Physiological and metabolic properties of a digestion-resistant maltodextrin, classified as type 3 retrograded resistant starch

There is a growing interest in highly fermentable dietary fibers having the potential to reduce risks of disease through the production of short-chain fatty acids (SCFA). Recently a digestion-resistant retrograded maltodextrin (RRM), classified as type 3 resistant starch was developed. Systematic work to determine its molecular and physiological properties was carried out to determine (1) the fraction resistant to digestion in vitro and in vivo, (2) its postconsumption effect on blood glucose in healthy volunteers, and (3) its in vitro fermentation pattern, at different ages, by use of pooled fresh human fecal inoculum. RESULTS: The digestion resistant fraction obtained in vivo from ileostomy patients (59.4%) is similar to that obtained by the AOAC method for measuring retrograded resistant starch (59.7%). The relative glycemic response after consumption of 50 g of RRM was 58.5% compared to glucose set as 100%. When exposed to colonic microbiota, in vitro obtained indigestible fractions behave similarly to those obtained in vivo in ileostomy patients. Fermentation of RRM and production of butyric acid is negligible during the first months of life but develops subsequently during weaning. In adults, RRM fermentation results in a high yield of SCFA, with butyrate representing 21-31 mol % of total SCFA. The high yield of SCFA during colonic fermentation, observed from weaning age on, as well as the potential to help reduce glycemic load may be of benefit to a number of health-related functions in the host. Further study on clear clinical end points is warranted.     

Effect of salinity on growth, survival and oxygen consumption of juvenile brown shrimp, Farfantepenaeus californiensis (Holmes)

The brown shrimp, Farfantepenaeus californiensis (Holmes), is a species native to north‐west Mexico, where its culture potential is presently being addressed. Because of the climatic conditions prevailing in the region, salinities over 40 g L^?1 is a commonly encountered problem. In the present study, the effect of salinity on the growth and mortality of juvenile F. californiensis is described. The change in short‐term routine metabolism at different salinities was also evaluated in order to define the adaptive capacity of the shrimp and to provide insight into the changes in the pathways of energy distribution. Groups of shrimp were exposed to increasing salinity (25, 35, 45 and 55 g L^?1), and growth and survival rates after 75 days were determined in duplicate 1.8‐m³ tanks for each salinity level. Significant differences were found in final weight, growth rate and mortality of shrimp as a result of salinity level. Final mean shrimp weights at increasing salinity levels were 10.0, 9.4, 8.6 and 7.8 g. Corresponding mortality was 24.4%, 15.1%, 33.6% and 55.7%. Oxygen consumption was found to depend significantly on salinity and was equivalent to 0.0027, 0.0037, 0.0043 and 0.0053 mg g^?1 min^?1 respectively for the increasing salinities. The increased rate of oxygen consumption at high salinities reflects the response of the organism to osmoregulatory and ionic imbalances. Increased energy requirements to fulfil basic metabolic function as salinity increased resulted in a reduction in the energy that could be diverted to growth. Consequently, the culture of the brown shrimp at salinities over 35 g L^?1 would probably result in reduced yields.     

Comprehensive study on the chemical structure of dioxane lignin from plantation Eucalyptus globulus wood

Results of a comprehensive study on the chemical structure of lignin from plantation Eucalyptus globulus Labill are presented. Lignin has been isolated by a modified mild acidolysis method and thoroughly characterized by functional group analysis, by a series of degradation techniques (nitrobenzene oxidation, permanganate oxidation, thioacidolysis, and Py-GC-MS), and (1)H and (13)C NMR spectroscopy. Plantation Eucalyptus globulus lignin was found to be of the S/G type with an extremely high proportion of syringyl (S) units (82-86%) and a minor proportion of p-hydrophenyl propane (H) units (roughly 2-3 mol %). Unknown C-6 substituted and 4-O-5' type syringyl substructures represent about 65% of lignin "condensed" structures. Eucalypt lignin showed high abundance of beta-O-4 (0.56/C(6)) structures and units linked by alpha-O-4 bonds (0.23/C(6)). The proportion of phenylcoumaran structures was relatively low (0.03/C(6)). Different kinds of beta-beta substructures (pino-/syringaresinol and isotaxiresinol types) in a total amount of 0.13/C(6) were detected. ESI-MS analysis revealed a wide molecular weight distribution of lignin with the center of gravity of mass distribution around 2500 u.     

Influence of thermal processing conditions on acrylamide generation and browning in a potato model system

Fried potato products such as French fries and chips may contain substantial amounts of acrylamide. Numerous efforts are undertaken to minimize the acrylamide content of these products while sensory properties such as color and flavor have to be respected as well. An optimization of the frying process can be achieved if the basic kinetic data of the browning and acrylamide formation are known. Therefore, heating experiments with potato powder were performed under controlled conditions (moisture, temperature, and time). Browning and acrylamide content both increased with heating time at all temperatures and moisture contents tested. The moisture content had a strong influence on the activation energy of browning and acrylamide formation. The activation energy strongly increased at moisture contents below 20%. At higher moisture contents, it was very similar for both parameters. At low moisture contents, the activation energy of acrylamide formation was larger as compared to the one for browning. This explains why the end of the frying process is very critical. Therefore, a lower temperature toward the end of frying reduces the acrylamide content of the product while color development is still good.     

Growth and survival of juvenile red drum,Sciaenops ocellatus,acclimated to freshwater at three different stocking densities in a partial recirculation system

Preliminary technical baseline information for the inland culture of juvenile red drum, Sciaenops ocellatus, in a freshwater fish hatchery is presented. Three initial stocking densities (d₁ = 83, d₂ = 167, and d₃ = 250 fish/m³) were tested in a semirecirculation system for 575 days using a commercially available feed (48.1% protein, 25% lipids, and 0.13% fiber). Initial and final mean fish weight were 7.11 ± 0.02 g and 287.6 ± 27 g. As carrying capacity appeared to have been reached, only data from Days 1–333 were analyzed. One‐way ANOVA analyses indicated that the survival rate of the smaller density (d₁ =40 ± 3.7%) was significantly different from the other two densities (d₃ = 21 ± 1.1% and d₂ = 23 ± 1.0%), which did not differ between them. Absolute growth rate (0.87 ± 0.02 g/day) was not significantly different between densities (F = 0.23. p = .801). Neither was weight significantly different between treatments. There were significant differences in the feed conversion rate (FCR) between densities (F = 8.54; p = .02). FCR for d₁ was significantly lower than for the two other densities, which did not differ from each other. A von Bertalanffy growth model was adjusted (R² = 0.95), and weight–length relationship presented negative allometric values (b = 2.85, R² = 0.98).     

Spoligotype diversity of Mycobacterium bovis and Mycobacterium caprae animal isolates

The genetic diversity of 283 Mycobacterium bovis (M. bovis) and 10 Mycobacterium caprae (M. caprae) strains, isolated between 2002 and 2007 from cattle, goat, red deer and wild boar from six different geographical regions of Portugal was investigated by spoligotyping. The technique showed a good discriminatory power (Hunter-Gaston Index, h=0.9) for the strains, revealing 29 different patterns. One pattern (SB0121) was clearly predominant, accounting for 26.3% of the isolates; ten patterns, representing 20.7% of the isolates, had never been reported previously. Multiple spoligotypes were detected in thirteen cattle and one goat herd, most of which were found in beef cattle and extensive management regions, suggesting different infection sources. With the exception of two spoligotypes, those in wildlife species were also found in domestic species.     

Dietary effects of commercial probiotics on growth performance,digestibility, and intestinal morphometry of broiler chickens

This study compared five commercially available probiotics vis-à-vis antibiotic growth promotant (AGP) supplementation and absence of feed additive based on efficiency, intestinal morphometry, and energy digestibility in improving broiler chicken production. A total of 630 straight run (Cobb) day-old broiler chicks were distributed to seven treatments following a completely randomized design, with ten replicates per treatment and nine birds per replicate per cage. Dietary treatments consisted of basal diet in combination with the following: without probiotics and AGP supplementation (treatment 1); 75 ppm each of chlorotetracycline (CTC) and Zn bacitracin (treatment 2); probiotic A, Bacillus subtilis (treatment 3); probiotic B, Bacillus subtilis (treatment 4); probiotic C, Enterococcus faecium (treatment 5); and probiotic D, Bacillus subtilis (treatment 6); probiotic E, Enterococcus faecium, Bifidobacterium spp., Pediococcus spp., and Lactobacillus spp. (treatment 7). At day 42, energy digestibility was determined by fasting three randomly selected birds from each treatment for 12 h and then subjecting them to their corresponding dietary treatments. Excreta were collected and pooled after 24 h of feeding. Pooled excreta were weighed, oven-dried, and subjected to energy analyses after 3-day collection. Apparent total tract metabolizable energy was then computed. At day 47, three birds were randomly selected per treatment for intestinal morphometry (villi height and crypt depth) of the duodenum, jejunum, and ileum. Dietary supplementation using probiotics showed no significant effect on overall body weight, weight gain, feed consumption, feed efficiency, dressing percentage, mortality, harvest recovery, carcass quality parameters (e.g., meat to bone ratio and abdominal fat content), intestinal morphometry, and energy digestibility. Birds under treatment 7 (basal feed + probiotic E) generated the highest income over feed and chick cost.

     

Performance of a photo‐heterotrophic,hypersaline system for intensive cultivation of white leg shrimp (Litopenaeus vannamei) with minimal water replacement in lined ponds using a stochastic approach

The aim of the study was to evaluate the performance of Litopenaeus vannamei in an intensive photo‐heterotrophic hypersaline system with minimal seawater replacement, and establish relationships between parameters of a stochastic production model and relevant water quality variables. Six experimental 1000 m² lined ponds were stocked at a density of 120 shrimp m^?2 for a 105‐day trial. Salinity increased from 37 to 45 ± 2 g/L, and the water level was maintained with the weekly addition of filtered seawater, equivalent to 1.6% per day. The stochastic model predicted that, at harvest, there is 95% confidence that the system produces between 12.1 and 14.7 t/ha with a mean final individual weight of 13.1 g and a mean survival of 84.2%. Sensitivity analyses showed that dissolved oxygen and individual final weight of shrimp were the main variables influencing yield variance. Nitrogenous compounds were maintained between optimal cultivation levels (NH₃–NH₄⁺ = 0.73 ± 0.43 mg/L, N–NO₂^? = 0.09 ± 0.05 mg/L, N–NO₃^? = 3.22 ± 0.11 mg/L). Heterotrophic bacteria (6.6 ± 3.4 × 10⁵ CFU/ml) and chlorophyll‐α concentration (108.5 ± 80.2 μg/L) showed a similar development pattern, indicating a strong relationship between bacteria and microalgae during cultivation. Vibrio spp. concentrations were low (1.24 ± 1.42 × 10³ CFU/ml). It was shown that the photo‐heterotrophic system could be used in hypersaline conditions, typical of semi‐arid regions, to consistently produce between 12.1 and 14.7 t/ha in 15 weeks.