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    Interactive effect of pre-fermentative grape freezing and malolactic fermentation on the anthocyanins profile in red wines prone to colour instability
    (Springer Nature, 2023-08-01) Darnal A; Poggesi S; Ceci AT; Mimmo T; Boselli E; Longo E
    The effects of pre-fermentative freezing of red grapes from Schiava variety and co-inoculation with lactic bacteria were evaluated on the profile of anthocyans of the musts and the finished wine. Peonidin-3-glucoside is the main anthocyanin in Schiava grape musts, but it was overcome by malvidin-3-glucoside at bottling. Grape freezing increased the extraction of all anthocyanins in the musts. However, the amount of all anthocyanins except peonidin-3-glucoside and malvidin-3-glucoside was lower in wines from frozen grapes than in control wines. Wines obtained with co-inoculation showed higher anthocyanin content than their respective controls. Petunidin-3-(6′′-p-coumaroyl)-glucoside, peonidin-3-(6′′-cis-p-coumaroyl)-glucoside and malvidin-3-(6′′-trans-p-coumaroyl)-glucoside were dramatically affected by the interaction of the two applied factors. Colorimetric hue (H*) was strongly correlated with peonidin-3-glucoside, and spectrophotometric tint (N) with malvidin-3-glucoside. Tint also showed a positive correlation with malolactic fermentation. Graphical abstract: [Figure not available: see fulltext.]
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    An improved MTT colorimetric method for rapid viable bacteria counting
    (Elsevier BV, 2023-11) Xu W; Shi D; Chen K; Palmer J; Popovich DG
    The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay has been employed in the analysis of bacterial growth. In comparison to experiments conducted on mammalian cells, the MTT bacterial assay encounters a greater number of interfering factors and obstacles that impact the accuracy of results. In this study, we have elucidated an improved MTT assay protocol and put forth an equation that establishes a correlation between colony-forming units (CFU) and the amount of formazan converted by the bacteria, drawing upon the fundamental principle of the MTT assay. This equation is represented as CFU=kF. Furthermore, we have explicated a methodology to determine the scale factor "k" by employing S. aureus and E. coli as illustrative examples. The findings indicate that S. aureus and E. coli reduce MTT by a cyclic process, from which the optimal reduction time at room temperature was determined to be approximately 30 mins. Furthermore, individual E. coli exhibits an MTT reduction capacity approximately four times greater than that of S. aureus. HPLC analysis proves to be the most accurate method for mitigating interferences during the dissolution and quantification of formazan. Additionally, this study has identified a new constraint related to the narrow linear range (0-125 μg/mL) of formazan concentration-absorbance and has presented strategies to circumvent this limitation.
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    Explainable spectral super-resolution based on a single RGB image : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) in Electronics and Computer Engineering at Massey University, Manawatu, New Zealand
    (Massey University, 2024-04-09) Chang, Yuan
    Hyperspectral imaging offers fine spectral measurements of target surfaces, finding utility in various fields. However, traditional hyperspectral systems grapple with high-cost issues. On the other hand, conventional RGB cameras, which provide relatively coarse measurements of surface spectra, are widely accessible. Consequently, the recovery of spectral information from RGB images has emerged as a popular approach for low-cost hyperspectral imaging, a venture also known as single-image spectral super-resolution. Yet, existing methods, mostly rooted in deep convolutional neural networks, tend to suffer from limited interpretability. In our research, we propose an explainable method for single-image spectral super-resolution. This method relies on the RGBPQR colour space, a low-dimensional spectral data model representing the spectrum. Leveraging the RGBPQR spectral model, we can transform the spectral reconstruction task into a regression problem. To tackle the metamerism issue, we analysed existing spectral super-resolution networks and discovered that these networks often depend on local textural information as context to mitigate metamerism. Informed by this insight, we utilized features extracted from multiscale local binary patterns as contextual information to design our explainable method. Furthermore, in this study, we discussed the error measurements and loss functions employed in this research area and proposed a new error measurement that can represent performance more accurately. We also endeavoured to put forward a method for quantitatively measuring the ability to resolve metamerism, a critical problem in spectral super-resolution. Through our research, we offered a simple, low-dimensional, and explainable spectral super-resolution solution.
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    Objective measurement of colour in naturally pigmented wool : a thesis submitted for the degree of Master of Applied Science (Animal Science) at Massey University, Palmerston North, New Zealand
    (Massey University, 2000) Nelson, Margaret Lorraine
    This thesis examines some issues important in considering production of naturally-pigmented wools in New Zealand. Major wool characteristics are reviewed in terms of processing requirements. Statistics of New Zealand production of naturally-pigmented wools are limited, as are data relating to the number and colour of black and coloured sheep farmed in New Zealand. Objective measurements are not widely used by the wool growers; in addition, the lack of a recognised colour standard for these wools limits the marketing of sale lines. The major characteristics of black and coloured wool samples sourced from three regions of New Zealand were analysed and presented. In the absence of a colour standard, tristimulus values (XYZ) and CIELAB (L*a*b*) values were measured using a spectrophotometer. The CIELAB scale provided better distinctions between black, brown and grey wools which had been subjectively graded into categories labelled 'light', 'medium', 'dark', and 'moorit'. CIELAB values for each colour grouping are proposed. To meet the requirements of wool processors, sheep breeders need to supply wools to specification. Wool production objectives are discussed in line with selection objectives, selection criteria and selection methods. The linkages between farmers and processors are reviewed in the light of existing New Zealand practices. The role of the Black and Coloured Sheep Breeders' Association of New Zealand, wool buyers, wool brokers and auction houses is examined In view of the limited quantity of naturally pigmented wools available in commercial (>500kg) quantities, the study suggests that the Association introduce a brand name for the wools produced by its members and establish one sale location only as a means of raising quality standards and the availability of marketable quantities.