The Effect of the Height of Coppicing and Harvest Season on the Yield and Quality of the Essential Oil of <i>Kunzea ambigua</i>

Kunzea ambigua is a small shrub belonging to the Myrtaceae family and the leaves are steam-distilled to produce a therapeutically active essential oil. With production moving from wild-harvested to orchardised stands, there is a need for harvest management of kunzea oil. This study compared the regrowth, essential oil content and composition of kunzea plants after harvesting vegetative material to a depth of 0.2 m above ground level (shallow-cut), relative to plants cut to a depth of 0.1 m above ground level (deep-cut) over the 2018/2019 growing season. Increased vegetative biomass accounted for the increased oil yield and was caused by consistently higher growth rates of 50 to 60% across all seasons in shallow-cut crops relative to those subject to deep-cut. Total soluble sugar concentrations were higher in the leaves and lower in the roots of deep-cut treated plants compared to the other treatments, indicating defoliated K. ambigua responds by mobilising sugars into above-ground biomass. The overall essential oil content of leaves was constant regardless of season, though the oil yield for shallow-cut was 1.9-fold higher at 11.79 ± 0.23 g/m2 compared to deep-cut (6.24 ± 0.18 g/m2). An interactive effect of harvest intensity with season was recorded for all major components except for a non-significant effect of season on terpinen-4-ol. Bicyclogermacrene and α-pinene were elevated in both shallow- and deep-cut treatments relative to control (un-cut) in spring, possibly due to the plant defense response after de-foliation. The highest percentage of bioactive compounds (1,8-cineole and viridiflorol) were present in autumn. Therefore, the recovery of biomass post-harvest is optimised by shallow-cut harvests, and the profile of kunzea oil can be manipulated to elevate levels of specific bioactive components by selecting to crop in autumn/spring

Focus on the role of seed tannins and pectolytic enzymes in the color development of Pinot noir wine

Maceration techniques which promote the extraction of color pigments and tannin from grapes are often sought in Pinot noir winemaking to optimise color stability; alternatively, exogenous grape tannins may be included during fermentation. To examine the effect of seed-derived tannins and the use of pectolytic enzymes on color development in wines, conventional must preparations of Vitis vinifera L. cv Pinot noir grapes were compared with wines made using a supplementary addition of either a commercial seed tannin product or previously fermented seeds, while in a complementary experiment, seeds were sequentially removed during fermentation. After 6 months bottle aging, wines supplemented with either a commercial seed tannin solution (0.4 ​g/L), or fermented seeds (20% w/w seeds) had from 60% to 95% higher tannin concentration than the untreated wine, and up to 60% more monomeric anthocyanins. Conversely, when a third of the seeds were removed from the fermenting wine, the concentration of both tannin and non-bleachable pigments was 20–30% lower than in untreated wines and the wine hue had more red-purple tones. Exploration of the use of pectolytic enzymes in conjunction with seed removal was also found to have a significant impact on wine color parameters. Further insights on the timing of egress of tannin precursors from seeds was obtained from histochemical examination of the seeds that had been removed during alcoholic fermentation

Uptake and Translocation of Foliar-Applied <span style="font-variant: small-caps">L</span>-Proline in Sweet Cherry (<i>Prunus avium</i> L.)

Foliar application of nitrogen (N) may supplement soil-applied N in sweet cherry orchards. The proteinogenic amino acid L-proline is a potential source of organic N. However, little is understood about its uptake and effects on fruit quality. In this study, 15N-labelled L-proline was spray-applied to branches of the cultivar ‘Lapins’ either pre- or post-harvest. Leaves, fruit, and whole branches were sampled to investigate the uptake and allocation of foliar-applied N. Both treatments resulted in elevated 15N levels in leaves, with N derived from proline (%NDP) comprising 0.22% and 0.45% after pre- and post-harvest applications, respectively. The fruit was a sink for pre-harvest L-proline, with the highest %NDP in the pedicel (0.21%), followed by the skin (0.17%) and flesh (0.12%). Quality outcomes of smaller, darker fruit with lower stem retention indicate advanced maturity following L-proline application. Both pre- and post-harvest treatments resulted in the recovery of 15N in branches at late dormancy, with %NDP in bark (0.12%), buds (0.15%), and wood (0.02%) of the post-harvest treatment twice as high compared with those from the pre-harvest treatment. This study demonstrates proof of concept of the uptake of L-proline into the leaves of sweet cherry plants and translocation into the fruit and storage organs of the branch

Novel Methods to Manipulate Autolysis in Sparkling Wine: Effects on Yeast

Sparkling wine made by the traditional method (Méthode Traditionelle) develops a distinct and desirable flavour and aroma profile attributed to proteolytic processes during prolonged ageing on lees. Microwave, ultrasound and addition of β-glucanase enzymes were applied to accelerate the disruption of Saccharomyces cerevisiae, and added to the tirage solution for secondary fermentation in traditional sparkling winemaking. Scanning electron microscopy and flow cytometry analyses were used to observe and describe yeast whole-cell anatomy, and cell integrity and structure via propidium iodide (PI) permeability after 6-, 12- and 18-months post-tirage. Treatments applied produced features on lees that were distinct from that of the untreated control yeast. Whilst control yeast displayed budding cells (growth features) with smooth, cavitated and flat external cell appearances; microwave treated yeast cells exhibited modifications like ‘doughnut’ shapes immediately after treatment (time 0). Similar ‘doughnut’-shaped and ‘pitted/porous’ cell features were observed on progressively older lees from the control. Flow cytometry was used to discriminate yeast populations; features consistent with cell disruption were observed in the microwave, ultrasound and enzyme treatments, as evidenced by up to 4-fold increase in PI signal in the microwave treatment. Forward and side scatter signals reflected changes in size and structure of yeast cells, in all treatments applied. When flow cytometry was interpreted alongside the scanning electron microscopy images, bimodal populations of yeast cells with low and high PI intensities were revealed and distinctive ‘doughnut’-shaped cell features observed in association with the microwave treatment only at tirage, that were not observed until 12 months wine ageing in older lees from the control. This work offers both a rapid approach to visualise alterations to yeast cell surfaces and a better understanding of the mechanisms of yeast lysis. Microwave, ultrasound or β-glucanase enzymes are tools that could potentially initiate the release of yeast cell compounds into wine. Further investigation into the impact of such treatments on the flavour and aroma profiles of the wines through sensory evaluation is warranted

Feasibility of Mechanical Pollination in Tree Fruit and Nut Crops: A Review

Pollination is essential for the production of most fruit and nut crops, yet it is often a limiting factor for both yield and product quality. Mechanical pollination (MP) systems offer the potential to increase productivity of a broad range of horticultural fruit and nut crops, and to manage the risk of reliance on current insect pollination services. To date, commercial MP systems have been developed for only a few crops (e.g., kiwifruit and date palm), suggesting that innovation in the use of MP systems has been stymied. Here, we review published and ‘grey’ literature to investigate the feasibility of MP systems of economically important tree fruit and nut crops. This review found that, whilst MP systems are a commercial reality for a wider range of fruit crops (e.g., sweet cherry) than nut crops (e.g., almond), promising results have been achieved at the experimental scale. Further we identified that the key barriers for progressing MP systems more widely include knowledge gaps in pollination biology, particularly of emerging fruit and nut species that are grown outside their native distributions, and access to proprietorial knowledge gained by commercial operators. What continues to remain unclear is detailed knowledge of the commercial development of MP systems and therefore, the opportunities to apply this knowledge to other tree crops where effective pollination limits yield and quality