Pedro Wesche-Ebeling

Changes in anthocyanin concentration in Lychee (Litchi chinensis Sonn.) pericarp during maturation

Abstract Lychee has an edible aril surrounded by an anthocyanin-rich pericarp. Chemical and physical changes during lychee ripening were studied focusing on anthocyanins (Acy). Length increased up to the 17th week after anthesis (waa), and width and weight increased continuously. Pericarp % decreased until the 17th waa while aril % increased until the 19th waa. The fruit became darker during ripening and changed from light green to yellow-green (12–15th waa), and from yellow-red to dark red (16–20th waa). pH decreased from 3.18 to 2.68 (12–15th waa), finally increasing to 4.49. Highest titratable acidity occurred in the 14th waa (4.44% malic acid) decreasing to a final 0.16%. Soluble solids were highest at ripeness (18 °Bx). Increases in monomeric (mAcy) and total Acy levels were observed up to the the 17th waa. Green fruits contained only malvinidin-3-acetylglucoside and polymeric pigment while the ripe fruit contained cyanidin-3-rutinoside (>75%), cyanidin-3-glucoside (

Purification and identification of capulin (Prunus serotina Ehrh) anthocyanins

Abstract Capulin (Prunus serotina Ehrh) anthocyanins were extracted from liquid nitrogen powdered epidermal tissue using acetone, the aqueous acetone extract partitioned with chloroform and purified in a C-18 solid-phase cartridge. pH-differential and bisulfite bleaching methods were used to determine monomeric anthocyanin content and polymeric color. Pigments were identified by spectral analyses, HPLC and mass spectroscopy. Information from HPLC profiles, saponification and acid hydrolysis of the capulin anthocyanins showed that the two major pigments were cyanidin-3-glucoside (34%) and cyanidin-3-rutinoside (63%), with no acylating groups. A third yellow/orange pigment (λmax 480 nm, MW=632) possibly containing rutinose was detected by MS.

Contributions to the botany and nutritional value of some wild amaranthus species (Amaranthaceae) of Nuevo leon, Mexico

Seeds and plants of Amaranthus have been a source of food for many cultures in the world. Some species can be found as weeds or growing wild under severe climatic and soil conditions, but their potential as food sources has not been studied. The objective of this work was to study the nutritional quality of four wild species ofAmaranthus,A. retroflexus (AR),A. viridis (A V),A. palmeri (AP) andA. blitoides (AB) as potential sources of vegetable greens. Histochemical studies showed higher levels of starch in leaves of AR and AB, moderate amounts of tannins in all leaves, high protein concentration in stems and leaves, and moderate amounts of alkaloids in all tissues of AV and AB. Antinutritional factors (nitrates, oxalates, cyanogenic glycosides, tannins and phytates) were quantified in plants at the preflowering stage, but only nitrates were found at levels (0.34-2% dw) above those generally considered as safe, but at similar levels found in spinach. No cyanogenic glycosides were detected in any species. Bromatologic analysis of whole or different plant parts at preflowering and maturity (mature seeds) showed that mature whole plants or individual sections can be recommended as animal feed since they contain high levels of protein (20.6-24.7% whole plant, 25.3-32.9% leaves) and soluble carbohydrate (>40%).Amaranthus plants could be best consumed as vegetables at the preflowering stage. At this stage, the highest protein concentrations were found in leaves (22.8-27.8%), while the remaining chemical composition was very similar to that found in other food vegetables. The four species showed similar chemical compositions, and had no detrimental chemicals which would deter their use as vegetable foods. Organoleptic taste preference studies would best indicate the stage at which the plant should be harvested for human consumption.AbstractLas semillas y plantas deAmaranthus (alegría) han sido fuente de alimento para muchas culturas del mundo. Algunas especies pueden encontrarse como maleza o creciendo en forma silvestre bajo condiciones climáticas o de suelo muy severas, pero su potencial como alimento no ha sido estudiado. El objetivo de este trabajo fue el de estudiar el potencial nutritional como hortaliza de cuatro especies silvestres deAmaranthus, A. retroflexus (AR),A. viridis (A V),A. palmeri yA. blitoides (AB). Los estudios histoquímicos demostraron altos niveles de almidón en hojas de AR y AB, cantidades moderadas de taninos en todas las hojas, una alta concentratión de proteína en tallos y hojas, y un contenido moderado de alcaloides en todos los tejidos de AV y AB. Se cuantificaron los factores antinutricionales (nitratos, oxalatos, glucósidos cianogénicos, taninos y fitatos) en plantas en la etapa de prefloración, y solamente los nitratos se encontraron en nivelesarriba de los considerados seguros (0.34-2% p.s.), pero a niveles similares a los de la espinaca. En ninguna especie se detectaron glucósidos cianogénicos. El análisis bromatológico mostró que plantas enteras y sus secciones en las etapas de prefloración y madura pueden ser recomendadas como alimento animal ya que contienen altos niveles de proteína (20.6-24.7% planta entera, 25.3-32.9% hojas) y carbohidratos solubles (>40%). Las plantas deAmaranthus pueden se consumidas como hortalizas en la etapa de prefloración. En esta etapa se encontraron los niveles máximos de proteína en las hojas (22.8-27.8%), mientras que la composición bromatológica restante fue muy similar a la encontrada en otras hortalizas. Las cuatro especies mostraron una compositión química muy similar y mostraron la ausencia de compuestos químicos dañinos que impediría su uso como hortaliza. Estudios de preferencia organoléptica serían los mejores indicadores de la mejor etapa de cultivo de estas especies para consumo humano.

Preservation factors and processing effects on anthocyanin pigments in plums

Abstract The use of a combination of preservation factors has been suggested as a viable alternative to minimally process fruits and preserve them for practical periods of time. Although microbiological stability is the main goal, in the case of prunes color preservation is also of great concern. Prunes (Prunus domestica L.) of the ‘Angeleno’ variety were employed. The fruits were cut in half and the seeds removed. A treatment of 150 s under steam resulted in the permanent inactivation of browning enzymes. The treated fruit was stored for 90 days in systems (aw = 0.98 with sucrose and 0.1 % benzoate) at three different pH values: 2.95, 3.45 and 3.95. After 90 days of storage at room temperature, 77% of the original anthocyanin remained at pH 2.95, but only 29% at pH 3.45 and 8% at pH 3.95. There was also an increase in the degradation index with time and with increasing storage pH. Color density values decreased as a result of anthocyanin degradation and not because of browning reactions. A marmalade prepared using the pH 2.95 preserved prunes was stored at room temperature for 90 days. An additional 27% of the original anthocyanin was destroyed, but the degradation index increased only slightly and remained constant throughout the storage period. Color density values remained very low. No microbial growth occurred in the stored prunes or marmalade, and the marmalade was classified organoleptically as good.

Chemical, nutritional and functional characterization of proteins extracted from wild mustard (Brassica campestris, Brassicaceae) seeds from Nuevo Leon, Mexico

Cultivated oilseeds are very important sources of protein-rich pastes that are widely used for their nutritional and functional properties in human foods and animal feed. The purpose of this research was to determine the potential of wild Brassica campestris seeds as a source of protein isolates and their characterization. Wild mustard meal contained 33.5% lipids, 26% protein, 13.4% crude fiber, 4.4% ash, 22.6% nitrogen free extract and 4.8% moisture. It contained low levels of phytates (32 mg/100 g) and glucosinolates (0.92%), and the thioglucosidase could be inactivated through heat (90°C/ 18 min) or after extracting the oil with hexane at 80°C: for 2 hr. Dehulled and defatted meal contained 3.8% crude fiber, 7% ash, and 48% protein, with a digestibility of 92.8% and a nutritive value of 98% (relative to casein). Phytate levels increased to 67 mg/100 g and glucosinolates to 2.3%. Protein was extracted from this meal at pH’s between 6 and 11. Maximum yields (>74%) were obtained at pH 7, 7.5 and 8, coinciding with a minimum extraction of phytate (70%). SDS-PAGE electrophoresis identified 12 protein bands with MW between 10 and 74 kDa in these extracts. Protein extracted at pH 7 was precipitated at pH’s between 3.5 and 5.5, with maximum yield at pH 3.5 (53%), but the pH 4 isolate was chosen (yield 36%) since it contained negligible amounts of phytates and no glucosinolates. It contained 93% protein and a nutritive value of 91%, and higher levels of sulphur amino acids and lysine than cereals and legumes. The best functional characteristics were its foaming capacity, foam stability and oil binding capacity (better than soybean isolate).RésuméLas oleaginosas cultivadas son fuente importante de pastas ricas en proteína que son ampliamente utilizadas por sus propiedades nutricionales y funcionales en alimentos para humanos y balanceados. El objetivo de esta investigación fue el de determinar el potencial de las semillas de la Brassica campestris silvestre como fuente de aislados proteicos y la caracterización de éstos. La compositión de la harina de mostaza silvestre fue: lípidos 33.5%, proteína 26%, fibra crude 13.4%, ceniza 4.4%, extracto libre de nitrógeno 22.6% y humedad 4.8%. Tuvo un contenido bajo de fitatos (32 mg/ 100 g) y glucosinolatos (0.92%), y la tioglucosidasa pudo inactivarse con color (90°C/18 min) o con la extractión del aceite con hexano a 80C por 2 hr. La composición de la harina descascarada y desgrasada fue: fibra cruda 3.8%, ceniza 7% y proteína 48%, con una digestibilidad de 92.8% y un valor nutritivo de 98% (relativo a la caseína). El nivel defitatos se incrementó a 67 mgl l00g y el de glucosinolatos a 2.3%. Se extrajo la proteína de esta harina a pH’s entre 6 y 11. Los rendimientos máximos (>74%) se obtuvieron a pH 7, 7.5 and 8, coincidiendo con la extractión mínima defitato (70%). Por medio de una electroforesis SDS-PAGE se identificaron 12 bands de proteína con PM entre 10 y 74 kDa en estos extractos. La proteína extaica a pH 7 se precipitó a pH’s entre 3.5 y 5.5, con un máximo rendimiento a pH 3.5 (53%), pero se escogió el aislado a pH 4 (rendimento de36%) ya que contenía cantidades traza defitatos y glucosinolatos. El aislado contenía 93% de proteína y un valor nutritivo de 91%, y niveles más altos de aminoácidos azufrados y lisina que cereales and leguminosas. La mejores características funcionales fueron la capacidad espumante, estabilidad de la espuma y capacidad de atado de aceite (mejor que los aislados de soya).