Electronic Noses and Tongues: Applications for the Food and Pharmaceutical Industries

The electronic nose (e-nose) is designed to crudely mimic the mammalian nose in that most contain sensors that non-selectively interact with odor molecules to produce some sort of signal that is then sent to a computer that uses multivariate statistics to determine patterns in the data. This pattern recognition is used to determine that one sample is similar or different from another based on headspace volatiles. There are different types of e-nose sensors including organic polymers, metal oxides, quartz crystal microbalance and even gas-chromatography (GC) or combined with mass spectroscopy (MS) can be used in a non-selective manner using chemical mass or patterns from a short GC column as an e-nose or “Z” nose. The electronic tongue reacts similarly to non-volatile compounds in a liquid. This review will concentrate on applications of e-nose and e-tongue technology for edible products and pharmaceutical uses

Inhibitory activities of vitamins on 7-ketocholesterol formation in both chemical model systems and beef patties

Technical Session V: abstract O-V-04Cholesterol Oxidation Products (COPs), produced by Cholesterol oxidation, are a family of oxidative products generated in high-temperature processing and prolonged storage. COPs could be differentiated into two distinct origins – enzymatic and non-enzymatic source. They are implicated in various food sources, and known to exert certain chemical effects like toxicity, HMG-COA reductase inhibition and atherogenesis effect on human. Considerable researches were conducted to develop strategies as to reduce the associated risk. Yet, direct evidence regarding their effects on COPs formation is still lacking. The formation pathways of COPs have partially elucidated. However, there is still controversy over the inhibition mechanism on COPs formation. The objective of the present study is to identify potent inhibitors of COPs formation from 15 vitamins using chromatographic methods in beef patties. Moreover, the roles of pyridoxamine (the most potent inhibitors) in the formation of 7-ketocholesterol is characterized. The detailed mechanism involved in cholesterol oxidation model system is elucidated. To conclude, vitamin C, A, E and PM can significantly lower the formation of 7-ketocholesterol. Their antioxidant activities only make minor contribution to their inhibitory activities. Their inhibitory activities are mainly mediated via their direct participation in Cholesterol oxidation: direct trapping of the final secondary oxidative product – 7-ketocholesterol.postprin

Application of MOOSY32 eNose to assess the Effects of Some Post Harvest Treatments on the Quality of "Salustiana" Orange Juice

A new prototype of Electronic Nose instrument, Multisensory Odor Olfactory System MOOSY32, with a processing method based on a multivariate classification analysis was used to assess different postharvest and storage treatments effects to Salustiana oranges. The analysis method is based on the measurement of the volatile compounds produced under different environmental and operational conditions. The Electronic Nose system revealed that orange juice flavor changes even when juices are analyzed right after each treatment and fruits are stored under refrigerated conditions. The instrument was able to detect even small changes in the aromatic pattern of the juices, confirming that the packing line itself is able to cause perceptible changes in the flavor. This can be a new and important finding in the Salustiana orange treatment that can lead to a significant improvement of fruits quality on the markets.Cupane, M.; Pelegrí Sebastiá, J.; Climent, E.; Guarrasi, V.; Sogorb Devesa, TC.; Germana, MA. (2015). Application of MOOSY32 eNose to assess the Effects of Some Post Harvest Treatments on the Quality of "Salustiana" Orange Juice. Journal of Biosensors and Bioelectronics. 6(4). doi:10.4172/2155-6210.1000184S6

Aroma profiles of sweet cherry juice fermented by different lactic acid bacteria determined through integrated analysis of electronic nose and gas chromatography–ion mobility spectrometry

Sweet cherries are popular among consumers, with a recent explosion in sweet cherry production in China. However, the fragility of these fruits poses a challenge for expanding production and transport. With the aim of expanding the product categories of sweet cherries that can bypass these challenges, in this study, we prepared sweet cherry juice fermented by three different lactic acid bacteria (LAB; Lactobacillus acidophilus, Lactobacillus plantarum, and Lactobacillus rhamnosus GG), and evaluated the growth, physiochemical, and aroma characteristics. All three strains exhibited excellent growth potential in the sweet cherry juice; however, Lactobacillus acidophilus and Lactobacillus plantarum demonstrated more robust acid production capacity and higher microbial viability than Lactobacillus rhamnosus GG. Lactic acid was the primary fermentation product, and malic acid was significantly metabolized by LAB, indicating a transition in microbial metabolism from using carbohydrates to organic acids. The aroma profile was identified through integrated analysis of electronic nose (E-nose) and headspace gas chromatography–ion mobility spectrometry (HS-GC–IMS) data. A total of 50 volatile compounds characterized the aromatic profiles of the fermented juices by HS-GC–IMS. The flavor of sweet cherry juice changed after LAB fermentation and the fruity odor decreased overall. Lactobacillus acidophilus and Lactobacillus plantarum significantly increased 2-heptanone, ethyl acetate, and acetone contents, bringing about a creamy and rummy-like favor, whereas Lactobacillus rhamnosus GG significantly increased 2-heptanone, 3-hydroxybutan-2-one, and 2-pentanone contents, generating cheesy and buttery-like odors. Principal component analysis of GC–IMS data and linear discriminant analysis of E-nose results could effectively differentiate non-fermented sweet cherry juice and the sweet cherry juice separately inoculated with different LAB strains. Furthermore, there was a high correlation between the E-nose and GC–IMS results, providing a theoretical basis to identify different sweet cherry juice formulations and appropriate starter culture selection for fermentation. This study enables more extensive utilization of sweet cherry in the food industry and helps to improve the flavor of sweet cherry products

Recent Developments on Aroma Biochemistry in Fresh Fruits

For fresh fruits to be consumed and relished, they have to stimulate the senses of taste and smell as well as have good visual properties. In terms of the consumption of a fruit, its aroma, which constitutes the taste and odor elements, is of major importance. Therefore, the wish of consumers to eat fresh fruits is largely due to their rich aroma. The components of aroma that are found in fruits, in very low concentrations, such as ppm or ppb, can easily be perceived sensorially. Flavor, usually composed of volatile compounds, is an important criterion that enhances the appeal of fresh fruits. The aroma in fruits is composed of dozens of compounds in different concentrations. Many researchers have reported that the components of fruit aroma are caused by aldehydes, esters, alcohols, lactones, ketones, terpenoids, and other chemical compounds. The features that make these volatile compounds significant and unite them at a common point are that, even in trace amounts, they are perceived by the senses, and play an extremely effective role on the quality of the fruit. Aroma formation and development takes place in fresh fruits under highly dynamic processes. In this review, aroma biochemistry in fresh fruits and the factors affecting this dynamic process are discussed

Monitoring the Shelf-Life of Minimally Processed Fresh-Cut Apple Slices By Physical–Chemical Analysis and Electronic Nose

Fresh-cut apples, in slices or in cubes, are minimally processed products, which are currently collecting a great interest by fruit marketers for their promising diffusion. Their shelf life, from a microbiological point of view, has been fixed about 2 or 3 weeks under refrigeration. However in a few days they undergo biochemical degradations with production of off-flavors and texture breakdown. In this work, the change of aromatic fingerprint of apple slices packaged in air and in a modified atmosphere (with 100% N2) and stored at 4°C was measured, by using a commercial electronic nose. The obtained data were also compared with sensory evaluation of judge’s panel. Moreover, quality parameters such as total acidity, total soluble solids and firmness were determined at different storage times (0, 4, 8 and 12 days). The data show that the electronic nose is able to discriminate between the two different storage conditions applied: the multivariate analysis, Principal Component Analysis, presents clearly differences among the four sampling times when the apple slices are stored in air and in N2. Our results indicate that the electronic nose can be considered a valid supplementary tool to human sensory panel assessment especially in food quality safety and control and it can be a simple, objective and rapid method to control the food quality during the storage

Electronic-nose applications for fruit identification, ripeness and quality grading

Fruits produce a wide range of volatile organic compounds that impart their characteristically distinct aromas and contribute to unique flavor characteristics. Fruit aroma and flavor characteristics are of key importance in determining consumer acceptance in commercial fruit markets based on individual preference. Fruit producers, suppliers and retailers traditionally utilize and rely on human testers or panels to evaluate fruit quality and aroma characters for assessing fruit salability in fresh markets. We explore the current and potential utilization of electronic-nose devices (with specialized sensor arrays), instruments that are very effective in discriminating complex mixtures of fruit volatiles, as new effective tools for more efficient fruit aroma analyses to replace conventional expensive methods used in fruit aroma assessments. We review the chemical nature of fruit volatiles during all stages of the agro-fruit production process, describe some of the more important applications that electronic nose (e-nose) technologies have provided for fruit aroma characterizations, and summarize recent research providing e-nose data on the effectiveness of these specialized gas-sensing instruments for fruit identifications, cultivar discriminations, ripeness assessments and fruit grading for assuring fruit quality in commercial markets

Characterization of the aroma properties in fragrant rapeseed oil and aroma variation during critical roasting phase

Rapeseed oil is one of the third most-produced vegetable oil in the world, which is appreciated for its characteristic flavor and high nutritional value. Fragrant rapeseed oil (FRO) produced by a typical roasting process is popular for its characteristic aroma, which has an annual consumption exceeding 1.5 million tons. However, the changes in aroma blueprint of FRO during the typical roasting processing are still unclear, which challenges rapeseed oil quality and consumer acceptance. Accordingly, the aim of this work was to investigate the aroma characteristics and their precursors pyrolysis behavior of FRO to provide a basis and guidance for the control of FRO aroma quality during production processing. First, a systematic review on summarizing, comparing, and critiquing the literature regarding the flavor of rapeseed oil, especially about employed analysis techniques (i.e., extraction, qualitative, quantitative, sensorial, and chemometric methods), identified representative/off-flavor compounds, and effects of different treatments during the processes (dehulling, roasting, microwave, flavoring with herbs, refining, oil heating, and storage) was performed. One hundred and thirty-seven odorants found in rapeseed oil from literature are listed, including aldehydes, ketones, acids, esters, alcohols, phenols, pyrazines, furans, pyrrolines, indoles, pyridines, thiazoles, thiophenes, further S-containing compounds, nitriles, and alkenes, and possible formation pathways of some key aroma-active compounds are also proposed. Nevertheless, some of these compounds require further validation (e.g., nitriles) due to lack of recombination experiments in the previous work. To wrap up, advanced flavor analysis techniques should be evolved toward time-saving, portability, real-time monitoring, and visualization, which aims to obtain a complete flavor profile of rapeseed oil. Aparting from that, studies to elucidate the influence of key roasting processing on the formation of aroma-active compounds are needed to deepen understanding of factors resulting in flavor variations of rapeseed oil. Following, a systematic comparison among five flavor trapping techniques including solid-phase microextraction (SPME), SPME-Arrow, headspace stir bar sorptive extraction (HSSE), direct thermal desorption (DTD), and solvent-assisted flavor evaporation (SAFE) for hot-pressed rapeseed oil was conducted. Besides, methodological validation of these five approaches for 31 aroma standards found in rapeseed oil was conducted to compare their stability, reliability, and robustness. For the qualification of the odorants in hot-pressed rapeseed oil, SAFE gave the best performance, mainly due to the high sample volumes, but it performed worse than other methods regarding linearity, recovery, and repeatability. SPME-Arrow gave good performances in not only odorant extraction but also quantification, which is considered most suitable for quantifying odorants in hot-pressed rapeseed oil. Taking cost/performance ratio into account, SPME is still an efficient flavor extraction method. Multi-method combination of flavor capturing techniques might also be an option of aroma analysis for oil matrix. Afterwards, by application of the Sensomics approach the key odorants in representative commercial FRO samples were decoded. On the basis of the aroma blueprint, changes of overall aroma profiles of oils and their key odorants were studied and compared in different roasting conditions. To better simulate industrial conditions, high temperatures (150-200 ºC) were used in our roasting study, which was rarely studied before. Identification and quantitation of the key odorants in FRO were well performed by means of the Sensomics concept. Glucosinolate degradation products were a special kind of key odorants existing in rapeseed oil. Most of the odorants showed first rising and then decline trends as the roasting process progressed. Aroma profile results showed that high-temperature-short time and low-temperature-long time conditions could have similar effects on the aroma profiles of roasted rapeseed oils, which could provide a reference for the time cost savings in industrial production. To gain the fundamental knowledge of the aroma formation in FRO, the thermal degradation behavior of progoitrin (the main glucosinolate of rapeseed) and the corresponding generated volatile products were investigated in liquid (phosphate buffer at a pH value of 5.0, 7.0, or 9.0) and solid phase systems (sea sand and rapeseed powder). The highest thermal degradation rate of progoitrin at high temperatures (150-200 ºC) was observed at a pH value of 9.0, followed by sea sand and then rapeseed powder. It could be inferred that bimolecular nucleophilic substitution reaction (SN2) was mainly taken place under basic conditions. The highest degradation rate under basic conditions might result from the high nucleophilicity of present hydroxide ions. Under the applied conditions in this study, 2,4-pentadienenitrile was the major nitrile formed from progoitrin during thermal degradation at high temperature compared to l-cyano-2-hydroxy-3-butene, which might be less stable. The possible formation pathways of major S-containing (thiophenes) and N-containing (nitriles) volatile (flavor) compounds were proposed. Hydrogen sulfide, as a degradation product of glucosinolates, could act as a sulfur source to react further with glucose to generate thiophenes. Overall, the present work comprehensively documented the effects of thermal conditions and matrices on the aroma characteristics, aroma profiles, and key odorants of hot-pressed rapeseed oil, which could provide data and theoretical basis for the flavor control of FRO under thermal treatment at actual production temperatures (150-200 °C).Rapsöl ist eines der am dritthäufigsten produzierten Pflanzenöle der Welt, welches für seinen charakteristischen Geschmack und hohen Nährwert geschätzt wird. Geröstetes Rapsöl (fragrant rapeseed oil, FRO), das durch ein typisches Röstverfahren hergestellt wird, ist wegen seines charakteristischen Aromas beliebt und jährlich werden mehr als 1,5 Millionen Tonnen produziert. Allerdings sind die Veränderungen im Aromaprofil von FRO während der typischen Röstverarbeitung noch unklar, was die Rapsölqualität und die Verbraucherakzeptanz herausfordert. Dementsprechend war das Ziel dieser Arbeit, die Aromaeigenschaften und das Pyrolyseverhalten der Vorläuferverbindungen von FRO zu untersuchen, um eine Grundlage und Anleitung für die Kontrolle der FRO-Aromaqualität während des Herstellungsprozesses zu liefern. Zuerst wurde eine systematische Übersicht aus der Literatur über die Zusammenfassung, den Vergleich und die Kritik zum Aroma von Rapsöl, insbesondere zu den verwendeten Analysetechniken (d. h. Extraktion, qualitative, quantitative, sensorische und chemometrische Methoden), identifizierte repräsentative Verbindungen und Fehlaromen, und Auswirkungen verschiedener Prozesse während der Herstellung (Schälen, Rösten, Mikrowellenbehandlung, Aromatisierung mit Kräutern, Raffination, Ölerhitzung und Lagerung) durchgeführt. Einhundertsiebenunddreißig in Rapsöl beschriebene Aromastoffe sind aufgelistet, darunter Aldehyde, Ketone, Säuren, Ester, Alkohole, Phenole, Pyrazine, Furane, Pyrroline, Indole, Pyridine, Thiazole, Thiophene, weitere S-haltige Verbindungen, Nitrile und Alkene. Die mögliche Bildungswege einiger wichtiger aromaaktiver Verbindungen werden ebenfalls vorgeschlagen. Dennoch erfordern einige dieser Verbindungen eine weitere Validierung (z. B. Nitrile) aufgrund fehlender Rekombinationsexperimente in den vorherigen Arbeiten. Abschließend sollten fortschrittliche Aromaanalysetechniken in Richtung Zeitersparnis, Übertragung, Echtzeitüberwachung und Visualisierung weiterentwickelt werden, um ein vollständiges Aromaprofil von Rapsöl zu erhalten. Abgesehen davon sind Studien zur Aufklärung des Einflusses wichtiger Röstverfahren auf die Bildung aromaaktiver Verbindungen erforderlich, um das Verständnis der Faktoren zu vertiefen, die zu Aromavariationen von Rapsöl führen. Im nächsten Schritt wurde in systematischer Vergleich zwischen fünf Techniken zur Extraktion von Aromastoffen, darunter Festphasen-Mikroextraktion (solidphase microextraction, SPME), SPME-Arrow, headspace sorptive extraction (HSSE), direkte thermische Desorption (DTD) und lösungsmittelunterstützte Aromaverdampfung (solvent assisted flavor evaporation, SAFE) für heißgepresstes Rapsöl durchgeführt. Außerdem wurde eine methodische Validierung dieser fünf Ansätze für einunddreißig in Rapsöl gefundene Aromastoffe durchgeführt, um ihre Stabilität, Zuverlässigkeit und Robustheit zu vergleichen. Bei der Qualifizierung der Aromasstoffe in heißgepresstem Rapsöl erzielte die SAFE, vor allem aufgrund der hohen Probenvolumina, die beste Performance, schnitt aber hinsichtlich Linearität, Wiederfindung und Reproduzierbarkeit schlechter ab als andere Methoden. SPME-Arrow zeigte gute Leistungen nicht nur bei der Extraktion von Aromastoffen, sondern auch bei der Quantifizierung. Sie wurde daher als am besten geeignet für die Quantifizierung von Aromastoffen in heißgepresstem Rapsöl angesehen. Unter Berücksichtigung des Preis-Leistungs-Verhältnisses ist die klassiche SPME aber immer noch eine effiziente Aromaextraktionsmethode. Eine Kombination aus mehreren Methoden zur Erfassung von Aromen könnte auch eine Option der Aromaanalyse für die Ölmatrix sein. Anschließend wurden durch Anwendung des Sensomics-Ansatzes die wichtigsten Aromastoffe in repräsentativen kommerziellen FRO-Proben entschlüsselt. Auf der Grundlage des Aroma-Blueprints wurden Änderungen im Gesamtaromaprofil der Öle und ihrer Schlüsselaromastoffe unter verschiedenen Röstbedingungen untersucht und verglichen. Um industrielle Bedingungen besser zu simulieren, wurden in unserer Röststudie hohe Temperaturen (150-200 ºC) verwendet, die zuvor selten untersucht wurden. Die Identifizierung und Quantifizierung der wichtigsten Aromastoffe in FRO wurde mithilfe des Sensomics-Konzepts gut durchgeführt. Glucosinolat-Abbauprodukte waren eine besondere Art von Hauptaromastoffen, die in Rapsöl vorhanden sind. Die meisten Aromastoffe zeigten mit fortschreitendem Röstvorgang zunächst steigende und dann fallende Tendenzen. Die Ergebnisse der Aromaprofile zeigten, dass Hochtemperatur-Kurzzeit- und Niedrigtemperatur-Langzeit-Bedingungen ähnliche Auswirkungen auf die Aromaprofile von gerösteten Rapsölen haben könnten, was eine Referenz für die Zeitkosteneinsparungen in der industriellen Produktion liefern könnte. Um grundlegende Erkenntnisse über die Aromabildung bei FRO zu gewinnen, wurde das thermische Abbauverhalten von Progoitrin (dem Hauptglucosinolat in Rapssamen) und den entsprechend entstehenden flüchtigen Produkten in Flüssigkeits- (Phosphatpuffer bei einem pH-Wert von 5,0, 7,0 oder 9,0) und Festphasensystemen (Seesand und Rapspulver) untersucht. Die höchste thermische Abbaurate von Progoitrin bei hohen Temperaturen (150-200 ºC) wurde bei einem pH-Wert von 9,0 beobachtet, gefolgt von Seesand und Rapspulver. Es konnte gefolgert werden, dass die bimolekulare nukleophile Substitutionsreaktion (SN2) hauptsächlich unter basischen Bedingungen stattfand. Die höchste Abbaurate unter basischen Bedingungen könnte aus der hohen Nukleophilie der vorhandenen Hydroxidionen resultieren. Unter den angewandten Bedingungen in dieser Studie war 2,4-Pentadiennitril das Hauptnitril, das während des thermischen Abbaus bei hoher Temperatur aus Progoitrin gebildet wurde, verglichen mit l-Cyano-2-hydroxy-3-buten, das weniger stabil sein könnte. Die möglichen Bildungswege der wichtigsten S-haltigen (Thiophene) und N-haltigen (Nitrile) flüchtigen (Aroma-)Verbindungen wurden vorgeschlagen. Schwefelwasserstoff als Abbauprodukt von Glucosinolaten könnte als Schwefelquelle dienen, die dann weiter mit Glucose zu reagieren, um Thiophene zu erzeugen. Insgesamt dokumentiert die vorliegende Arbeit umfassend die Auswirkungen thermischer Bedingungen und Matrizes auf die Aromaeigenschaften, Aromaprofile und Hauptaromastoffe von heißgepresstem Rapsöl, die Daten und theoretische Grundlagen für die Aromakontrolle von FRO unter thermischer Behandlung bei den in der Produktion tatsächlichen verwendeten Temperaturen (150-200 °C)