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Macadamia nuts (Macadamia integrifolia) grown in Venezuela have showed an average total fat content of 70%. Oleic acid (18:1) was the main monounsaturated fatty acid (MUFA) (51.3%), followed by palmitoleic acid (16:1, 22.6%). The content of polyunsaturated fatty acids (PUFAs), C18:2 and C18:3 represented 5.4%. Thus, MUFAs and PUFAs together constituted more than 80% of the total fatty acids present. Trans-vaccenic acid was also present (3%). As regards to other phytochemical compounds, tocopherols and tocotrienols were not found in the sample, but the presence of squalene was detected. The antioxidant activity (44.2%) of the extract was produced by the phytochemicals present.

Studies were carried out on P. butyracea kernels to determine their nutritional and antinutritional composition. The kernels contained 41.9% of butter. The physicochemical properties of the butter are as follows: saponification value, 192.5 mg KOH/g of oil; refractive index (20°C), 1.462; unsaponifiable matter, 1.8%; acidity, 0.41%; peroxide value, 17.3 meq O2/kg of butter. The butter contains high levels of oleic acid (47.3%) and stearic acid (47.2). The composition of triacylglycerols (TAGs) was characterized by two components SOO and SOS. The DSC melting curves of butter revealed two melting points of 20.4°C and 39.3°C and melting enthalpy values of 30.6 J/g and 78.2 J/g. Stigmasterol (56.3%) and campesterol (27.6%) were the abundant sterols. Protein content (7.3 % dry weight) was recorded in the kernel containing eighteen amino acids in varying proportions. Three sugars (glucose, fructose, sucrose) were identified. An ash content of (4.1% dry weight) was contained calcium, magnesium potassium, nitrogen and phosphorus. The result of the anti-nutritional factors showed that levels of phytate (0.42%), total phenol (0.14%) and oxalate (1.06%).

Some lipases preserve good activity in organic solvent and their ability to catalyze transesterification reactions in organic media is known and well documented. However, most organic solvents can be environmentally damaging or toxic. Therefore, in a context of green chemistry a number of studies have attempted to resolve this dramatic environmental impact and try to realize lipase–catalyze reaction in green solvent. Ionic liquids were the first potentially alternatives to organic solvents for biotransformation; they are non volatile, thermally stable and have high solvation properties. Nevertheless, the limitations of ionic liquids are their cost, toxicity and the need for high purity. Deep eutectic solvents (DESs) are a new class of solvent typically formed by mixing an ammonium salt and a hydrogen–ond donor. Like ionic liquids, DESs often have melting points close to room temperature, low volatility and high thermal stability. Unlike them, they are biodegradable, cheap and very easy to prepare. In this context, it will be very interesting to develop lipase–compatible DES from inexpensive and biodegradable cholinium salt. Therefore, in order to know the potential of DESs to be friendly–media for lipase–catalyzed reaction we investigated iCALB compatibility in eutectic solvents with a focus of the activity, selectivity and stability after long incubation–time.

The shea tree Vitellaria paradoxa L. is the most prevalent tree crops in northern Ghana with the shea butter fat as the most important product from the tree. Difference in the shea butter fat quality is mainly attributed to bioclimatic variations in temperature and rainfall. The purpose of this study was to apply near infrared, wet chemistry and gas chromatography to characterize the fat and free fatty acid profiles of shea butter fat from three locations (Paga, Nyankpala and Kawampe) in Ghana. The shea nuts from the tree locations in Ghana conformed to the West Africa shea nuts on the global data base on shea nuts compiled at CIRAD. Samples from Paga recorded the highest moisture content ranging between 5.63 % and 12.04 % (dry matter) with a mean content of 6.83 % and a standard deviation of 1.30 % whilst from Kawampe recorded the lowest moisture content with a mean of 5.23 %. Samples from Kawampe recorded the highest fat content ranging from 47.07 % to 57.39 % (dry matter) with a mean content of 52.69 % and a standard deviation of 2.55 % with samples from Paga recording the lowest fat content with a mean of 48.84 %. Stearic acid content of the samples was higher than oleic acid content from the three locations with virtually the same ratio of saturated and unsaturated fatty acids. Correlation between wet chemistry values and near infrared spectroscopy (NIRS) predicted values for moisture content (calibration set) with regression of 0.974 indicating the ability of NIRS to differentiate between nuts from different regions. The nature of the dried shea nuts before processing affected the quality of the shea butter fat as moulded samples recorded higher free fatty acids reducing the quality of the shea butter fat. Fatty acid methyl esters (FAME) analyses indicated that the samples from the three locations in Ghana were mostly saturated with stearic and oleic acids and less of palmitic, vaccenic, linoleic and arachidic acids in the fatty acid profiles of shea butter fats.

Pentadesma butter is still traditionally extracted starting from pretreated almonds by traditional techniques of heating. The aim of this work was to study the effect of the almonds post-harvest pretreatments on the physicochemical characteristics, the extraction yield and the quality of the Pentadesma butter. In addition, the effect of the various unit operations of the extraction technology on the quality of the extracted butter from pretreated almonds was studied. According to the same traditional process of extraction, two various butters of Pentadesma were extracted starting from almonds differing only by the post-harvest pretreatment applied (roasting or boiling). The color, the aspect and the breaking strength of the almonds were different. The butter extraction yield varied according to the pretreatment applied. The best yields (33.5 _ 4.1%) were obtained from boiled almonds, but their transformation was more difficult than that of roasted. The analysis of the samples at different stages of the transformation allowed the appreciation of the effect of the almonds pretreatments on the acidity and the peroxide value variations at each unit operation of the butter extraction. The fatty acid composition and the tocopherol content of the two extracted butters varied with the almonds pretreatments. The roasted almonds provided a richer butter in stearic acid, a and d-tocopherols and less rich in oleic acid than that provided by the boiled almonds. The pretreatments allowed a total loss of the contained linolenic acid, b and dtocopherols in the butters and decreased the oleic acid and a- tocopherol contents. The physico-chemical characteristics of the Pentadesma butter varied according to the almonds pretreatments. Thus, it would be interesting to make a reasoned choice of the most suitable post-harvest pretreatment in order to obtain a butter with a good quality and an acceptable extraction yield.

The characterisation of the studied Columbian red palm oil (fatty acid composition, regiodistribution, solid content...) makes it a potential oil of speciality which may be passed for the tropical equivalent of olive oil.

La noix du Brésil, Bertholletia excelsa, a une teneur importante en biomolécules que nous avons dosées finement. Son huile, ses protéines et ses minéraux ont été analysés en détail. La composition en acides gras, stérols, tocophérols, phospholipides de l'huile est précisée. Le tourteau résultant de l'extraction de l'huile est particulièrement riche en sélénium (126 ppm) qui est connu pour ses capacités anti-oxydantes et anti-radicalaires. Le facteur de conversion azote/protéine a été recalculé à 6,97, en tenant compte de la composition en acides aminés des protéines. La teneur élevée en sélénium de la noix du Brésil et de ses dérivés fait de ces produits une base pour la création d'aliments à propriétés anti-radicalaires.

Enzymes are used more and more in various applications of different fields such as pharmaceutical, cosmetic or food industry. In the past years, a better understanding of enzymes functionalities and catalytic behaviors, together with the progress of molecular engineering has lead to new applications for various types of enzymes. Concerning lipases, they are used in various sectors, as pharmaceutical, food or detergency industry. Their advantages versus classical chemical catalysts is that they exhibit a improved substrate specificity and operate in milder reaction conditions. Moreover, the fact that they retain their activity in organic solvents extends their range of application. In the pharmaceutical industry, lipases can be used for racemic mixtures resolution or as biocatalysts for the synthesis of chiral synthesis intermediates. In the food sector, these enzymes are principally employed in oils and fats restructuration processes allowing the production of specific triacylglycerols with predetermined fatty acids composition and distribution.. Similar processes are also described for the synthesis of partial glycerides or fatty acids concentrates. Besides their application in oils and fats processes, these enzymes have proved to be very attractive for others lipase-catalyzed reactions with unusual substrates. In particular, they appear to be very effective for the synthesis of molecules involving the grafting of a lipophilic moiety or a hydrophilic one. The major example of this capacity is certainly the synthesis of glycolipids derivatives such as sugar esters that can be used as surfactants in the food, pharmaceutical or cosmetic industry. In this presentation, will be described and discussed some of the recent results in the field of the lipase assisted lipophilization of bioactive compounds such as phenolic derivatives in order to modify the hydrophilic/lipophilic properties of the initial molecules to obtain new products with multi-functionnal properties combining for example, microbial, antioxidant and emulsifying properties. More specifically, to illustrate this topic, will be presented in details the enzymatic lipophilization of phenolic acids from green coffee, namely chlorogenic acids, via esterification by fatty alcohols, in order to obtain new antioxidant molecules with improved activity in emulsified systems. (Texte intégral)

The palm tree grove in Elche has a wide genetic variety and as a direct consequence its fruit : the Date. The research set out during the campaign 1994-95 aims to analyze several approaches on the chemical composition of these dates produced by different genotypes among the population (#Phoenix dactylifera# L.), that represent two physiological states found, full-ripening and incomplete-ripening, and to study its evolution within different ripening stages. Several differences in the metabolism of sugars, moisture, total contained of free aminoacids and mineral elements seem to be observed in fruits whose ripening takes place in a natural way in the tree in relation to others whose ripening stops before reaching this stage. Situation caused because Elche is a boundary area of date palm tree growing. This preliminary research, should contribute to lay the foundations in order to set up a wide research of the biochemical and physiological process implied in the ripening of the dates of Elche, being one of the aims having a complete knowledge of the possibilities in artificial ripening.

La mise en cultures de nouvelles terres arables, en zone tropicale humide, se heurte à des contraintes physico-chimiques relatives à la nature des composés argileux d'altération (kaolinite). L'acidité qui en résulte et l'aluminium libéré ont des effets néfastes sur les plantes. L'aluminium est toxique à faible concentration dans la solution du sol, et il est, de plus, difficile à libérer. Deux solutions sont envisagées : la correction de l'acidité par des amendements ou l'adaptation de la plante au caractère acide et alumique des sols. L'adaptabilité du maïs à ces types de sols semble être une solution séduisante d'autant que cette plante, par sa variabilité génétique se prête à l'amélioration variétale. Des tests de culture in vitro dans une solution nutritive équivalente à celle de la solution d'un sol acide tropical sont expérimentés. A partir de sept jours de culture, il est possible de discriminer significativemen t les variétés de maïs tolérantes ou sensibles à la toxicité alumique

L'oxalate (anion organique) joue un rôle important dans les relations sol, racine, micro-organismes. Le but de ce travail est de proposer une méthode d'analyse du dosage de l'oxalate. L'extraction est réalisée par l'acide chlorhydrique normal à chaud avec un volume déterminé d'après la teneur en calcaire de l'échantillon. Une étude théorique préalable réalisée à l'aide du logiciel de calcul GEOCHEM (détermination de la composition à l'équilibre des différents éléments présents dans la solution étudiée), montre que pour solubiliser complètement l'oxalate il faut se trouver en milieu suffisamment acide et libérer par ailleurs l'oxalate de ses complexes avec le fer par réduction de cet élément. En vue du dosage par chromatographie ionique de l'oxalate, la solution ainsi obtenue est purifiée par élimination des cations (résine de type Amberlite IR 77), pour éviter une redistribution des espèces, et des chlorures en excès par l'emploi de colonnes contenant un sel d'argent (On-Guard Ag+ préconisées par Dionex). La méthode d'analyse conduit à un taux de recouvrement de 100% d'oxalate de calcium introduit

Certains critères physiques et physico-chimiques de 21 variétés de dattes cultivées au sud de la Tunisie, dont la Deglet Nour, ont été étudiés. Cela a abouti au classement des cultivars en fonction de critères de qualité spécifiques de l'industrie dattière. Des caractères morphologiques particulièrement intéressants (dimensions des fruits et teneur en pulpe) ont été trouvés pour les variétés Menakher, Boufagous et Trongea. Sept acides aminés sont présents dans la pulpe des dattes à une teneur significative, mais les taux d'acides aminés totaux sont très variables selon les variétés (de 82 à 700 mg/100g de matière sèche). Les variétés qui ont les plus fortes teneurs en acides aminés sont les moins aptes à une bonne conservation. Les fortes teneurs en malate ont été relevées chez les dattes sèches et pourraient expliquer en partie leur faible valeur aromatique

Des analyses de la composition chimique (teneurs en eau, sucres, acides aminés libres et sels minéraux) de 5 cultivars de dattes (Bou Skri, Deglet Nour, Mejhool, Thoory et Zahidi) ont été effectuées à différents stades de la maturation des fruits. Les teneurs en eau et en sucres, notamment en saccharose, sont variables au cours de la maturation et permettent de regrouper les différents cultivars en fonction de la qualité de leurs fruits : cultivars à dattes molles, demi-molles et sèches. Par ailleurs, sur les 18 acides aminés libres analysés, la sérine, l'isoleucine, la leucine, la lysine, la méthionine, la phénylalanine et la valine sont prédominants aux stades verts alors que les acides glutamiques et gamma-aminobu-tyrique et la glycine sont présents à des concentrations plus élevées dans les dattes mûres. L'analyse de la composition en sels minéraux montre une forte teneur en potassium des cendres, et une teneur en calcium variable selon la provenance géographique des fruits. Cependant, la composition en acides aminés libres et en sels minéraux ne représente pas des marqueurs variétaux suffisants pour la caractérisation des différents cultivars. L'analyse de la composition chimique des dattes semble être un outil mieux adapté aux études de la physiologie du fruit, notamment au cours de sa maturation.

Dans un sol ferrallitique du Brésil, le rapport C/N ne différencie pas la matière organique d'un horizon de surface de celle d'un horizon profond. Ce rapport décroît des sables à l'argile, et plus intensément en surface qu'en profondeur. Le rapport des fractions hydrolysables de l'azote organique, Nhnd/Nhd, différencie quant à lui très nettement l'horizon de surface de l'horizon profond et permet d'attribuer aux matières organiques récentes associées à l'horizon de surface, et particulièrement aux fractions granulométriques grossières, une part prédominante dans le compartiment le plus biodégradable des matières organiques azotées. Par le rapport entre fractions hydrolysables de l'azote, on établit que des matériaux de rapport C/N élevé peuvent avoir des degrés d'évolution très différents, comme le montrent les matières organiques associées aux fractions supérieures à 50um des deux horizons d'un sol ferrallitique