Nutritional value of cowpea (Vigna unguiculata L. Walp) meals as ingredients in diets for Pacific white shrimp (Litopenaeus vannamei Boone)

The nutritional value of cowpea (Vigna unguiculata L. Walp) meals, as ingredients in diets for Litopenaeus vannamei, was evaluated. Five experimental meals were prepared in the laboratory: whole raw cowpea (WRC), dehulled (DC), cooked (CC), germinated (GC) and extruded (EXC). The crude protein content of WRC (26.1%) increased after germination (29.5%). Carbohydrates ranged from 69.4% to 85.9%. The trypsin inhibitor activity of WRC meal was low (7.52 U/mg dry matter), and was reduced or eliminated by cooking and extrusion. Apparent digestibility of dry matter, protein and carbohydrate of the diet containing whole raw cowpea meal (71.1%, 85.9% and 76.7%, respectively) was similar to the control diet. Cooking and extruding of cowpea significantly increased dry matter, protein and carbohydrate digestibility in the diets. The results suggest that cowpea meals are good sources of nutrients and can be used as ingredients in diets for L. vannamei.     

Effects of alkaline treatment on the structure of phosphorylated wheat starch and its digestibility

Phosphorylated wheat starch (PWS) was prepared with sodium trimetaphosphate and sodium tripolyphosphate (99/1, w/w), and the modified starch gave 88.8% total dietary fibre by the Prosky method and 68.7% resistant starch (RS) by the Englyst method. The stability of the phosphate esters in aqueous sodium hydroxide was investigated and related to total dietary fibre and RS contents. The phosphorylated starch was slurried (40%, w/w) at 40 °C for 4 h at pH 9.0, 10.0, 11.0, and 12.0. The phosphorus content of the PWS decreased from 0.37% to 0.29% after treatment at pH 12.0, whereas only a slight decrease in phosphorus content occurred after treatments at pH 9.0–11.0. Despite the 22% decrease in total phosphorus content, total dietary fibre content and RS content of the alkali-treated PWS changed only slightly. ³¹P nuclear magnetic resonance spectroscopy showed that after the alkali treatment at pH 12.0, cyclic monostarch monophosphate and monostarch diphosphate were not detectable and that the level of total monostarch monophosphate decreased from 0.077% to 0.067%. Conversely, distarch monophosphate increased from 0.17% to 0.20%, of ≈18%. The increase in distarch monophosphate (cross-linking) content after alkali treatment at pH 12.0 probably explained the retention of total dietary fibre and RS contents in the alkali-treated PWS.     

Digestion stability and evaluation of the metabolism and transport of olive oil phenols in the human small-intestinal epithelial Caco-2/TC7 cell line

The aims of this study were to investigate (i) the metabolism of olive oil phenolics by intestinal epithelial cells and (ii) their transport across epithelial cell monolayers. The various conjugates and derivatives produced by the intestinal epithelial cells were identified following separation by ultra-performance liquid chromatography (UPLC), using a combination of UV/visible spectra, mass spectrometry and specific enzyme treatments (β-glucuronidase and aryl-suphatase). Limited metabolism of olive oil phenolics was observed using Caco-2/Tc7 cells as a model of the human intestinal epithelium, and the methyslated conjugates were the major metabolites detected. The results of the transport rate data for phenols and their metabolites to the apical, cellular, and basolateral compartments after apical loading of the phenol at 100 μM showed a time-dependent efflux of various free and conjugated forms of phenols.     

In vitro digestibility of bacillus fermented soya bean

Bacillus fermented legume products include among others dawadawa and soumbala made from African locust bean, and natto and kinema made from soya bean. Bacillus subtilis is the dominant species involved in the fermentation. During Bacillus fermentation for 48 h of autoclaved soya bean the quantity of soluble and dialyzable matter increased from 22% and 6% up to 65% and 40%, respectively. Protein and carbohydrate degradation during fermentation of soya bean with several Bacillus spp. was investigated and appeared to be substantial during the first 18 h of fermentation resulting in the release of high levels of peptides and oligosaccharides. In vitro digestibility was increased from 29% up to 33–43% after Bacillus fermentation for 48 h. It was shown that Bacillus spp. were able to degrade soya bean macromolecules to a large extent resulting in water-soluble low molecular weight compounds. In vitro digestion of Bacillus fermented soya bean using gastrointestinal enzymes only slightly increased the amount of dialyzable matter, which clearly demonstrated the beneficial effect of Bacillus fermentation on food nutrient availability.     

Genetic variation in degradability of wheat straw and potential for improvement through plant breeding

The degradability of cereal straw is of importance when it is used for animal feed, biological means of bioenergy production such as bioethanol production and when it is incorporated in soil. We examined wheat straw from 106 different winter wheat cultivars representing the northwest European contemporary gene pool. The cultivars were grown at two different locations to assess the potential for breeding for improved degradability. The straws exhibited much variation in degradability ranging from 258 g kg⁻¹ to 407 g kg⁻¹ of dry matter. The heritability for degradability was estimated to 29% indicating a reasonable potential for response to selection. Inclusion of height as a regression-term, indicated that only a minor part of genetic differences are directly related to plant height and that improvements in degradability may be achieved without unacceptable changes in straw length. Finally, a lack of correlation between degradability and grain yield indicated that straw degradability may be improved through breeding without serious negative effect on grain yield.     

In-Vitro Simulated Gastric Fluid Digestion and Immunogenicity of Different Crustacean Protein Extracts

To compare the immunogenicity and digestibility in-vitro simulated gastric fluid, the protein extracts of white-leg shrimp, Chinese shrimp (female and male shrimp were separated), Southern rough shrimp, Acetes chinensis, Mantis shrimp and crawfish were analyzed by SDS-PAGE, indirect ELISA and Western blotting. The results showed that except for Acetes chinensis, the larger proportion of molecular mass were near to 25 kDa (sarcoplasmic calcium-binding protein) and 38 kDa (tropomyosin). White-leg shrimp protein and Southern rough shrimp protein had a maximum similarity of 68.2%. White-leg shrimp protein had higher immunogenicity than others. There were much more IgE-binding bands in male Chinese shrimp protein, while Crawfish just had only one IgE-binding band (38 kDa, tropomyosin). In simulated gastric fluid system, the protein such as 25 kDa was rapidly degraded within 0.5 mins, while tropomyosin (38 kDa) was relatively resistant to pepsin digestion. The Western blotting results indicated that the allergenicity of those crustacean protein extracts still remained even they were digested with simulated gastric fluid for 60 min.