Search

Vanilla flavor is derived from the cured fruits of two orchid species Vanilla planifolia and V. × tahitensis. About twenty other Vanilla species are also credited with scented fruits, but very little is known about their aromatic features. We investigated the aromatic compound content of the ripe fruits of 30 vanilla accessions obtained from eight species and three hybrids. Glucovanillin plus six phenolic and one anisic aglycones, extracted after enzymatic hydrolysis, were quantified by High-Performance Liquid Chromatography and Ultra-Violet detection. The analysis of the aromatic contents and the principal components showed clear-cut differences in the aromatic content of the species and varieties studied. The total content of aromatic compounds separated the three species most distantly related to V. planifolia, namely V. lindmaniana, V. crenulata and V. imperialis, from the other species notably by the absence of vanillin potential and a very low total aromatic potential (

Eight yam species (Dioscorea spp.) represented by 522 accessions (landraces and hybrids) were analysed for the individual sugars, catechins, phenolic acids and saponins contents of their tuber flours. Maltose, sucrose, glucose and fructose were quantified. Reducing sugars mean values were highly variable within species and ranged from 0.16%dry weight (DW) (SD ± 0.12) in D. dumetorum to 3.15%DW (±2.49) in D. esculenta. Maltose was detected only in D. esculenta. Chlorogenic acid, gallic acid and other phenolic acids ranged from 4.33 mg/g DW in D. bulbifera to 4.87 mg/g in D. alata and 9.55 mg/g in D. nummularia but were not detected in other species. Catechins (epicatechin and catechin) were highest in D. bulbifera bulbils (25.18 mg/g) and tubers (6.96 mg/g), and lowest in D. esculenta (0.32 mg/g). Their content is significantly correlated with dark flour colour and they most likely contribute to the oxidation of tuber flesh. Saponins (dioscin and gracillin) were quantified in only two species: D. cayenensis (5.94 mg/g, SD ± 3.78) and D. esculenta (3.74 mg/g, SD ± 3.72). Varietal selection may tend to reduce sugars levels and increase secondary metabolites with bioactive properties. HP-TLC is a suitable technique for the rapid quantification of compounds related to yam tuber flour quality.

The present study aimed at evaluating the potential of diethyl ether extracts UV/visible (UV/vis) absorbance for assessing the suitability of commercial lots of kava (Piper methysticum). The UV/vis absorption spectra of diethyl ether root extracts of 15 cultivars clustered them into three groups in parallel to their known genetic relatedness and their chemical composition determined by GC–MS and LC–MS analyses. Absorption peaks at 250 nm and 290 nm respectively corresponded to kavain, the most health-promoting kavalactone, and dihydromethysticin a non-desirable kavalactone. The absorbance peak at 340–350 nm reflected the yellow coloration of the extract, which was mainly due to the undesirable flavokavins, desmethoxyyangonin and yangonin. Ratios of absorbance values at 250 nm and 290 nm significantly differentiated all three groups of cultivars, namely 'noble' which provide health benefits from 'two-day' and 'wichmannii' that are health damaging. These results provide a robust and rapid colorimetric test for routine control of a critical aspect of the quality of kava batches. (Resume d'auteur)

International audience; Direct-injection mass spectrometry (DIMS) techniques have evolved into powerful methods to analyse volatile organic compounds (VOCs) without the need of chromatographic separation. Combined to chemometrics, they have been used in many domains to solve sample categorization issues based on volatilome determination. In this paper, different DIMS methods that have largely outperformed conventional electronic noses (e-noses) in classification tasks are briefly reviewed, with an emphasis on food-related applications. A particular attention is paid to proton transfer reaction mass spectrometry (PTR-MS), and many results obtained using the powerful PTR-time of flight-MS (PTR-ToF-MS) instrument are reviewed. Data analysis and feature selection issues are also summarized and discussed. As a case study, a challenging problem of classification of dark chocolates that has been previously assessed by sensory evaluation in four distinct categories is presented. The VOC profiles of a set of 206 chocolate samples classified in the four sensory categories were analysed by PTR-ToF-MS. A supervised multivariate data analysis based on partial least squares regression-discriminant analysis allowed the construction of a classification model that showed excellent prediction capability: 97% of a test set of 62 samples were correctly predicted in the sensory categories. Tentative identification of ions aided characterisation of chocolate classes. Variable selection using dedicated methods pinpointed some volatile compounds important for the discrimination of the chocolates. Among them, the CovSel method was used for the first time on PTR-MS data resulting in a selection of 10 features that allowed a good prediction to be achieved. Finally, challenges and future needs in the field are discussed.

The aim of this study was to determine the multi-mycotoxin occurrence in cereal and oilseed products most consumed in Cote d’Ivoire. A total of 238 samples of rice (88 produced locally or imported), maize (79, cracked or flour) and peanut paste (71) were collected in the main markets of Abidjan, Bouake and Korhogo. An UHPLC-MS/MS method allowed the analysis of 77 mycotoxins. All the peanut paste samples were contaminated by aflatoxin B1 (AFB1) with 99% exceeding the EU limits of 2 μg kg−1 for AFB1 and 4 μg kg−1 for total aflatoxins (AFT: B1+B2+G1+G2), and concentrations reaching up to 4535 μg kg−1 (AFB1) and 8094 μg kg−1 (AFT). Maize (96%) and rice (57%) samples were also contaminated by AFB1 with 58% and 24% respectively above the EU limits and maximum levels of 80 μg kg−1 for maize and 14 μg kg−1 for rice. Only 6% of the cereal samples (3 rice and one maize samples) had ochratoxin A content above the EU limit (3 μg kg−1). Fumonisins and zearalenone were detected, respectively, in 91% and 8% of the maize samples, and in 18% and 5% of the rice samples but at levels below EU limits. Out of the 238 samples, 91% were contaminated with more than one mycotoxin including EU regulated mycotoxins and/or other mycotoxins mainly beauvericin (79% of the samples), equisetin (71%), aflatoxin M1 (45%), cyclopiazonic acid (32%), fumonisin B3 (29%), sterigmatocystin (24%), citrinin (18%), ochratoxin B (16%) and fusaric acid (15%). The peanut paste samples represented the highest risk to consumer health followed by maize and rice samples.

Food traceability is a growing consumer concern worldwide. Traceability is undertaken primarily at the administrative level, where the use of advanced analytical tools is not available. Nevertheless, the determination of geographical origin is a requirement of the traceability system for the import and export of foodstuffs (EU regulation 178/2002). The topics covered in this book include the history of traceability; legislations and rules; the actual traceability techniques and the potential analytical techniques for food traceability such as molecular methods (e.g. DGGE, SSCP), next generation sequencers (NGS), bio-captors, chromatographic techniques, isotopic analysis that are used for discrimination of organic food, fish, oils. The chromatographic techniques help in the use of volatile compounds analysis. The isotope analysis helps in distinguishing between chicken meat and vegetable oils. Ambient mass spectrometry is used for studying mycotoxines and alkaloids in foodstuffs and their management, food and feed authentication in olive and other plant oils, and wine. Vibrational methods (e.g. NMR and NIRS) are used to trace food by global spectrum. The book reviews the current and future techniques including metabolomic techniques. (Resume d'auteur)

Phenolic compounds from jujube fruits and related antioxidant activities were investigated during the ripening stages. Three different antioxidant assays, including ORAC, FRAP and DPPH, were monitored on crude jujube extract (CJE). Jujube fruits were additionally fractionated into three selective fractions F1, F2, and F3. However, only the FRAP assay gave the relative antioxidant activity for the three fractions. Furthermore, HPLC-ESI-MSMS (Q-Tof) and GC-MS were used to identify the compounds in each purified fraction. Using FRAP, F1 mainly composed of lipids, exhibited the lowest antioxidant activity (?0.080 ± 0.015 mmol trolox/100 g, p < 0.05). F2, rich in flavanols and flavonols, displayed 50-fold higher activity (4.27 ± 0.11 mmol trolox/100 g). Remarkably, F3 with an elevated content of condensed tannins (polymeric proanthodelphinidins), exhibited the highest antioxidant activity (25.4 ± 0.35 mmol trolox/100 g). The presented results showed that the phenolic profiles of the fruits were influenced by their developmental stage. Furthermore, during ripening, the antioxidant activity may be more impacted by the flavanols and condensed tannins. The purified condensed tannins of jujube fruits may be used as natural antioxidant extracts.

International audience; The determination of geographical origin is part of the demand of the traceability system of food products. A hypothesis of tracing the source of a product is to analyse in a global way the bacterial communities of the food samples after their production. For this purpose, molecular techniques employing 16S rDNA profiles generated by PCR–DGGE were used to detect the variation in bacterial community structures of salts from four French regions. When the 16S rDNA profiles were analysed by multivariate analysis, distinct microbial communities were detected. The band profiles of the salt bacteria from different producing areas were different and were specific for each location and could be used as a bar code to certify the origin of salts. These band profiles can be used as specific markers for a specific location. This method is proposed as a new traceability tool which provides salts with a unique bar code that permits to trace back salts from store shelves to their original location.

When a raw sweet potato root is analysed, only sucrose, glucose and fructose are present but during cooking, starch is hydrolysed into maltose giving the sweet flavour to cooked roots. This study aimed at developing an HPTLC protocol for the rapid quantitative determination of maltose and total sugars in four commercial varieties and to compare them to 243 hybrids grouped by flesh colour (white, orange, purple). In commercial varieties, mean maltose content varied from 10.26 to 15.60% and total sugars from 17.83 to 27.77% on fresh weight basis. Hybrids showed significant variation in maltose content within each group, with means ranging from 7.65% for white-fleshed, to 8.53% in orange- and 11.98% in purple-fleshed. Total mean sugars content was 20.24, 22.11 and 26.84% respectively for white, orange and purple flesh hybrids. No significant correlations were detected between individual sugars but maltose and total sugars content were highly correlated. Compared to the best commercial variety (Baby), 25 hybrids (10.3%) presented a higher maltose content and 40 (16.5%) showed a higher total sugars content. HPTLC was observed as an attractive, cost efficient, high-throughput technique for quantitating maltose and total sugars in sweet potatoes. Perspectives for improving sweet potato quality for consumers' requirements are also discussed.

Hibiscus sabdariffa L. is a worldwide consumed plant, principally after infusion of its dried sepals and calyces, which are usually discarded. Nevertheless, they represent a potential source of natural bioactive compounds, e.g. polyphenols, which could add value to this under-exploited plant. Protocatechuic acid (PA) was chosen as a model of the phenolic acids that can be extracted from H. sabdariffa. In order to modify PA hydrophilic character, which limits its use in lipid-rich food products, PA was esterified to C-1-C-18 alcohols, and the impact of lipophilization on its antioxidant activity was evaluated in both, an homogeneous (DPPH and ORAC methods) and an heterogeneous (CAT method) system. Results herein obtained showed that, depending on the grafted alkyl chain length, lipophilization could positively affect the antioxidant activity of PA in heterogeneous media; therefore, support its use as an innovative way to synthesize molecules with an improved antioxidant capacity and potential to be used as multifunctional preservatives in food

The development of quality standards to regulate the trade of kava (Piper methysticum) in the Pacific necessitates new analytical techniques for routine control of high-quality raw material. In the present study, varieties and parts of the plant were compared for their kavalactone and flavokavin (FK) profiles. Three hundred and eight samples corresponding to 25 noble, 25 two-days and five wichmannii varieties were collected from 203 different plants. Commercial samples were also analysed to test the technique. Overall, 353 samples were prepared (221 roots, 114 stumps, nine basal stems and nine stem peelings). Their acetonic extracts were measured for UV absorbance and analysed by HP-TLC. Two ratios were computed after scanning the plates at 245 nm (K/KL = kavain/total kavalactones) and 366 nm (FK/KL = flavokavins/kavalactones). The results indicate that noble varieties suitable for daily consumption of kava are characterised by high K/KL and low FK/KL. At 400 nm, the mean UV absorbance of acetonic extracts from noble, two-days and wichmannii varieties are 0.69, 0.94 and 1.04, respectively. The significant (+0.757**) correlation between the total FK content and the extracts absorbance at 400 nm indicates that a simple colorimeter can be used to detect poor-quality raw material. (Resume d'auteur)

International audience; The objectives of the present study were to develop a simple high performance thin layer chromatography (HPTLC)-based protocol: (i) to allow high-throughput profiling of phenolic compounds of microwaved roots from 295 sweet potato varieties and breeding lines, (ii) to quantify the content of anthocyanins and caffeoylquinic acid (CQA) derivatives, and (iii) to determine their respective contributions to the antioxidant activity of sweet potato methanolic extracts using the DPPH test. Analysed accessions were separated into three groups: white-fleshed (n = 100), orange-fleshed (n = 64) and purple-fleshed (n = 131). Purple-fleshed accessions presented the highest mean CQA content. After DPPH treatment and transmittance scanning of the plate at 517 nm, the most active free radical scavengers were found to be the four CQAs (CGA, 3,4-, 4,5- and 3,5-diCQA) while the anthocyanins were found to be less active. The total antioxidant capacity of the sweet potato methanolic extracts was mostly linked to total CQAs content. This method can now be used for fast routine analysis and selection of sweet potato breeding clones.

This study describes a new and suitable method for the rapid evaluation of rice (Oryza sativa, L.) aroma by analysis of the volatile fraction using solid-phase microextraction coupled with mass spectrometry (SPME/MS). The abundance list of unresolved mass fragments of the SPME extracted volatile fraction formed the “fingerprint” of a rice sample. Fingerprints of 61 rice samples were recorded in duplicate. Pollutants originating from the extraction system induce fingerprint background that could be lowered by careful cleaning of vials and caps and by exclusion of specific mass fragments. A good discrimination between scented and nonscented rice samples was obtained using the SIMCA procedure. Most of the discriminating mass fragments could be directly or indirectly assigned to potential aromatic molecules present in rice. Keywords: Scented rice; aroma; 2-acetyl-1-pyrroline; solid-phase microextraction; mass spectrometry; fingerprint

Globalization of trades and industrialization of food have increased the occurrence of food fraud. Cases of food contamination now have a global impact and lead to far-reaching consequences both on the economy and the health of consumers (Cubero-Leon et al., 2014). Thus, fraud and authentication became important topics in the food sector. Especially as food frauds are becoming more sophisticated to bypass controls and are therefore more difficult to detect by classical approaches. Organic foods are part of foods that are the most likely to be subject of fraud. But traceability of foods is mainly performed by administrative means (UE Regulation 178/2002). That is why it is necessary to resort advanced analytical techniques to detect non-compliant products and to ensure traceability and authentication of foods, including those from organic agriculture. Our study is based on the hypothesis that treatments associated to various farming types have a measurable impact on food microflora. That is why, the main objective of this study was to use the microbial environment of foods to discriminate them according to their production mode. PCR-DGGE, a molecular tool of microbial ecology, could be used as to discriminate food production modes using bacterial and fungal rDNA profiles. The analysis of microbial genetic profiles of nectarines, peaches, bananas and apples showed that it was possible to differentiate fruits according to their farming types. It was possible to verify the robustness of our methodology by comparing results obtained on two successive harvest years. We estimated also the intra-plot variations and observed that organic apples could be discriminated from conventional ones independently upon their position in the field (centre or border) or even on the tree. The observed differences in microflora between organic and conventional apples were significant enough to conclude that the applied treatments have a significant impact on this microflore. Furthermore, the analysis of DNA sequences obtained from PCR-DGGE and NGS allowed some microbial groups (fungal and bacterial) to be identified as specific to organic foods. However, the “terroir effect” is an important criterion to take into account for the implementation of an authentication tool for organic products. So, an application in the field would be difficult to predict if it is plot-specific. This study constitutes the basis for the development of an analytical tool that could meet the needs of food industry professionals in terms of authenticity and food safety, especially to assist certifying bodies to control and authenticate organic food products. This study enabled also to enrich the existing knowledge on the microbial ecosystem of fruits from different agricultural practices., Avec la mondialisation et l'industrialisation de l'alimentation, la fraude et les cas de contamination des aliments peuvent avoir un impact international et entraîner des conséquences de grande envergure à la fois sur l'économie et la santé des consommateurs (Cubero-Leon et al., 2014). La fraude et l'authentification sont donc devenues des sujets émergents dans le secteur alimentaire. D'autant que les fraudes sont de plus en plus sophistiquées pour contourner au mieux les contrôles et donc de plus en plus difficiles à détecter par des analyses classiques. Les aliments issus de l'agriculture biologique (AB ou bio) font d'ailleurs partie des aliments qui risquent le plus de faire l'objet de fraude. Mais la traçabilité des aliments est principalement garantie par des moyens administratifs (règlement UE 178/2002). C'est pourquoi il est nécessaire de recourir à des techniques analytiques avancées pour détecter les produits non-conformes et pour garantir la traçabilité et l'authenticité des aliments, notamment ceux issus de l'AB. Notre étude est basée sur l'hypothèse que les traitements, associés à différents types d'agriculture, ont un impact mesurable sur la microflore des aliments. L'objectif principal était de pouvoir utiliser l'environnement microbien des aliments pour les discriminer en fonction de leur mode de production. La PCR-DGGE, un outil moléculaire d'écologie microbienne, pourrait servir à discriminer les modes de production d'aliments par analyse des profils génétiques des ADNr bactériens et fongiques. L'analyse des profils génétiques microbiens de nectarines, pêches, bananes et de pommes a montré qu'il était possible de différencier les fruits en fonction de leur mode de production. La robustesse de notre méthodologie a été démontrée en comparant les résultats obtenus sur deux années de récolte successives. Létude des variation intra-parcellaires ont également permis de démontrer que les fruits bio pouvaient être différenciés des conventionnels indépendamment de leur position dans la parcelle (centre vs bord) ou encore sur l'arbre. Les différences observées au niveau de la structure des communautés microbiennes étaient donc suffisamment importantes pour conclure que les traitements appliqués ont un impact significatif sur ces communautés. De plus, l'identification des espèces microbiennes obtenues après PCR-DGGE et NGS a révélé que certains groupes microbiens (fongiques et bactériens) pourraient être spécifiques aux aliments bio. Cependant, l'effet terroir est un critère important à prendre en compte dans la mise en place d'un outil d'authentification des aliments bio. Une application sur le terrain serait donc difficile à prévoir si elle est parcelle-spécifique. Cette étude s'inscrit à la base de la mise au point d'un outil analytique qui pourrait permettre de répondre aux besoins des professionnels de l'industrie alimentaire en termes d'authenticité et de sûreté alimentaire, en particulier pour aider les organismes certificateurs à contrôler et authentifier les aliments bio. Cette étude a également permis d'enrichir les connaissances actuelles sur l'écosystème microbien des fruits en fonction des pratiques agricoles.

We will consider the Grignard chemical deacylation to study the regioanalysis of triacylglycerols (TAGs). Using a given TAG structure, a cross-contamination model is developed and used for evaluating the incidence of the acyl migration and its influence on the accuracy of a regiospecific analysis of the molecule. Despite unavoidable isomerization, the newly formed [alpha],[bêta]-diacylglycerols are considered as most representative of the original TAG composition. In this paper, we present evidence that in conditions of limited acyl migration, the regiospecific distribution could more accurately be determined from the [alpha]-monoacylglycerol rather than through calculations based on the [alpha],[bêta]-diacylglycerols fraction.

Producer organizations are often said to have the potential to help farmers meet the increasing quality requirements of agricultural value chains. However, the external environment may influence producer organizations’ room for maneuver in implementing effective quality management. This article assesses the influence of the relations between producer organizations, producers and other actors in the value chain on the capacity of producer organizations to implement quality management. Our analysis focuses on four Moroccan milk collection cooperatives that started using a milk analyzer with the aim of eliminating cheating by their suppliers. The cooperatives’ room for maneuver in improving quality management was limited by the presence of competitors for milk collection and by the agro-industry’s lack of transparency in the way its own quality controls were applied. Future studies on how producer organizations can meet the quality challenge should include the strategies of other actors in the value chain in their analyses.

International audience; Coumarins and furanocoumarins are secondary metabolites commonly found in citrus plants. These molecules are allelochemical compounds in plants that have controversial effects on humans, such as phototoxicity and the commonly described interactions with drugs, referred to as the ``grapefruit juice effect''. Thus, it is important to develop a reliable method to identify and quantitate the coumarins and furanocoumarins in citrus extracts. For this purpose, we herein describe an ultraperformance liquid chromatography coupled with mass spectrometry (UPLC-MS)-based method. We first developed a rapid UPLC method (20 min) to separate the isomers of each furanocoumarin. A subsequent single ion monitoring MS detection method was performed to distinguish between the molecules, which were possibly coeluting but had different molecular weights. The method was successfully used to separate and quantitate 6 coumarins and 21 furanocoumarins in variable amounts within peel extracts (flayed and albedo) of 6 varieties of Citrus (sweet orange, lemon, grapefruit, bergamot, pummelo, and clementine). This method combines high selectivity and sensitivity in a rapid analysis and is useful for fingerprinting Citrus species via their coumarin and furanocoumarin contents.

International audience; To be able to account for sensory qualities earlier in the assessment of a new banana hybrid in a selection scheme, predicting the sensory perception of banana texture and taste by instrumental parameters was investigated. Thirteen cultivated banana and four new triploid hybrids were characterized by sensory profiling, and rheological and chemical analyses. Multilinear regressions were used to calibrate predictions using 13 cultivated bananas, and the quality of predictions was validated using four hybrids. The sensory characteristics sourness and sweetness were predicted by titratable acidity (R-2 = 0.68) and pH (R-2 = 0.66). Malate and citrate were the main contributors to sweetness and sourness. Astringency was predicted by total tannins (R-2 = 0.55). Rheological parameters from texture profile analyses (stress at fracture, fracturability) were more suitable than pulp puncture force to predict the sensory texture properties firmness (R-2 = 0.47) and melting (R-2 = 0.60). These textural properties were predicted by titratable acidity and dry matter content (R-2 = 0.62). Predictions of mealiness, adhesiveness, and heterogeneity were not efficient. Differences of 3.6-3.7 meq 100 g(-1) FW in titratable acidity or of 0.30 g 100 g(-1) FW in malate or. citrate were required to ensure a detectable difference in sourness or sweetness (p = 0.9). Pulp puncture force needed to differ by a minimum of 0.9 N before a difference in firmness could be perceived by the panelists. In conclusion, while models to predict sourness and sweetness can now be used for high throughput phenotyping, we recommend additiqnal tests for other sensory attributes. (C) 2013 Elsevier B.V. All rights reserved.

The occurrence of lactic acid bacteria flora (LAB) was investigated on Ivorian fermented fish Adjuevan products produced with sea fish at different salt concentration (10, 15, 20, 25, 30%) according two traditional methods. LAB biodiversity was investigated using traditional culture-dependent method and culture-independent method (DGGE). LAB isolates were Lactobacillus fermentum 54%, Leuconostoc lactis subsp lactis 27%, Pediococcus pentosaceus 19% according method 1 and Pediococcus pentosaceus 61%, Lactococcus garviae 32%, Streptococcus difficilis 7% for method 2. The results of culture-independent method using DGGE patterns and sequencing of DNA bands revealed a higher number of lactic acid bacteria species even if the identification of several lactic acid bacteria species were not possible by traditional microbiological procedures. LAB were Lactobacillus delbrueckii subsp bulgaricus, Lactobacillus helveticus, Leuconostoc lactis, Lactococcus raffi nolactis. Microflora was influence by salt percentage and more by the method of fermentation used. The molecular method DGGE which used three primers Lac1, Lac2GC and Lac3 to study LAB biodiversity directly in the fermented fish matrix, have allowed us to get a more complete picture of the dominant lactic acid bacteria diversity in these fermented product Adjuevan.

Les graves risques que l'ochratoxine A (OTA) engendre sur la santé des consommateurs, ont conduit les instances sanitaires de l'Union Européenne à établir des normes qui définissent les limites maximales tolérables dans plusieurs denrées agricoles et dans le café en particulier. Avec le nouveau règlement européen 178/2002 imposant la détermination d'origine géographique dans le processus de traçabilité des produits alimentaires au cours des transactions commerciales, les normes se durcissent. Dans la pratique, il est difficile de déterminer avec exactitude l'origine géographique des produits alimentaires. Le présent travail a eu pour objectif de déterminer les teneurs en OTA du café par dosage chromatographique, d'identifier et de mettre en oeuvre une méthode utilisant la PCR-DGGE pour analyser la totalité des flores fongiques présentes sur les échantillons de café et de déterminer l'origine géographique de ce dernier. 104 échantillons de café ont été collectés dans la région de l'Ouest (Bafoussam, Dschang, Bafang et Santchou) et dans la plaine côtière (Melong) du Cameroun durant deux campagnes caféières: 2009 et 2010. Deux traitements ont été évalués (voie sèche et voie humide) à trois étapes différentes du procédé de transformation (café en parche, en coque et café vert). La caractérisation du profil fongique des échantillons de café, s'est faite par les techniques microbiologiques classiques et par PCR-séquençage, les niveaux d'OTA ont été évalués par HPLC après extraction et filtration dans une colonne d'immunoaffinité. Les résultats obtenus ont indiqué un pourcentage de contamination fongique totale compris entre 60-92% en 2009 et 70-90% en 2010; la mycoflore toxinogène associée aux grains de café contaminés par l'OTA est constituée majoritairement d'A. carbonarius et d'A. niger. Le stade de prélèvement a eu une influence significative sur la teneur en OTA du café, et le site n'a eu aucune influence sur celle-ci. Exception faite des échantillons de cafés issus du traitement par voie humide du début de la campagne caféière 2009 (124,1 ?g/Kg et 46,81 ?g/Kg), les analyses réalisées sur les échantillons de café montrent que de façon globale, les grains de café provenant des deux campagnes caféières ont des faibles teneurs en OTA (0,1 - 5,11 ?g/Kg). Dans la présente étude, la technique moléculaire employant l'ADNr 28S en PCR-DGGE a été utilisée afin de détecter la variation des structures de la communauté fongique du café des cinq localités soumises à cette étude. Cette technique a permis de mettre en évidence un plus grand nombre d'espèces fongiques comparé à la méthode culturale classique. De plus, la PCR-DGGE a révélé que chaque site a un profil fongique qui lui est caractéristique, et malgré le fait que le type de traitement influence sur la population fongique, il y a eu des bandes communes aux échantillons de café provenant de tous les sites, ceux-ci peuvent constituer des marqueurs biologiques potentiels pour assurer la traçabilité du café de ces régions. La PCR-DGGE ayant l'avantage d'être plus rapide (24h) que l'ensemble des techniques utilisées en microbiologie classique, permet d'éviter l'analyse précise des champignons par biochimie ou en biologie moléculaire (séquençage). Elle peut donc être proposée comme un outil de traçabilité analytique rapide pour le café camerounais.

International trade intensifies the process of globalization which has extended to the entire planet and extends to the entire planet. In view of the difficulties of installing these documentary systems in developing countries, in particularly the countries of sub-Saharan Africa, the new strategies of traceability emerge. Among the new tools of tracing the products of vegetable origin, a "biological code bar" based on the analysis of the DNA of micro-organisms present on the fruits is an interesting tool. A molecular technique employing 26S rDNA profiles generated by PCR-DGGE was used to detect the variation in yeast community structures of Shea tree fruits (Vitellaria paradoxa) from Senegal, Ghana and Mali. When the 26S rDNA profiles were analyzed by image analysis and multivariate analysis, distinct microbial communities were detected on Shea tree fruits. The band profiles of yeasts from different countries were specific for each location and could be used as a bar code to discriminate the origin of the fruits. This method is a new traceability tool which provides fruit products with an unique biological bar code and makes it possible to trace back the fruits to their original location.

In this article we give the results of definition of ability of lactic acid bacteria to interact with ions of heavy metals. We developed method of lactic acid bacteria's ability definition to adsorb lead and cadmium ions on qualitative reaction. 3 cultures of 6 observable strains of lactic acid bacteria isolated from camel milk and shubat have showed this ability. The developer was the mixture of concentrated HCl with saturated solution of Na2S.

E-mail peyron@univ-montp2.fr; International audience; A rapid, easy to handle and low cost assay of ascorbic acid was developed, which consists in miniaturization on microplate of a redox reaction monitored spectrophoto metrically, the signal being directly related to the concentration of ascorbic acid in the sample. This method was investigated in accordance with the prerogative of regulation covering food additives in terms of linear range/linearity, limits of detection and quantification, accuracy (including trueness and precision), robustness and selectivity. The application of the method was tested to determine ascorbic acid diffusivity in agar gel used as an aqueous food simulant. The diffusivity value obtained was 0.31 x 10(-9) m(2) s(-1), with a confidence interval of 20% at 95% level. Accuracy of the assay and of the point's location on ascorbic acid profiles were examined by Monte-Carlo method to assess their influence on accuracy of diffusivity value obtained. Assay uncertainty was clearly demonstrated to be a critical parameter

The titration of cholesterol is a difficult matter due to the large number of stages involved in the standardized method: extraction of the fat, then the unsaponifiable fraction, and sterol separation using TLC and gas chromatography analysis. The diversity of the products to be analyzed (milks, creams, butter and margarines, powders, etc.) also complicates fat extraction. Titration is however necessary due to the considerable role attributed to cholesterol. The rapid method developed is based on placing the sample in solution or direct suspension in DMF, without prior fat extraction. The protocol then includes extraction of the unsaponifiable fraction, sterol silylation using a micromethod and gas chromatography analysis. The method was successfully applied to cholesterol titration in dairy products and in the routine analysis of oil/water as well as water/oil type emulsions, irrespectively of product consistency. Eine Schnellmethode zur Cholesterin-Titration in komplexen Medien Die Cholesterin-Titration ist schwierig aufgrund der grosen Anzahl von Stufen, die die Standardmethode umfast: Fettextraktion, Extraktion der unverseifbaren Fraktion, Sterin-Trennung unter Anwendung von TLC und Gaschromatographie. Die Verschiedenheit der zu analysierenden Produkte (Milch, Creme, Butter und Margarine, Mehle usw.) erschwert auserdem die Fettextraktion. Die Titration ist aufgrund der beachtenswerten Rolle, die dem Cholesterin zugeschrieben wird, notwendig. Die entwickelte Schnellmethode basiert auf der Einbringung der Probe in Losung oder direkte Suspension in DMF, ohne vorherige Fettextraktion. Die Vorgehensweise umfast dann die Extraktion der unverseifbaren Fraktion, die Sterinsilylierung unter Verwendung einer Mikromethode und die gaschromatographische Analysen. Die Methode wurde bei der Titration von Milchprodukten und bei Routineanalysen von Ol/Wasser- sowie von Wasser/Ol-Emulsionen, unabhangig von der Produktkonsistenz, erfolgreich angewandt.

International audience; Volatile compounds of cooked rice from scented (Aychade, Fidji) and nonscented (Ruille) cultivars grown in the Camargue area in France were compared to that of a marketed Asian scented one (Thai) by gas chromatography−olfactometry (GC−O) and gas chromatography−mass spectrometry (GC−MS). GC−O analyses of the organic extracts resulted in the perception of 40 odorous compounds. Only two compounds, oct-1-en-3-one and 2-acetyl-1-pyrroline, were almost always perceived. Hierarchical cluster analysis showed that most of the difference between rice odors was linked to quantitative differences with only 11 compounds being specific to some of the rice. Sixty compounds were identified and quantified by GC−MS, including a few new odor-active components. Principal component analysis enabled us to differentiate scented cultivars from a nonscented one, and scented rice cultivars from Camargue from a Thai sample. Calculated odor-active values evidenced that the Thai sample odor differed from that of scented Camargue cultivars because of the degradation of lipids and of cinnamic acid compounds.

The objective of this work was to compare the effectiveness of three chemical families, namely, chlorogenic acids, fatty acids, and elements, for the discrimination of Arabica varieties (traditional versus modern introgressed lines) and potential terroirs within a given coffee-growing area. The experimental design included three Colombian locations in full combination with five (one traditional and four introgressed) Arabica varieties and two field replications. Chlorogenic acids, fatty acids, and elements were analyzed in coffee bean samples by HPLC, GC, and ICP-AES, respectively. Principal component analysis and discriminant analysis were carried out to compare the three methods. Although elements provided an excellent classification of the three locations studied, this chemical class was useless for Arabica variety discrimination. Chlorogenic acids gave satisfactory results, but fatty acids clearly offered the best results for the determination of both varieties and environments, with very high percentages of correct classification (79 and 90%, respectively).

La détermination de l'origine géographique est une des exigences de la traçabilité des produits alimentaires. Notre hypothèse était que l'environnement de l'aliment pouvait avoir une influence sur la diversité des flores bactériennes commensales des poissons. L'origine géographique des poissons a donc été approchée par la caractérisation de la flore microbienne spécifique de la ferme de production ou du lieu de transformation et de stockage. Une technique de biologie moléculaire couplée à une analyse d'images et à des méthodes statistiques a été développée afin de relier les profils bactériens obtenus par PCR-DGGE à l'origine géographique des fermes aquacoles. Dans la première partie, nous avons différencié par DGGE des poissons d'espèces différentes qui venaient de sites différents: les bars de France, les poissons-chats Pangasius du Vietnam et du Cambodge. Les profils DGGE microbiens des poissons et de l'eau d'un même étang sont étroitement similaires, confirmant notre hypothèse de départ. Le séquençage des bandes issues de la DGGE a permis d'identifier les souches bactériennes dominantes des poissons-chats au Vietnam. Dans la deuxième partie, nous avons confirmé la pérennité des profils microbiens au cours de la saison des pluies et de la saison sèche au Vietnam. Les poissons péchés en mer ont un profil bactérien variable alors que la même espèce élevée en aquarium obtient un profil similaire pour tous les poissons. Les traitements de transformation tels que le séchage et le marinage ont une forte influence sur la communauté bactérienne des poissons. La congélation ou la réfrigération ne modifient pas fortement les profils DGGE. La persistance des marqueurs bactériens au cours des traitements technologiques a été vérifiée au niveau industriel dans une usine de transformation en filets des poissons-chats Pangasius qui sont les principaux produits exportés du Vietnam. L'écologie bactérienne des poissons a été suivie par PCRDGGE à chaque étape de leur transformation montrant que le profil bactérien entre le produit initial et le produit fini est différent mais conserve suffisamment d'information pour discriminer l'origine. Dans la dernière partie, nous avons eu recours à la Rep-PCR pour étudier la diversité des souches de Pseudomonas qui ont montré une persistance aux procédures de transformation. Les Pseudomonas restent présents sur des filets finis ainsi que sur la surface des équipements après le nettoyage et la désinfection. 27 souches de Pseudomonas ont été classées dans 7 grandes groupes par rep-PCR et identifiées par séquençage.

introduction. La consommation des agrumes et de leur jus s'est fortement développée pendant ces dernières décennies. Cependant, à l'heure actuelle, la traçabilité de cette filière est uniquement documentaire. En cas de doute ou de fraude, aucune analyse normalisée ne permet de discriminer ou de déterminer l'origine géographique de la culture du fruit. Matériel et méthodes. Une méthode d'écologie bactérienne, la PCR-DGGE, a été utilisée pour caractériser la flore bactérienne des clémentines importées en France d'Espagne et du Maroc afin de montrer qu'il existe une relation entre les communautés bactériennes des fruits et leurs origines géographiques. Le principe repose sur la détermination de marqueurs biologiques spécifiques d'une localisation donnée. Les protocoles d'extraction et d'amplification des ADN microbiens ont été optimisés. Résultats. Le profil de DGGE étudié par une analyse multivariée a permis de déterminer les profils microbiens spécifiques des différentes régions étudiées. Conclusion. Nous proposons d'utiliser la méthode de la PCR-DGGE comme un nouvel outil de traçabilité qui fournirait un code barres unique aux produits issus d'agrumes et permettrait de relier les agrumes à leur zone de culture originale.

Mango fruit ( Mangifera indica L.), cv. ‘Cogshall’, ‘Kent’ and ‘Keitt’ were harvested at different maturities (61–115 d past flowering and 80–307 average g fresh weight for ‘Cogshall’) and at different sizes (364–1563 and 276–894 average g fresh weight for ‘Keitt’ and ‘Kent’, respectively). Immediately after harvest (green) or after 1 week of ripening at room temperature (ripe), fruit were homogenized or left intact and evaluated by electronic nose (enose) or by gas chromatography (GC) for aroma and other volatiles as well as for soluble solids and acids. Volatile data from the different harvest maturities and ripening stages were discriminated by using multivariate statistics (discriminant factor analysis). Both the enose and GC were able, in most cases, to separate fruit from different harvest maturities, especially for ‘Cogshall’ mangoes, at both the green and ripe stages as well as discriminate green from ripe fruit and fruit from the different varieties within a maturity stage. Solids and acids data indicated that later harvest maturities resulted in sweeter fruit and later-harvested fruit had a different volatile profile from earlier-harvested fruit. Mango fruit volatiles may be useful as maturity markers to determine optimal harvest maturity for mango fruit that results in full quality upon ripening.

Oxidative degradation of lipids leads to quality deterioration of foods and cosmetics and has received increasing attention as a causative or associative factor in a variety of pathological conditions. A current very promising way to counteract lipid oxidation is to use vegetable antioxidants for nutritional, therapeutic or food quality preservation purpose. A major challenge is to develop analytical tools to assess the real antioxidant power of these molecules. In this way, many in vitro tests are now available, which monitor generally the inhibitory effect of antioxidant on the oxidative degradation of lipid or lipid-like substrate under natural or artificial oxidizing conditions. Overall, this measurement necessitates focusing either on the oxidizable substrate loss, or on the formation of oxidation products. To perform the first strategy, fluorophores such as cis-parinaric acid, BODIPY, and phospholipidic derivatives of fluorescein are often used, whereas the second employs usually linoleic acid, its methyl ester or natural lipids. After a brief recall of antioxidation mechanisms, this review presents a panorama of the available in vitro methodologies and of the last advances in this field. A comparative study between methods will be also discussed in terms of advantages and drawbacks.

The discrimination of scented rice is a major stake for the producers. There is however not any fast and reliable method for discriminating scented from non scented rice. In this perspective, we have developed tools based on the multivariate discriminated analysis of the spectral data obtained by Near InfraRed Spectroscopy (NIRS) or Mass Spectrometry (MS). Spectral data of whole rice grains were registered between 800 and 2500 nm. A set of 117 samples including 65 scented and 52 non scented rice was analysed. A model set comprising 90% of these samples was used to develop the discrimination model using the SIMCA procedure. The validation set was then predicted with the model with a success rate of 84%. Rice volatile compounds were extracted by SPME and directly injected in MS apparatus to obtain a mass spectral fingerprint of the volatile fraction. A set of 114 samples including 57 scented and 57 non scented samples was analyzed. A discrimination model was developed using SIMCA procedure on a model set of 102 samples. The validation set (12 samples) was predicted with the model with a success rate of 91,6%. The discriminated model was proved to be linked to some specific mass fragments resulting from 2-acetyl-1-pyrroline, the main aroma compound of scented rice. Both methods proved their ability to rapidly discriminate scented rice and practical automated procedures are under development.

The use of amylolytic lactic acid bacteria (ALAB) in new methods to prepare high energy density complementary foods for young children was investigated. Using gelatinised slurry, composed of a mixture of rice with soybean, fermentation kinetics by the ALAB Lactobacillus plantarum A6, and chemical and theological changes were studied at different dry matter (DM) contents. At high DM content (23%), it was possible to obtain a semi-liquid fermented gruel presenting the necessary characteristics to fulfil the energy requirement of young children. Furthermore, combination with spray-drying, as a post-treatment after fermentation by strain A6, had the additional advantage of enabling the use of spray-dried fermented flour to prepare gruels with higher DM content (30-33%) corresponding to 128-140 kcal/100 g of gruel. (c) 2005 Elsevier Ltd. All rights reserved.

This poster presents an innovative method for determining coconut (Cocos nucifera) fruit quality. Several tools were used to assess the coconut fruit quality of two cultivars - PB121 or MYD × WAT from Côte d'Ivoire and VRD × VTT from Vanuatu - at different ripening stages. Chemical analyses were performed using classical and innovative methods. Total soluble sugar and lipid concentrations of the freeze-dried kernel were measured using high performance liquid chromatography (HPLC), accelerated solvent extraction (ASE®) and near infrared spectroscopy (NIRS). These new innovative methods were able to keep the cost of the study down by 70%, while the volume of solvent (petroleum ether) used was reduced by more than 90%. The poster also presents CIRAD's proposals to improve the quality of the traditional aqueous coconut oil extraction process. Part of this proposal was developed in the period 2001-03 (with French Development Agency (AFD) funding) after an analysis of the small-scale coconut processing sector in Ghana. Local traditional processes were characterised within their socioeconomic context, and their environmental impact was assessed. CIRAD experts made several proposals to improve both the productivity and working conditions of processors. The suggested improvements, including graters, presses and furnaces, were all suitable for the small-scale processing procedure and were easy to handle and did not change the characteristics of the final product as assessed by the market. A small effluent treatment unit was also designed to reduce pollution. (Texte intégral)

The purpose of our work was to examine the impact of four wet processing methods on the quality of roasted coffee, with three degrees of roasting. The volatile fraction of the coffees was analysed by combining Headspace-SPME (HS-SPME), GC-olfactometry (GC-O) and mass spectrometry (GC-MS). Post-harvest processing has a major impact on the aroma quality of the roasted coffees produced by those processes. This was more or less acknowledged for differentiating between the dry and wet methods. Our work has shown that modifications to the wet method also lead to aromatic differences in roasted coffees. Coffee produced by the traditional wet method was of better aromatic quality than coffee produced by the mechanical method recently introduced because it uses less water and is more ecological. Indeed, this last aspect resulted in coffees with more aroma defects. The fact of carrying out microbial mucilage removal in water or under dry conditions also led to differences between the coffees. Mucilage removal in water gave coffees with more particular fruity, floral and caramel attributes, whereas dry mucilage removal gave more neutral coffees. When the latter process was also combined with dry pulping, sourness defects occurred with light roasting and those coffees developed bitterness and harshness with darker roasting. Light roasting made it possible to more effectively distinguish between treatments based on aroma criteria associated with the volatile compounds produced during post-harvest processing. Dark roasting also enabled a distinction to be made, but based on aromatic criteria linked to the thermal reactions of roasting. Medium roasting enabled the least distinction to be made between treatments, undoubtedly because a higher degree of roasting cancelled out the olfactory differences detected with light roasting, which were associated with highly volatile compounds, such as esters, and because that degree of roasting was not yet high enough to give aroma and sensory differences associated with roasting. The next stage in this work will be to analyse volatile compounds of green coffee produced during post-harvest processing, along with chemical compounds that are precursors of the thermal aroma that develops during roasting, and which also play a role in the taste of roasted coffee, in order to gain a clearer understanding of the differences seen in our work on roasted coffee.

Mycotoxin contamination of food and feedstuffs is among the top priorities for human and animal safety. The currently used techniques for mycotoxin determination, either chromatography or ELISA, are unsuitable for routine in-field assessment. There is an urgent need for other accurate, simple and cost-effective techniques that can be used as a screening tool for a rapid estimation of mycotoxin contamination in commodity lots. This paper reviews the literature on the use of chemiluminescence (CL) and bioluminescence (BL) assays for direct or indirect mycotoxin assessment. The chemiluminescence immunoassays, adenosine triphosphate (ATP) bioluminescence and bioassays are reviewed and their advantages and limitations discussed. These techniques used in food testing and the pharmaceutical industry offer promise as rapid techniques for mycotoxin determination. Chemiluminescence and bioluminescence bioassays are the most innovative alternatives to the conventional techniques used for mycotoxin determination in food and feed. Copyright © 2004 John Wiley & Sons, Ltd.

Semi-quantitative methods based on Solid Phase Micro Extraction/Mass Spectroscopy (SPME/MS) and Near Infrared Spectrometry (NIRS) were used to evaluate the aroma of the grain of 53 samples including 48 samples of aromatic rices (Nang Thom Cho Dao and OM3536) collected in Viet Nam and 5 samples of non-aromatic rices from France. Results show that both methods allow to distinguish aromatic varieties from non aromatic ones. Furthermore, analysis with SPME/MS allows as well to discriminate the 2 aromatic varieties used in this work. Further works are needed to improve the methods.

Ce rapport expose le cheminement de l'étude nécessaire pour concrétiser les deux objectifs formulés en début de stage: 1- Mettre au point une méthode instrumentale rapide, pour permettre l'analyse en routine d'un grand nombre d'échantillons; 2- Mettre au point une méthode instrumentale globale, qui s'adresse à la fraction aromatique totale et non plus seulement au 2-AcPy. (Extrait de la conclusion de l'auteur)

International audience; A near-field acoustic (NFA) method was applied to characterize viscoelastic properties of mango pulp tissue. The developed sensor was a stepped horn consisting of a cylindrical body and a coupled cylindrical tip to be inserted into the pulp sample. The properties of the pulp altered the mechanical resonance of the horn and the electrical resonance of the piezoelectric element, which served as both input and output port. The measured acoustic parameters represented the shift of the resonance frequency (Δf) and the attenuation of the peak amplitude (Δ(l/Z)) of the probe when its vibrating tip was immersed in air, the reference medium, and then inserted into the pulp sample. Acoustic testing was carried out on each fruit at four locations evenly distributed in the middle parenchyma tissue of an equatorial section. The acoustic data were then compared to the 10 mm depth penetration force values obtained for the same four pulp locations. The results obtained for 45 mangoes with a wide range of maturity showed that Δf was very sensitive to the quality of the probe-medium interface, especially for unripe fruit, and poorly correlated with puncture test values. In contrast, the acoustic parameter Δ(l/Z) was significantly correlated with mango pulp firmness Fp (r = 0.92) assessed by puncture test. The relationship between these two parameters was slightly improved by a hyperbolic equation (r = 0.95). The NFA method developed appears to be a promising tool for assessing mango pulp texture and for following texture changes during fruit ripening.

L'étude porte sur le développement d'un test de mesure de dureté du mais frit équatorien. Un test au grain par grain est considéré et des mesures en compression-cisaillement de la force maximale (à la rupture) et du travail sont effectuées au TAXT2: parmi 4 dispositifs (couteau Craft, couteau en plexiglas, poinçons, cellule de Voldokevitch), le couteau Craft est retenu. Le grain est positionné germe en dessous et la mesure s'effectue dans le sens de la largeur à une vitesse de 1 mm/s, une pénétration dans le grain de 4 mm. 40 mesures sont nécessaires pour obtenir une précision de 85% avec le couteau. Les caractéristiques physiques des grains (largeur, épaisseur, masse) ne montrent pas d'influence sur la dureté pour le dispositif utilisé. La reproductibilité du test et sa répétitivité, sont vérifiées. Un panel de 12 personnes évalue la qualité des échantillons de mais frit provenant de variétés sélectionnées par l'INIAP et des échantillons commerciaux. Les variétés proposées par l'INIAP, après friture, s'avèrent beaucoup plus dures que les échantillons commerciaux. Des corrélations linéaires sont obtenues entre la dureté à l'analyse sensorielle et instrumentale (R2 = 0,8 pour 27 échantillons), elles démontrent que le test instrumental est fiable pour remplacer le panel sur le critère de dureté, et que les critères farineux et croquant ne sont pas pris en compte.

Caffeine and theobromine are involved in cocoa flavour development. Measurement of their contents is still used to determine the cocoa content of chocolate. It also seems to be accepted that the contents of these two compounds are linked to genetic and geographical origin. This study, which was conducted on cocoa varieties of different geographical origins, showed that near infrared spectroscopy can be a rapid and non-destructive alternative for determining these compounds.

Shubat and Koumiss are traditional fermented products widely consumed in Kazakhstan and Central Asia. Microflora of those fermented products is composed of bacteria and yeasts, which could have deep impacts on beverages quality. Although, the known presence of yeast in such fermented foods, few studies on yeast microflora of Shubat and Koumiss were available. The aim of the study was to identify the main indigenous yeasts in these traditional beverages and additionally, the differences between these 2 types of fermented products. Five samples of fresh and fermented camel and mare's milk from tank were collected in 5 different farms, located in South of Kazakhstan. Farms were selected because of their importance of production of fermented milk at the regional level and the reputation of these products among the consumers. Yeast biodiversity in Shubat and Koumiss was studied using denaturing gradient gel electrophoresis (DGGE). Target DNA bands were identified according to the reference species ladder, constructed in this study. Co-migrating bands present in the DGGE profiles were resolved by species-specific PCR. Galactomyces geotrichum, Kluyveromyces marxianus, Kazachstania unispora, Saccharomyces cerevisiae, Dekkera anomala, Dekkera bruxellensis yeast were identified. Some yeasts were not identified by used primers. In all samples of Shubat and Koumiss the dominant yeast species were Kazakhstania unispora, Kluyveromyces marxianu. Other species were not present in all samples.

Ce stage consistait à réaliser des analyses diverses et variées sur des prélèvements de fraisiers, bananes, palme et marinade de sprat. Les méthodes et matériels utilisés pour la préparation des échantillons en vue d'un dosage des sucres et de l'amidon ont été la méthode "classique" et l'utilisation de l'ASE 200. Concernant l'analyse des échantillons et le dosage des sucres, ces analyses ont été menées avec utilisation de la chromatographie ionique et l'indice de Brix a été mesuré. Les autres types d'analyses ont consisté en la détermination de la teneur en eau, de l'acidité titrable, de l'indice de peroxyde, de l'acidité dans les corps gras d'origine animale ou végétale

An analytical procedure was developed for regiodistribution analysis of TAG using [alpha]-MAG prepared by an ethyl magnesium bromide deacylation. In the present communication, the deacylation procedure is shown to lead to representative [alpha]-MAG, allowing the composition of the native TAG in the a-position to be determined directly. The composition in the [bêta]-position can then be estimated from the composition of the [alpha]-MAG and TAG according to the formula 3 x TAG - 2 x [alpha]-MAG. The estimates are superior to those obtained using the [alpha],[bêta]-DAG and Brockerhoff calculations as they come closer to the theoretical value and have smaller SID. The present procedure, first demonstrated on a synthetic TAG, was then successfully applied to the analysis of borage oil, milkfat, and tuna oil.

Classically enzymatic hydrolysis of starch is conducted in batch reactor in a two-step process including liquefaction and saccharification. This paper presents some ideas to simplify this process and decrease its cost. Because today, either saccharifying enzymes able to attack native starch or strong liquefying catalysts leading to sufficient low-molecular weight hydrolysates may be easily found on the market, one can imagine to develop a one-step process just involving a unique species of enzymes. The process can also be improved by operating in a continuous way and reusing enzymes. Among the various reactors, the continuous recycle membrane reactor, briefly CRMR, seems to be the most attractive since it allows to perform hydrolysis while separating at the same time syrups from enzymes and non-hydrolyzed starch.

Detailed field surveys in Botswana and Tanzania on food habits and on consumer preferences were conducted by various project partners including CIRAD. The recipes for the preparation of traditional porridges made with sorghum and millets, the cooking procedures and the characteristics of commercial and traditional flours were collected by the CIRAD Cereal Technology Laboratory in order to develop specific laboratory tests to characterize the cooking quality of the thick porridge " bogobe " in Botswana and " ugali " in Tanzania. The texture defined as the consistency of the cooked product was identified as the main quality criteria for the african consumers and was measured using extrusion tests on the Instron Universal Texturometer. The relationships with some physicochemical characteristics of sorghum grains and flours were established showing the importance of the amylose content of the flour and to a lesser extent of the ash content of the grain. The differentiation among the sorghum varieties and their ranking according to the extrusion test were confirmed by another field survey in Botswana where cooking tests and texture evaluation by villagers were conducted. This laboratory test was applied on 31 sorghum varieties from Botswana and ICRISAT, Zimbabwe. Sorghum cultivars with high amylose content and good dehulling properties should be selected. The tests should also be useful in evaluating and therefore improving the quality of the sorghum flours obtained on mechanical dehulling and grinding equipment. It will help promoting commercially the milled products in towns and the industry. It was shown also that the ranking of the sorghum varieties according to their quality for bogobe and ugali was similar to the ranking obtained using a compression test already developed on " tô " quality, a west african soft porridge. It was concluded that the SADC variettes good for bogobe and ugali could also be good for thick " tô ".

On décrit d'abord les méthodes générales qui s'appliquent à divers produits comme : la détermination de l'humidité, la détermination de la teneur en matière grasse (le beurrage), la détermination de la finesse de broyage, la mesure du pH, la détermination des cendres totales, solubles dans l'eau et insolubles dans l'acide chlorhydrique et de leur alcalinité (sauf pour les insolubles dans l'acide), la détermination de l'azote total (protéines) dans le cacao et les produits de chocolat, puis les méthodes de contrôle qualité comme la préparation des échantillons, la détermination du niveau de fermentation, l'analyse des composés volatils et non volatils du cacao. On traite ensuite des méthodes plus spécifiques pour les fèves, la masse et la poudre, les chocolats et les matières grasses telles que la mesure de la dureté du beurre de cacao et la viscosité du chocolat. On trouve les méthodes de routine, les méthodes rapides et les méthodes officielles de l'OICCC, AOCS, IUPAC et AOAC