Comparison of the effect of various sources of saturated fatty acids on infant follow-on formulas oxidative stability and nutritional profile.

Fortification of infant follow-on formulas (IFF) with docosahexaenoic acid (DHA), which is prone to lipid oxidation, is required by European regulation. This study aimed to identify lipid formulation parameters that improve the nutritional profile and oxidative stability of IFF. Model IFF were formulated using different lipid and emulsifier sources, including refined (POM) or unrefined red palm oil (RPOM), coconut oil (COM), dairy fat (DFOM), soy lecithin, and dairy phospholipids (DPL). After an accelerated storage, RPOM and DFOM with DPL had improved oxidative stability compared to other IFF. Specifically, they had a peroxide value twice lower than POM and 20% less loss of tocopherols for DFOM-DPL. This higher stability was mainly explained by the presence of compounds such as carotenoids in RPOM and sphingomyelin in DFOM-DPL very likely acting synergistically with tocopherols. Incorporation of dairy lipids and carotenoids into DHA-enriched IFF compositions seems promising to enhance their stability and nutritional quality.

Tocopherols as antioxidants in lipid-based systems: The combination of chemical and physicochemical interactions determines their efficiency.

Lipid oxidation is a major concern in the food, cosmetic, and pharmaceutical sectors. The degradation of unsaturated lipids affects the nutritional, physicochemical, and organoleptic properties of products and can lead to off-flavors and to the formation of potentially harmful oxidation compounds. To prevent or slow down lipid oxidation, different antioxidant additives are used alone or in combination to achieve the best possible efficiency with the minimum possible quantities. In manufactured products, that is, heterogeneous systems containing lipids as emulsions or bulk phase, the efficiency of an antioxidant is determined not only by its chemical reactivity, but also by its physical properties and its interaction with other compounds present in the products. The antioxidants most widely used on the industrial scale are probably tocopherols, either as natural extracts or pure synthetic molecules. Considerable research has been conducted on their antioxidant activity, but results regarding their efficiency are contradictory. Here, we review the known mechanisms behind the antioxidant activity of tocopherols and discuss the chemical and physical features that determine their efficacy. We first describe their chemical reactivity linked with the main factors that modulate it between efficient antioxidant capacity and potential prooxidant effects. We then describe their chemical interactions with other molecules (phenolic compounds, metals, vitamin C, carotenes, proteins, and phospholipids) that have potential additive, synergistic, or antagonist effects. Finally, we discuss other physical parameters that influence their activity in complex systems including their specific interactions with surfactants in emulsions and their behavior in the presence of association colloids in bulk oils.

Stability to oxidation and interfacial behavior at the air/water interface of minimally-processed versus processed walnut oil-bodies.

Oil bodies (OB), the form of triacylglycerol storage in seeds, are interesting natural assemblies for nutritional applications. In walnuts, OB contain an important amount of polyunsaturated fatty acids that could be interesting food ingredients but may be prone to oxidation. The oxidative and interfacial behavior of walnut OB, either minimally-processed or after processing, were compared with processed complex walnut juice. The good oxidative stability of minimally-processed OB over 10 days (PV ≤ 8.4 meq O2/kg, TBARS = 1.4 mmol eq MDA/kg) and of processed walnut complex matrixes over 20 days (PV ≤ 4.8 meq O2/kg, TBARS = 1.4 mmol eq MDA/kg) was evidenced. In comparison, processing of OB promoted their oxidation. The interfacial studies led to the proposition of a new model of adsorption for minimally-processed OB that will be useful to design functional emulsion or foam in which OB act as emulsifiers.

Lipophilization and MS characterization of the main anthocyanins purified from hibiscus flowers.

Hibiscus sabdariffa flowers represent an interesting source of anthocyanins, one of the most important plant pigments, which are responsible of the intense red color of the calyces, and have potential as natural colorants for food applications. Nevertheless, anthocyanins are highly hydrosoluble and unstable compounds. On this basis, the aim of this work was to increase the lipophilicity of the hibiscus anthocyanins by lipophilization, in order to obtain amphiphilic colorants, which could be easily incorporated in lipid-rich food matrices. Octanoyl derivatives of delphinidin-3-O-sambubioside and cyanidin-3-O-sambubioside were chemically obtained for the first time, and characterized by means of HPLC-ESI-MS data.

Lipase Activity of Tropical Oilseed Plants for Ethyl Biodiesel Synthesis and Their Typo- and Regioselectivity.

The aim of this work was to investigate lipase activities in crude extracts from Adansonia suarezensis, Adansonia grandidieri, Moringa drouhardii, Moringa oleifera, Jatropha mahafalensis, and Jatropha curcas seeds in ethanolysis and hydrolysis reactions. All crude extracts from germinated seeds showed both ethanolysis and hydrolysis activities. The influence of germination, the delipidation procedure, and the triacylglycerol/ethanol molar ratio on their ethanolysis activity was studied. Crude extracts of Jatropha and Adansonia seeds showed optimal activity at pH 8 with an optimum temperature of 30 and 40 °C, respectively. The study of the regioselectivity of crude extracts from J. mahafalensis and A. grandidieri seeds, which had the most active hydrolysis reaction, showed 1,3 regioselectivity in the hydrolysis reaction of vegetable oils. The crude extract from A. grandidieri seeds showed no typoselectivity, whereas the typoselectivity of the crude extract of J. mahafalensis seeds depended on the type of reaction.

Antioxidant activity of protocatechuates evaluated by DPPH, ORAC, and CAT methods.

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 C1-C18 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.

Bioefficacy of essential and vegetable oils of Zanthoxylum xanthoxyloides seeds against Acanthoscelides obtectus (Say) (Coleoptera: Bruchidae).

Experiments were conducted in the laboratory to evaluate the bioefficacy of essential and vegetable oils of Zanthoxylum xanthoxyloides (Rutaceae) against Acanthoscelides obtectus (Coleoptera: Bruchidae). The chemical composition of the essential oil and the fatty acid composition of the vegetable oil extracted from the seeds of Z. xanthoxyloides were determined. The insecticidal activities of these oils and the associated aromatized clay powder were evaluated against A. obtectus. Both oils were strongly repellent (100% repellency at 0.501 µl/cm² essential oil and 3.144 µl/cm² vegetable oil) and highly toxic (LC50 = 0.118 µl/cm² for essential oil) to this beetle after contact on filter paper. The vapors of the essential oil were highly toxic to adult insects (LC50 = 0.044 µl/cm³), and the aromatized powder made from clay and essential oil was more toxic (LD50 = 0.137 µl/g) than the essential oil alone (LD50 = 0.193 µl/g) after 2 days of exposure on a common bean. Both oils greatly reduced the F1 insect production and bean weight loss and did not adversely affect the bean seed viability. In general, the results obtained indicate that these plant oils can be used for control of A. obtectus in stored beans.

Carica papaya lipase: a naturally immobilized enzyme with interesting biochemical properties.

Triacylglycerol (TAG) lipases have been thoroughly characterized in mammals and microorganisms, whereas very little is known about plant TAG lipases. The lipolytic activity occurring in all the laticies is known to be associated with sedimentable particles, and all attempts to solubilize the lipolytic activity of Carica papaya latex have been unsuccessful so far. However, some of the biochemical properties of the lipase from Carica papaya latex (CPL) were determined from the insoluble fraction of the latex. The activity was optimum at a temperature of 37°C and a pH of 9.0, and the specific activities of CPL were found to be 2,000 ± 185 and 256 ± 8 U/g when tributyrin and olive oil were used as substrates, respectively. CPL was found to be active in the absence of any detergent, whereas many lipases require detergent to prevent the occurrence of interfacial denaturation. CPL was inactive in the presence of micellar concentrations of Triton X-100, sodium dodecyl sulfate (SDS) and tetradecyl trimethylammonium bromide (TTAB), and still showed high levels of activity in the presence of sodium taurodeoxycholate (NaTDC) and the zwitterionic Chaps detergent. The effects of various proteases on the lipolytic activity of CPL were studied, and CPL was found to be resistant to treatment with various enzymes, except in the presence of trypsin. All these properties suggest that CPL may be a good candidate for various biotechnological applications.

Conjugated autoxidizable triene (CAT) assay: a novel spectrophotometric method for determination of antioxidant capacity using triacylglycerol as ultraviolet probe.

Described here is a novel spectrophotometric method for estimating antioxidant capacity in a 96-well microplate using as UV probes the conjugated triene triacylglycerols (TAGs) naturally present in tung oil. The TAGs of this commercially available oil contain around 86% eleostearic acid, an octadecatrienoic acid with conjugated trienes exhibiting strong UV absorption at 273 nm. In an oil-in-water emulsion at 37 degrees C, the azo initiator 2,2'-azobis(2-amidinopropane) dihydrochloride generated a constant flux of peroxy radicals, which destroyed the conjugated trienes. The absorbance decay at 273 nm, related to oxidative degradation of conjugated triene TAGs, was monitored in the absence and presence of various concentrations of antioxidants. To validate this new method, the antioxidant capacity of four phenolic compounds (gallic acid, (-)-epicatechin, chlorogenic acid, and rosmarinic acid) was measured using an area-under-the-curve calculation and expressed as Trolox equivalents, the value for Trolox being taken as reference. The order of efficacy was found to be rosmarinic acid > chlorogenic acid approximately epicatechin>Trolox>gallic acid, which can be partially explained by the number of catecholic moieties and the polarity of these antioxidants. Moreover, the conjugated autoxidizable triene (CAT) assay provided good insight into antioxidant behavior (i.e., retarder or chain breaker). The same molecules were then analyzed in 2,2-diphenyl-1-picrylhydrazyl and fluorescein-based oxygen radical absorbance capacity assays, and the results are discussed critically with respect to those obtained with the CAT assay. This new method may constitute an easy-to-use, sensitive, and high-throughput in vitro protocol for evaluation of the antioxidant capacity of pure molecules and natural extracts in lipid oxidation.

Comparison of the lipase activity in hydrolysis and acyl transfer reactions of two latex plant extracts from babaco (Vasconcellea x Heilbornii Cv.) and Plumeria rubra: Effect of the Aqueous microenvironment.

The enzymatic properties of Plumeria rubra latex have been evaluated for the first time, showing a high activity in both hydrolysis and synthesis reactions, and compared to the biocatalytic behavior of babaco (Vasconcellea x Heilbornii cv.) latex. Both biocatalysts have been optimized by studying the various parameters that influence reaction kinetics. The optimum temperatures for hydrolysis reactions were 50 and 55 degrees C for babaco and Plumeria, respectively. The optimum pH for babaco latex was 7, whereas for Plumeria latex, two optimal pH values (4 and 7) were observed. With regard to esterification and acyl transfer reactions such as alcoholysis and interesterification, the influence of thermodynamic water activity on reaction yields was determined and correlated with water sorption and desorption isotherms. When babaco latex is used as a biocatalyst, optimal synthesis reaction yields are obtained when the enzymatic extract is stabilized at a water activity value of 0.38, which corresponds to a water content of 5.7%. This optimal level of hydration is located on the linear portion of the biocatalyst's sorption isotherm, where the water molecules exhibit high-energy interactions with the protein network. In synthesis reactions (esterification, alcoholysis, and interesterification) biocatalyzed by Plumeria latex, correlation between best reaction yields and water activity cannot be done. Indeed, the sorption isotherm plot has an atypical shape, indicating that water might be trapped in the latex matrix and, consequently, that the water content of the biocatalyst is highly dependent on the hydration history of the latex.