Effect of enzymatic and technological treatments on solubilisation of arabinoxylans from brewer's spent grain

Brewer's spent grain (BSG), the most abundant brewing by-product, has hidden and underexploited nutritional potential. In order to valorize BSG, the effects of three commercial xylanases and a peptidase on water unextractable arabinoxylans (WUAX) were studied. Comparing all treatments, higher addition of xylanase resulted in an increase in water extractable arabinoxylans (WEAX). In the most efficient treatment, xylanase alone was able to solubilise 23.7% of WUAX, while the peptidase showed no effect. However, when added together with xylanase, peptidase increased the solubilisation of WUAX up to 1.6 folds. A positive correlation between particle size reduction and solubilisation of WUAX was also proved through milling BSG. These results suggest that access to xylan backbone increases with proteolytic activities, proving a synergistic effect of these specific enzymes. Therefore, if properly treated before being added as ingredient, BSG could add health functionalities to foodstuff while reducing the environmental impact of brewing industries.     

Modelling the food web for assessment of the impact of stock supplementation in a reservoir ecosystem in India

Comparative estimates of trophic status and energy flow were carried out in a tropical reservoir ecosystem in India to assess the impact of fish stocking. Mass‐balanced models of the reservoir ecosystem were constructed for two periods – 1982–1983 and 2002–2003 – using ecopath software to determine the impacts on different groups before and after stocking. Mixed trophic impact (MTI) analyses indicated that phytoplankton and detritus have a positive impact on most groups. There was a decrease in nutrient flow through the system from pre‐stocking to post‐stocking (22.28%). The baseline was higher by 0.29% in the post‐stock phase indicating maturity. The ecosystem indices tested indicate that the reservoir was in a more resilient state post‐stocking than during the pre‐stocking phase. The ‘health’ of the ecosystem showed an improvement, which indicates a positive impact of stocking.     

Stable carbon isotopes accurately predict diet selection by sheep fed mixtures of C3 annual pastures and saltbush or C4 perennial grasses

The stable carbon isotope technique has been widely used to infer the dietary ecology of a range of animal species; however calibration of the technique with animals fed known diets is essential for accurate back-calculation of dietary preferences. The aim of this study was to identify suitable samples and back-calculation methods to predict short-term (2 to 3 week) dietary selection by sheep among plants with C₃ and C₄ photosynthetic pathways. Variation in integration time of dietary carbon into plasma and faeces; diet-tissue discrimination of carbon isotopes (fractionation) and the importance of accounting for the digestible or indigestible components of the diet was investigated. The results indicate that faecal and rumen samples provided the most accurate prediction of short term dietary changes in sheep selecting between C₃ and C₄ plants. The most accurate back-calculation method for these samples used δ¹³C of the C₃ and C₄ plants and accounted for both diet-tissue discrimination and differences in the indigestibility between the C₃ and C₄ forage. For faecal samples, the organic matter content of the diet originating from C₄ plants could be predicted with a mean error as low as 2.7%. Wool and plasma samples were not conducive to predicting proportion of C4 forage in the diet within 18 days after a change in diet; however plasma could be used to discriminate between animals fed 100% C₃ and C₄ diets after 3 days. The δ¹³C technique provides a valuable tool for researchers when designing pastures for dual environmental and production purposes. An understanding of what sheep select allows for development of appropriate grazing management strategies to optimise productivity and/or persistence of target species.     

黄曲霉毒素限量标准对我国居民消费安全和花生产业的影响

2009-2010年对全国花生黄曲霉毒素污染进行了普查监测,根据检测结果,利用蒙特卡罗方法,开展了我国与CAC、欧盟、日本、澳大利亚和新西兰等国际组织和主要贸易国不同花生黄曲霉毒素限量对我国人群直接食用花生的致癌风险和对产业影响的研究。结果表明,不同花生黄曲霉毒素限量标准对我国人群摄入产后花生导致的原发性肝细胞癌年发生率影响差异不显著,但对经济和产业造成的影响差异显著。研究结果为制定我国花生黄曲霉毒素限量标准以及促进花生生产、贸易提供技术参考。     

膳食纤维研究进展

论述了膳食纤维的定义和测定方法,介绍了膳食纤维的理化特性及生理功能,对膳食纤维的研究进行了展望。我国居民膳食纤维摄入量不足,应充分利用我国膳食纤维资源丰富的优势,大力推动膳食纤维产业的发展。     

Glycaemic response to frozen stored wheat rolls enriched with inulin and oat fibre

The aim of this study was to examine the effect of dietary fibre addition to partially baked and frozen wheat rolls on the glycaemic index (GI).     

盐度波动和中草药制剂对脊尾白虾存活·生长和免疫的影响

[目的]为大规模脊尾白虾的养殖提供理论基础。[方法]研究了盐度波动幅度（S0、S3、S6和S9分别代表盐度波动幅度为0、3、6和9）和中草药制剂（0、1%、2%和4%）对脊尾白虾存活、生长和免疫的影响,试验周期60 d。[结果]1%中草药和S6盐度波动处理组脊尾白虾的特定生长率、饲料转换效率和超氧化物歧化酶活性均高于其他处理,且显著高于同一中草药添加水平的S0,S3和S9盐度波动处理组。回归分析结果表明,在S0、S3和S6 3个盐度波动水平,随盐度波动幅度增加,饲料中的中草药制剂的最适添加量呈下降趋势,分别为2.74%、1.77%和0.51%;在4个中草药制剂添加水平,随饲料中的中草药制剂添加量增加,脊尾白虾生长的最适盐度波动幅度呈下降趋势,分别为5.26、4.95、3.54和1.97。[结论]盐度、中草药制剂及其相互作用对脊尾白虾的存活、生长和免疫均有显著影响,因此在养殖时应加以注意。     

Inflammation-associated responses in piglets induced with post-weaning colibacillosis are influenced by dietary protein level

Forty piglets (average body weight = 5.32 kg) were used to investigate the effect of dietary crude protein (CP) content on immunological responses following a challenge with enterotoxigenic Escherichia coli (ETEC) K88. Pigs, housed 4 per pen, were randomly allotted to 2 diets: 1) a high, 225 g/kg CP diet (HCP) or 2) a low, 176 g/kg CP diet (LCP) supplemented with crystalline amino acids. Pigs were orally challenged with 6 mL of an ETEC K88 suspension containing 10¹⁰ cfu/mL on d 8 after weaning. Blood samples were collected from 10 pigs (1 pig/pen) on d 7 (at weaning), −24 h, 8 h, 72 h and 7 d after the challenge for determination of plasma urea N (PUN) and serum concentrations of tumor necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β) and haptoglobin (Hp). Tumor necrosis factor alpha, IL-1β and Hp were measured as indicators of inflammatory responses. The concentrations of serum TNF-α at 8 h, 72 h and 7 d after challenge were similar to the level observed at 24 h before challenge but higher (P < 0.05) than the weaning level. Pigs fed the LCP diet had lower (P = 0.032) concentrations of IL-1β (72 vs. 116 pg/mL) at 8 h post-challenge compared with those fed the HCP diet. Likewise, pigs fed the LCP diet tended to have lower (P = 0.088) concentration of Hp (9 vs. 25 mg/dL) compared with those fed the HCP diet at 8 h post-challenge. Compared with the weaning concentration, PUN concentration at 72 h after ETEC challenge was higher (P < 0.05) in pigs fed the HCP diet. The results indicate that the LCP diet supplemented with crystalline amino acids reduced inflammatory responses, as indicated by serum IL-1β, in piglets infected with ETEC K88.     

Analysis of polyphenols in cereals may be improved performing acidic hydrolysis: A study in wheat flour and wheat bran and cereals of the diet

Most analytical studies on polyphenols in cereals refer to compounds determined in aqueous-organic extracts and alkali hydrolysates, but an appreciable amount of polyphenols bound to cell wall constituents may remain insoluble in the residues of extraction and alkali hydrolysis. The main objective of this work was to determine if sulphuric acid hydrolysis may release significant amounts of polyphenols to be considered for analytical and nutritional studies. HPLC/MS analyses of polyphenols were performed in methanol–acetone extracts, alkali and sulphuric acid hydrolysates of wheat flour, bran and a pool of cereals of the diet. The amount of polyphenols found in the acidic hydrolysates (200–1600 mg/100 g) was higher than in alkali hydrolysates (0.2–372 mg/100 g). Lower amount of polyphenols were found in the methanol–acetone extracts (44–160 mg/100 g). Hydroxybenzoic, caffeic, cinammic, ferulic and protocatechuic acids were the main constituents of the hydrolysates. The contribution of cereals to the intake of dietary polyphenols in Spain was estimated around 360 mg/person/day (65 mg of extractable and 295 mg nonextractable polyphenols).     

Digestibility and nitrogen utilization in sheep fed enset (Ensete ventricosum) pseudostem or corm and graded levels of Desmodium intortum hay to wheat straw‐based diets

The aim of this study was to investigate the effects of different levels of Desmodium intortum (Desmodium) hay supplementation in sheep fed fixed amounts of enset pseudostem or corm and a basal diet of wheat straw on intake, digestibility and nitrogen utilization. Eighteen male sheep with a mean (± SD) live weight of 20.5 ± 1.45 kg were assigned to six treatments in a completely randomized design and fed either 108 g dry matter (DM) enset pseudostem or 165 g DM enset corm each with three levels (100, 200 and 300 g) of hay supplementation. For the pseudostem diets, there was no significant difference in total DM intake. Total crude protein (CP) intake and N retention increased with increasing levels of hay in both pseudostem and corm diets. The apparent digestibility of DM, OM, CP, acid detergent fibre and neutral detergent fibre (NDF) and microbial nitrogen supply (MN) at 100 g was lower that other levels of supplementation. For the corm diets, total DM and OM intake and MN supply increased with increasing levels of hay. The digestibility decreased (p < 0.001) with increasing levels of supplementation. The results suggest that at least 300 g (395 g/kg dietary DM) of Desmodium hay is required in pseudostem diets, whereas 200 g (337 g/kg dietary DM) may be sufficient in corm diets for efficient nutrient utilization.