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Background: There is increasing consumer demand for olive oil to be traceable. However, genotype, environmental factors, and stage of maturity, all affect the flavor and composition of both the olives and olive oil. Few studies have included all three variables. Key metabolites include lipids, phenolics, and a wide range of volatile organic compounds (VOCs), which provide the olives and oil with their characteristic flavor. Here we aim to identify markers that are able to discriminate between cultivars, that can identify growth location, and can discriminate stages of fruit maturity. 'Nocellara messinese' and 'Carolea' olive fruits were grown at three locations differing in altitude in Calabria, Italy, and harvested at three stages of maturity. Oil was analyzed from the two most mature stages., Results: Nine and 20 characters discriminated all fruit and oil samples respectively, and relative abundance of two fatty acids distinguished all oils. Whole VOC profiles discriminated among the least mature olives, and oil VOC profiles discriminated location and cultivar at both stages. Three VOCs putatively identified as hexanal, methyl acetate, and 3-hexen-1-ol differentiated all samples of oils from the most mature fruit stage., Conclusion: The results confirm that interactions of location, cultivar and fruit maturity stage are critical for the overall pattern of aroma compounds, and identify potential markers of commercial relevance. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry., (© 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.)

Volatile organic compounds (VOCs) detected in human breath, urine, stool, sweat, saliva, and blood result from metabolic processes in the body during health or disease. Using sophisticated measurement systems, small amounts of these compounds can be detected in the above bodily fluids. Multiple studies in adults and children have shown the potential of these compounds to differentiate between healthy individuals and patients by detecting profiles of compounds in non-invasively collected samples. However, the detection of biomarkers in VOCs from neonates is particularly attractive due to the non-invasive nature of its approach, and its ability to track disease progress by longitudinal sampling. In this work we have reviewed the literature on the use of VOCs in neonates and identified areas for future work. Overview of VOCs and their usefulness as metabolic signatures. Detailed review of studies on VOCs in neonates Learn about potential uses of VOCs as derived from adult and paediatric studies. Examine current limitations and identify future work. Detailed studies on VOCs involving neonatal patients including sick preterm infants and term infants with specific morbidities are needed. These studies should collect longitudinal samples using non-invasive methods for the detection of potential biomarkers. Underlying metabolic processes need to be identified so that any therapeutic options can be clarified., (Creative Commons Attribution license.)

Peaches have a short shelf life and require chilling during storage and transport. Peach aroma is important for consumer preference and determined by underlying metabolic pathways and gene expression. Differences in aroma (profiles of volatile organic compounds, VOCs) have been widely reported across cultivars and in response to cold storage. However, few studies used intact peaches, or used equilibrium sampling methods subject to saturation. We analysed VOC profiles using TD-GC × GC-ToF-MS and expression of 12 key VOC pathway genes of intact fruit from six cultivars (three peaches, three nectarines) before and after storage at 1 °C for 7 days including 36 h shelf life storage at 20 °C. Two dimensional GC (GC × GC) significantly enhances discrimination of thermal desorption gas chromatography time-of-flight mass spectrometry (TD-GC-ToF-MS) and detected a total of 115 VOCs. A subset of 15 VOCs from analysis with Random Forest discriminated between cultivars. Another 16 VOCs correlated strongly with expression profiles of eleven key genes in the lipoxygenase pathway, and both expression profiles and VOCs discriminated amongst cultivars, peach versus nectarines and between treatments. The cultivar-specific response to cold storage underlines the need to understand more fully the genetic basis for VOC changes across cultivars.

Melons are prized for their characteristic aroma, however, pre-harvest growth, stage of ripening at harvest, post-harvest processing and storage conditions lead to quality changes in fresh-cut fruit. We considered changes in metabolites and gene expression over 14 days storage to assess underlying mechanisms and identify potential quality markers. Overall, 99 volatile organic compounds (VOCs) were detected and VOC profiles discriminated between two melon seasons, cut-size, storage temperatures and storage time, although season affected their discriminatory power. Abundance of two VOCs fell rapidly and was not associated with cut size, indicating their use as markers for early changes post-processing. Non-acetate to acetate ester ratio differed between the seasons and correlated with changes in alcohol acyl-transferase (CmAAT1) gene expression. Furthermore, CmAAT1 expression clustered with two ester VOCs that may be potential new products of this enzyme. Season also strongly affected post-harvest sugar content, most likely attributable to meteorological differences during growth. Storage temperature and cut size affected expression of transcription factors ERF71, ERF106, and TINY, whose expression generally rose during storage, probably related to increased stress. Thus, although time × temperature of storage are key factors, pre-harvest conditions and fruit processing impact significantly gene expression and aroma loss post-harvest.

Across multiple taxa, population structure and dynamics depend on effective signalling between individuals. Among mammals, chemical communication is arguably the most important sense, underpinning mate choice, parental care, territoriality and even disease transmission. There is a growing body of evidence that odours signal genetic information that may confer considerable benefits including inbreeding avoidance and nepotism. To date, however, there has been no clear evidence that odours encode population-level information in wild mammals. Here we demonstrate for the first time the existence of 'odour dialects' in genetically distinct mammalian subpopulations across a large geographical scale. We found that otters, Lutra lutra, from across the United Kingdom possess sex and biogeography-specific odours. Subpopulations with the most distinctive odour profiles are also the most genetically diverse but not the most genetically differentiated. Furthermore, geographic distance between individuals does not explain regional odour differences, refuting other potential explanations such as group odour sharing behaviour. Differences in the language of odours between subpopulations have the potential to affect individual interactions, which could impact reproduction and gene-flow.

Rocket salad (Diplotaxis tenuifolia; wild rocket) is an important component of ready to eat salads providing a distinct peppery flavour and containing nutritionally relevant compounds. Quality deteriorates during post-harvest, in relation to time and storage temperature amongst other factors. Volatile organic compounds (VOCs) are easily measurable from rocket leaves and may provide useful quality indicators for e.g. changes in isothiocyanates derived from nutritionally important glucosinolates. VOC profiles discriminated storage temperatures (0, 5 and 10°C) and times (over 14days). More specifically, concentrations of aldehydes and isothiocyanates decreased with time paralleling a fall in vitamin C and a reduction in sensorial quality at the two higher temperatures. Sulphur containing compounds rise at later time-points and at higher temperatures coincident with an increase in microbial titre, mirroring a further drop in sensorial quality thus indicating their contribution to off-odours., (Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Fleshy fruits develop from an unripe organ that needs to be protected from damage to a ripe organ that attracts frugivores for seed dispersal through production of volatile organic compounds (VOCs). Thus, different responses to wounding damage are predicted. The aim of this study was to discover whether wound-induced changes in the transcriptome and VOC production alter as tomato transitions from unripe to ripe. Transcript changes were analysed 3h post-wounding using microarray analysis in two commercial salad-tomato (Solanum lycopersicum L.) cultivars: Luna Rossa and AVG, chosen for their high aroma production. This was followed by quantitative PCR on Luna Rossa genes involved in VOC biosynthesis and defence responses. VOCs elicited by wounding at different ripening stages were analysed by solid phase micro extraction and gas chromatography-mass spectrometry. Approximately 4000 differentially expressed genes were identified in the cultivar AVG and 2500 in Luna Rossa. In both cultivars the majority of genes were up-regulated and the most affected pathways were metabolism of terpenes, carotenoids, and lipids. Defence-related genes were mostly up-regulated in immature stages of development, whereas expression of genes related to VOCs changed at riper stages. More than 40 VOCs were detected and profiles changed with ripening stage. Thus, both transcriptome and VOC profiles elicited by wounding depend on stage of ripening, indicating a shift from defence to attraction., (© The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

Scent is used across taxa to communicate information about signaler identity. Eurasian otters Lutra lutra are mainly solitary and thought to use scent as their primary means of communication. Little is known, however, about what information otters communicate through scent or what social function this performs. Headspace solid-phase microextraction and gas chromatography-mass spectrometry were used to sample and analyze volatile organic compounds from anal scent gland secretion from 158 otters of differing sex, age, and female reproductive status. Univariate and multivariate differences were clear between adult and juvenile otters. Complex sex differences were apparent in adult otters but not in younger individuals, suggesting the use of this scent secretion in mate attraction. The scent of pregnant and lactating females was highly differentiated from male and juvenile scent, but anecdotal reports suggest females avoid communication during these times., (© The Author 2011. Published by Oxford University Press. All rights reserved.)

Apple cultivars 'Annurca' and 'Limoncella' are grown locally in the Campania region of Italy and are valued for their distinctive flavour and characteristics, including a high content of nutritionally important bioactive compounds. However, apples are typically stored chilled for several months before consumption, so it is important to assess if the valuable characteristics are still present after postharvest storage. Here, we compare the quality, nutritional parameters, and aroma of these two cultivars with two widely grown international cultivars, 'Golden Delicious' and 'Fuji', after 60 days of storage. The aroma profiles of all four apples were analysed using thermal desorption and gas chromatography–time-of-flight mass spectrometry. We show that the local cultivars are distinct from the international cultivars in their bioactive compound content and their antioxidant activity. 'Limoncella' shows high sugar content, which may be acting as a cryoprotectant during storage, and high total phenolics in the flesh, which is of nutritional interest. We identified 104 volatile organic compounds (VOCs) and showed that the overall aroma profile is distinct for each cultivar, containing 11 published odorant compounds. The 'Annurca' profile is uniquely low in esters. Seven VOCs retain good discrimination across the four cultivars and, together with the quality and nutritional data, separate the two local cultivars from the international cultivars by hierarchical clustering. Overall, the data emphasize the unique characteristics of the two local cultivars and their value. [ABSTRACT FROM AUTHOR]

Rocket salad is a valuable commercial product often sold as a bagged ready to eat salad. Two different species from the Brassicaceae family are sold as rocket salad: Diplotaxis tenuifolia and Eruca sativa. Both are aromatic, and previous studies have shown that their aroma is composed of a complex mixture of volatile organic compounds (VOCs) from several different chemical families. Of particular interest are isothiocyanates that are generated from the metabolism of glucosinolates produced by Brassicaceae species. Both types of rocket salad have a limited shelf-life and there has been interest in assessing whether analysis of VOCs could be used to help set 'use by dates' assess quality changes, and report on issues within the supply chain. However, different methods have been used to sample and analyse the VOC profiles. Here we compare the profiles from D. tenuifolia using two VOC sampling methods (solid phase microextraction, SPME) and sampling onto thermal desorption (TD) tubes. We also compare the VOC profiles sampled onto TD tubes from both species from leaves subjected to different levels of damage: intact, chopped and blended. We find that both the method of VOC sampling and the level of leaf damage have important effects on the VOC profile. In the comparison, fewer VOCs are detected when sampling with SPME compared to TD tubes. Overall, 41 different VOCs are detected in the leaf damage experiment but many fewer are detected in intact leaves. While the two rocket species are distinct based on the VOC profile of chopped leaves, they are not discriminated by VOC profiles of blended or intact leaves. When species are considered separately VOC profile discriminates level of damage. Very few isothiocyanates are detected in intact or chopped leaves, presumably due to the requirement for leaf damage to activate their production from glucosinolates. To conclude, level of leaf damage will strongly influence VOC profiles from rocket leaves, and medium damage seems to elicit the most discriminatory profiles. [ABSTRACT FROM AUTHOR]

Hypogean petrels return to the same nest burrow to breed on remote islands during the summer months. Their nocturnal behavior at the colony, strong musky odor and olfactory anatomy suggest an important role of olfaction in homing behavior and nest recognition. Behavioral experiments showed that olfactory cues are sufficient to allow nest identification, suggesting a stabile chemical signature emanating from burrows and facilitating nest recognition. However, the chemical nature and sources of this odor remain unknown. To better understand the nest odor composition, we analyzed volatile organic compounds (VOCs) of nests of blue petrels (Halobaena caerulea) derived from three different odor sources: nest air, nest material and feather samples. We also compared, during two successive years, VOCs from burrows with an incubating breeder on the nest, and burrows used during the breeding season by blue petrels but shortly temporally unoccupied by breeders. We found that the nest air odor was mainly formed by the owners' odor, which provided an individual chemical label for nests that appeared stabile over the breeding season. These findings, together with the previous homing behavioral studies showing an essential role of the sense of smell in blue petrels, strongly suggest that the scent emanating from burrows of blue petrels provides the information that facilitates nest recognition and homing. [ABSTRACT FROM AUTHOR]

Introduction: Strawberry fruit are highly valued for their aroma which develops during ripening. However, they have a short shelf-life. Low temperature storage is routinely used to extend shelf-life for transport and storage in the supply chain, however cold storage can also affect fruit aroma. Some fruit continue to ripen during chilled storage; however, strawberries are a non-climacteric fruit and hence ripening postharvest is limited. Although most strawberry fruit is sold whole, halved fruit is also used in ready to eat fresh fruit salads which are of increasing consumer demand and pose additional challenges to fresh fruit storage. Methods: To better understand the effects of cold storage, volatilomic and transcriptomic analyses were applied to halved Fragaria x ananassa cv. Elsanta fruit stored at 4 or 8°C for up to 12 days over two growing seasons. Results and discussion: The volatile organic compound (VOC) profile differed between 4 or 8°C on most days of storage. Major differences were detected between the two different years of harvest indicating that aroma change at harvest and during storage is highly dependent on environmental factors during growth. The major component of the aroma profile in both years was esters. Over 3000 genes changed in expression over 5 days of storage at 8°C in transcriptome analysis. Overall, phenylpropanoid metabolism, which may also affect VOCs, and starch metabolism were the most significantly affected pathways. Genes involved in autophagy were also differentially expressed. Expression of genes from 43 different transcription factor (TF) families changed in expression: mostly they were down-regulated but NAC and WRKY family genes were mainly up-regulated. Given the high ester representation amongst VOCs, the down-regulation of an alcohol acyl transferase (AAT) during storage is significant. A total of 113 differentially expressed genes were co-regulated with the AAT gene, including seven TFs. These may be potential AAT regulators. [ABSTRACT FROM AUTHOR]

Insects play crucial roles in nearly every ecosystem and provide a wide array of ecosystem services. However, both managed and wild insect populations face threats from parasites and pathogens, which require surveillance to mitigate. Current infectious disease surveillance methods for insects often involve invasive, time‐consuming and occasionally destructive techniques, such as manual inspections and molecular detection. Volatile organic compound (VOC) surveillance provides a real‐time, accurate and non‐invasive alternative for disease detection and has been well‐established in humans and livestock. Recent advances in sensor technology now allow for the development of in‐field VOC surveillance devices. This review explores the need for disease surveillance in insects and highlights recent advances of using VOCs for this purpose, focusing on honey bees as an example. We outline potential applications, challenges and future prospects of using VOCs for insect disease surveillance, providing examples of how this technology could be globally applied to mitigate the impacts of disease in a range of insect systems. [ABSTRACT FROM AUTHOR]

The decreasing number of veteran trees in Europe threatens old‐growth habitats and the fauna they support. This includes rare taxa, such as the violet click beetle, Limoniscus violaceus (Müller, 1821).Samples of wood mould were taken from all beech trees in Windsor Forest previously confirmed to have contained L. violaceus larvae, and from trees where L. violaceus had not previously been detected, the latter categorised as having high, medium or low likelihood of containing the beetle during recent surveys. Habitat characteristics were measured, and volatile profiles determined using gas‐chromatography mass‐spectrometry.Water content significantly differed between tree hollows of different violet click beetle status, high‐potential habitats having higher and relatively stable water content compared with habitats with medium or low potential of beetle occupancy. Several volatile organic compounds (VOCs) were significantly associated with L. violaceus habitats. No differences in other characteristics were detected.The distinction in water regime between habitats highlights that recording this quantitatively could improve habitat surveys. Several potential L. violaceus attractant VOCs were identified. These could potentially be integrated into existing monitoring strategies, such as through volatile‐baited emergence traps or volatile‐based surveying of habitats, for more efficient population monitoring of the beetle. [ABSTRACT FROM AUTHOR]

Once harvested, leaves undergo a process of senescence which shares some features with developmental senescence. These include changes in gene expression, metabolites, and loss of photosynthetic capacity. Of particular interest in fresh produce are changes in nutrient content and the aroma, which is dependent on the profile of volatile organic compounds (VOCs). Leafy salads are subjected to multiple stresses during and shortly after harvest, including mechanical damage, storage or transport under different temperature regimes, and low light. These are thought to impact on later shelf life performance by altering the progress of post-harvest senescence. Short term stresses in the first 24 h after harvest were simulated in wild rocket (Diplotaxis tenuifolia). These included dark (ambient temperature), dark and wounding (ambient temperature), and storage at 4 °C in darkness. The effects of stresses were monitored immediately afterwards and after one week of storage at 10 °C. Expression changes in two NAC transcription factors (orthologues of ANAC059 and ANAC019), and a gene involved in isothiocyanate production (thiocyanate methyltransferase, TMT) were evident immediately after stress treatments with some expression changes persisting following storage. Vitamin C loss and microbial growth on leaves were also affected by stress treatments. VOC profiles were differentially affected by stress treatments and the storage period. Overall, short term post-harvest stresses affected multiple aspects of rocket leaf senescence during chilled storage even after a week. However, different stress combinations elicited different responses. [ABSTRACT FROM AUTHOR]

BACKGROUND: Strawberries are perishable fruits that decay quickly after harvest, but are valued for their distinctive taste and aroma. Melatonin is involved in plant resistance against stress, plant senescence and fruit ripening, and was shown to delay post-harvest spoilage of strawberries. OBJECTIVE: The effects of melatonin postharvest treatment on shelf-life and volatile organic compound profile were assessed in strawberry fruits cv "Luca". METHODS: Strawberry fruit were treated with 100 μM melatonin and stored at 4°C for 12 days to assess whether melatonin treatment could delay spoilage without adversely affecting aroma. RESULTS: Melatonin treatment delayed fruit deterioration by reducing weight loss and incidence of decay as well as maintaining total soluble solids, titratable acidity, anthocyanin, and taste. Melatonin treatment also significantly reduced CO2 production compared to control fruits. The relative abundance of the majority of volatile organic compounds (VOCs) was not affected, however abundance of two VOCs that are important components of strawberry aroma were affected by melatonin treatment. CONCLUSIONS: Post-harvest treatment of strawberries with 100 μM melatonin improved strawberry quality and conserved bioactive compounds after 12 d of storage. However, components of the aroma profile were altered in a way which may affect consumer perception of quality. [ABSTRACT FROM AUTHOR]

The role and use of olfactory cues by penguins is largely under‐investigated, with only a few studies suggesting that odours are involved in prey detection, orientation and for interspecific communication. This also applies to King Penguins Aptenodytes patagonicus where little is known about their chemoreception abilities and, subsequently, the role of odours in their behavioural ecology. Here, we investigated the chemical composition of volatile organic compounds (VOCs) from feathers of King Penguins in the Kerguelen Archipelago and their potential to carry information on identity and sex. We analysed VOCs using direct thermal desorption, a novel approach for extracting volatile compounds directly from solid matrices. We were only able to test at desorption temperatures of 70 and 100 °C to optimize conditions for VOC analysis. We found a profile of 26 VOCs present in most individuals, which varied significantly between individuals but not between sexes. Results suggested that VOCs could possibly be used by King Penguins to locate the colony and recognize individuals, if similar VOCs are also present at ambient conditions. Further studies and behavioural experiments are encouraged to explore olfactory‐based communication in this species. [ABSTRACT FROM AUTHOR]

An important step in breeding for nutritionally enhanced varieties is determining the effects of the post-harvest supply chain on phytochemicals and the changes in VOCs produced over time. TD-GC–TOF-MS was used and a technique for the extraction of VOCs from the headspace using portable tubes is described. Forty-two compounds were detected; 39 were identified by comparison to NIST libraries. Thirty-five compounds had not been previously reported in Eruca sativa. Seven accessions were assessed for changes in headspace VOCs over 7 days. Relative amounts of VOCs across 3 time points were significantly different – isothiocyanate-containing molecules being abundant on ‘Day 0’. Each accession showed differences in proportions/types of volatiles produced on each day. PCA revealed a separation of VOC profiles according to the day of sampling. Changes in VOC profiles over time could provide a tool for assessment of shelf life. [ABSTRACT FROM AUTHOR]

Fresh-cut cantaloupe melon is valued for its aroma but is highly perishable. Temperature of storage (typically 0–5 °C) is critical for maintaining fresh-cut melon quality, but often reaches 10 °C during transportation and in retail outlets. A comparison amongst 0, 5 and 10 °C storage temperatures for fresh-cut melon over 14 days reveals that storage at 0 °C is optimal for avoiding increases in microbial load and loss of vitamin C especially at later time points. However, higher temperatures maintain better the balance of esters (acetate versus non-acetate) and phenolic content. The whole volatile organic compound (VOC) profile can be used to discriminate both time and temperature effects especially at earlier time points. Potential VOC markers for changes in vitamin C from day 0 to day 6 of storage (3-methyl butane nitrile) and temperature (limonene) are identified through a multi-trait analysis. [ABSTRACT FROM AUTHOR]

Ready-to-eat fresh cut fruits and vegetables are increasingly popular, however due to their minimal processing there is a risk of contamination with human pathogens. Listeria monocytogenes is of particular concern as it can multiply even at the low temperatures used to store fresh cut products pre-sale. Current detection methods rely on culturing, which is time consuming and does not provide results in the time frame required. Growth of bacteria on a substrate alters its chemical composition affecting the profile of volatile organic compounds (VOCs) emitted. Use of VOCs as a detection method has been hampered by lack of sensitivity and robust sample collection methods. Here we use thermal desorption gas chromatography time of flight mass spectrometry (TD-GC-TOF-MS) followed by analysis with PerMANOVA to analyse VOC profiles. We can discriminate between fresh cut melon cubes inoculated with 6 log CFU/g of L. monocytogenes and uninoculated controls, as well as melon cubes inoculated with <1 log CFU/g of L. monocytogenes stored for 7 days at 4 °C and following equilibration for 6 h at 37 °C. This is a substantial advance in sensitivity compared to previous studies and additionally the collection method used allows remote sampling and transport of the VOCs, greatly facilitating analyses. [ABSTRACT FROM AUTHOR]

Garlic (Allium sativum L.) has long been grown for its culinary and health-promoting qualities. The seasonal nature of garlic cropping requires that bulbs be stored for many months after harvest to ensure a year-round supply. During this time, quality is known to deteriorate, and efforts have been made to improve the longevity of stored bulbs. Cold temperatures within the stores prolong shelf life, but fine temperature control is needed to avoid freezing damage or cold induced stress. Here, quality traits (alliinase activity, firmness, and water content) are measured in response to a 96 h − 5 °C cold stress, to simulate the effect of non-isothermic temperature control in a − 1.5 °C warehouse. Volatile organic compounds (VOCs) are measured by thermal desorption gas chromatography time of flight mass spectrometry to identify markers of non-isothermic storage in garlic. 129 compounds were putatively identified and four (L -lactic acid, 2,6-dimethylhetpadecane, 4-methyldodecane, and methylcyclopentane) showed high predictive accuracy for cold stress. VOCs were also sampled directly from a cold storage facility and the whole profile discriminated between sampling time points. Five VOCS were highly predictive for storage time in the warehouse but were different to VOCs previously shown to discriminate between storage times in a laboratory setting. This indicates the need for realistic warehouse experiments to test quality markers. • Four VOC markers can detect breaches in a garlic cold storage regime. • VOCs provide a tool for monitoring garlic quality in the warehouse. • VOCs discriminate storage time of garlic bulbs in a warehouse. • Time discrimination based on VOCs was independent from garlic variety. [ABSTRACT FROM AUTHOR]

• Garlic bulb storage affects biotechnological quality (alliinase yield and activity). • Garlic bulb storage elicits changes in volatile organic compound (VOC) patterns. • VOC profiles from stored garlic are affected by temperature of storage. • Storage temperature has negative effects on bulb alliinase activity and spoilage. • Specific VOCs are identified as potential markers for garlic quality changes over time. Garlic (Allium sativum L.) has a long history of use as a culinary seasoning and source of health-promoting compounds. In particular organosulphur compounds derived from the action of alliinase on alliin are of interest for their antimicrobial action. Due to the seasonal nature of the garlic harvest, long-term storage is required to ensure year-round supply of high-quality bulbs. However, quality is known to deteriorate throughout storage, and storage regimes are aimed at maintaining culinary, not biochemical quality, posing challenges for biotech firms extracting high value products, such as alliinase, from garlic. Storage typically involves extended periods of up to 9 months at -1.5 °C. Here, quality parameters (disease incidence and moisture content) as well as biotechnological quality parameters (alliinase yield and activity) were measured, and correlated with gene expression and volatile organic compound (VOC) profiles comparing storage at -1.5 °C and 22 °C. The aim is to develop potential molecular markers for garlic quality assessment. Alliinase activity fell in the first 6 months of storage, with garlic stored at -1.5 °C losing more activity, however 22 °C stored garlic suffered higher spoilage after 12 months storage. Alliinase activity loss was not proportional to gene transcript levels, suggesting post-translational control. A total of 150 VOCs were detected across all samples using thermal desorption gas chromatography, time of flight mass spectrometry of intact garlic bulbs, the most abundant of which were organosulphur compounds. Storage temperature significantly affected the whole VOC profile and discrete profiles were detected from garlic cold-stored for different time periods. Using weighted correlation network analysis 17 VOCs were identified that correlated with storage time, six VOCs that were indicative for storage temperature and four VOCs (azulene, octanal, o-Xylene and 4-methylhexadecane) were significantly associated with alliinase activity. [ABSTRACT FROM AUTHOR]