High Hydrostatic Pressure Assisted by Celluclast® Releases Oligosaccharides from Apple By-Product.

A novel and green procedure consisting of high hydrostatic pressure (HHP) aided by a commercial cellulase (Celluclast®) has been applied to valorise the apple by-product, a valuable source of dietary fibre but mainly composed by insoluble fibre. Optimal conditions for solubilisation of dietary fibre were first determined at atmospheric pressure as 2% (w/v) of substrate concentration and 20 Endo-Glucanase Units of cellulase. Monitoring of polysaccharides and oligosaccharides released from apple by-product was carried out by means of a newly validated HPLC method with refractive index detector. A synergistic effect was observed when the combined HHP plus cellulase treatment was used. Thus, the application of 200 MPa at 50 °C for 15 min enabled a significant increase in the release of water-soluble polysaccharides (1.8-fold) and oligosaccharides (3.8-fold), as well as a considerable decrease in the time required (up to 120-fold), compared to control at 0.1 MPa. Therefore, this technology could be a promising alternative approach to transform an industrial by-product into a novel rich-in-oligosaccharide food ingredient and a step forward into shaping the world of prebiotics.

Improved evaporative light scattering detection for carbohydrate analysis.

Optimization and validation of evaporative light scattering detector (ELSD), aided by response surface methodology (RSM), has been developed for the liquid chromatography analysis of a wide molecular weight (MW) range of carbohydrates, including polysaccharides and oligosaccharides. Optimal experimental parameters for the ELSD detection were: 88.8°C evaporator temperature, 77.9°C nebulizer temperature and 1.1 standard litres per minute nitrogen flow rate. Optimal ELSD detection, used together with high performance size exclusion chromatography (HPSEC) of carbohydrates, gave a linear range from 250 to 1000 mg L(-1) (R(2)>0.998), with limits of detection and quantitation of 4.83-11.67 and 16.11-38.91 mg L(-1), respectively. Relative standard deviation was lower than 1.8% for intra-day and inter-day repeatability for apple pectin, inulin, verbascose, stachyose and raffinose. Recovery ranged from 103.7% to 118.3% for fructo-oligosaccharides, α-galacto-oligosaccharides and disaccharides. Optimized and validated ELSD detection is proposed for the analysis of high- to low-MW carbohydrates with high sensitivity, precision and accuracy.

Effects of Undaria pinnatifida, Himanthalia elongata and Porphyra umbilicalis extracts on in vitro α-glucosidase activity and glucose diffusion.

BACKGROUND: Seaweeds are good sources of dietary fibre, which can influence glucose uptake and glycemic control. OBJECTIVE: To investigate and compare the in vitro inhibitory activity of different extracts from Undaria pinnatifida (Wakame), Himanthalia elongata (Sea spaghetti) and Porphyra umbilicalis (Nori) on α-glucosidase activity and glucose diffusion. METHODS: The in vitro effects Chloroform-, ethanol- and water-soluble extracts of the three algae were assayed on α- glucosidase activity and glucose diffusion through membrane. Principal Components Analysis (PCA) was applied to identify patterns in the data and to discriminate which extract will show the most proper effect. RESULTS: Only water extracts of Sea spaghetti possessed significant in vitro inhibitory effects on α-glucosidase activity (26.2% less mmol/L glucose production than control, p < 0.05) at 75 min. PCA distinguished Sea spaghetti effects, supporting that soluble fibre and polyphenols were involved. After 6 h, Ethanol-Sea spaghetti and water-Wakame extracts exerted the highest inhibitory effects on glucose diffusion (65.0% and 60.2% vs control, respectively). This extracts displayed the lowest slopes for glucose diffusion-time lineal adjustments (68.2% and 62.8% vs control, respectively). CONCLUSIONS: The seaweed hypoglycemic effects appear multi-faceted and not necessarily concatenated. According to present results, ethanol and water extracts of Sea spaghetti, and water extracts of Wakame could be useful for the development of functional foods with specific hypoglycemic properties.

Antecedentes: Las algas son importante fuente alimentaria de fibra dietética y puede influir sobre la absorción de glucosa y el control glucémico. Objetivo: Evaluar y comparar in vitro los efectos de diferentes extractos de las algas Undaria pinnatifida (Wakame), Himanthalia elongata (Espagueti de mar) y Porphyra umbilicalis (Nori) sobre la actividad enzimática -glucosidasa y la difusión de glucosa. Métodos: Se estudiaron los efectos de los extractos clorofórmicos, etánólicos y acuosos de las tres algas sobre la actividad -glucosidasa y la difusión de glucosa a través de una membrana de diálisis. Se aplicó a los resultados un análisis de los componentes principales (PCA) para identificar posibles patrones de composición y seleccionar el extracto que mejores propiedades posea. Resultados: El extracto acuoso de Espagueti de mar inhibió de forma significativa la actividad -glucosidasa (26,2% menos liberación de glucosa, p < 0,05). El PCA sugiere que la fibra soluble y los polifenoles son los responsables de tal efecto. Respecto a la difusión de glucosa, el extracto etanólico de Espagueti de mar y el acuoso de Wakame mostraron un mayor efecto inhibidor después de 6 horas (65% y 60,2% vs control, respectivamente) y las menores pendientes en los ajustes lineales difusión de glucosa- tiempo (68,2% y 62,8% vs control respectivamente). Conclusiones: Los resultados de los diferentes extractos sugieren que los efectos hipogluceminates de las algas son variados y no están necesariamente concatenados. Los extractos acuosos y etanólicos de Espagueti de mar y los acuosos de Wakame parecen los más adecuados para el desarrollo de alimentos funcionales con propiedades hipoglucemiantes.

Effects of Undaria pinnatifida, Himanthalia elongata and Porphyra umbilicalis extracts on in vitro alpha-glucosidase activity and glucose diffusion / Efectos de extractos de undaria pinnatifida, himantalia elongata y porfira umbilicalis sobre la actividad alpha-glucosidasa y la difusion de la glucosa in vitro

Background: Seaweeds are good sources of dietary fibre, which can influence glucose uptake and glycemic control. Objective: To investigate and compare the in vitro inhibitory activity of different extracts from Undaria pinnatifida (Wakame), Himanthalia elongata (Sea spaghetti) and Porphyra umbilicalis (Nori) on α-glucosidase activity and glucose diffusion. Methods: The in vitro effects chloroform-, ethanol- and water-soluble extracts of the three algae were assayed on α- glucosidase activity and glucose diffusion through membrane. Principal Components Analysis (PCA) was applied to identify patterns in the data and to discriminate which extract will show the most proper effect. Results: Only water extracts of Sea spaghetti possessed significant in vitro inhibitory effects on α-glucosidase activity (26.2% less mmol/L glucose production than control, p < 0.05) at 75 min. PCA distinguished Sea spaghetti effects, supporting that soluble fibre and polyphenols were involved. After 6 h, Ethanol-Sea spaghetti and water-Wakame extracts exerted the highest inhibitory effects on glucose diffusion (65.0% and 60.2% vs control, respectively). This extracts displayed the lowest slopes for glucose diffusion-time lineal adjustments (68.2% and 62.8% vs control, respectively). Conclusions: The seaweed hypoglycemic effects appear multi-faceted and not necessarily concatenated. According to present results, ethanol and water extracts of Sea spaghetti, and water extracts of Wakame could be useful for the development of functional foods with specific hypoglycemic properties (AU)

Antecedentes: Las algas son importante fuente alimentaria de fibra dietética y puede influir sobre la absorción de glucosa y el control glucémico. Objetivo: Evaluar y comparar in vitro los efectos de diferentes extractos de las algas Undaria pinnatifida (Wakame), Himanthalia elongata (Espagueti de mar) y Porphyra umbilicalis (Nori) sobre la actividad enzimática α-glucosidasa y la difusión de glucosa. Métodos: Se estudiaron los efectos de los extractos clorofórmicos, etánólicos y acuosos de las tres algas sobre la actividad α-glucosidasa y la difusión de glucosa a través de una membrana de diálisis. Se aplicó a los resultados un análisis de los componentes principales (PCA) para identificar posibles patrones de composición y seleccionar el extracto que mejores propiedades posea. Resultados: El extracto acuoso de Espagueti de mar inhibió de forma significativa la actividad α-glucosidasa (26,2% menos liberación de glucosa, p < 0,05). El PCA sugiere que la fibra soluble y los polifenoles son los responsables de tal efecto. Respecto a la difusión de glucosa, el extracto etanólico de Espagueti de mar y el acuoso de Wakame mostraron un mayor efecto inhibidor después de 6 horas (65% y 60,2% vs control, respectivamente) y las menores pendientes en los ajustes lineales difusión de glucosa-tiempo (68,2% y 62,8% vs control respectivamente). Conclusiones: Los resultados de los diferentes extractos sugieren que los efectos hipogluceminates de las algas son variados y no están necesariamente concatenados. Los extractos acuosos y etanólicos de Espagueti de mar y los acuosos de Wakame parecen los más adecuados para el desarrollo de alimentos funcionales con propiedades hipoglucemiantes (AU)

Effect of the red seaweed Mastocarpus stellatus intake on lipid metabolism and antioxidant status in healthy Wistar rats.

Health-promoting effect of dietary supplementation with the red seaweed Mastocarpus stellatus was studied. Its major component is dietary fibre (31.7/100 g dry weight), 72% as soluble fibre, mainly formed by carrageenans, sulphated-galactans of red seaweeds. Thus, rats were fed either a basal- or an algal-supplemented diet (10%). Then, lipid metabolism was assessed in serum, and reducing power measured in serum and caecum by FRAP method. Also, caecal pH was monitored and short chain fatty acids analysed by gas-liquid chromatography. Seaweed intake reduced significantly triglycerides and total cholesterol in healthy rats, but not atherogenic index. Also, a significant increase in caecal moisture and proportion of acetic and propionic acids was obtained but no clear prebiotic effect was shown. Sulphated-galactans seemed to be related to the antioxidant status improvement in caecum and also to the 1.7-fold increase in anticoagulant capacity of plasma. Therefore, Mastocarpus could be regarded as a source of functional ingredients but its health benefits need to be further explored depending on specific use.

Molecular weight distribution of polysaccharides from edible seaweeds by high-performance size-exclusion chromatography (HPSEC).

Biological properties of polysaccharides from seaweeds are related to their composition and structure. Many factors such as the kind of sugar, type of linkage or sulfate content of algal biopolymers exert an influence in the relationship between structure and function. Besides, the molecular weight (MW) also plays an important role. Thus, a simple, reliable and fast HPSEC method with refractive index detection was developed and optimized for the MW estimation of soluble algal polysaccharides. Chromatogram shape and repeatability of retention time was considerably improved when sodium nitrate was used instead of ultrapure water as mobile phase. Pullulan and dextran standards of different MW were used for method calibration and validation. Also, main polysaccharide standards from brown (alginate, fucoidan, laminaran) and red seaweeds (kappa- and iota-carrageenan) were used for quantification and method precision and accuracy. Relative standard deviation (RSD) of repeatability for retention time, peak areas and inter-day precision was below 0.7%, 2.5% and 2.6%, respectively, which indicated good repeatability and precision. Recoveries (96.3-109.8%) also showed its fairly good accuracy. Regarding linearity, main polysaccharide standards from brown or red seaweeds showed a highly satisfactory correlation coefficient (r>0.999). Moreover, a good sensitivity was shown, with corresponding limits of detection and quantitation in mg/mL of 0.05-0.21 and 0.16-0.31, respectively. The method was applied to the MW estimation of standard algal polysaccharides, as well as to the soluble polysaccharide fractions from the brown seaweed Saccharina latissima and the red Mastocarpus stellatus, respectively. Although distribution of molecular weight was broad, the good repeatability for retention time provided a good precision in MW estimation of polysaccharides. Water- and alkali-soluble fractions from S. latissima ranged from very high (>2400 kDa) to low MW compounds (<6 kDa); this high heterogeneity could be attributable to the complex polysaccharide composition of brown algae. Regarding M. stellatus, sulfated galactans followed a descending order of MW (>1400 kDa to <10 kDa), related to the different solubility of carrageenans in red seaweeds. In summary, the method developed allows for the molecular weight analysis of seaweed polysaccharides with very good precision, accuracy, linearity and sensitivity within a short time.

A simple ion chromatography method for inorganic anion analysis in edible seaweeds.

A new, simple, fast and sensitive ion chromatography (IC) method, for the simultaneous analysis of fluoride, chloride, nitrite, bromide, nitrate, phosphate and sulphate in edible seaweeds was developed and reported for the first time. The validation of the analytical method was studied in terms of linearity, sensitivity, precision and accuracy. All standard calibration curves showed very good correlation between anion peak area and concentration (r>0.999). Limits of detection and quantitation ranged between 0.002-0.05 mg/L and 0.01-0.1mg/L, respectively and indicated the high sensitivity of the method. Relative standard deviation values of repeatability and inter-day precision for standard anions with the same sample were less than 2%. Anion recoveries ranged from 97 to 113% for chloride and from 87 to 105% for sulphate, respectively and showed the fairly good accuracy of the method. The method was applied to the analysis of inorganic anions in brown and red edible seaweeds. Brown seaweeds were characterized by higher chloride content up to 33.7-36.9%, while red seaweeds were characterized by higher sulphate content (45-57%). Sulphate content in seaweeds is related to the presence of sulphated polysaccharides of biological importance. The method developed was well applicable to mineral anion analysis in edible seaweeds and shows suitability and reliability of use in other food samples of nutritional importance.

Soybean whey enhance mineral balance and caecal fermentation in rats.

BACKGROUND: Soybean whey, a by-product of tofu manufacturing, is currently discarded by the food industry. However, it contains valuable compounds such as non-digestible oligosaccharides (NDO), which promote the growth of beneficial lactic acid bacteria in the colon, and are therefore recognized as prebiotics. Acidic fermentation of NDO in the caecum appears to be related with an increase in mineral absorption. AIM OF THE STUDY: To evaluate the effect of consuming soybean whey containing galacto-oligosaccharides (GOS) on mineral absorption and caecal fermentation in rats. METHODS: An in vivo assay was carried out in rats over a period of 4 weeks; previously, the nutritional composition of soybean whey was determined and NDO were measured by high-performance liquid chromatography (HPLC). Faeces and urine were collected weekly throughout the experiment for mineral balance analyses. Animals were killed under anaesthesia, organs were removed and weighed, and short-chain fatty acids in the caecal contents were determined by gas chromatography. RESULTS AND CONCLUSIONS: Non-digestible carbohydrates such as GOS stachyose (318 +/- 3 mg/100 mL) and traces of inulin were identified by HPLC. When soybean whey was used as a source of GOS in rats, the consumption of diluted soybean whey (75 mL/day per rat) containing GOS (120 mg/day per rat) exhibited a prebiotic effect and led to an improved mineral balance, especially for calcium and magnesium. In view of its composition and potential health-promoting properties, soybean whey could be used as a valuable ingredient in new functional foods.

Health-promoting effects of a dietary fiber concentrate from the soybean byproduct okara in rats.

Okara (a byproduct of the soy milk industry) is rich in proteins (24.5-37.5 g/100 g of dry matter (dm)), lipids (9.3-22.3 g/100 g of dm), and dietary fiber (DF) (14.5-55.4 g/100 g of dm). It also contains isoflavones (0.14 g/100 g of dm). In the present study we fed female healthy Wistar rats either a standard rat diet or a supplemented 10% DF-rich okara (DFRO) diet for 4 weeks, and then we assessed several health parameters in the serum and the cecum compartments. In comparison to the control group, rats fed DFRO showed a significant decrease in weight gain (5.00 +/- 1.22 g vs 2.00 +/- 1.46 g, P < 0.03, during week 4) and in total cholesterol (65 +/- 8 mg/dL vs 51 +/- 5 mg/dL, P < 0.05) and a significantly increased antioxidant status (36.71 +/- 15.31 micromol of Trolox equivalents (TEs)/g vs 69.75 +/- 16.11 micromol of TEs/g, P < 0.0003) and butyrogenic effect (39.37%, P < 0.003) in the cecum. In addition, a significant enhancement in the apparent absorption (41.89 +/- 1.64% vs 47.02 +/- 2.51%, P < 0.004) and in the true retention (41.62 +/- 1.60% vs 46.68 +/- 2.55%, P < 0.005) of calcium was appreciated. In summary, these findings show for the first time that a concentrate DF from a soybean byproduct protects the gut environment in terms of antioxidant status and prebiotic effect. These results may highlight the development of an innovative soybean byproduct rich in DF which could be useful as a functional ingredient with health-promoting attributes.

Potential antioxidant capacity of sulfated polysaccharides from the edible marine brown seaweed Fucus vesiculosus.

Fucus vesiculosus was sequentially extracted with water at 22 degrees C (fraction 1 (F1)) and 60 degrees C (F2), and with 0.1 M HCl (F3) and 2 M KOH (F4) at 37 degrees C. Soluble fractions (42.3% yield) were composed of neutral sugars (18.9-48 g/100 g), uronic acids (8.8-52.8 g/100 g), sulfate (2.4-11.5 g/100 g), small amounts of protein (< 1-6.1 g/100 g), and nondialyzable polyphenols (0.1-2.7 g/100 g). The main neutral sugars were fucose, glucose, galactose, and xylose. Infrared (IR) spectra of the fractions showed absorption bands at 820-850 and 1225-1250 cm(-1) for sulfate. F1, F2, and F4 also exhibited an absorption band at 1425 cm(-1), due to uronic acids, and their IR spectra resembled that of alginate. F3 had an IR spectrum similar to that of fucoidan with an average molecular weight of 1.6 x 10(6) Da, calculated by molecular exclusion high-performance liquid chromatography. The presence of fucose in this polysaccharide was confirmed by (1)H NMR spectroscopy. This fraction showed the highest potential to be antioxidant by the ferric reducing antioxidant power (FRAP) assay, followed by the alkali- and water-soluble fractions. Sulfated polysaccharides from edible seaweeds potentially could be used as natural antioxidants by the food industry.