Development and implementation of novel sensory evaluation procedures of consumer acceptability towards chocolate based on emotions and biometric responses

© 2019 Thejani Maduka GunaratneChocolate is a condensed suspension of different particles, with a continuous phase containing cocoa butter and milk fat, and a diffused phase containing cocoa particles, sugar, and non-fat milk solids. Chocolate is the most commonly consumed confectionery product worldwide. Sensory evaluation is a scientific discipline which uses human senses for evaluating consumer products with the application of experimental design and statistical analysis. The application of novel procedures in sensory analysis is needed to prevent the high failure rate of new market launches based on testing with conventional sensory protocols. Hence, the objective of this study was to use novel sensory evaluation procedures including subconscious biometrics [skin temperature (ST), heart rate (HR) and facial expressions (FE)] and self-reported responses to determine consumer acceptance to food, using chocolate. Initially, in Chapter 3, a cross cultural study using Asians and Westerners was conducted to develop lexicons of emotions for milk and dark chocolate using online surveys (N = 206) and by conducting tasting sessions of the chocolates (N = 75). As per the responses of the survey and according to previous research findings, the main reasons for chocolate consumption were emotional satisfaction and indulgence. The main factor that consumers considered in making their purchase decision was the taste/flavour of the chocolate. Three separate emotion lexicons were developed using the results of this experiment, and they were used for further studies conducted using chocolate. In Chapter 4, chocolate with five basic tastes (bitter, salty, sour, sweet and umami) were developed to obtain sensory and physiological responses of consumers to different tastes using 45 participants. An integrated camera system coupled with a tablet-PC using Android OS and containing a BioSensory application was employed to capture infrared images, videos and sensory responses. Inputs from this application were used to determine ST, HR and FE. Sensory responses were gathered using hedonic scales and emotions elicited were obtained using lexicons. Results revealed that the most liked sample was the sweet chocolate, while the least liked was the salty chocolate. Findings of this study can be used to assess novel tastes of chocolate in the industry. Furthermore, in Chapter 5, flavour was added to chocolate directly to produce different flavoured chocolate (caramel, cinnamon chai, mandarin, strawberry and peppermint). A sample without any flavour was considered as the control. These six samples were used for sensory evaluation with 113 participants. ST, HR, FE, sensory responses and emotions elicited were determined like the previous experiment. Results revealed that the most liked sample was the strawberry and the least liked was cinnamon chai chocolate. Findings of this study can be used to determine the acceptability for different flavoured chocolate based on self-reported and subconscious responses. In Chapter 6, encapsulated flavours were developed to be added to chocolate and release the flavour in a different way compared to the experiment reported in Chapter 5. Samples [normal strawberry (NS), normal mint (NM), encapsulated strawberry (ES), encapsulated mint (EM) and control (with no flavour)] were developed and tested by 52 participants to obtain biometric (ST, HR and FE) as well as sensory and emotional responses. Encapsulated chocolate samples showed higher liking compared to normal flavoured chocolate. Findings of this study can be used to determine the acceptability of differently flavoured chocolate in future studies using chocolate. As the next step, in Chapter 7, artificial intelligence was used to develop machine learning models with near-infrared spectroscopy (NIRS) to assess the quality of chocolate based on chemical fingerprinting. Chocolate samples with basic tastes (bitter, salty, sour, sweet and umami) were used for this experiment with 45 respondents and their chemometrics (pH, brix and viscosity), colour (CieLab scale) and sensory properties (basic taste intensities) were determined. Data were used to develop two machine learning models to predict the chemical parameters (Model 1) and sensory parameters (Model 2). These models showed high accuracies of R = 0.99 and R = 0.93 respectively. The developed models can be used as a substitute method to determine sensory properties of chocolate with low cost more accurately. In this study, emotion lexicons were developed and used for sensory sessions conducted using chocolate. Conventional and novel sensory techniques were used for analysis. Results revealed significant differences in emotional terms selected based on gender and culture for different samples. Furthermore, there were significant correlations between conscious and subconscious responses of chocolate. A combination of implicit, explicit and emotional responses may help to better understand the acceptability to different food products. Moreover, models with high accuracy were developed to predict sensory properties of chocolate using chemometrics. Findings of this study can be used for future acceptability research on chocolate

The Dynamics of Satellite Galaxy Planes

First created to explain the discrepancies between the predictions and observations, dark matter makes up around 25% of the universe’s energy budget. Λ Cold Dark Matter (ΛCDM) cosmology accurately represents the large scale structure of the current universe, but shows significant variation in the small ℨscale structure. The recently discovered planes of dwarf satellite galaxies orbiting the Milky Way and M31 adds to the mystery of the small scale distribution of the Local Group. Though similar planar structures are seemingly rare occurrences in ΛCDM cosmological simulations, they could shed light on the dark matter environment of their host galaxies. This thesis explores the factors that affect the stability and longevity of a plane of satellite galaxies in a M31-like system, with numerical simulations. The most influential factors are the shape of the host dark matter distribution, and the plane’s inclination to the axes of the dark halo. For the M31 plane to be older than 4 Gyrs, it either needs to exist in a near spherical dark halo, or be aligned with the dark halo axes. Lifetimes of planar formations inclined to the halo axes, in a prolate/ oblate halo are limited to ≤3 Gyrs, and a populous environment of dark subhalos disperse the planar formation by increasing its thickness over 3 Gyrs. As the fraction of total dark matter mass that is included in the subhalo population reaches ∼40%, the overall shape of the dark matter distribution also becomes unstable over ≥5 Gyrs. Massive, non-planar, interloping galaxies have a notable effect on planes only when their mass is ≥ 1010 M, and any orbital plane misalignments exaggerate this effect. The shape of the M31 host halo also exerts a significant influence on the orbit of M33. In conclusion, planes of satellites are generally short lived in ΛCDM cosmology, and hence we must be located at a special time in the evolution of the M31 plane, and are lucky enough to see its coherent pattern

New Insights into the Microbial Diversity of Cake Layer in Yttria Composite Ceramic Tubular Membrane in an Anaerobic Membrane Bioreactor (AnMBR)

Cake layer formation is an inevitable challenge in membrane bioreactor (MBR) operation. The investigations on the cake layer microbial community are essential to control biofouling. This work studied the bacterial and archaeal communities in the cake layer, the anaerobic sludge, and the membrane cleaning solutions of anaerobic membrane bioreactor (AnMBR) with yttria-based ceramic tubular membrane by polymerase chain reaction (PCR) amplification of 16S rRNA genes. The cake layer resistance was 69% of the total membrane resistance. Proteins and soluble microbial by-products (SMPs) were the dominant foulants in the cake layer. The pioneering archaeal and bacteria in the cake layer were mostly similar to those in the anaerobic bulk sludge. The dominant biofouling bacteria were Proteobacteria, Bacteroidetes, Firmicutes, and Chloroflexi and the dominant archaeal were Methanosaetacea and Methanobacteriacea at family level. This finding may help to develop antifouling membranes for AnMBR treating domestic wastewater

Clogging due to struvite formation in leachate recirculation pipes of bioreactor landfills

Bibliography: p. 109-12

Photochemical, UV and Ozone Based Advanced Oxidation Processes for Treatment of Aqueous Contaminants

In this research, advanced oxidation processes for the degradation of certain aqueous contaminants in municipal and industrial wastewater were studied. Carbamazepine (CBZ) was selected as it is an emerging contaminant in municipal wastewater. Sulfolane and acid extractable organics (AEOs) of oil sands process water (OSPW) were selected as candidates for industrial wastewater. The studies were conducted using a variety of advanced oxidation processes including a sunlight mediated photochemical process using ferric ions. Degradation kinetics of different oxidation processes in spiked water and post-secondary treated wastewater/sulfolane contaminated groundwater/OSPW were investigated. Batch experiments as well as flow through photo-reactor experiments were conducted. Degradation of CBZ in spiked water and post-secondary treated wastewater was studied using UVC, UVA, UVC/H2O2, UVA/H2O2, UVC/TiO2, UVA/TiO2, O3, UVC/O3 and UVA/O3 in a batch photo-reactor. The optimum parameters of each process were identified and their impacts on degradation rates were investigated. Relationship between UV intensity and CBZ degradation rate was extrapolated to the performance of the UV disinfection unit of a local wastewater treatment plant in Calgary, Canada. Addition of 100 mg/L of H2O2 to the secondary treated wastewater effluent entering UV disinfection unit could achieve over 60% degradation of CBZ. The effective parameters of UVC/H2O2 process in the batch experiments were further advanced to a flow through photo-reactor for degradation of CBZ. The kinetics of degradation in the flow-through reactor were in good agreement with the relationships developed using batch photo-reactor in spiked water and post-secondary treated wastewater. Experiments on ozone and photo-assisted ozone for the treatment of CBZ have shown that photo-assisted ozonation leads to greater mineralization of CBZ in water/wastewater matrices. This study recommends that UV and ozone doses for photo-assisted ozonation applications should also consider organic constituents of water matrices along with target contaminants of interest. Finally, the feasibility of a sunlight mediated photochemical process using ferric ions for the treatment of a wide range of organic contaminants was studied. Batch experiments were conducted under natural sunlight to study the degradation of CBZ, sulfolane and AEOs of OSPW. Complete CBZ degradation and more than 60% reduction of AEOs were obtained using this process. The presence of organic matter decreased the kinetics of sulfolane degradation where 30% degradation in spiked contaminated groundwater was noted. The unique ability to degrade a wide range of contaminants from this process using only natural solar irradiation, suggest a higher application potential in wastewater treatment

Transfersomes: A Promising Nanoencapsulation Technique for Transdermal Drug Delivery

Transdermal delivery systems have gained much interest in recent years owing to their advantages compared to conventional oral and parenteral delivery systems. They are noninvasive and self-administered delivery systems that can improve patient compliance and provide a controlled release of the therapeutic agents. The greatest challenge of transdermal delivery systems is the barrier function of the skin’s outermost layer. Molecules with molecular weights greater than 500 Da and ionized compounds generally do not pass through the skin. Therefore, only a limited number of drugs are capable of being administered by this route. Encapsulating the drugs in transfersomes are one of the potential approaches to overcome this problem. They have a bilayered structure that facilitates the encapsulation of lipophilic and hydrophilic, as well as amphiphilic, drug with higher permeation efficiencies compared to conventional liposomes. Transfersomes are elastic in nature, which can deform and squeeze themselves as an intact vesicle through narrow pores that are significantly smaller than its size. This review aims to describe the concept of transfersomes, the mechanism of action, different methods of preparation and characterization and factors affecting the properties of transfersomes, along with their recent applications in the transdermal administration of drugs

Zebrafish Embryo Toxicity of a Binary Mixture of Pyrethroid Insecticides: d-Tetramethrin and Cyphenothrin

Pesguard FG161™, a mixture of d-tetramethrin and cyphenothrin (1:3 ratio), is extensively used to achieve rapid control of adult dengue vector, Aedes aegypti, during the disease outbreaks. Both d-tetramethrin and cyphenothrin are synthetic pyrethroids that are known to have adverse effects on non-mammalian organisms such as fish. The present study intended to use zebrafish embryo toxicity model to investigate the toxic effect of the above binary mixture on fish. Particularly, zebrafish embryo toxicity model provides an alternative to acute fish toxicity tests in terms of animal welfare perspective as the embryos are not considered live until 5 days after fertilization. The zebrafish embryos (2 hrs after fertilization) were exposed to a binary mixture of pyrethroids at different concentrations (d-tetramethrin: 0.01 – 1.20 μmolL-1 and cyphenothrin: 0.03 – 3.20 μmolL-1) for 24, 48, and 72 hrs at room temperature (26°C) according to the OECD guideline no. 236. Percentage mortality of embryos were calculated by observing the lethal endpoints and LC50 values were calculated for each time interval employing the probit analysis. This binary mixture was highly toxic to zebrafish embryos and was found to be concentration and time dependent. LC50 values at 24 hrs (d-tet: 0.58 μmolL-1, cyp: 1.74 μmolL-1) were significantly reduced in 48 hrs (d-tet: 0.11 μmolL-1, cyp: 0.33 μmolL-1) and 72 hrs (d-tet: 0.03 μmolL-1, cyp: 0.09 μmolL-1). Coagulation of embryos was the most common lethal effect observed and lack of somite formation and lack of heartbeat were also observed. The present study revealed that the binary mixture is highly toxic to zebrafish embryos even when based on nominal concentrations. Hence, extensive use of these pesticides could be detrimental to fish population and integrated vector control methods which involve the minimum use of insecticides are recommended. Further, this study highlights the applicability of zebrafish embryo toxicity model as an alternative method to investigate the toxicity of pyrethroids to fish

Prediction of the Long-Term Effect of Iron on Methane Yield in an Anaerobic Membrane Bioreactor Using Bayesian Network Meta-Analysis

A method for predicting the long-term effects of ferric on methane production was developed in an anaerobic membrane bioreactor treating food processing wastewater to provide management tools for maximizing methane recovery using ferric based on a batch test. The results demonstrated the accuracy of the predictions for both batch and long-term continuous operations using a Bayesian network meta-analysis based on the Gompertz model. The prediction bias of methane production for batch and continuous operations was minimized, from 11~19% to less than 0.5%. A biochemical methane potential-based Bayesian network meta-analysis suggested a maximum 2.55% ± 0.42% enhancement for Fe2.25. An anaerobic membrane bioreactor improved the methane yield by 2.27% and loading rate by 4.57% for Fe2.25, operating in the sequenced batch mode. The method allowed for a predictable methane yield enhancement based on the biochemical methane potential. Ferric enhanced the biochemical methane potential in batch tests and the methane yield in a continuously operated reactor by a maximum of 8.20% and 7.61% for Fe2.25, respectively. Copper demonstrated a higher methane (18.91%) and sludge yield (17.22%) in batch but faded in the continuous operation (0.32% of methane yield). The enhancement was primarily due to changing the kinetic patterns for the last period, i.e., increasing the second methane production peak (k71), bringing forward the second peak (λ7, λ8), and prolonging the second period (k62). The dual exponential function demonstrated a better fit in the last three stages (after the first peak), which implied that syntrophic methanogenesis with a ferric shuttle played a primary role in the last three methane production periods, in which long-term effects were sustained, as the Bayesian network meta-analysis predicted

Preparation, Characterization and Permeation Study of Topical Gel Loaded with Transfersomes Containing Asiatic Acid

The objective of this study is to investigate the in vitro permeation of asiatic acid (AA) in the form of a topical gel after entrapment in transfersomes by Franz diffusion cells. Transfersomes composed of soybean lecithin and three different edge activators including Tween 80 (TW80), Span 80 (SP80) and sodium deoxycholate (SDC) at the ratio of 50:50, 90:10 and 90:10, respectively, together with 0.3% w/w of AA, were prepared by a high-pressure homogenization technique and further incorporated in gels (TW80AATG, SP80AATG and SDCAATG). All transfersomal gels were characterized for their AA contents, dynamic viscosity, pH and homogeneity. Results revealed that the AA content, dynamic viscosity and pH of the prepared transfersomal gels ranged from 0.272 ± 0.006 to 0.280 ± 0.005% w/w, 812.21 ± 20.22 to 1222.76 ± 131.99 Pa.s and 5.94 ± 0.03 to 7.53 ± 0.03, respectively. TW80AATG gave the highest percentage of AA penetration and flux into the Strat-M® membrane at 8 h (8.53 ± 1.42% and 0.024 ± 0.008 mg/cm2/h, respectively) compared to SP80AATG (8.00 ± 1.70% and 0.019 ± 0.010 mg/cm2/h, respectively), SDCAATG (4.80 ± 0.50% and 0.014 ± 0.004 mg/cm2/h, respectively), non-transfersomal gels (0.73 ± 0.44 to 3.13 ± 0.46% and 0.002 ± 0.001 to 0.010 ± 0.002 mg/cm2/h, respectively) and hydroethanolic AA solution in gel (1.18 ± 0.76% and 0.004 ± 0.003 mg/cm2/h, respectively). These findings indicate that the TW80AATG might serve as a lead formulation for further development toward scar prevention and many types of skin disorders