Rapid Method for Classification of Cheddar Cheese Based on Flavor Quality using Infrared Spectroscopy

Flavor quality of Cheddar cheese significantly influences its consumer acceptance, price and food processing application. Cheese flavor is currently determined using trained human tasting panels. This approach is expensive and time consuming. Rapid and high-throughput instrumental methods for predicting the flavor quality of Cheddar cheese would save time and money for the cheese industry. The objective of this research was to develop a rapid and simple technique based on Fourier transform infrared spectroscopy to predict the flavor quality of Cheddar cheese. Fifteen Cheddar cheese samples were ground into powders using liquid nitrogen. The water-soluble compounds from the cheese powder, without interfering compounds such as complex fat and protein, were extracted using water and organic solvents. Aliquots (10 µL) of the extract were placed on the sampling accessory, dried and scanned in the spectrometer (4000 to 700 cm-1). The spectra were matched with the flavor quality to build statistical classification models. The models provided 3D plots in which all the 15 cheese samples formed well separated clusters, whose orientation correlated well with their cheese flavor characteristics (fermented, unclean, low flavor, sour, good cheddar, etc.). The discrimination of the samples was mainly due to organic and fatty acids and their esters (1500 to 900 cm-1), which are known to contribute significantly to cheese flavor. The total analysis time, including the sample preparation time, was less than 20 min per sample. This technique can be a rapid, inexpensive, high-throughput and simple tool to the cheese industry for predicting the flavor quality of cheese.DairiConcepts LP. (Springfield, MO) and Midwest Advanced Food Manufacturing Allicance (MAFMA)A five-year embargo was granted for this item

Monitoring composition and flavor quality of Cheddar cheese during ripening using a rapid spectroscopic method

FAES and Human Ecology: 3rd Place (The Ohio State University Edward F. Hayes Graduate Research Forum)About 9.13 billion pounds of cheese is produced in the US every year, of which 34% is cheddar cheese. Cheddar cheese composition and flavor quality, which influence the consumer acceptance, price and food processing application, develop during the ripening process. However, ripening is not well understood due to complexity of the process and heterogeneous nature of cheese. Rapid monitoring of composition and flavor quality of cheese and understanding cheese ripening hold many advantages for the cheese-maker. Cheese composition and quality are currently determined using chromatographic techniques and trained human expert sensory panels, which are expensive and time consuming. Rapid methods capable of simultaneous monitoring of multiple components can save time and money. Fourier transform Infrared (FT-IR) spectroscopy, which monitors the light absorbing properties of chemical compounds, can be used as a rapid, inexpensive, and sensitive method to analyze cheese quality. Unlike many chromatographic techniques, FT-IR spectroscopy provides unique overall chemical fingerprints of cheese samples that can be analyzed through multivariate statistical techniques to rapidly determine cheese composition and flavor quality. Hence the objective of this research was to develop a rapid method based on FT-IR spectroscopy to monitor composition and flavor quality of Cheddar cheese during ripening. Twelve different Cheddar cheese samples ripened for a period of 73 days were provided by a commercial cheese manufacturer, along with their final moisture, pH, salt, fat content and flavor quality data. Samples were collected on days 7, 15, 30, 45 and 73 during ripening and analyzed for organic acid content using chromatographic techniques (reference method). For FT-IR analysis the samples were treated using organic solvents and the extracts were dried on zinc selenide crystal and scanned in the spectrometer (4000-700 wavenumbers). Infrared profiles (spectra) of the samples were matched with their composition and quality data to develop multivariate statistical regression and classification models. The infrared spectra of the samples were well defined, highly consistent within each sample and distinct from other samples. The regression models showed excellent fit (r-value>0.95) and could determine moisture, pH, salt, fat, organic acid contents in less than 20 min, which is significantly less than the current methods. Furthermore, cheeses could also be classified based on their flavor quality (sour, whey taint, good cheddar, etc.). The discrimination of the samples was due to organic acids, amino acids and short chain fatty acids (1800 to 900 cm-1), which are known to contribute significantly to cheese flavor. FT-IR spectroscopy based method shows great promise as a rapid, simple and cost-effective analytical and quality control tool for the industry. It will enable monitoring and controlling cheese ripening process to produce cheese of desired quality. For the cheese industry, this can be an extremely valuable tool as it will enable identification of quality defects early in the ripening process. The identification of defects will assist in deciding whether the cheese is marketable prior to incurring storage and interest charges associated with aging as well as deciding the future application of the cheese.A five-year embargo was granted for this item

Hybrid Metaheuristics for the Clustered Vehicle Routing Problem

The Clustered Vehicle Routing Problem (CluVRP) is a variant of the Capacitated Vehicle Routing Problem in which customers are grouped into clusters. Each cluster has to be visited once, and a vehicle entering a cluster cannot leave it until all customers have been visited. This article presents two alternative hybrid metaheuristic algorithms for the CluVRP. The first algorithm is based on an Iterated Local Search algorithm, in which only feasible solutions are explored and problem-specific local search moves are utilized. The second algorithm is a Hybrid Genetic Search, for which the shortest Hamiltonian path between each pair of vertices within each cluster should be precomputed. Using this information, a sequence of clusters can be used as a solution representation and large neighborhoods can be efficiently explored by means of bi-directional dynamic programming, sequence concatenations, by using appropriate data structures. Extensive computational experiments are performed on benchmark instances from the literature, as well as new large scale ones. Recommendations on promising algorithm choices are provided relatively to average cluster size.Comment: Working Paper, MIT -- 22 page

Calibration and application of a B-dot sensor to study the initiation of vacuum surface flashover

\u27Calibration\u27, as the name suggests is the act of checking or adjusting the accuracy of a measuring instrument by comparison with a standard. Two techniques, the equal length test and the short circuit test, have been developed to determine the characteristic impedance and propagation coefficient of a single lossy transmission line and a lossy transmission line network in cascade based solely on the input reflection coefficient S-parameter, S11, VNA measurements over a wide bandwidth of frequencies. For the transmission line network case, the characteristic impedance and propagation coefficient for each line in the cascade, excluding the last line, are known. Theoretical expressions needed for interpreting VNA measured data have been developed. A wideband, coaxial cable calibration test stand is characterized based on the novel equal length technique. The test stand is used to calibrate a B-dot in the frequency domain to obtain its response function. To verify the calibration process, the calibrated B-dot will be used to measure the surface current density on a radial transmission driven by a pulsed power source. These results will be compared against simulation using a Graphical Large Scale Plasma (GLSP) code. This calibrated B-dot will be used in future surface breakdown pulse power experiments on plastics measuring fast sub-nanosecond rise time phenomena

Characterization of pharmacological modulators and study of ASIC activation with cysteine-based cross-linking

Acid-sensing ion channels (ASICs) are proton-gated, voltage-insensitive Na+ channels that are localized in the central and the peripheral nervous system participating in a range of physiological and pathological functions such as pain sensation, learning and memory, fear, and neurodegeneration after stroke. ASICs form homo- or heterotrimeric channels. ASIC structures of the closed, toxin-bound open and the desensitized state have been solved. Despite the available high-resolution ASIC structures, it is not known exactly how protons activate ASICs. Using experimental approaches, the structure-function relationship of ASIC activity was investigated here in three sub-projects. 1) 2-guanidine-4-methylquinazoline (GMQ) is a known pharmacological modulator of ASIC1a and ASIC3. New derivatives of GMQ were studied. Several quniazoline and quinoline derivatives produced a modulatory effect on ASIC activity in a sub-type specific manner. Guanidinopyridines strongly inhibited the peak current at pH5 in ASIC1a and ASIC3 with 20-fold better potency than GMQ. Interestingly, 2-guanidino- quinolines and -pyridines produced in ASIC1a a potentiation at low, and an inhibition at high concentrations. 2) Comparison of the rare mutation D212 in hASIC1a that was used in many laboratories as wild type, with the real wild type human ASIC1a-G212 showed slower current decay kinetics, higher current amplitude per surface-expressed channel, increased surface expression of the channel, and a stronger dependence of the current decay kinetics on the extracellular anion in hASIC1a-G212. 3) To test the effect of distance constraints on channel function, the optical tweezer 4,4’-bis(maleimido)azobenzene (BMA) and bis-methane- thiosulfonate (MTS) cross-linkers were used. In hASIC1a-I428C to which BMA was tethered, light-dependent activation by 440nm light was observed, however without the formation of a cross-link. A modulatory effect by BMA upon 360nm light illumination was found in three double mutants of the extracellular domain. In a second approach, MTS cross-linkers of different lengths were used. In comparison to control condition, treatment with MTS-17-MTS produced an acidic-shift of the pH dependence of activation in hASIC1a-D237C/I312C, and an alkaline or a small acidic-shift in the single mutants, hASIC1a-I312C and -D237C. Further validation of cross-linking is required in D237C/I312C. Our findings provide structural insights into ASIC1a activity. -- Les canaux ioniques sensibles à l'acide (ASIC) sont des canaux à sodium, proton- dépendants et insensibles au voltage, localisés dans le système nerveux central et périphérique. Ils participent à une gamme de fonctions physiologiques et pathologiques telles que la sensation de douleur, l'apprentissage et la mémoire, la peur et sont impliqués dans la neurodégénérescence après un AVC. Les ASIC forment des canaux homo- ou hétérotrimériques. La structure du poulet ASIC1a a été résolue à l'état fermé, dans l’état ouvert lié à la toxine, et désensibilisé et pour l'ASIC1a humaine (hASIC1a) dans l'état fermé. Malgré les structures ASIC haute résolution disponibles, on ne sait pas exactement comment les protons activent les ASIC. À l'aide d'approches expérimentales, la relation structure-fonction de l'activité ASIC1a a été étudiée. Dans ce contexte 1) la 2-guanidine-4-méthylquinazoline (GMQ) est un modulateur pharmacologique connu des ASIC1a et ASIC3, et ses dérivés quniazoline et quinoléine ont produit un effet modulateur à 1 mM sur l'activité ASIC par sous-type de manière spécifique. Les guanidinopyridines ont fortement inhibé le courant de pointe à pH 5 dans ASIC1a et ASIC3 avec une puissance 20 fois supérieure à celle du GMQ. Fait intéressant, les 2guanidino-quinoléines et -pyridines ont produit un effet d'inhibition ou de potentialisation dépendant de la concentration sur le sous-type ASIC et dans les ASIC1a/2a et ASIC3/2a hétéromères, seuls quelques composés, y compris le GMQ, ont produit un petit effet modulateur sur l'activité, 2 ) Une comparaison de la mutation rare D212 dans hASIC1a qui a été utilisée dans de nombreux laboratoires comme type sauvage, avec le vrai type sauvage hASIC1a-G212 a montré une cinétique de décroissance du courant plus lente, une amplitude de courant plus élevée par canal exprimé en surface, une expression de surface accrue du canal, et cinétique de désintégration actuelle dépendante de l'anion extracellulaire dans hASIC1a-G212, et 3) en utilisant l'approche de réticulation et pour trouver une paire de résidus impliqués dans les changements de conformation lors de l'activation d'ASIC1a, les deux pinces optiques 4,4'-bis (maléimido) azobenzène (BMA) et des agents de réticulation bis-méthane-thiosulfonate (MTS) ont été appliqués. Dans hASIC1a-I428C attaché à BMA, une activation dépendante de la lumière sous une lumière de 440 nm a été observée sans la formation de la réticulation. Un effet modulateur par BMA sur une illumination lumineuse de 360 nm a été trouvé dans les mutants hASIC1a-D237C/E315C, -D237C/E355C et - K246C/D347C. Dans une seconde approche, des réticulant MTS de différentes longueurs ont été utilisés. Par rapport à la condition témoin, le traitement avec MTS-17-MTS a produit un changement acide de la dépendance au pH dans hASIC1a-D237C/I312C, et un changement alcalin ou petit acide chez les mutants simples, hASIC1a-I312C et -D237C. Une validation supplémentaire de la réticulation est requise dans D237C/I312C. Nos résultats fournissent de nouvelles informations structurelles sur l'activité ASIC1a. -- Une cellule est considérée comme un bloc l’unité de base de tout organisme vivant, et elle est composée de composants intracellulaires séparés des cellules voisines par la membrane plasmique et travaille 24 heures sur 24 pour maintenir différentes fonctions comme le support structurel, produire de l'énergie, permettre le transport passif et actif de divers ions et molécules, la gestion des réactions métaboliques et la respiration. Pour l’important échange d'ions mentionné ci-dessus, la cellule a recourt à des protéines traversant la membrane cellulaire et qui possèdent un pore sélectif permettant le passage des ions : les « canaux ioniques ». Ces canaux ioniques contrôlent divers processus biologiques comme la fonction cardiaque, la contraction des muscles squelettiques et lisses, le transport épithélial, etc. Le canal ionique peut être activé par un ligand, une tension électrique et mécaniquement. Dans notre recherche, nous travaillons avec des canaux ioniques sensibles à l'acide (ASIC) qui sont activés par acidification extracellulaire et localisés dans les neurones. Lorsqu'ils sont activés, ils sont parfois fermés ou ouverts, le passge d’ions qu’ils entrainent active les neurones. Ils sont impliqués dans diverses conditions physiopathologiques comme la douleur, les démangeaisons, l'apprentissage et la mémoire, l'épilepsie, les accidents vasculaires cérébraux, la maladie d'Alzheimer etc. On ne sait pas comment l'acidification extracellulaire peut activer le canal et quels sont les changements conformationnels associés dans ces domaines ? En mettant l'accent sur l'identification du mécanisme d'activation du canal, j'ai trouvé que 1) certaines petites molécules dérivées d'une molécule existante appelée 2-guanidine-4-méthylquinazoline (GMQ) peuvent moduler l'activité ASIC, 2) ont caractérisé une mutation rare dans l'ASIC1a humaine clone, ayant des propriétés légèrement modifiées par rapport à l'ASIC1a humain de type sauvage réel, 3) Les composés de liaison croisée, à savoir le 4,4'-bis (maléimido) azobenzène (BMA), est un composé qui peut se fixer à ses deux extrémités à un résidu cystéine modifié dans l'ASIC1a et exercer une force mécanique sur les domaines en étendant ou en pliant son forme par application d'une longueur d'onde spécifique de la lumière. Les composés à base de bis-méthane-thiosulfonate (MTS) sont de différentes longueurs qui peuvent également se fixer aux deux extrémités au résidu de cystéine modifié sans changer de forme. Les deux composés ont affecté l'activation de l'ASIC1a. Une enquête plus approfondie est nécessaire pour conclure les changements de conformation dans les domaines identifiés pendant l'activation du canal. Dans l’ensemble, plusieurs aspects associés à la relation structure-fonction de l'activité ASIC1a ont été identifiés. À l'avenir, les études présentées dans cette thèse seront utiles pour concevoir des molécules thérapeutiques en mesure d’inhiber ou d’activer le canal

FINGER DISABILITIES AND HIGHER LEVEL TASKS – DEVELOPING AND VALIDATING MTM MULTIPLIERS

MTM multipliers are presented for higher level tasks such as manual lifting, lowering, carrying, and assembly with hands and assembly with manual tools. These MTM multipliers and those developed in the previous work were applied to estimate the cycle time of individuals with finger disabilities for a combination assembly and handling task. Once the cycle time was estimated, the actual task was performed and the performance cycle time was determined from video analysis. The estimated and observed cycle times were compared. Additionally, estimated and observed elemental times were compared. The results of statistical comparison indicated that the difference between the estimated and actual cycle times was insignificant (α ≥ 0.10). Further, elemental times based on observation were not significantly different from those estimated from multipliers established in the earlier work and the work presented here

Inertial migration of a sphere in plane Couette flow

We study the inertial migration of a torque-free neutrally buoyant sphere in wall-bounded plane Couette flow over a wide range of channel Reynolds numbers, $Re_c$, in the limit of small particle Reynolds number\,($Re_p\ll1$) and confinement ratio\,($\lambda\ll1$). Here, $Re_c = V_\text{wall}H/\nu$ where $H$ denotes the separation between the channel walls, $V_\text{wall}$ denotes the speed of the moving wall, and $\nu$ is the kinematic viscosity of the Newtonian suspending fluid; $\lambda = a/H$, $a$ being the sphere radius, with $Re_p=\lambda^2 Re_c$. The channel centerline is found to be the only (stable)\,equilibrium below a critical $Re_c\,(\approx 148)$, consistent with the predictions of earlier small-$Re_c$ analyses. A supercritical pitchfork bifurcation at the critical $Re_c$ creates a pair of stable off-center equilibria, symmetrically located with respect to the centerline, with the original centerline equilibrium simultaneously becoming unstable. The new equilibria migrate wallward with increasing $Re_c$. In contrast to the inference based on recent computations, the aforementioned bifurcation occurs for arbitrarily small $Re_p$ provided $\lambda$ is sufficiently small. An analogous bifurcation occurs in the two-dimensional scenario, that is, for a circular cylinder suspended freely in plane Couette flow, with the critical $Re_c$ being approximately $110$