Furan quantification in bread crust: development of a simple and sensitive method using headspace-trap GC-MS

To study reactivity in bread crust during the baking process in the pan, we followed furan mainly resulting from Maillard and caramelisation reactions in cereal products. Furan quantification is commonly performed with automatic HS-static GC-MS. However, we showed that the automatic HS-trap GC-MS method can improve the sensitivity of the furan quantification. Indeed, this method allowed the LOD to be decreased from 0.3 ng g^–1 with HS-static mode to 0.03 ng g^–1 with HS-trap mode under these conditions. After validation of this method for furan quantification in bread crust, a difference between the crust extracted from the bottom and from the sides of the bread was evident. The quantity of furan in the bottom crust was five times lower than in the side crust, revealing less reactivity on the bottom than on the sides of the bread during the baking process in the pan. Differences in water content may explain these variations in reactivity.     

Biocontrol of Listeria monocytogenes by lactic acid bacteria isolated from brewer's grains used as feedstuff in Argentina

Brewer's grains are the most important by-product of the brewery industry and it is mostly used as a protein and energy source in animal nutrition. Listeria monocytogenes is a food-borne pathogen can cause invasive diseases such as meningoencephalitis, sepsis, abortion, and gastroenteritis in humans and several animal species. The aim of this work was to study the antilisterial activity of lactic acid bacteria (LAB) isolated from brewer's grains. The incidence of Listeria spp. in brewer's grains was 3.12%. Twenty-one LAB inhibited the growth of the eight strains of L. monocytogenes. The mean inhibition halo of cell free supernatants of LAB ranged between 11.5 and 24.5 mm. The isolation of lactic acid bacteria with antilisterial activity from brewer's grains is promising based on their capacity to produce antimicrobial compounds. The production of antimicrobial metabolites by LAB in the substrate would generate an unfavorable environment for the growth of the pathogenic bacterium under study.     

陶融型酒醅中产香芽孢杆菌的筛选、鉴定及发酵产物分析

通过传统微生物分离法和纯种固态发酵产香试验,从陶融型酒醅微生物资源中分离、筛选产香能力优良的芽孢杆菌,采用形态观察、生理生化试验及分子生物技术对其进行鉴定,并对其耐受性进行研究。结果表明,从陶融型酒醅中共分离得到11株芽孢杆菌,其中,菌株YSB11产香较好,固态发酵产物中含有浓郁的焦香、糊香和酱香味,包含酚类、吡嗪类、呋喃类、芳香类、酯类等多种白酒中重要的呈香物质,为优良产香芽孢杆菌。菌株YSB11被鉴定为贝莱斯芽孢杆菌（Bacillus velezensiss）,可耐高温53 ℃、酒精度6%vol、NaCl含量8%及低pH值6.0。     

谷物挥发物对储粮害虫行为的影响及其应用研究进展

对谷物挥发物研究现状、谷物挥发物对害虫行为的影响、植食性昆虫学习行为对储粮害虫行为的影响、谷物挥发物与储粮害虫防治的关系等进行综述,以期对今后开展谷物挥发物在储粮害虫综合防治方面的研究与应用提供一定的借鉴。     

Ruminal fermentation,kinetics, and total-tract digestibility of lactating dairy cows fed distillers dried grains with solubles in low- and high-forage diets

The objective of this study was to investigate the effects of concentrations of forages and corn distillers dried grains with solubles (DDGS) on ruminal fermentation, ruminal kinetics, and total-tract digestibility of nutrients in lactating dairy cows. Four lactating Holstein cows with ruminal cannulas were assigned to a 4 × 4 Latin square in a 2 × 2 factorial arrangement of treatments. Diets were formulated to contain low forage [LF; 17% forage neutral detergent fiber (NDF)] or high forage (HF; 24.5% forage NDF) and DDGS at 0 or 18% (0DG or 18DG) of diet dry matter (DM). Intake of DM was not affected by the diets. Daily mean ruminal pH was affected by forage NDF × DDGS interactions, as the lowest ruminal pH was observed among cows fed LF18DG (6.02). Apparent total-tract digestibility for DM, organic matter, crude protein, NDF, acid detergent fiber, and starch was not affected by diets. Cows fed LF diets had a greater total volatile fatty acid concentration compared with cows fed HF (122 vs. 116 mM). Molar proportions of acetate were greater for HF compared with that of LF diets (62.6 vs. 57.5 mmol/100 mmol) and greater for 0DG diet compared with that of 18DG diets (61.3 vs. 58.7 mmol/100 mmol) diets. The molar proportion of propionate was affected by forage × DDGS interaction as the greatest propionate molar proportion was observed with cows fed LF18DG diet (27.7 mmol/100 mmol). Also, molar proportion of butyrate was affected by forage × DDGS interaction, as the greatest butyrate molar proportion was observed in cows fed HF18DG diet (13.5 mmol/100 mmol). Average fractional dilution rate for all diets was 11.9%/h and was not affected by diets. Fractional passage rate of the solid phase was greater for HF than for LF (4.40 vs. 3.76%/h). The ruminal retention time of solid phase was greater for LF compared with HF diets (27.3 vs. 23.3 h). Fractional passage rate of DDGS was affected by forage × DG interaction, as the highest fractional passage rate of DDGS was observed with cows fed HF18DG diet (7.72%/h). Our results demonstrated that concentrations of forage, DDGS, and their interaction influence ruminal degradation and kinetics of diets fed. Diets formulated at 17% forage NDF at 17% (DM basis) can decrease milk fat concentration compared with diets formulated at 25% forage NDF. Additionally, feeding DDGS at 18% DM basis to lactating dairy cows did not affect milk fat concentration or yield.     

吹扫捕集气相色谱法测定粮食中熏蒸剂氰与氰化氢残留量

采用吹扫捕集气相色谱法建立了熏蒸剂氰和氰化氢在粮食(玉米、高粱、稻谷、小麦和大麦)中的分析方法,对粮食中氰和氰化氢预处理的吹扫温度、吹扫载气(N2)流量和吹扫时间等参数进行了优化,分析了吹扫捕集气相色谱测定的回收率、精密度、检出限和定量限等质量控制参数,并测定了实际熏蒸粮食中氰及其降解产物氰化氢残留量.结果表明,用50％磷酸溶液作溶剂,吹扫温度80℃、吹扫载气(N2)流量40 mL/min和吹扫时间90 rain为最佳的吹扫方法参数.采用该方法测定粮食中氰和氰化氢的加标回收率分别为90.88％～96.25％和91.17％～95.83％,相对标准偏差(RSD)分别为0.36％～5.55％和0.90％～6.24％(n=6),检出限(LOD)分别为0.003 6 mg/kg和0.005 3 mg/kg(S/N=3),定量限(LOQ)分别为0.012 0 mg/kg和0.017 7mg/kg (S/N=10).用吹扫捕集法检测熏蒸粮食中氰其降解产物氰化氢的残留量与溶剂顶空法测定结果相一致.     

全谷物成分对面制品品质及加工特性影响研究进展

文章介绍了全谷物中的淀粉、蛋白质、油脂、多酚等成分对面团加工特性和面制品品质的影响,并分析了全谷物面制品中存在的问题以及改善措施。     

黄曲霉毒素检测方法研究进展

黄曲霉毒素主要是由黄曲霉和寄生曲霉产生的一类次级代谢产物,经常污染粮油原料及其制品,具有强致癌性.介绍了黄曲霉毒素毒性及一些国家和地区的残留限量标准;针对不同基质间组分存在较大差异,概述了液液萃取、超临界流体萃取、固相萃取及免疫亲和柱净化等样品前处理方法;同时对薄层色谱、高效液相色谱、酶联免疫吸附等测定黄曲霉毒素的方法、原理、应用及特点进行了综述;最后分析了黄曲霉毒素检测技术的发展趋势.