Oral/taste sensitivity to non-esterified long-chain fatty acids with varying degrees of unsaturation.

Understanding human oral/taste sensitivity to long-chain non-esterified fatty acids (NEFA) with varying physicochemical properties is essential to reducing the intake of fats and altering the intake composition. This study investigated the differences in human taste sensitivity to two NEFA: oleic acid and linoleic acid. Twenty-four female subjects were divided into two equal sensitivity groups, and they performed discrimination tests for both fatty acids against bottled water using either the triangle or the DR A-Not A test. To achieve an accurate measurement of NEFA sensitivity, the stimulus was carefully prepared, avoiding additives that could interfere with the binding of fatty acids to receptors. Stimuli concentrations were selected to be within the lowest range (9.9 to 177.3 µM) evaluated in previous research. Through a systematic stimulus control process, this study confirmed that greater sensitivity was exhibited to linoleic acid than oleic acid, resulting in better discrimination than previous studies.

Comparison of reminder-preference test to difference and preference tests: An affective approach yielding d-prime results for sensory difference and preference.

Preserving the sensory characteristics of reformulated products is crucial for a successful market launch. This underscores the need for precise measurement of consumer perceptions regarding sensory differences and preferences. One approach to assess these aspects is through the utilization of the reminder-preference test, an affective difference-preference test employing the A-Not A with the reminder (A-Not AR) test design. This test measures sensory differences and preferences by employing a consolidated d' index rooted in signal detection theory and Thurstonian modeling. The aim of this study was to assess the efficacy of the reminder-preference test in measuring the degree of sensory differences and interpreting their relevance concerning consumer preference. To achieve this, the test was compared with both the A-Not AR difference test and the 2-alternative choice (2-AC) preference test. A lemon-lime-flavored carbonated drink and two types of reformulated samples were tested. Young female adult subjects were randomly divided into three groups. Each took one of the following three tests: the reminder-preference test, the reminder test of A-Not AR, or the 2-AC preference test. The reference framing in the reminder-preference and reminder tests was preceded by subjects watching the product's advertisement to assist them in framing evaluative criteria. This would also facilitate memorizing the perception of the reference product. Test sensitivity in reminder-preference matched reminder and 2-AC tests for sensory differences and preferences. Affective framing enhanced sensitivity to sensory differences resulting in a higher d' value of the sensory difference than the preference. From the results, it was possible to interpret that the measured sensory differences did not affect consumer preference. The test also illuminated brand marketing effects on preferences through branded reference comparison. Thus, the reminder-preference test shows potential as an efficient sensory method to measure sensory differences and the preference of consumers, while concurrently measuring the effects of marketing on the consumers. Therefore, it can assist in making efficient business decisions regarding product reformulations.

Sensory test A-Not A rating signal detection: Panel's sensory learning and stability of decision criteria.

Signal detection theory (SDT) sensory discrimination analysis using A-Not A with a two-step rating is an efficient approach to in-house sensory quality management in the food industry. For such sensory analysis using an internal panel, the panels' ability to use stable decision criteria and provide a consistent response distribution responding to "A" vs "Not A" is critical for guaranteeing the data quality. This study examined the effects of the familiarization procedure (FP) and reference presentation probability (RPP) in the SDT A-Not A rating protocol on the panels' sensory learning of samples and stability of decision criteria using SDT parameters, recognition d' (d'Rec),criteria location (c), and discrimination d' indices. Three different protocols were compared using ice-tea samples with small differences: Control, 0.25 RPP with repeated reference tasting (FPR); Modified-1, 0.25 RPP with reference categorization (FPC); Modified-2, 0.5 RPP with reference categorization (FPC). An independent sample design with three groups having equal sensitivity was used to identify the differences among the protocols. For each protocol, two sub-groups with similar decision criteria (response bias) were formed according to the results obtained from the pre-test and used for the main-test analysis. SDT analysis results indicated that the Modified-2 protocol with a higher RPP (0.5) induced the most efficient sensory learning of the reference. The protocol improved the subjects' recognition of the reference and test samples, better differentiating from the reference and stabilizing the decision criterion, resulting in higher discrimination performance (larger d'). The results showed that d'Rec analysis, together with d' analysis using a sensory panel, is a useful tool for monitoring the panel performance and checking for the sensory data quality of the sensory difference tests. In the present paper, a detailed illustration of the A-Not A sensory test procedure and examples of how to apply the SDT indices for different business decision-making is also introduced using the design and results of the present experiment.

Variability of oral/taste sensitivity to fat: An investigation of attribution from detection threshold methods with repeated measurements.

Accumulating psychophysical evidence suggests substantial individual variability in oral/taste sensitivity to non-esterified, long-chain fatty acids (NEFA), which is commonly referred to as fat taste or oleogustus. Recent studies have sought to determine its associations with human factors such as body mass index (BMI) and food preferences, as it has been claimed that excessive fat consumption is related to several health conditions, including obesity. Yet, the findings are controversial. On the other hand, it has been noted that considerable variability also occurs based on the methodology used to measure the fatty acid taste. Specifically, learning effects have been observed over repeated measurements of the detection threshold of NEFA, yet there has been no methodology available to take into account these learning effects. Accordingly, in the present study, a novel methodology using a descending-block dual reminder A-Not A (DR A-Not A) method with a warm-up has been proposed to measure the NEFA detection threshold based on the signal detection theory and considering NEFA taste learning effects over repeated sessions. Homogeneous subjects (young adult Korean females within the normal BMI range, non-vegetarians) were randomized to either the novel descending-block DR A-Not A method or ascending triangle method that is commonly used for fat perception studies. Pure oleic acid emulsions were used as fat taste stimuli to be discriminated from pure mineral water. Each subject completed 14 repeated visits. For the ascending triangle method, 14 thresholds were determined using a stopping rule, while for the novel method, 7 thresholds were determined each per two consecutive days, using a criterion of a lower limit of 50% confidence interval of d' = 0.5, considering the practical aspects of taste studies in food sensory science. Based on the group median results of the last two visits, the variability of the detection thresholds was reduced using the novel descending-block DR A-Not A method due to better learning effects over repeated sessions. This shows the potential of the descending-block DR A-Not A threshold method for further studies on oral/taste sensitivity to fat.

Valorization of Soy Lecithin by Enzyme Cascade Reactions Including a Phospholipase A2, a Fatty Acid Double-Bond Hydratase, and/or a Photoactivated Decarboxylase.

A huge amount of phospholipids or lecithin is produced as a byproduct in the vegetable oil industry. However, most are just used as a feed additive. This study has focused on enzymatic valorization of lecithin. This was exploited by enzymatic transformation of soy lecithin into lysolecithin liposomes, including functional free fatty acids, hydroxy fatty acids, hydrocarbons, or secondary fatty alcohols. One of the representative examples was the preparation of lysolecithin liposomes containing secondary fatty alcohols [e.g., 9-Hydroxyheptadec-11-ene (9) and 9-heptadecanol (10)] by using a phospholipase A2 from Streptomyces violaceoruber, a fatty acid double-bond hydratase from Stenotrophomonas maltophilia, and a photoactivated decarboxylase from Chlorella variabilis NC64A. The engineered liposomes turned out to range ca. 144 nm in diameter by dynamic light scattering analysis. Thereby, this study will contribute to application of functional fatty acids and their derivatives as well as valorization of lecithin for the food and cosmetic industries.

Reminder-preference test, affective difference-preference test using reference framing with a brand: 1. Sensitivity comparisons with the same-different difference-preference test.

Attempts to reduce the sugar content of carbonated drinks are ongoing. Reducing the sugar content while maintaining the sensory quality requires the development of an effective sensory test method that can measure a consumers' perceived sensory difference and preference of reformulated products against the reference product. The A-Not A with reminder (A-Not AR) method (sometimes called the reminder method) allows blind sensory tests of multiple test samples vs. a reference, while for the reference, marketing information, such as brand name and advertisements emphasizing the consumer benefit, can be provided to improve the marketing effects and consumer expectation. Thus, a preference test method can also simulate branded tests using A-Not AR design with a branded reference, making them suitable for consumer sensory tests. In the present study, an affective difference-preference test method using an A-Not AR design with the reference familiarization procedure of providing marketing information was developed, called the "reminder-preference test". The "reminder-preference test" sensitivity was compared with the previously suggested version of the "same-different difference-preference test", using signal detection d' analyses. A lemon-lime flavored carbonated drink was used as the reference and compared with two types of reformulations. The consumers were divided randomly into two groups that performed one of the two difference-preference test methods. With the "reminder-preference test", the consumers watched a commercial advertisement for the reference by providing its brand name before the tests to evoke the marketing effects. The proposed sensory test of the "reminder-preference test" was more sensitive than the "same-different difference-preference test", in terms of both sensory and preference discriminations. Hence, brand effects can be incorporated into the consumer sensory evaluation to achieve the reformulation objective and the potential of the "reminder-preference test" and its signal detection d' analyses to improve the effectiveness and efficiency of consumer sensory measurements.

Thermal Percolation Behavior in Thermal Conductivity of Polymer Nanocomposite with Lateral Size of Graphene Nanoplatelet.

In this study, the thermal percolation behavior for the thermal conductivity of nanocomposites according to the lateral size of graphene nanoplatelets (GNPs) was studied. When the amount of GNPs reached the critical concentration, a rapid increase in thermal conductivity and thermal percolation behavior of the nanocomposites were induced by the GNP network. Interestingly, as the size of GNPs increased, higher thermal conductivity and a lower percolation threshold were observed. The in-plane thermal conductivity of the nanocomposite containing 30 wt.% M25 GNP (the largest size) was 8.094 W/m·K, and it was improved by 1518.8% compared to the polymer matrix. These experimentally obtained thermal conductivity results for below and above the critical content were theoretically explained by applying Nan's model and the percolation model, respectively, in relation to the GNP size. The thermal percolation behavior according to the GNP size identified in this study can provide insight into the design of nanocomposite materials with excellent heat dissipation properties.

Investigation of human flavor perception and discrimination of the fat content in food using DR A-Not A and 3-AFC methods.

This study examined human flavor perception and discrimination of powdered milk samples with various fat contents using two different sensory discrimination methods, DR A-Not A and 3-AFC. DR A-Not A was expected to be more effective. Using skim milk and whole milk powder, five different samples with various fat contents were prepared. An independent samples design was used to compare DR A-Not A and 3-AFC. Each subject performed 24 repeated tests consisting of comparisons of four different test samples from the reference sample. Signal detection d' results showed that sample discrimination was possible using DR A-Not A, but not 3-AFC. Moreover, the just noticeable difference (JND) was calculated using the results of DR A-Not A. The calculated JND was 0.47% (w/v), and the Weber fraction was 0.82. These results confirm that the DR A-Not A method is more effective for studying the human sensitivity to the fat content in food.

Two-step rating-based 'double-faced applicability' test for sensory analysis of spread products as an alternative to descriptive analysis with trained panel.

Descriptive analysis with a trained sensory panel has thus far been the most well defined methodology to characterize various products. However, in practical terms, intensive training in descriptive analysis has been recognized as a serious defect. To overcome this limitation, various novel rapid sensory profiling methodologies have been suggested in the literature. Among these, attribute-based methodologies such as check-all-that-apply (CATA) questions showed results comparable to those of conventional sensory descriptive analysis. Kim, Hopkinson, van Hout, and Lee (2017a, 2017b) have proposed a novel attribute-based methodology termed the two-step rating-based 'double-faced applicability' test with a novel output measure of applicability magnitude (d'A) for measuring consumers' product usage experience throughout various product usage stages. In this paper, the potential of the two-step rating-based 'double-faced applicability' test with d'A was investigated as an alternative to conventional sensory descriptive analysis in terms of sensory characterization and product discrimination. Twelve commercial spread products were evaluated using both conventional sensory descriptive analysis with a trained sensory panel and two-step rating-based 'double-faced applicability' test with an untrained sensory panel. The results demonstrated that the 'double-faced applicability' test can be used to provide a direct measure of the applicability magnitude of sensory attributes of the samples tested in terms of d'A for sensory characterization of individual samples and multiple sample comparisons. This suggests that when the appropriate list of attributes to be used in the questionnaire is already available, the two-step rating-based 'double-faced applicability' test with d'A can be used as a more efficient alternative to conventional descriptive analysis, without requiring any intensive training process.

Photothermally Amplified Therapeutic Liposomes for Effective Combination Treatment of Cancer.

Near-infrared photothermal therapy has been investigated extensively with regard to selective tumor eradication, yet its clinical translation has been limited because of the absence of FDA-approvable agents with effective phototherapeutic function and minimal systemic toxicity. In this work, we developed photothermally amplified therapeutic liposomes in an attempt to synergize chemotherapy and hyperthermia for effective cancer phototherapy. The anticancer drug cisplatin and the photothermal agent indocyanine green (ICG) were encapsulated in a thermosensitive liposomal formulation at the lipid/ICG ratio maximizing the ICG loading efficiency. These liposomes released cytotoxic cisplatin molecules selectively via ICG-mediated photothermal stimulation. In phototherapeutic studies, these liposomes amplified therapeutic effects both in vitro in cancer cells and in vivo in mouse tumor models significantly over chemotherapy or photothermal therapy alone. We believe that these photothermally amplified therapeutic liposomes composed solely of already FDA-approved components (cisplatin, ICG, and phospholipids) have enormous potential for clinical translation in treating various tumors compatible with laser irradiation.

Liposomal Indocyanine Green for Enhanced Photothermal Therapy.

In this study, we engineered liposomal indocyanine green (ICG) to maximize its photothermal effects while maintaining the fluorescence intensity. Various liposomal formulations of ICG were prepared by varying the lipid composition and the molar ratio between total lipid and ICG, and their photothermal characteristics were evaluated under near-infrared irradiation. We showed that the ICG dispersity in the liposomal membrane and its physical interaction with phospholipids were the main factors determining the photothermal conversion efficiency. In phototherapeutic studies, the optimized formulation of liposomal ICG showed greater anticancer effects in a mouse tumor model compared with other liposomal formulations and the free form of ICG. Furthermore, we utilized liposomal ICG to visualize the metastatic lymph node around the primary tumor under fluorescence imaging guidance and ablate the lymph node with the enhanced photothermal effect, indicating the potential for selective treatment of metastatic lymph node.

Idiographic duo-trio tests using a constant-reference based on preference of each consumer: Sample presentation sequence in difference test can be customized for individual consumers to reduce error.

As reformulations and processing changes are increasingly needed in the food industry to produce healthier, more sustainable, and cost effective products while maintaining superior quality, reliable measurements of consumers' sensory perception and discrimination are becoming more critical. Consumer discrimination methods using a preferred-reference duo-trio test design have been shown to be effective in improving the discrimination performance by customizing sample presentation sequences. However, this design can add complexity to the discrimination task for some consumers, resulting in more errors in sensory discrimination. The objective of the present study was to investigate the effects of different types of test instructions using the preference-reference duo-trio test design where a paired-preference test is followed by 6 repeated preferred-reference duo-trio tests, in comparison to the analytical method using the balanced-reference duo-trio. Analyses of d' estimates (product-related measure) and probabilistic sensory discriminators in momentary numbers of subjects showing statistical significance (subject-related measure) revealed that only preferred-reference duo-trio test using affective reference-framing, either by providing no information about the reference or information on a previously preferred sample, improved the sensory discrimination more than the analytical method. No decrease in discrimination performance was observed with any type of instruction, confirming that consumers could handle the test methods. These results suggest that when repeated tests are feasible, using the affective discrimination method would be operationally more efficient as well as ecologically more reliable for measuring consumers' sensory discrimination ability.

Optimal difference test sequence and power for discriminating soups of varying sodium content: DTFM version of dual-reference duo-trio with unspecified tetrad tests.

As sodium reduction has become very important in the food industry, various types of unspecified duo-trio tests have been studied to improve its efficiency for studying samples with high sodium content, and a constant-saltier-reference duo-trio test with dual reference, one reference in the first position and the second reference in the middle between the two test stimuli (DTFM), has been recommended. For the duo-trio test, a 'comparison of distance' (COD) strategy has been generally assumed. Yet, theoretically for DTFM, the 2-AFC reminder (2-AFCR) τ-strategy is also possible, which would make DTFM more efficient than the unspecified tetrad test. In this study, the hypothesis was that when subjects are pre-exposed to two types of samples, the 2-AFCR τ-strategy can be adopted in a constant-reference DTFM using a fixed design experiment. In order to test this hypothesis, unspecified tetrad tests involving categorization tasks were used as a means of pre-exposure to the two types of samples for DTFM, and a performance comparison was conducted. Two groups of 39 untrained/naive subjects performed both the unspecified tetrad and DTFM tests in varying orders for the purpose of discriminating two different soup samples of varying sodium content. A comparison of the d' estimate across different methods supported the hypothesis that the more efficient 2-AFCR τ-strategy was appropriate when the tetrad test preceded DTFM, while when DTFM was performed first without pre-categorization of samples, the conventional duo-trio COD strategy was appropriate for the constant-reference DTFM.

Quantification of sensory and food quality: the R-index analysis.

The accurate quantification of sensory difference/similarity between foods, as well as consumer acceptance/preference and concepts, is greatly needed to optimize and maintain food quality. The R-Index is one class of measures of the degree of difference/similarity, and was originally developed for sensory difference tests for food quality control, product development, and so on. The index is based on signal detection theory and is free of the response bias that can invalidate difference testing protocols, including categorization and same-different and A-Not A tests. It is also a nonparametric analysis, making no assumptions about sensory distributions, and is simple to compute and understand. The R-Index is also flexible in its application. Methods based on R-Index analysis have been used as detection and sensory difference tests, as simple alternatives to hedonic scaling, and for the measurement of consumer concepts. This review indicates the various computational strategies for the R-Index and its practical applications to consumer and sensory measurements in food science.

Effects of order of tasting in sensory difference tests using apple juice stimuli: development of a new model.

3-AFC discrimination tests between 2 confusable versions of apple juice were performed using a variety of interstimulus rinsing regimes, to investigate the effects of order of tasting on difference test sensitivity. The results were compared to predictions from the sequential sensitivity analysis (SSA) model and the conditional stimulus (CS) model, which have been developed to account for differences in model systems. These models did not account for the data for this beverage system. A new model was developed. This took a Thurstonian/signal detection approach but included new elements. It considered the gradual build-up of adaptation effects that would be encountered as a judge proceeded through a 3-AFC test with a relatively strong flavored food system. It further considered cognitive contrast effects, which had not been considered in the prior models. The model was named the sequential perception analysis (SPA) model and it accounted for the data found with the apple juice stimuli. The predictions of the model were precise enough to account for differences between individual triads, which the former models had not been able to do.