Classification of cocoa beans based on their fluorescent fingerprint to predict sensory poles of chocolates?

Natures and quantities of aroma compounds present in chocolate vary according to several criteria such as the origin and the variety of cocoa beans, the cocoa post-harvest treatment and the process of manufacturing chocolate. These organoleptic qualities are evaluated through sensory evaluation. This method enable to define the sensory profiles of chocolates and then their belonging to a sensory pole. Could a classification of merchantable cocoa beans based on their fluorescent fingerprint be an alternative to predict sensory poles of chocolate? The objective of our study was to develop a chemometric model obtain with fluorescent fingerprint. To do this, 3D spectral analyses were performed at 20°C by Front Face Fluorescence Spectroscopy (FFFS) on refined cocoa powder samples (N=208). All of them were analyzed following similar operating conditions. At the same time, a sensory analysis was performed on the corresponding dark chocolates, prepared by and standardized and controlled fabrication process. The prediction model was developed on the 208 samples divided into the four sensory poles, and validated by a set of 50 samples. The prediction error was around 30%. To interpret the data, preprocessing of signals and cleaning of non-informative areas (Rayleigh scattering) was carried out. Subsequently, a multiway exploratory analysis (PARAFAC) was carried out to determine the discriminant wavelengths in the distribution of classes. Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) were performed on spectral data to identify sensory pole separation and to elaborate chemometric model. As a result, analysis of fluorescent fingerprints enabled to reach a reliable distribution of cocoa beans according to the sensory pole of chocolate

The impact of fruit texture and human saliva on the release of aroma compounds using fresh and dried mango samples

Flavour is one of the main factors affecting consumer's food preference. Our aromatic perception is greatly influenced by the release of aroma compounds during consumption itself influenced by the food matrix[1], the human oral physiology and oral processing[2]. In vivo or in vitro techniques were conducted on simple or model matrices to understand impact factors on the release of aroma compounds. However, very few studies were performed on real food matrices as fruits to understand the effect of food matrix and the oral physiology on the release of aroma compounds during oral processing. The present study investigated the impact of fruit texture and human saliva on the release of aroma compounds using in vivo and in vitro tests respectively. Mango was chosen as model fruit because of its richness in aroma compounds and its ability to process it into various products. To obtain different textures, two fresh mango products (puree, cubic pieces) and two dried mango products (powder, cubic pieces) were prepared from a homogenous fruit batch. The aroma compounds of mango samples were extracted by a convenient technique SAFE[3] (Solvent assisted flavour evaporation) and characterized by GC-MS analysis. Among volatile compounds detected, nineteen are considered as potential key flavour compounds from in mango samples. Aroma released during in vivo consumption of mango samples by trained panellists (n=8) was studied using RATD[4] technique (retronasal aroma-trapping device) mounted with Tenax. Volatile compounds trapped on Tenax were further analyzed by GC-MS. Twenty terpenes and one ester were identified in the exhaled nostril breath of panellists. They were amongst major volatile compounds of mango samples. Ten of which were reported as potential key flavour compounds in mango. The in vivo release of volatile compounds was affected by the matrix texture. The intact samples (fresh and dried cubic pieces) released more aroma compounds than disintegrated samples (fresh puree, dried powder). To understand the effect of saliva on aroma release, in vivo experiments with P&T[5] technique (purge and trap, Tenax as adsorbent) were carried out in the presence of saliva collected from the panellists and mango samples in the conditions as closely as possible to those in vivo consumption. The presence of human saliva didn't have a significant effect on the release of aroma compounds. In conclusion, the fruit texture but not saliva seemed to be the main factor in the release of volatile compounds during mango fruit consumption. (Résumé d'auteur

In the heart of volatile compounds of jicaro seeds

In Central America, a popular beverage is made from some roasted oilseeds, named jicaro seeds. Jicaro seeds are numerous and embedded in the pulp of the fruit of jicaro (Crescentia alata H.B.K), a calabash tree, native from Mexico and spread in dry areas of Central America. After fermentation, the seeds are separated from the pulp, sun dried and roasted in order to develop a specific flavor before being ground and used for making the beverage. These seeds are highly valued in several countries of Central America due to their high nutritional value and pleasant aroma. The aim of this study was to understand the effect of roasting on the composition of volatile compounds of jicaro seeds. Qualitative and quantitative determinations of volatile compounds in unroasted and roasted jicaro seeds (140 oC for 140 s) were carried out using Solvent Assisted Flavor Evaporation (SAFE) and Gas Chromatography/Mass Spectrometry (GC/MS). A total of 27 volatile compounds were identified and quantified. Styrene appeared to be the main compound with a concentration of 22.57 and 47.0 mg/kg in unroasted and roasted seeds respectively. Many volatile compounds were already found in the unroasted seeds (19 out of 27). Others appeared in roasted seeds such as pyrazines and aldehydes. Most of compound concentrations increased with the roasting process, except for some alcohols or esters. A decrease of some reducing sugars and free amino acids was observed, probably due to Maillard reactions. Additionally, 22 impacting odor compounds of roasted seeds, extracted by Headspace Solid Phase Micro Extraction (HS-SPME), were identified by ten untrained panelists using Gas Chromatography Olfactometry (GCO). Ethyl-2-methylbutyrate was the only one recognized by 100% of the panelists as characteristic of jicaro note with concentrations of 0.16 mg/kg and 0.47 mg/kg in unroasted and roasted seeds respectively, while pyrazines were associated to roasted note. This ester, along with pyrazines, aldehydes, ketones and alcohols, contributes to the specific and pleasant aroma of jicaro seeds and its beverage. Its odor activity value (OAV) was of 1808, with an odor threshold at 0.26 ppb

D 5.4.1.3. Final Report on sensory testing in Europe for Group 3. Project AFTER “African Food Tradition rEvisited by Research”

The work presented in this deliverable had as main objective the sensory profiling of products resulting from process reengineering of traditional products from group 3 − plant based extracts. The new processing expected to improve food safety and product quality to facilitate their promotion and introduction to EU markets. The products belonging to this group were Bissap - Hibiscus sabdariffa L., Baobab - Adansonia digitata L. and Jaabi - Ziziphus mauritiana Lam. However, due to restrictions of Jabbi product only Bissap and Babobab was studied in Europe. In previous study in Europe sensory evaluation of the cake samples was carried out by 5 semi-trained panellists from CIRAD Montpellier (paper under submission), and sensory aspect of jaabi was not well accepted by the European consumer. For that reason, and because the reengineered product was only improved in terms of nutritional value ith no sensory improvement, we did not reached conditions to test this product in Europe. In the case Baobab samples, four different samples were included: two syrups obtained from Baobab powder by two different processes: hot dissolution and cold dissolution; two syrups one produced from Baobab fruit and one from Baobab fruit pulp and control: a commercial pear nectar selected for comparison as standard sample recognised by Portuguese consumers and resembling similar sensory attributes. The samples were assessed by a Portuguese trained panel (n=18). The results of sensory profiling showed similar results between the four samples, however samples produced from similar raw material, Baobab powder or fruit showed to be closer in particular concerning color hue and turbidity. The attribute that was highlighted in all samples was sweetness and all samples were considered very swee. The Baobab fruit pulp syrup was the most appreciated sample in consumer testing (see Deliverable 5.4.2.3), possibly by its sensory profile, since higher values in the attributes, namely fruit odor intensity and color hue were obtained. Concerning Bissap descriptive analysis was performed on three hibiscus drinks, an hibiscus infusion prepared freshly from dried calyces according to Senegalese recipe for baseline comparison and two new hibiscus drinks developed under as reengineered products – an ultra-vacuum concentrate and improved syrup. The samples were assessed by a Portuguese trained panel (n=16). Results showed a greater proximity between UVc and FTi, than with REs. REs was characterized for its strong sweetness, low acidity and weak colour intensity, while FTi showed the stronger hibiscus character. FTi and UVc had similar colour intensity, acidity and bitterness. These results are in line with the ones obtained using the consumer profiling technique, Check-all-that-apply, according to which REs was perceived to have a highly distinct sensory profile when compared with FTi and UVc, being attributed with mild descriptors (sweet, watery, syrupy and light red), and UVc and FTi were related to more aggressive ones (strong taste, acidic, bitter, astringent, dark red). So these studies make evidence that reengineered products presented similar profiles, in particular for baobab drinks, while for baobab a very clear difference in some drinks were observed mainly in terms of Intensity. These results of Groups 3 will support the introduction of the new products in Europe and will allow selecting the best strategy to do it. (Résumé d'auteur

Classification des chocolats selon leur empreinte globale fluorescente ?

La nature et la quantité des composés d'arôme présents dans le chocolat varient selon plusieurs critères, comme la variété des fèves de cacao, le processus de production du cacao marchand et le processus de fabrication du chocolat. Evaluées sensoriellement, ces qualités organoleptiques permettent de définir les profils sensoriels des chocolats et de les classer dans des pôles sensoriels caractéristiques. Ces évaluations sont essentielles mais demeurent encore trop longues et onéreuses. Une classification des chocolats à partir de leurs empreintes globales fluorescentes pourrait-elle être une solution alternative pour identifier les pôles sensoriels ? L'objectif de notre étude était de différencier 200 chocolats noirs répartis suivant 4 pôles sensoriels (A, B, C, D) à partir de leur " empreinte globale fluorescente " sans passer par une étape de dégustation associée. Pour ce faire, des analyses spectrales 3D ont été réalisées par Spectrométrie de Fluorescence Frontale sur des échantillons de chocolats fondus à 45°C. Les chocolats ont tous été préparés suivant le même processus de fabrication, évalués sensoriellement puis analysés dans les mêmes conditions opératoires (LO excitation : 250-650 nm_ pas de 5nm ; LO émission 290-800nm_ pas de 2nm). Afin de clarifier les données, un prétraitement des signaux et une gestion des zones non informatives (diffusion Rayleigh) ont été effectués. Par la suite, une analyse exploratoire multiway (PARAFAC) a été réalisée de manière à connaitre l'importance des longueurs d'ondes dans la répartition des classes. Une Analyse en Composante Principale (ACP) a également été réalisée sur l'ensemble des données spectrales afin de voir si une séparation des pôles était visible. Les analyses des empreintes globales fluorescentes ont ainsi permis d'en déduire une répartition fiable des chocolats suivant leur pole sensoriel sans passer par une étape de dégustation. (Résumé d'auteur

D 5.4.2.3. Report on near-market consumer testing of new improved products in Europe for Group 3. Project AFTER “African Food Tradition rEvisited by Research”

This deliverable describe the main results concerning the studies of European consumer acceptance of reengineered products from group 3 (plant based extracts for functional foods) in order to understand acceptance in EU markets and facilitate their promotion and introduction in these markets. The products belonging to this group were Bissap - Hibiscus sabdariffa L., Baobab - Adansonia digitata L. and Jaabi - Ziziphus mauritiana Lam, but only Bissap and Baobab were submitted to European consumers testing. The methodological approach performed to establish consumer's acceptance and sensory profile included consumer hedonic acceptance, Just-About-Right intensity evaluation of specific descriptors (JAR) and Check-All-That-Apply questions (CATA). Results on 4 reengineered Baobab fruit juices used in this consumer test showed that all fruit juices were evaluated as very sweet and slightly fruity flavour and very light colour and were in the acceptable range since the average scores were between 5 (neither like nor dislike) and 7 (like moderately), which can be considered satisfactory taking into account that the Baobab is not commonly consumed in Europe and even unknown to the public. For all the samples assessed the diluted from Syrup from Baobab fruit pulp (BSFP) showed to be the most appreciated and obtained a positive value on the consumption probability, possibly because this sample showed the highest values in the fruit odour and intensity and colour hue. Results on 2 reengineered bissap drinks - an ultra-vacuum concentrate and a syrup evaluated in Europe by comparable consumers' samples in France, Portugal and United Kingdom, along with a hibiscus infusion prepared freshly from ground dried calyces, showed that all the hibiscus drinks evaluated were in average positively appreciated by consumers, however new drinks were significantly more appreciated then the traditional infusion. Similar preference profiles were observed across countries although French participants were those that most appreciated the drinks. Clusters analysis performed showed new hibiscus drinks were liked slightly too moderately by participants in Clusters C1 (Overall likers) and C2 (New drinks' likers), representing about 75% of participants in the study. The evaluation of the intensity of three sensory attributes - colour, sweet taste and acid taste -, relatively to participants' ideal level and it's relation with overall liking ratings, showed for reengineered syrup a significant negative impact of the high sweetness on the drink overall liking. Oppositely for ultra-vacuum AFTER (G.A n°245025) – Deliverable 5.4.2.3 Report on near-market consumer testing of new improved products in Europe for Group 3 4 concentrate the strong colour and acidity and weak sweetness led to a significant decrease in overall liking. CATA profiles were similar in the three countries, concerning both the actual drinks tested and an ideal theoretical drink. Reengineered syrup was perceived to have a highly distinct sensory profile when compared with the others, and these with the described ideal drink. In the case of reengineered syrup although being the most appreciated drink, its high sweetness was an important penalizing factor in consumers acceptance as a drink, nevertheless other uses for this syrup can be foreseen. In the case of ultra-vacuum concentrate drink where the strong character, robust colour and strong acidity was not so appreciated in Europe as in Senegal, could benefit European consumers' acceptance if we increase the dilution of the concentrate with an equilibrated degree of added sugar. Besides exploring further opportunities for enhancing the sensory profiles of the new drinks of group 3 in line with European taste, future studies should also investigate the levels of marketing activities (pricing, distribution and promotional information – including nutritional and healthiness attributes) which will best support their successful introduction in European markets. (Résumé d'auteur

New approach for better assessing consumer acceptability of improved cassava food products. [S20-05]

A new approach for better assessing consumer accept ability of improved traditional cassava products has been developed. It involves several successive steps. Qualitative surveys were conducted all along the food chain to have a good knowledge of the variability of processes, varieties, and products, and identify quality criteria of a good cassava product with the various stakeholders. Active and effective participation of women processors was essential in the adoption of new processes or varieties. Their observations and comments on cassava behaviour throughout the processing were used to identify the ability of new varieties or processes to make a good product. Physicochemical analyses of products complemented processors' selection by identifying quality traits. Focus groups and sensory evaluation were used to generate sensory descriptors and classify cassava products in separate groups according to their sensory properties. The acceptability and preferences of improved products by a large number of consumers were assessed using a "all-in-one" method coupling hedonic test, JAR "Just All Right" test, CATA "Check All That Apply" question and "willingness to pay”. Three case studies on bobolo or “bâton de manioc” and gari in Cameroon, and on gari in Benin will be given as examples and detailed. The methodological approach was different for each case, depending on the product, the local conditions, and the objectives of the study. The originality of the approach was the participatory involvement of a group of women processors in the selection, at each step of the processing, of the improved varieties with appropriate characteristics for traditional uses. This might be very useful for providing information to breeders early in varietal improvement programmes. (Texte intégral

RTBfoods Manual - Part 3 - Tutorial: Statistical Analyses (PCA and multiple regression) to visualise the sensory analysis data and relate it to the instrumental data. Biophysical characterization of quality traits, WP2

After sensory evaluation by a trained panel, and biophysical evaluation using the instrumental measurements of the different products, statistical treatments can be used to interpret the results. The objective of this tutorial, using XLSTAT software, is to perform and interpret 2 types of statistical treatments: (1) principal component analysis (PCA) which enables rapid visualisation of the correlations between the sensory attributes, and (2) linear regression, which allows prediction of the sensory attributes based on the biophysical (textural, biochemical) parameters. The performance of the panel has previously been checked, and the sensory data were prepared for statistical analysis (see RTBfoods_F.2.4A_Tutorial for Performance Monitoring & Sensory Data Cleaning Before Statistical Analysis_2021.pdf). The present tutorial is based on an example presented in a published Excel file that goes through one step after another. The selected PCA uses sensory data to identify major trends and sensory diversity between groups of products and between individual products. The PCA also makes it possible to measure differences between repeated products that reflect the performance of the panel (if the products are indeed identical). Multiple linear regression was used to predict sensory attributes from biophysical parameters. For this purpose, in our example, the dataset was split into two datasets: a calibration set representing ¾ of the data and a validation set containing the remaining data. Three prediction indicators were calculated to assess the accuracy and robustness of the prediction: the coefficient of determination (R²), the mean difference between observed and predicted values (RMSEC) in the calibration set, and the mean difference between the observed and predicted values in the validation set (RMSEV). The relevance of the validation and the minimum number of observations necessary to build predictive models are discussed

Guidance for consumer testing data analysis & reporting - Supplement to Step 4. Understanding the drivers of trait preferences and the development of multi-user RTB product profiles, WP1, Step 4

This is a guidance document that gives a step-by-step description of the different analyses that should be included for consumer testing data analysis and reporting, referred to as WP1 Step 4 within RTBfoods project. The objectives of this document are to provide country partners with a guide and a template to follow when reporting on the activity. The main document is divided into Study context; Methodology that includes sampling, consumer testing, data analysis; Results including overall liking (9-point scale hedonic testing), segmentation (Ward cluster analysis), Just-About Right (JAR), Check-all-that-applies (CATA), Sensory mapping (Principal Component Analysis (PCA)); and Conclusions. In addition, there are appendices that give detailed guidance on the use of the XLStat software to conduct the various statistical tests. This appendix is downloadable at https://mel.cgiar.org/reporting/download/report_file_id/25496