Permalink for this collection
The Department of Wine, Food and Molecular Biosciences covers course areas including animal and plant science, biochemistry, food science, horticulture, microbiology, sensory science, viticulture and wine science.
Browse
Recent Submissions
Publication Embargo Integrative dynamics of action potential in Axon Initial Segment (AIS) of neurons: A novel computational model : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University(Lincoln University, 2023) Pashang, AbolghasemThe Axon Initial Segment (AIS) plays a critical role in neuronal excitability and action potential initiation. Computational modelling of the AIS can provide valuable insights into the biophysical mechanisms underlying these processes and their relevance to various AIS-related disorders. The Hodgkin-Huxley model laid the foundation for understanding action potential initiation, utilising empirical differential equations to describe sodium and potassium ion conductance and their gating functions. However, the specific role of the scaffold protein Ankrin-G (AnkG) in regulating ion channel function and ion currents in the AIS remains poorly understood. This thesis investigates the impact of AnkG concentration on sodium (Nav) and potassium (Kv) channel gating and ion current properties using electrophysiology, molecular biology, and computational modelling approaches. AnkG acts as a molecular bridge between the Nav and Kv channels and the cytoskeleton, ensuring proper channel localisation and density in the AIS. Disruptions to AnkG expression can lead to alterations in channel localisation and function, affecting neuronal excitability and firing properties. This thesis endeavors to unravel the mechanisms underlying AnkG's influence on Nav and Kv channel function and its subsequent impact on ion currents in the AIS. Understanding these interactions is crucial for comprehending the pathogenesis of AIS-related disorders and shed light on the complexities of action potential initiation and propagation in neurons.Publication Embargo Can the presence of a fungal volatile organic compound improve plant resilience to abiotic stress? : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University(Lincoln University, 2023) Echaide Aquino, Jesus FranciscoClimate change is a matter of increasing concern, as the severity, duration, and area affected by drought have steadily risen since the 1970s. These changes have severely affected the agricultural industry, as drought stress is a major contributor to crop loss. Therefore, it is crucial to develop new strategies to address this problem. Seed coating shows the potential to mitigate the challenges faced by the agricultural industry, as it provides physical and physiological properties to seeds, helping alleviate both biotic and abiotic stress. This research aims to evaluate the protective effect of the fungal volatile (FVOC) organic compound when applied via polymer seed coating. The FVOC seed coating treatment's effects were assessed regarding plant emergence, resilience to drought stress, and transgenerational stress adaptations. By conducting a comprehensive transcriptomic analysis, it was possible to identify the transcriptional changes induced by the presence of the FVOC molecule. The application of the FVOC led to significant changes in gene expression in plants under drought-stress conditions, enabling them to cope more effectively with stress. Moreover, when plants grown from FVOC-treated seeds were exposed to a second round of drought stress, they exhibited a more specific and refined response to this stress. Moreover, when the second-generation plants derived from FVOC-treated seeds were exposed to drought, they exhibited improved resilience to environmental stress. This observation strongly suggests the occurrence of transgenerational changes. The drought stress initially triggered these changes in the first-generation plants and was further enhanced by the presence of the FVOC molecule. Subsequently, these changes were transmitted to the second generation, resulting in enhanced resilience plants.Item Open Access Combined affects of pH adjustment and bentonite addition timing on protein stability of Sauvignon Blanc wine(Wiley, 2024-01) Hung, W; Harrison, R; Morton, James; Trought, M; Frost, A; Tian, Bin; Waters, LBackground and Aims. Bentonite fining is commonly used in white wine production, which can lead to the loss of wine volume and aroma compounds. Many factors influence the efficacy of bentonite fining. The effect of pH adjustment and timing of bentonite addition were studied for their combined effects on Sauvignon Blanc wine protein haze formation and bentonite requirement at microscale and commercial scale. Methods and Results. Three bentonite addition timings were conducted on a juice pH adjustment trial: before fermentation, during fermentation, and after fermentation. The hot and cold test was utilized to determine the bentonite requirement for protein stabilization. Wine proteins were analyzed using a modified Coomassie brilliant blue (CBB) assay, lithium dodecyl sulphate polyacrylamide gel electrophoresis (LDS‐PAGE), and sodium dodecyl sulphate capillary gel electrophoresis (SDS‐CGE). Lower juice pH (2.80 and 3.00) resulted in sluggish fermentation, whereas the presence or absence of bentonite during fermentation showed similar fermentation kinetics at each pH. The presence of bentonite remaining in contact with ferment improved the completion of fermentation for the most sluggish ferment (pH 2.80). Commercial wine made from same batch of juice was adjusted to different pH values, and low‐pH wines had a lower wine protein content and an increasing protein adsorption efficiency of bentonite fining, leading to lower bentonite requirement. Conclusions. Bentonite addition during fermentation was the most efficient in protein removal but fining after fermentation required the least overall bentonite dosage. The different fermentation scales (i.e., microscale versus commercial scale) slightly affected wine protein contents but not molecular weight (MW) profiles. Protein contents and MW profiles in stabilized wines were affected by the original juice pH with more complex patterns from high‐pH juice. Significance of the Study. The findings of this study provide valuable information on optimization of bentonite fining to minimize the dosage so as to reduce the loss of wine volume and quality.Item Open Access Drought and endophyte impact African black beetle feeding on perennial ryegrass(New Zealand Grassland Association, 2024-05-28) Hewitt, KG; Phillips, CB; Hofmann, RW; Ball, OJ; Luo, D; Popay, AJWater is essential to plant growth, driving interactions between plants, herbivorous insects and fungal Epichloë endophytes. However, water availability fluctuates, a phenomenon intensified by climate change, challenging the success of New Zealand’s pastoral industry. The impacts of climatic changes, such as intensifying drought, on pastoral insect pests have received little attention. In a no-choice bioassay, African black beetle (ABB) were fed semi-synthetic diets containing freeze-dried foliage material from drought-exposed and well-watered perennial ryegrass containing endophyte strains AR37 or NZCT, or with material free of endophyte (Nil). Diet consumption, beetle weight change, fungal alkaloid concentrations, phytohormones, and NRI (nitrogen reflectance index) concentrations were measured and compared. Except for AR37, ABB consumed more diets containing drought-exposed rather than well-watered material, with a 61% increase in Nil and a 50% increase in diets containing NZCT, though these effects were not accompanied by corresponding ABB weight changes. Here, we discuss the implications of these results on ABB damage in New Zealand pastures in the context of increasing drought and illustrate how spatial patterns of ABB damage could change over the next 75 years. Areas that do not currently have high populations of ABB such as Manawatū-Whanganui, Wairarapa and Marlborough will become increasingly vulnerable to damage.Item Open Access Nodule occupancy of effective rhizobia vary between historical and modern cultivars of white clover(Taylor & Francis Group, 2024) Ramana, JV; Griffiths, AG; Hofmann, RW; Ridgway, HJThe ability of plants to select effective symbiotic partners is crucial for optimum plant growth. In New Zealand, breeding programmes for white clover (Trifolium repens) have made selections largely based on above-ground characteristics, with little direct attention given to the ability of cultivars to form effective below-ground associations. The ability of three pairs of historical (1930s–1950s), and modern (2000s) cultivars of white clover, to form associations with effective strains of Rhizobium leguminosarum (rhizobia) from a mixture of strains was tested in vitro. First, the efficacy of six individual strains of rhizobia was ranked against all six clover cultivars with shoot biomass used as a direct measure of symbiotic effectiveness for each strain × cultivar combination. Next, each cultivar was inoculated with a mixture of all rhizobia strains at the same cell concentration to examine the identity and frequency of strains found on each host. There was a positive relationship between nodule occupancy and strain effectiveness for historical but not modern cultivars. Cultivars Grasslands Huia and Louisiana (both historical) had nodule occupancy increase with strain effectiveness. This study provides some evidence that historical cultivars may be better able to form associations with effective strains of rhizobia compared with modern cultivars.Item Open Access Serratia-based toxin cluster elements are associated with a type I fimbria(Wiley-Blackwell, 2024-02) Sitter, L; Schoof, M; Glare, Travis; Cox, MP; Fineran, PC; Gardner, PP; Hurst, MRHA soil bacterium in the Serratia genus, carrying a 153 kb conjugative amber disease-associated plasmid (pADAP), is commercially exploited for population control of the New Zealand endemic pest beetle Costelytra giveni (Coleoptera: Scarabaeidae). The main insecticidal elements are an anti-feeding prophage and the Sep ABC toxin complex (Tc). Homologs of pADAP, encoding variant Tcs, convey different beetle disease phenotypes. To investigate the correlation between variable bioactivity and the Tc variant, 76 Serratia plasmids were sequenced, resulting in the identification of four additional tc variants. All Serratia tc variants were found to be colocated with a conserved type 1 sef fimbrial-like operon, indicating a conserved sef-tc genetic island not observed outside of the Serratia genus. The conserved co-location of the fimbrial and tc genes suggests the fimbriae somehow contribute to the lifestyle of Tc-producing cells. Expression of the sef operon in a fim-null Escherichia coli strain revealed fimbriae presence while a constructed sef-deficient mutant showed no reduction of virulence or host colonization. Although no detectable contribution of Sef to amber disease in C. giveni was observed, the Sef adhesin sequences clustered similarly to the Serratia species encoding it, suggesting Sef has a species-specific function.Item Open Access Cork taint of wines: The formation, analysis, and control of 2,4,6- trichloroanisole(Maximum Academic Press, 2024-05-20) Zhou, H; Xie, Y; Wu, T; Wang, X; Gao, J; Tian, Bin; Huang, W; You, Y; Zhan, JCork taint has devastating effects on the aroma and quality of the wine, which can cause an annual loss of may be up to more than one billion dollars. There are many causes of cork taint, but 2,4,6-trichloroanisole (2,4,6-TCA) is a major contributor, giving the wine a wet-moldy smell. This study provided a comprehensive overview of the occurrence, detection, and control/remediation of 2,4,6-TCA. The occurrence and formation mechanisms of 2,4,6-TCA mainly include microbial O-methylation of chlorophenols and chlorination of anisole. The source of 2,4,6-TCA in wine is the cork or other woodworks, but it is also possible to contaminate wine from the environment. Due to the extremely low odor threshold concentration of 2,4,6-TCA, the effective sample pre-enrichment for instrument identification and quantification is more important. The control/remediation strategies of 2,4,6-TCA mainly include eliminating 2,4,6-TCA in cork and removing 2,4,6-TCA from wine by adsorption. Finally, the challenges and possible future research directions in this research field were discussed and proposed.Publication Open Access Epigenetic changes in Saccharomyces cerevisiae alters the aromatic profile in alcoholic fermentation(Cold Spring Harbor Laboratory, 2022-08-11) Kong, Y; Olejar, KJ; On, Stephen; Winefield, Christopher; Wescombe, PA; Brennan, CS; Hider, RN; Chelikani, VenkataEpigenetic changes in genomics provide phenotypic modification without DNA sequence alteration. This study shows that benzoic acid, a common food additive and known histone deacetylase inhibitor (HDACi), has an epigenetic effect on Saccharomyces cerevisiae. Benzoic acid stimulated formation of epigenetic histone marks H3K4Me2, H3K27Me2, H3K18ac and H3Ser10p in S. cerevisiae and altered their phenotypic behavior, resulting in increased production of phenylethyl alcohol and ester compounds during alcoholic fermentation. Our study demonstrates the HDACi activity of certain dietary compounds such as sodium butyrate, curcumin and anacardic acid, suggests the potential use of these dietary compounds in altering S. cerevisiae phenotypes without altering host-cell DNA. This study highlights the potential to use common dietary compounds to exploit epigenetic modifications for various fermentation and biotechnology applications as an alternative to genetic modification. These findings indicate that benzoic acid and other food additives may have potential epigenetic effects on human gut microbiota, in which several yeast species are involved.Publication Embargo Exploring the nutritional quality and bioactivity of different rice crackers and the influence of oyster/mussel protein fortification on potential health benefits : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University(Lincoln University, 2024) Sui, LiminIn New Zealand, a quarter of the population faces multiple chronic health conditions (Ministry of Health, 2023). Nutrient-dense foods containing essential constituents such as protein, fibre, vitamins, and minerals are pivotal for enhancing immunity, maintaining health, and preventing chronic diseases. Rice crackers, a popular modern convenience snack, are favoured for their ease of preparation, extended shelf-life, and appealing texture (Patil, Brennan, Mason, & Brennan, 2016). However, these crackers primarily utilise refined white rice flour obtained by removing the bran layer from brown rice, leading to low levels of protein, dietary fibre, and bioactive compounds, alongside high levels of rapidly digestible carbohydrates. This nutritional profile raises concerns about their potential high glycaemic index and potential implications for chronic health problems (Lafiandra, Riccardi, & Shewry, 2014). As a result, ongoing research is directed toward innovative reformulations of rice-based products to address these nutrient deficiencies. To comprehensively evaluate the quality of white rice crackers, this study examined and compared rice crackers produced from different rice varieties: white rice, brown rice, and black rice. Brown rice and black rice, being whole grain foods, retain their bran layer and offer higher protein, fibre content, and bioactive compounds such as polyphenols and anthocyanins, associated with reduced risks of hypercholesterolemia, cardiovascular diseases, and type 2 diabetes (Ali, Wani, Wani, & Masoodi, 2016; D. Zhu et al., 2023). The investigation encompassed assessments of physical characteristics, nutritional composition, in vitro starch digestion, and glycaemic response. Results showed that brown and black rice crackers exhibited significantly higher essential nutrient levels, including protein, ash, fat, dietary fibre, and resistant starch, compared to white rice crackers (p < 0.05). In contrast, white rice crackers exhibited a higher glycaemic response, characterised by a higher reduced sugar release and a greater content of rapidly digestible starch, along with a lower content of resistant starch during the in vitro starch digestion process. Regarding quality evaluation, white rice crackers exhibited the highest values for brightness (L* = 73.00) and yellowness (b* = 30.89), while black rice crackers demonstrated the lowest brightness (L* = 25.12) and the highest redness (a* = 6.31). Furthermore, black rice crackers displayed the greatest hardness (1022.46 g), whereas brown rice crackers showcased the highest fracturability (18.27 mm). To future examine phenolic compounds in rice crackers and establish links between in vitro digestion, antioxidative properties, and enzyme inhibition, this study extended its investigation to evaluate total phenolic content (TPC), total anthocyanin content (TAC), and antioxidant activities of white, brown, and black rice crackers. Additionally, the study evaluated changes in these parameters following simulated in vitro digestion. The identification of specific phenolic compounds within the rice crackers was carried out using high-performance liquid chromatography (HPLC). Moreover, the study explored the inhibitory effects of these phenolic compounds on the enzymatic activities of α-amylase and α-glucosidase. The findings revealed that black and brown rice crackers consistently displayed higher TPC, TAC, DPPH, and FRAP values compared to white rice crackers. In vitro digestion led to substantial TPC release, approximately 3.81-4.95 times higher, significantly increased DPPH values by 14.96-24.14 times, and elevated FRAP values by 4.25-4.90 times (p < 0.05). However, there was a reduction of TAC values following digestion. HPLC analysis indicated the presence of various phenolic compounds, including gallic acid, 2,5-dihydroxybenzoic acid, catechin, vanillic acid, rutin, p-coumaric acid, p-hydroxybenzoic acid, ferulic acid, and quercetin, in brown and black rice crackers, while white rice crackers primarily contained gallic acid and 2,5-dihydroxybenzoic acid. Furthermore, brown and black rice crackers exhibited stronger inhibitory effects on α-amylase and α-glucosidase compared to white rice crackers, with lower IC50 values. These findings highlight substantial variations among the different rice varieties, indicating the potential of brown and black rice for the production of rice crackers with lower glycaemic responses, higher nutritional value and the potential health benefits associated with enhanced phenolic composition and strong inhibitory effect on carbohydrate-digesting enzymes. Protein is essential for tissue growth, repair, and maintenance, as well as the production of enzymes, hormones, and antibodies, contributing to metabolic processes, bodily functions, and immune system function (Wu, Gao, Yu, & Wang, 2022). In response to the prevalent protein insufficiency in white rice crackers, a novel research avenue involves the formulation and advancement of protein-fortified rice crackers. Oysters (Crassostrea gigas) and mussels (Perna canaliculus) are valuable seafood resources consumed widely in New Zealand and contain higher levels of easily digestible protein and iron compared to traditional fish and red meats (Yaghubi et al., 2021). Oyster and mussel proteins are explored for functional foods and supplements, providing essential amino acids and potential health gains. Mussel proteins aid tissue engineering and drug delivery via biocompatibility and adhesion. Oyster proteins offer nutraceutical potential, aiding heart health, immunity, and antioxidants (Harnedy & FitzGerald, 2012; Ulagesan, Krishnan, Nam, & Choi, 2022). Fortifying white rice crackers with oyster and mussel proteins presents an opportunity to boost their nutritional content, lower glycaemic impact, and introduce potential bioactivity, including noteworthy antioxidant capacity and functional effects on inflammatory responses. This study evaluated the overall enhancement in the quality of crackers fortified with oyster and mussel powder at concentrations of 5%, 10%, and 20%, and assessed their impact on glycaemic response and protein bioaccessibility using in vitro starch and protein digestion assays. Additionally, antioxidative capacity was examined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and the Ferric Reducing Antioxidant Power (FRAP) assay. Results indicated that oyster and mussel powders inclusion led to a substantial reduction in starch content, resulting in a decrease of approximately 30% in glucose release and area under the curve (AUC) values during starch digestion compared to the control sample (white rice crackers). Furthermore, the addition of oyster and mussel powders significantly (p < 0.05) increased TPC, with values ranging from 16.74 mg GAE/100g sample to 104.90 mg GAE/100g sample in 20% oyster enriched sample and 77.65 mg GAE/100g sample in 20% mussel enriched sample. Moreover, the release of phenolic compounds during gastric and intestinal digestion was enhanced by nearly 150% and 50%, respectively, compared to the control sample. Antioxidant activity (DPPH and FRAP value) of enriched crackers also exhibited a significant increase corresponding to higher oyster and mussel powder incorporation. However, despite the increase in protein levels from 6.36% to 12.60%, protein digestibility declined from 77.64% to 63.05%. This reduction could be attributed to interactions between phenols and proteins in the samples, potentially affecting overall protein digestion. Furthermore, to evaluate protein availability and bioaccessibility, the research examined alterations in soluble protein content and amino acid composition after in vitro digestion and assessed the protein quality using the Digestible Indispensable Amino Acid Score (DIAAS). Additionally, the study evaluated bioactive peptides by measuring ACE inhibition and anti-inflammatory effects using LPS-stimulated RAW264.7 macrophages. Outcomes revealed heightened protein content and soluble protein content following digestion in oyster and mussel-enriched samples (oyster20, mussel20) compared to the control. Amino acid analysis showcased the increased release of essential and non-essential amino acids during digestion in enriched samples. DIAAS analysis underscored enhanced amino acid bioavailability in enriched rice crackers. Notably, molecular weight distribution exhibited the formation of smaller peptides during digestion. ACE inhibitory activity displayed significantly elevated values in enriched samples, suggesting potential cardiovascular benefits. Anti-inflammatory assessments demonstrated decreased NO production and pro-inflammatory cytokine levels in enriched samples compared to LPS-induced RAW 264.7 macrophages. Overall, this study underscores the significant variations among rice varieties and emphasizes the potential of brown and black rice for producing crackers with enhanced nutritional value, lower glycaemic responses, and health-promoting phenolic compounds. The exploration of marine-based protein fortification further offers a promising avenue for improving rice cracker quality and bioactivity. Through comprehensive analyses, this research contributes to a better understanding of the potential benefits and quality improvements that can be achieved through innovative approaches in rice cracker production.Publication Open Access Unveiling a microexon switch: novel regulation of the activities of sugar assimilation and plant-cell-wall-degrading xylanases and cellulases by Xlr2 in Trichoderma virens(MDPI, 2024-05) Castañeda-Casasola, CC; Nieto-Jacobo, MF; Soares, A; Padilla-Padilla, EA; Anducho-Reyes, MA; Brown, C; Soth, S; Esquivel-Naranjo, EU; Hampton, John; Mendoza-Mendoza, AFunctional microexons have not previously been described in filamentous fungi. Here, we describe a novel mechanism of transcriptional regulation in Trichoderma requiring the inclusion of a microexon from the Xlr2 gene. In low-glucose environments, a long mRNA including the microexon encodes a protein with a GAL4-like DNA-binding domain (Xlr2-∝), whereas in high-glucose environments, a short mRNA that is produced encodes a protein lacking this DNA-binding domain (Xlr2-β). Interestingly, the protein isoforms differ in their impact on cellulase and xylanase activity. Deleting the Xlr2 gene reduced both xylanase and cellulase activity and growth on different carbon sources, such as carboxymethylcellulose, xylan, glucose, and arabinose. The overexpression of either Xlr2-∝ or Xlr2-β in T. virens showed that the short isoform (Xlr2-β) caused higher xylanase activity than the wild types or the long isoform (Xlr2-∝). Conversely, cellulase activity did not increase when overexpressing Xlr2-β but was increased with the overexpression of Xlr2-∝. This is the first report of a novel transcriptional regulation mechanism of plant-cell-wall-degrading enzyme activity in T. virens. This involves the differential expression of a microexon from a gene encoding a transcriptional regulator.Publication Open Access Biofilm formation, sodium hypochlorite susceptibility and genetic diversity of Vibrio parahaemolyticus(Elsevier, 2023-01-16) Wang, D; Fletcher, GC; On, Stephen; Palmer, JS; Gagic, D; Flint, SHVibrio parahaemolyticus is a marine oriented pathogen; and biofilm formation enables its survival and persistence on seafood processing plant, complicating the hygienic practice. The objectives of this study are to assess the ability of V. parahaemolyticus isolated from seafood related environments to form biofilms, to determine the effective sodium hypochlorite concentrations required to inactivate planktonic and biofilm cells, and to evaluate the genetic diversity required for strong biofilm formation. Among nine isolates, PFR30J09 and PFR34B02 isolates were identified as strong biofilm forming strains, with biofilm cell counts of 7.20, 7.08 log₁₀ CFU/cm², respectively, on stainless steel coupons after incubation at 25 °C. Free available chlorine of 1176 mg/L and 4704 mg/L was required to eliminate biofilm cells of 1.74–2.28 log₁₀ CFU/cm² and > 7 log₁₀ CFU/cm², respectively, whereas 63 mg/L for planktonic cells, indicating the ineffectiveness of sodium hypochlorite in eliminating V. parahaemolyticus biofilm cells at recommended concentration in the food industry. These strong biofilm-forming isolates produced more polysaccharides and were less susceptible to sodium hypochlorite, implying a possible correlation between polysaccharide production and sodium hypochlorite susceptibility. Genetic diversity in mshA, mshC and mshD contributed to the observed variation in biofilm formation between isolates. This study identified strong biofilm-forming V. parahaemolyticus strains of new multilocus sequence typing (MLST) types, showed a relationship between polysaccharide production and sodium hypochlorite resistance.Publication Open Access Extraction of tannin, colour and aroma compounds in pinot noir wines as affected by clone selection and whole bunch addition(Elsevier, 2024-09) Wimalasiri, PM; Harrison, Roland; Hider, R; Donaldson, I; Kemp, B; Tian, BinOur previous study revealed stem inclusion fermentation reduced anthocyanin, and increased tannin and aroma compounds responsible for green notes. This study further investigated the effect of clone selection and whole bunch fermentation on Pinot noir wine composition, with focus on tannin composition. Three treatments were conducted using two clones (AM10/5 and UCD5) in 2021 and 2022: 100% destemmed (DS), 30% whole bunch (WB30), and 60% whole bunch (WB60). WB60 increased stem and skin derived tannins but reduced seed derived tannin proportion in wines. Clone selection had an impact on tannin composition and an even greater impact on tannin concentration, colour, and aroma compounds. AM10/5 produced wines with higher tannin, polymeric pigments and darker colour. AM10/5 wines also had higher concentration of phenylethyl alcohol, but lower concentrations of 3-isobutyl-2-methoxypyrazine and ethyl esters, indicating more floral but less fruity and green notes.Publication Open Access A potted vine model to facilitate the understanding of Pinot noir yield-quality seesaw according to root growing conditions(2023) Schelezki, Olaf; Moukarzel, Romy; Gregan, S; Trought, M; Jordan, B; Parker, AmberPresentation at the inaugural New Zealand Wine Centre Scientific Research Conference on 14 November 2023.Publication Open Access Snail meat consumption in Buea-Cameroon: Exposures to foodborne pathogens through social practices assessed in 2019 and 2021(Springer Nature, 2022-12) Tanyitiku, MN; Nicholas, G; Sullivan, Jon; Njombissie Petcheu, IC; On, StephenBackground: Snail meat is an important source of nutrition in Cameroon, but the food safety risks are poorly understood. We characterized public health risks from snail meat consumption as a social system in Cameroon, by examining local snail practices that expose snail meat handlers and consumers to foodborne pathogens. Methods: We used exploratory qualitative approaches, that is, lived experience, face-to-face in-depth interviews, participant observation and a focus group, to explore fifteen key informants’ routines and lived experiences, and perceptions of two health officials on the food safety practices around snail meat consumption in Cameroon. This information was organized and interpreted using Soft Systems Methodology and Social Practice Theory, which permitted a systemic appreciation of local practices. Results: We distinguished five kinds of actors (snail vendors, market sellers, street vendors, street eaters and home consumers), who performed seven successive practices (picking, selling, cracking, washing, cooking, hawking and eating). We then identified three worldviews about snails: family support or to reduce poverty, a source of nutrition and a food choice (taste, preference). Our findings revealed participants’ competences were based on childhood learning and ‘inborn’ experiences, and materials used in snail activities reflected participants’ parentage and ‘state of poverty’. Although most interviewees highlighted ‘unhygienic conditions’ when explaining snail picking locations, participants believed washing and cooking should kill all contaminants. Conclusion: Several opportunities for human exposures to foodborne pathogens including snail picking in domestic wastes and sewage, the selling of unpackaged live snails, improper snail meat washing and hawking in loosely closed buckets, were apparent from our analysis. These findings suggest fruitful opportunities aimed at improving health outcomes among African snail meat handlers and consumers.Publication Open Access Elevated abundance of Komagataeibacter results in a lower pH in kombucha production; insights from microbiomic and chemical analyses(Elsevier, 2024) Ohwofasa, A; Dhami, M; Winefield, Christopher; On, StephenKombucha consumption has grown rapidly worldwide in the last decade, with production at both small- and large scales. The complex fermentation process involves both bacterial and yeast species, but little is known regarding the progression of microbial development during production. We explored the microbial diversity of multiple batches across two kombucha types, i. e commercial scale versus laboratory-made (hereafter “home”) kombucha brew using metabarcoding to characterize both fungal and bacterial communities. We found the microbial community of the commercial kombucha brew to be more complex than that of the home brew. Furthermore, PERMANOVA uncovered significant compositional differences between the bacterial (F = 2.68, R² = 0.23, p = 00.001) and fungal (F = 3.18, R² = 0.26, p = 00.006) communities between batches. For the home brew, both alpha and beta diversity analyses revealed no significant differences between all batches and replicates. When the microbial diversity of the home and commercial kombucha types were directly compared, the former had higher proportions of Ammoniphilus and Komagataeibacter. The commercial kombucha on the other hand were high in Anoxybacillus, Methylobacterium and Sphingomonas. For the fungal communities, the most dominant fungal genera detected in both kombucha types were similar. Linear model revealed significant correlations between some microorganisms and the sugars and organic acids assayed in this study. For example, rising glucose levels correlated with an increase in the relative abundance of Komagataeibacter (F = 7.115, Adj. R² = 0.44, p = 00.0003). We believe these results contribute towards achieving a better control of the kombucha fermentation process and may assist in targeted product diversification.Publication Open Access Comparative genome identification of accessory genes associated with strong biofilm formation in Vibrio parahaemolyticus(Elsevier, 2023-04) Wang, D; Fletcher, GC; Gagic, D; On, Stephen; Palmer, JS; Flint, SHVibrio parahaemolyticus biofilms on the seafood processing plant surfaces are a potential source of seafood contamination and subsequent food poisoning. Strains differ in their ability to form biofilm, but little is known about the genetic characteristics responsible for biofilm development. In this study, pangenome and comparative genome analysis of V. parahaemolyticus strains reveals genetic attributes and gene repertoire that contribute to robust biofilm formation. The study identified 136 accessory genes that were exclusively present in strong biofilm forming strains and these were functionally assigned to the Gene Ontology (GO) pathways of cellulose biosynthesis, rhamnose metabolic and catabolic processes, UDP-glucose processes and O antigen biosynthesis (p < 0.05). Strategies of CRISPR-Cas defence and MSHA pilus-led attachment were implicated via Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation. Higher levels of horizontal gene transfer (HGT) were inferred to confer more putatively novel properties on biofilm-forming V. parahaemolyticus. Furthermore, cellulose biosynthesis, a neglected potential virulence factor, was identified as being acquired from within the order Vibrionales. The cellulose synthase operons in V. parahaemolyticus were examined for their prevalence (22/138, 15.94 %) and were found to consist of the genes bcsG, bcsE, bcsQ, bcsA, bcsB, bcsZ, bcsC. This study provides insights into robust biofilm formation of V. parahaemolyticus at the genomic level and facilitates: identification of key attributes for robust biofilm formation, elucidation of biofilm formation mechanisms and development of potential targets for novel control strategies of persistent V. parahaemolyticus.Publication Open Access Synthesis of β-cyclodextrin@gold nanoparticles and its application on colorimetric assays for ascorbic acid and salmonella based on peroxidase-like activities(MDPI, 2024-03-31) Fan, X; Bao, Y; Chen, Y; Wang, X; On, Stephen; Wang, JThe peroxidase-like behaviors of gold nanoparticles (AuNPs) have the potential to the development of rapid and sensitive colorimetric assays for specific food ingredients and contaminants. Here, using NaBH₄ as a reducing agent, AuNPs with a supramolecular macrocyclic compound β-cyclodextrin (β-CD) capped were synthesized under alkaline conditions. Monodispersal of β-CD@AuNPs possessed a reduction in diameter size and performed great peroxidase-like activities toward both substrates, H₂O₂ and TMB. In the presence of H₂O₂, the color change of TMB oxidization to oxTMB was well-achieved using β-CD@AuNPs as the catalyst, which was further employed to develop colorimetric assays for ascorbic acid, with a limit of detection as low as 0.2 μM in ddH₂O. With the help of the host-guest interaction between β-CD and adamantane, AuNPs conjugated with nanobodies to exhibit peroxidase-like activities and specific recognition against Salmonella Typhimurium simultaneously. Based on this bifunctional bioprobe, a selective and sensitive one-step colorimetric assay for S. Typhimurium was developed with a linear detection from 8.3 × 10⁴ to 2.6 × 10⁸ CFU/mL and can be provided to spiked lettuce with acceptable recoveries of 97.31% to 103.29%. The results demonstrated that the excellent peroxidase-like behaviors of β-CD@AuNPs can be applied to develop a colorimetric sensing platform in the food industry.Publication Open Access Efficacy of commercial peroxyacetic acid on Vibrio parahaemolyticus planktonic cells and biofilms on stainless steel and Greenshell™ mussel (Perna canaliculus) surfaces(Elsevier, 2023-11-16) Wang, D; Palmer, JS; Fletcher, GC; On, Stephen; Gagic, D; Flint, SHThe potential of using commercial peroxyacetic acid (PAA) for Vibrio parahaemolyticus sanitization was evaluated. Commercial PAA of 0.005 % (v/v, PAA: 2.24 mg/L, hydrogen peroxide: 11.79 mg/L) resulted in a planktonic cell reduction of >7.00 log₁₀ CFU/mL when initial V. parahaemolyticus cells averaged 7.64 log₁₀ CFU/mL. For cells on stainless steel coupons, treatment of 0.02 % PAA (v/v, PAA: 8.96 mg/L, hydrogen peroxide: 47.16 mg/L) achieved >5.00 log₁₀ CFU/cm² reductions in biofilm cells for eight strains but not for the two strongest biofilm formers. PAA of 0.05 % (v/v, PAA: 22.39 mg/L, hydrogen peroxide: 117.91 mg/L) was required to inactivate >5.00 log₁₀ CFU/cm² biofilm cells from mussel shell surfaces. The detection of PAA residues after biofilm treatment demonstrated that higher biofilm production resulted in higher PAA residues (p < 0.05), suggesting biofilm is acting as a barrier interfering with PAA diffusing into the matrices. Based on the comparative analysis of genomes, robust biofilm formation and metabolic heterogeneity within niches might have contributed to the variations in PAA resistance of V. parahaemolyticus biofilms.Publication Open Access Effects of repeated tasting sessions on acceptability, emotional responses, and purchasing behaviors of waste-to-value-addedSCOBY (symbiotic culture of bacteria and yeast) ice cream(Wiley Periodicals LLC., 2024-04) Mehta, A; Serventi, Luca; Kumar, Lokesh; Torrico, DamirThis study investigated the effects of repeated exposure on acceptability, emotional responses, and purchase intention of a novel symbiotic culture of bacteria and yeast (SCOBY) ice cream, compared to a control (no extra additives) and a guar gum ice cream sample, using three sessions: a survey (SCOBY information) and two tasting sessions (repeated-exposure effect). Participants initially conducted blind evaluations of all samples, followed by an informed tasting. The blind tasting sessions evoked high arousal emotions for the SCOBY ice cream and positive emotions for the control and guar gum samples. The second session showed a rise in liking for sweetness (5.6–6.5) and texture (5.6–6.7) of the SCOBY samples. Sensory attributes such as flavor (odds ratio = 1.7) and texture (odds ratio = 1.7), coupled with positive emotions such as “happy” (odds ratio = 3.8), “pleasant” (odds ratio = 0.4), and “interested” (odds ratio = 3.8) affected purchase intention. The findings of this study provide valuable insights into participants' liking and emotional responses during repeated exposures to stimuli. Practical Applications: The study's findings show that repeated exposure to novel products enhances consumer acceptance and emotional responses, challenging the current formats of traditional sensory studies. This implies that the introduction of novel products can be successful with repeated tasting exposure strategies. The focus on improving familiarity with sensory attributes, especially flavor and texture, can positively impact purchase intention. This insight can guide product positioning, marketing campaigns, and flavor development efforts, encouraging the successful integration of innovative products into the market.Publication Open Access Wine aromas(MDPI, 2023-12) Tian, Bin; Zhang, JWine has a complex matrix with many volatile compounds present, which evolves over time. These volatile compounds are important to wine quality as they contribute to the aroma and varietal characteristics of wine. Recent development in the analysis of volatile compounds in wine has greatly improved our understanding of the complexity of wine aroma. Analytical methods used for wine aroma fingerprinting have shown potential in determining the origin and quality of wine. Thus, research on volatile compounds responsible for wine aroma and their correlation with wine provenance and wine quality have increasingly attracted great interest from researchers and winegrowers. This Special Issue presents the latest research regarding wine aroma compounds, including, but not limited to, the topics on the characterization of aroma compounds in grapes and wine, factors influencing the production of aroma compounds in wine during fermentation and maturation, and analytical methods for wine aroma analysis.