. The nortriketones are structurally similar to the bioactive tetramethylated β-trike...

Squalene is sourced predominantly from shark liver oils and to a lesser extent from plants such as olives. It is used for the production of surfactants, dyes, sunscreen, and cosmetics. The economic value of shark liver oil is directly related to the squalene content, which in turn is highly variable and species-dependent. Presented here is a valida...

Hops, Humulus lupulus, are grown worldwide for use in the brewing industry to impart characteristic flavour and aroma to finished beer. Breeders produce many varietal crosses with the aim of improving and diversifying commercial hops varieties. The large number of crosses critical to a successful breeding program imposes high demands on the support...

The N ew Z ealand mānuka shrub, L eptospermum scoparium , and the Australian L . morrisonii produce herbicidal β‐triketones in their leaves. The localization of these potential self‐toxicants has not been proven. We investigated the localization of these compounds in leaves using R aman microscopy. The results are presented as heat maps derived fro...