The capacity of silage inoculant bacteria to bind aflatoxin B1 in vitro and in artificially contaminated corn silage

The objectives were to examine the aflatoxin B₁ (AFB₁)-binding capacity of silage bacteria and factors affecting the responses. Experiments 1 and 2 examined the effects of bacterial strain and population on the AFB₁-binding capacity of 10 bacteria. When applied at 10⁶ cfu/mL to an in vitro medium, only Lactobacillus plantarum PT5B bound the AFB₁ and the binding capacity was low (4%). When applied at 10⁹ cfu/mL, all 10 bacteria bound AFB₁, but L. plantarum R2014 (Lp) and EQ12, Lactobacillus buchneri R1102 (Lb), and Pediococcus acidilactici R2142 and EQ01 (Pa) had the greatest capacity (23.9 to 33%). Experiment 3 examined the AFB₁-binding capacity of viable and nonviable (HCl-treated) forms of Lp, Lb, and Pa at different pH. Nonviable Lb and Lp, but not Pa, increased AFB₁ binding. Binding of AFB₁ was greatest at pH 2.5 and least at pH 8. As the nonviable Lb and Lp that bound AFB₁ in experiment 3 would not be effective silage inoculants, experiment 4 examined effects of benign versus severe treatments (85 vs. 100°C; pH 2.5 vs. <1) on the viability of Lp, Lb, and Pa. The population of bacteria was reduced from 9 to 4 log cfu/mL by treatment with HCl at pH 2.5 and to 2 log cfu/mL by 85 or 100°C, whereas acidification at pH <1 eliminated the bacteria. Experiment 5 determined the effect of the ensiling duration and benign treatment methods [37 (viable cells) or 85°C (heated cells) or acidification with HCl at pH 2.5 (acid-treated cells)] on binding of AFB₁ and silage quality during the fermentation of corn forage. Corn forage was ensiled after treatment with only deionized water (control), AFB₁ (30 µg/kg of fresh forage), or a mixture of AFB₁ and 10⁹ cfu/g of each of the treated bacteria. Adding AFB₁ alone to corn forage reduced the pH decline during the first 3 d of ensiling and increased or tended to increase butyric acid concentration and final pH after ensiling for 21 d. Bacterial inoculation inhibited these negative effects. The fermentation profile of silage treated with Lb and Pa did not differ from those of the control silage. In all silages treated with the toxin, the AFB₁ concentration decreased linearly (from 30 to ≤0.35 µg/kg) within 3 d of ensiling. Certain silage bacteria can bind AFB₁ but the efficacy depends on several factors.     

Selection of tropical lactic acid bacteria for enhancing the quality of maize silage

The objective of this study was to select lactic acid bacteria (LAB) strains isolated from silage and assess their effect on the quality of maize silage. The LAB strains were inoculated into aqueous extract obtained from maize to evaluate their production of metabolites and pH reduction. The ability to inhibit the pathogenic and silage-spoilage microorganisms’ growth was evaluated. Nine LAB strains that showed the best results were assessed in polyvinyl chloride experimental silos. The inoculation of the LAB strains influenced the concentration of lactic and acetic acids and the diversity of Listeria. The inoculation of silages with Lactobacillus buchneri (UFLA SLM11 and UFLA SLM103 strains) resulted in silages with greater LAB populations and improvements after aerobic exposure. The UFLA SLM11 and SLM103 strains identified as L. buchneri showed to be promising in the treatment of maize silage.     

深海粗鱼油的精炼工艺研究

对深海杂鱼粗鱼油精炼工艺进行优化,考察了磷酸体积分数、超量碱和活性白土添加量对鱼油酸值、回收率和感官品质的影响,并对精炼鱼油的理化指标及脂肪酸组成进行分析。结果表明:适宜的精炼条件为采用占鱼油质量1%、体积分数80%的磷酸脱胶,脱胶油中加入占鱼油质量1.5%的超量碱和理论碱量的Na OH(4 mol/L)脱酸,脱色选用添加占鱼油质量20%的活性白土;精炼鱼油的理化指标均达到我国水产行业精制鱼油的一级标准(SC/T 3502—2000),酸值(KOH)由(5.52±0.12)mg/g下降到(0.29±0.11)mg/g;精炼工艺对鱼油脂肪酸组成的影响较小,其中二十碳五烯酸和二十二碳六烯酸的总量约占总脂肪酸含量的38%,且分别占多不饱和脂肪酸含量的35.99%和51.59%,品质较优。     

Natural populations of lactic acid bacteria isolated from vegetable residues and silage fermentation

Natural populations of lactic acid bacteria (LAB) and silage fermentation of vegetable residues were studied. Fifty-two strains of LAB isolated from cabbage, Chinese cabbage, and lettuce residues were identified and characterized. The LAB strains were gram-positive and catalase-negative bacteria, which were divided into 6 groups (A to F) according to morphological and biochemical characteristics. The strains in group A were rods that did not produce gas from glucose and formed the d and l isomers of lactate. Groups B and C were homofermentative cocci that formed l-lactic acid. Groups D, E, and F were heterofermentative cocci that formed d-lactic acid. Based on 16S rDNA gene sequence analysis, group A to F strains were identified as Lactobacillus plantarum, Lactococcus piscium, Lactococcus lactis, Leuconostoc citreum, Weissella soli and Leuconostoc gelidum, respectively. The prevalent LAB, predominantly homofermentative lactobacilli, consisted of Lactobacillus plantarum (34.6%), Weissella soli (19.2%), Leuconostoc gelidum (15.4%), Leuconostoc citreum (13.5%), Lactococcus lactis (9.6%), and Lactococcus piscium (7.7%). Lactobacillus plantarum was the dominant member of the LAB population in 3 types of vegetable residues. These vegetable residues contained a high level of crude protein (20.2 to 28.4% of dry matter). These silages prepared by using a small-scale fermentation system were well preserved, with low pH and a relatively high content of lactate. This study suggests that the vegetable residues contain abundant LAB species and nutrients, and that they could be well preserved by making silage, which is a potentially good vegetable protein source for livestock diets.     

Identification of lactic acid bacteria in the rumen and feces of dairy cows fed total mixed ration silage to assess the survival of silage bacteria in the gut

The survival of silage lactic acid bacteria (LAB) in the gut of dairy cows was evaluated by examining the LAB communities of silage and gut contents. Samples were collected at 2 different research institutes (Mie and Okayama) that offered total mixed ration (TMR) silage throughout the year. Silage and feces were sampled in August, October, and November at the Mie institute, whereas silage, rumen fluid, and feces were sampled in June and August at the Okayama institute. Denaturing gradient gel electrophoresis using Lactobacillus-specific primers was performed to detect LAB species in the samples. The selected bands were purified for species identification and the band patterns were used for principal component analysis. Lactic acid was the predominant fermentation product in all the TMR silages analyzed, and the lactic acid level tended to be constant regardless of the sampling time and region. A total of 14 LAB species were detected in the TMR silage samples, of which 5 (Lactobacillus acetotolerans, Lactobacillus pontis, Lactobacillus casei, Lactobacillus suebicus, and Lactobacillus plantarum) were detected in the dairy cow feces. Most of the denaturing gradient gel electrophoresis bands for the feces samples were also detected in the rumen fluid, suggesting that any elimination of silage LAB occurred in the rumen and not in the postruminal gut segments. The principal component analysis indicated that the LAB communities in the silage, rumen fluid, and feces were separately grouped; hence, the survival of silage LAB in the cow rumen and lower gut was deemed difficult. It was concluded that, although the gut LAB community is robust and not easily affected by the silage conditions, several LAB species can inhabit both silage and feces, which suggests the potential of using silage as a vehicle for conveying probiotics.     

海洋鱼油的生产与应用

全面回顾了国内外海洋鱼油生产与应用的历史与现状,指出海洋鱼油作为二十碳五烯酸(EPA)、二十二碳六烯酸(DHA)等ω-3多不饱和脂肪酸的重要来源,正在饲料、食品以及药品等领域展示其良好的应用前景.     

Enhanced lactic acid fermentation of silage by the addition of green tea waste

The effects of green tea waste (GTW) addition on the ensiling of forage were investigated. Wet and dried GTW added at 10, 50, 100 and 200 g kg^?1 of fresh matter (FM) and at 2, 10 and 20 g kg^?1 FM, respectively, decreased pH and increased lactic acid concentration of the silages, whereas the butyric acid concentration and ammonia nitrogen content, as a proportion of a total nitrogen, were lowered, compared with silage without additives (control). To investigate the effect of GTW‐associated LAB on silage fermentation, wet GTW was sterilized by autoclaving or gamma irradiation and added at 50 g kg^?1 FM. The silages made with sterilized GTW showed higher lactic acid concentrations, and lower pH and butyric acid concentrations than controls. The counts of lactic acid bacteria (LAB) were higher in silages made with sterilized GTW than control until 10 days after ensiling. The enhanced lactic acid fermentation was not found when green tea polyphenols (GTP) were added. These data suggested that GTW could enhance LAB growth and lactic acid production of silage, particularly when added at 50 g kg^?1 FM in a wet form or at the equivalent in a dry form. Although neither GTW‐associated LAB nor GTP accounted for the enhancement of lactic acid fermentation, GTW would possibly supply some nutrients which are heat‐stable and effective for LAB growth during silage fermentation. Copyright © 2004 Society of Chemical Industry     

淡水鱼油性质测定及其在人乳替代脂市场的应用研究

对巴沙鲶鱼油等市场上常见的10种淡水鱼油脂肪酸、sn-2脂肪酸组成进行了测定与分析。结果表明:大部分淡水鱼油中棕榈酸含量在15%~25%、油酸含量在25%~45%,和人乳脂肪较为接近;巴沙鲶鱼油、黑鱼油、鲈鱼油、鲤鱼油、白鲢鱼油sn-2棕榈酸含量分别为44.27%、40.91%、31.31%、30.02%和31.02%,且sn-2棕榈酸分布均高于50%;巴沙鲶鱼油、黑鱼油的sn-1,3油酸含量在50%左右,并通过UPLC-MS/MS验证了OPO的存在,推测适合作为人乳替代脂的基料油;鲤鱼油中中碳链脂肪酸C10∶0和C12∶0总含量超过10%,易于婴幼儿吸收;鲈鱼油中DHA含量为12.73%,对于婴幼儿智力发育有着关键作用,鲤鱼油和鲈鱼油适合作为人乳替代脂的配料油。     

Characteristics of lactic acid bacteria isolated from forage crops and their effects on silage fermentation

Enterococcus faecalis CA 6, E faecium CA 10, E casseliflavus CA 13, Weissella paramesenteroides CA 14, Leuconostoc pseudomesenteroides CA 17, Pediococcus pentosaceus CA 21, P acidilactici CA 25 and Lactobacilus plantarum CA 28 isolated from forage crops were characterised and their effects on silage fermentation were studied. Strains CA 6, CA 10 and CA 13 grew only at relatively high pH (above 5.0), while strains CA 21, CA 25 and CA 28 were able to grow at pH values below 4.0. Strain CA 25 grew at 50 °C, but the others did not grow at above 45 °C. These strains were used as inoculants for perennial ryegrass silage ensiled at 25 or 45 °C. At 25 °C all strains significantly (P < 0.01) reduced the pH value and butyric acid content and greatly increased the lactic acid content compared with the control, particularly strains CA 21, CA 25 and CA 28. At 45 °C strain CA 25 markedly improved the fermentation quality of silage, but the others did not. These silages had a lower lactic acid content and a higher proportion of L (+)‐ to total lactic acid than equivalent silages kept at 25 °C. The results confirmed that at 25 °C P pentosaceus CA 21, P acidilactici CA 25 and L plantarum CA 28 were the most effective, whereas at 45 °C only P acidilactici CA 25 had a beneficial effect on silage fermentation quality. © 2000 Society of Chemical Industry     

鱼油品质光谱检测技术的研究进展

鱼油制品具有丰富的营养功能,深受消费者喜欢。常规检测鱼油品质方法,由于操作困难、破坏性强、试剂污染等缺点,不能满足快速无损、高效无污染的检测要求。光谱检测技术(如近红外光谱技术和核磁共振技术),伴随着化学计量学的发展,突破了常规检测方法局限性,是鱼油品质检测技术的发展趋势。在大量文献的基础上,综述目前光谱检测技术在鱼油品质的应用情况,特别分析光谱方法、化学计量学和仪器设备,指出现阶段利用光谱技术检测鱼油品质存在的主要问题,并对今后的研究方向进行展望。     

接种乳酸菌对腌干鱼总脂肪及游离脂肪酸的影响

在低盐腌制的鱼肉中接种复合乳酸菌,发酵及干燥制成腌干鱼。研究接种复合乳酸菌对腌干鱼总脂肪和游离脂肪酸的影响,结果表明:接种乳酸菌腌制的鱼肉(EG)总脂肪相对含量低于非接种组(CK),游离脂肪酸总量高于非接种组。EG组鱼的不同游离脂肪酸含量高低顺序为:多不饱和脂肪酸>单不饱和脂肪酸>饱和脂肪酸。CK组鱼的不同游离脂肪酸含量高低顺序为:多不饱和脂肪酸>饱和脂肪酸>单不饱和脂肪酸。其游离脂肪酸变化与非接种组比较,表现为饱和脂肪酸含量显著减少,不饱和脂肪酸含量显著增加。其饱和脂肪酸含量显著减少的有:棕榈油酸(C16∶0)和十八酸(C18∶0),不饱和脂肪酸显著增加的有:花生四烯酸(C20∶4)和二十碳五烯酸(C20∶5)。接种乳酸菌在一定程度上提高了腌干鱼肉的营养价值和食用价值。      

Effect of heating fatty fish: Baltic herring (Clupea harengus membras), European sprat (Sprattus sprattus) and rainbow trout (Oncorhynchus mykiss) on lipid oxidation and contents of eicosapentaenoic and docosahexaenoic acids

In this study, analyses were carried out to establish the impact of heating three species of fatty fish: trouts, herrings and sprats, on the lipids oxidation and on contents of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. The comminuted fish tissue was heated at restricted access of oxygen at temperature of 60, 100 and 160 °C for 15–120 min. Lipids, extracted with the Bligh‐Dyer method, were determined for peroxide value (PV) and anisidine value (AV). The Fatty acid methyl esters were prepared directly from the tissue, whereas contents of EPA and DHA were determined with the GC/MS method. Depending on the temperature applied, 15‐min heating of fish meat tissue caused 30–80% decrease of PN and 20–40% decrease of AV, on average. Generally, the continued heat treatment caused successive decreases in both PV and AV and the rate of this process was observed to increase along with an increasing temperature. The heating of trout and sprats at temperature of 60, 100 and 160 °C even for 1–2 h did not evoke losses either in EPA or in DHA content. In turn, in the case of herring caught during the pre‐spawning season, ca. 90–120 min of heat treatment contributed to ca. 20–25% decrease in contents of these fatty acids.     

甜高粱青贮饲料中乳酸菌最佳添加剂量的探讨

研究自制复合乳酸菌制剂对甜高粱秸秆青贮品质的影响,以探讨自制复合乳酸菌制剂对甜高粱秸秆青贮的最佳添加剂量。以甜高粱秸秆为材料,分别接种0.5mL/kg、1.0mL/kg、1.5mL/kg、2.0mL/kg、2.5mL/kg的自制菌剂和一定比例的台湾、美国商品青贮 菌剂,并以不加菌剂为空白对照（CK）进行青贮,青贮后检测分析评价。添加自制菌剂后,乳酸含量明显提高（P＜0.05）,中性洗涤纤 维含量显著降低（P＜0.05）,氨基酸态氮/总氮含量下降。添加量为1.5mL/kg时,乳酸含量最高,较对照高了177.15%,较美国、台湾分 别高出29.90%、31.18%;粗蛋白含量最高,比对照高了25.61%,比美国、台湾分别高出13.51%、8.91%;同时,1.5mL/kg处理组总糖含量 较美国、台湾高出14.01%、6.81%。经综合评价,自制乳酸菌剂可提高甜高梁青贮发酵品质,最佳添加量为1.5mL/kg。     

腌鱼制品中乳酸菌及其对品质影响的研究进展

随着人们生活水平的提高,饮食结构和消费习惯的变化,人们对食品品质的要求也越来越高,改变传统食品加工方式,开发低盐、健康、安全的腌制品加工技术势在必行。腌鱼是我国重要的传统水产食品,具有咸鲜相宜、风味独特的特点,深受国内外消费者的喜爱。腌鱼加工过程中,蛋白质和脂肪被肌肉中的内源酶和微生物酶降解为小肽、氨基酸和脂肪酸等,这个过程中发生的蛋白水解、脂肪氧化和脂肪水解三大反应决定了腌鱼制品的营养品质。乳酸菌是腌制食品自然发酵中的常见菌种之一,可通过参与一系列的物理化学反应,改善食品的营养特性,提升产品品质和安全性,赋予产品独特的风味,延长食品保质期,在食品行业被广泛应用。本文综述了国内外腌鱼制品中的乳酸菌及其对产品品质的影响,为创新开发新型腌鱼制品提供理论依据,也为传统食品的技术改造提供新的思路。     

Fatty acid profile and proximate composition of Pacific mullet (Mugil so‐iuy) caught in the Black Sea

This study demonstrates proximate composition and fatty acid profile of Pacific mullet caught in Turkey. The highest moisture and protein contents were observed with muscle tissues as 83.74 and 10.52%, while the highest fat and ash contents were attributed to female gonads as 11.80 and 0.94%, respectively, with a significant variation amongst months (P < 0.05). Significant variation (P < 0.05) usually occurred amongst months within the same sex for total saturated fatty acids ( ∑ SFA), monosaturated fatty acids ( ∑ MUFA), polyunsaturated fatty acids ( ∑ PUFA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in muscle, although overall mean values between sexes were not found significant. Except for EPA, no variation observed for gonads while significant changes occurred (P < 0.05) with liver samples amongst months. Overall total values of ∑ SFA, ∑ MUFA, ∑ PUFA, DHA and EPA in muscle samples were 29.59, 29.26, 18.06 and 4.48%, respectively, while in gonads ranged as 30.26–33.23%, 35.17–37.47%, 11.87–14.88%, 4.38–5.34% and 3.02–5.02%. These FAs were 21.57–33.11%, 32.89–50.96%, 14.78–20.08%, 0.89–9.94% and 5.85–9.54% for liver, respectively. The results of this study showed that muscle and gonads of Pacific mullet were rich in n‐3 PUFA, especially, EPA, DHA, increasing the value of this species for human consumption.     

Gas-liquid chromatography and the arachidonic acid content of Atlantic food fish

Some gas-liquid chromatographic analyses have overlaps among fatty acid chain lengths. In fish depot fats the resulting peak coincidence of docosenoic acids with arachidonic acid can lead to exaggeration of the indicated content of arachidonic acid in edible flesh of marine fish. Modern wall-coated open-tubular columns also resolve the isomers of docosenoic acid, creating potential further problems in fatty acid identifications. Case histories for Atlantic food fish and recent publications are used to emphasize that only accurate marine fish fatty acid data should be used for dietary fatty acid-blood lipid dietary correlations.     

Nutritive value of diets containing fish silage for juvenile Litopenaeus vannamei (Bonne, 1931)

BACKGROUND: Fish wastes has been used for many years as an alternative in feeds for aquaculture. In the present study weight gain of juvenile white shrimp Litopenaeus vannamei fed diets including fish waste silage (WS), fish waste silage with soybean meal SBM (WS + S) or fish waste meal (WM) was compared. A conventional acidic silage process was applied to obtain from wastes (skin, heads, bones and viscera) of snapper (Lutjanus spp.), grunt (Haemulon plumieri), and grouper (Epinephelus spp.) an ingredient rich in protein. RESULTS: After 3 days ensilage more than 90% protein was hydrolysed. Waste material processed at pH 3.8 lost about 24% tryptophan. Butylated hydroxytoluene (BHT) prevented lipid oxidation, as shown after 45 days with malonaldehyde production. Shrimp fed WS + S diet gained 0.7 g per week higher than those fed WS and WM diets with 0.3 g per week (P < 0.05). CONCLUSION: WS processed with formic acid under conditions of low pH is beneficial for the white shrimp L. vannamei. It sustained reasonable weight gain combined with soybean meal in practical diets. On the other hand, BHT addition was beneficial in preventing oxidative action during silage preparation. Copyright © 2012 Society of Chemical Industry