Efecto del tostado sobre los tocoferoles de semillas de calabaza (Cucurbita pepo)

The effect of roasting at high temperatures on the Vitamin E in hulled gourd seeds of Cucurbita pepo was studied. Roasting at 140°C for 5 min induced a swelling of the seed with an increase in volume of 43 %, and a weight loss of 6.5 %.The seed acquired the desired puffed-up appearance. The water activity of raw seeds was 0.544 and decreased during roasting to 0.105. Cucurbita pepo seeds contained 51.0 % fat. Tocopherol content of roasted seeds was 68mg/100g oil and of non roasted seeds was 107mg/100g oil. γ-tocopherol represented 96% of the total tocopherols. Total tocopherol loss during roasting was 36%. β-tocopherol loss was the highest at 50%; for α-tocopherol it was 41% and for γ-tocopherol it was 36%.Se ha estudiado el efecto del tostado a alta temperatura sobre la vitamina E en semillas de calabaza Cucurbita pepo. El tostado a 140°C durante 5 min indujo una hinchazón de la semilla con un aumento en el volumen del 43 %, y una pérdida de peso del 6,5 %. La semilla adquirió la apariencia deseada después del tostado. La actividad del agua en la semilla cruda fue de 0,544 y disminuyó durante el tostado a 0,105. Las semillas de Cucurbita pepo contenían un 51,0 % de grasa. El contenido de tocoferol de las semillas tostadas fue de 68mg/100g y el de las semillas no tostadas de 107mg/100g de aceite. El γ-tocoferol representó el 96% de los tocoferoles totales. La pérdida de tocoferoles totales durante el tostado fue del 36% siendo la má alta la del β-tocoferol con un 50%; la del α-tocoferol fue del 41% y la del γ-tocoferol del 36%

Variations in Chlorella lipid content in commercial and in-lab produced biomass☆

Microalgae appear as a sustainable source of biomass with relevant nutritional qualities. Still, regulatory restrictions currently limit the use of eukaryotic microalgae for human consumption to a short list of species dominated by Chlorella spp. Chlorella biomass contains valuable proteins but also interesting lipids, including polyunsaturated fatty acids (PUFA) ω3 and ω6. The amount of PUFA and the ω6/ω3 ratio vary significantly depending on the species and cultivation trophic mode. While the lipid profils of in-lab produced Chlorella has been widely studied, the variability of lipid content in commercial biomasses is barely described. Here, lipid classes and fatty acid profiles of six commercial biomasses of Chlorella spp. as well as those of lab-produced C. sorokiniana grown in photo-autotrophy and in four mixotrophy conditions were characterized. Results showed significant lipid composition variations between the biomasses, such as the triacylglycerols/glycolipids and ω6/ω3 contents. The ω6/ω3 ratios were lower in photo-autotrophic mode (2.5) while they ranged between 1.3 and 8.9 in commercial biomasses. The free fatty acids level was also variable (1.4% to 17.9% of total lipids). As a consequence, Chlorella lipid content and quality differed significantly, impacting the potential nutritional benefits of the consumption of commercial biomass. Processing and post-processing conditions should therefore be carefully controlled to optimize lipid profiles

Homogenization Pressure and Temperature Affect Protein Partitioning and Oxidative Stability of Emulsions

The oxidative stability of 10 % fish oil-in-water emulsions was investigated for emulsions prepared under different homogenization conditions. Homogenization was conducted at two different pressures (5 or 22.5 MPa), and at two different temperatures (22 and 72 °C). Milk proteins were used as the emulsifier. Hence, emulsions were prepared with either a combination of α-lactalbumin and β-lactoglobulin or with a combination of sodium caseinate and β-lactoglobulin. Results showed that an increase in pressure increased the oxidative stability of emulsions with caseinate and β-lactoglobulin, whereas it decreased the oxidative stability of emulsions with α-lactalbumin and β-lactoglobulin. For both types of emulsions the partitioning of proteins between the interface and the aqueous phase appeared to be important for the oxidative stability. The effect of pre-heating the aqueous phase with the milk proteins prior to homogenization did not have any clear effect on lipid oxidation in either of the two types of emulsions. (Résumé d'auteur

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 degrees 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