The Use of an Extracellular Ferulic Acid Esterase from Lactobacillus acidophilus K1 for the Release of Phenolic Acids During Mashing

A purified extracellular ferulic acid esterase from Lactobacillus acidophilus K1 was successfully used during mashing for the release of free phenolic acids into sweet wort. The enzyme was produced in bioreactors and partially purified to obtain the monoenzyme preparation. Release of free ferulic and vanillic acid into the wort at 52°C (with the use of 4.09–14.60 enzyme activity units/L of the mash) and ferulic acid at 62°C (14.60 units/L) was observed. Free p‐OH‐benzoic and syringic acids were effectively released at 26°C at each enzyme concentration used. Free p‐OH‐benzoic acid was also released by the enzyme (14.60 U/L) at 52°C‐74°C. Free protocatechuic acid was effectively hydrolyzed by the enzyme preparation (8.75 U/L and 14.60 U/L) at 26°C‐52°C. Free caffeic acid (effectively released at 26°C‐62°C) originated from chlorogenic acid. No p‐coumaric acid was released due to the action of bacterial esterase during mashing. Ferulic acid esterase from L. acidophilus K1 exhibited no ability to release free phenolic acids during mashing at 62°C or at 74°C due to its low thermostability. In conclusion, L. acidophilus K1 is an attractive source for the production of ferulic acid esterase, which can be useful for the release of antioxidant phenolic acids in the early stages of mashing.     

糖化过程中应用嗜酸乳杆菌K1胞外阿魏酸酯酶释放酚酸

将来自嗜酸乳杆菌K1的胞外阿魏酸酯酶应用于糖化过程,以释放游离酚酸进入到麦汁中.该酶在生物反应器中制成,并部分纯化从而获得单酶.在52℃时,游离阿魏酸和香草酸释放到麦汁中（糖化醪中酶的用量为4.09-14.60 U/L）,在62℃能检测到阿魏酸（酶的添加量为14.60个单位/L）.在26℃时,酶的任一浓度都能使游离P-羟基安息香酸和丁香酸得到有效释放;在52-74℃,游离的P-羟基安息香酸也能释放（酶使用量为14.60U/L）;在26-52℃时,游离儿茶酸也能被酶制剂（酶用量为8.75 U/L和14.60U/L）有效水解;起源于绿原酸的游离咖啡酸在26-62℃也能有效释放.在糖化过程中,虽有细菌酯酶的活性,但没有P-香豆酸释放出来.而由于其较低的热稳定性,在62℃或74℃时,嗜酸乳杆菌K1的阿魏酸酯酶不能释放酚酸.综上所述,嗜酸乳杆菌K1是一个很有前景的产生阿魏酸酯酶的来源物质,在糖化初期可用于抗氧化酚酸的释放.     

两种丝状真菌发酵小麦麸皮中酚酸的释放及与阿魏酸酯酶和木聚糖酶的关系

为了评价两种丝状真菌对小麦麸皮降解能力,以及对酚酸释放能力的差异,本实验在不同时间进行总酚和9种酚酸组分的变化监测并且结合阿魏酸酯酶和木聚糖酶活性,电镜观察小麦麸皮表面结构对黑曲霉和棒曲霉进行综合评估。黑曲霉发酵7 d阿魏酸含量达到416.56μg/g麦麸。次之是没食子酸,从7.71μg/g麦麸增加到105.77μg/g麦麸。棒曲霉阿魏酸含量达到200.81μg/g麦麸。次之是丁香酸,没食子酸,对羟基苯甲酸和香豆酸,从分别从原麦麸中含量14.7μg/g麦麸、7.71μg/g麦麸、8.57μg/g麦麸和5.62μg/g麦麸增长至88.4μg/g麦麸,60.38μg/g麦麸,55.56μg/g麦麸,52.93μg/g麦麸。黑曲霉对麦麸的降解能力及对阿魏酸和没食子酸的释放能力都显著优于棒曲霉,而对丁香酸的释放能力略差于棒曲霉。电镜结果显示,黑曲霉降解能力优于棒曲霉。     

Lactic acid fermentation of brewer's spent grain hydrolysate by Lactobacillus rhamnosus with yeast extract addition and pH control

Lactic acid (LA) is a versatile chemical with a wide range of applications in food, pharmaceutical, cosmetic, textile and polymer industries. Brewer's spent grain (BSG) is the most abundant brewing by‐product. In this study BSG hydrolysates were used for LA fermentation by Lactobacillus rhamnosus ATCC 7469. The aim of this study was to evaluate the effects of pH control during fermentation, reducing sugar content and yeast extract content in BSG hydrolysate on LA fermentation parameters. The pH control greatly increased reducing sugar utilization, l ‐(+)‐LA content, yield and volumetric productivity. The highest l ‐(+)‐LA yield and volumetric productivity were achieved with the reducing sugar content of 54 g/L. Yeast extract addition significantly increased reducing sugar utilization, l ‐(+)‐LA content, L. rhamnosus cell viability, l ‐(+)‐LA yield and volumetric productivity. The highest l ‐(+)‐LA content (39.38 g/L), L. rhamnosus cell viability (9.67 log CFU/mL), l ‐(+)‐LA yield (91.29%) and volumetric productivity (1.69 g/L/h) were achieved with the reducing sugar content of 54 g/L and yeast extract content of 50 g/L. Copyright © 2017 The Institute of Brewing & Distilling     

阿魏酸酯酶与纤维素酶协同水解麦麸释放阿魏酸的研究

研究了重组阿魏酸酯酶和纤维素酶协同作用水解去淀粉麸皮对阿魏酸释放量的影响。以高效液相色谱法检测阿魏酸的提取量,结果显示,底物的超声预处理最佳条件为350 W,20 min,是未经超声处理的底物阿魏酸释放率的1.45倍,单独使用阿魏酸酯酶(re Ao Fae A)30 U时阿魏酸的释放率仅为4.1%,单独使用纤维素酶(r Au Cel12A)并不释放阿魏酸,当两种酶协同作用时,阿魏酸的释放率明显提高,经单因素试验确定双酶协同作用的最佳条件为:re Ao Fae A的最适添加量为30 U,r Au Cel12A的最适添加量为70 U,水解时间为10 h,水解温度为40℃,水解p H为5.0,料液质量体积比为1 g:30 m L,此时阿魏酸的释放率为23.6%。该结果表明,去淀粉麸皮中纤维素的降解,对提高阿魏酸酯酶水解释放阿魏酸效率具有重要作用。     

Use of spent brewer's yeast in L‐(+) lactic acid fermentation

The application of by‐products from the brewing industry in lactic acid (LA) production was investigated in order to replace expensive nitrogen sources (such as yeast extract) with cheaper and renewable nitrogenous materials such as brewer's yeast (BY). In this study, brewer's spent grain (BSG) hydrolysate was used for L‐(+)‐LA fermentation by Lactobacillus rhamnosus ATCC 7469. The effect of pH control during the fermentation and the addition of various BY contents (5–50 g/L) in BSG hydrolysate on fermentation parameters was evaluated. BY addition significantly increased free amino nitrogen (FAN) concentration (by 25.2% at 5 g/L to 616% at 50 g/L). A strong positive correlation between FAN concentration in the hydrolysate and concentration of L‐(+)‐LA produced was observed (correlation coefficient of 0.913). A high cell viability of L. rhamnosus ATCC 7469 (1.95–3.32 × 10⁹ CFU/mL at the end of fermentation) was achieved in all fermentations with the addition of brewer's yeast. The addition of BY increased L‐(+)‐lactic acid yield and volumetric productivity up to 8.4% (5 g/L) and 48.3% (50 g/L). The highest L‐(+)‐LA yield (89%) and volumetric productivity (0.89 g/L h^?1) were achieved in fermentation of BSG hydrolysate with 50 g/L of BY. © 2019 The Institute of Brewing & Distilling     

Effects of Brewer's Spent Grain on the Quality and Dietary Fibre Content of Cookies

Dried and ground brewer's spent grain (BSG) was blended with soft wheat flour at levels of 5–25%. BSG preparations of fine (<212 μm), medium (212–425 μm) and coarse (425–850 μM) particle sizes were used in the production of wire‐cut cookies. The protein content decreased and the dietary fibre content (acid detergent fibre, neutral detergent fibre and total dietary fibre) increased, as the particle size of the BSG samples increased. The results indicated that BSG preparations with high dietary fibre content have potential as a source of dietary fibre. The effects of BSG on the quality and dietary fibre content of cookies have been investigated. Total dietary fibre (TDF) contents of the cookies supplemented with different particle size BSG increased significantly (p<0.05) as the addition level increased. Cookies prepared with BSG of medium and coarse particle sizes resulted in better properties in terms of Spread Ratio, Hunter color values and overall sensory score as compared to those made with BSG of fine particle size. Cookies made with medium and coarse particle size BSG gave better cookie properties up to the 15% addition and deteriorated significantly above this level (p<0.05).     

Antibacterial activity of Lactobacillus acidophilus strains isolated from honey marketed in Malaysia against selected multiple antibiotic resistant (MAR) Gram-positive bacteria

A total of 32 lactic acid bacteria (LAB) were isolated from 13 honey samples commercially marketed in Malaysia, 6 strains identified as Lactobacillus acidophilus by API CHL50. The isolates had antibacterial activities against multiple antibiotic resistant's Staphylococcus aureus (25 to 32 mm), Staphylococcus epidermis (14 to 22 mm) and Bacillus subtilis (12 to 19 mm) in the agar overlay method after 24 h incubation at 30 °C. The crude supernatant was heat stable at 90 °C and 121 °C for 1 h. Treatment with proteinase K and RNase II maintained the antimicrobial activity of all the supernatants except sample H006-A and H010-G. All the supernatants showed antimicrobial activities against target bacteria at pH 3 and pH 5 but not at pH 6 within 72 h incubation at 30 °C. S. aureus was not inhibited by sample H006-A isolated from Libyan honey and sample H008-D isolated from Malaysian honey at pH 5, compared to supernatants from other L. acidophilus isolates. The presence of different strains of L. acidophilus in honey obtained from different sources may contribute to the differences in the antimicrobial properties of honey.     

Production of L‐Lactic Acid from Spent Grain,a By‐Product of Beer Production

L‐lactic acid production from spent grain with immobilized lactic acid bacteria was investigated. Spent grains were liquefied by a steam explosion treatment to obtain liquefied sugar. When 1 kg of wet spent grain was treated under the 30 kg/cm²pressure for 1 min using a 5‐L steam explosion reactor, 60 g of total sugar was obtained from the liquefied spent grain. Furthermore, 1.3% (w/v) of glucose, 0.4% (w/v) of xylose, and 0.1% (w/v) of arabinose were produced when the liquefied spent grain was treated with glucoamylase, cellulase, and hemicellulase enzymes. When batch L‐lactic acid production was carried out by Lactobacillus rhamnosus NBRC14710, 19.0 g/L L‐lactic acid was produced from the Tween 80 liquefied spent grain after 5 days. Furthermore, during repeated batch production with immobilized Lactobacillus rhamnosus NBRC14710 from Tween 80 liquefied spent grain at 37°C, the productivity of L‐lactic acid was maintained at a 10 time higher level over a period of 40 days.     

雪莲菌中乳酸菌的益生特性

对分离自雪莲菌的乳酸菌进行益生特性评价。耐酸性和模拟胃肠液耐受性初筛结果表明,20株乳酸菌中有11株乳酸菌在pH 3.0和pH 2.5的培养基中具有耐受性,经过模拟胃肠液培养后有8株乳酸菌的活菌数大于10⁶ CFU/mL;疏水性、自凝聚性、抗氧化能力和抑菌实验结果表明,副干酪乳杆菌(Lactobacillus paracasei)KF2-5和鼠李糖乳杆菌(Lactobacillus rhamnosus)RG疏水性较高、抑菌性最强,菌株RG的自凝聚能力和抗氧化能力较强;耐药性实验结果显示,菌株KF2-5和RG对红霉素、卡那霉素、氯霉素和四环素敏感,对头孢噻肟和万古霉素具有耐药性;溶血性实验表明,2株菌均无溶血。本研究筛选得到2株具有益生特性的乳酸菌KF2-5和RG,在益生产品开发中具有潜在的应用前景。     

Fed‐batch l‐(+)‐lactic acid fermentation of brewer's spent grain hydrolysate

Brewer's spent grain (BSG) hydrolysates were used for l ‐(+)‐lactic acid (LA) fermentation by Lactobacillus rhamnosus ATCC 7469. The aim of this study was to evaluate fed‐batch LA fermentation of BSG hydrolysate with the addition of glucose, glucose and yeast extract, and wort during LA fermentation and its effect on fermentation parameters such as LA concentration, its volumetric productivity and yield, and L. rhamnosus cell viability. The highest LA yield, volumetric productivity and concentration of 93.3%, 2.0 g/L/h, and 116.1 g/L, respectively, were achieved with glucose and yeast extract addition during fermentation. In fed‐batch fermentation with glucose and yeast extract addition significantly higher LA concentration, yield and volumetric productivity (by 194.8; 2.2, and 20.7%, respectively) were achieved compared with batch fermentation. The results indicated that fed‐batch fermentation could be used to increase LA fermentation efficiency. Copyright © 2017 The Institute of Brewing & Distilling     

Physicochemical Properties,Fatty Acid Profiles,and Sensory Characteristics of Fermented Beef Sausage by Probiotics Lactobacillus plantarum IIA‐2C12 or Lactobacillus acidophilus IIA‐2B4

Probiotics may be used to enhance the functionality and nutritional values of fermented sausages. This study aims to evaluate the physicochemical and sensory properties of beef sausages fermented by lactic acid bacteria of Lactobacillus plantarum IIA‐2C12 and L. acidophilus IIA‐2B4. These strains were isolated from beef cattle and have shown to display probiotic features. While the nutrient contents were not affected by the probiotics, the pH, texture, and color varied among the sausages. Further analysis on fatty acids showed different profiles of saturated (C14:0, C17:0, and C20:0) and unsaturated (C14:1, C18:1n9c, C18:2n6c, and C22:6n3) fatty acids in sausages with probiotics. Gas chromatography–mass spectrometry further revealed some flavor development compounds including acid, alcohols, aldehydes, aromatic, ketones, sulfur, hydrocarbons and terpenes, varied among the sausages. Hedonic test showed no difference in the preference toward aroma, texture, and color for untrained panelists.     

Comparison of Enrichment Media for Routine Detection of Beer Spoiling Lactic Acid Bacteria and Development of Trouble‐shooting Medium for Lactobacillus backi

The beer spoiling lactic acid bacteria (LAB) are known to have a substantial financial impact in the brewing industry and their rapid detection is essential. Thus more effective media for the cultivation of LAB in both routine quality control and special trouble‐shooting situations are needed. In this study, different media were tested for the routine detection of LAB at a commercial brewery. The results showed that the use of an enzyme controlled glucose delivery system, in combination with beer‐MRS medium, can significantly decrease the total analysis time. For more effective trouble‐shooting in contamination incidents a trouble‐shooting media, including the reducing agents L‐cysteine‐HCl and sodium bicarbonate, was developed. The presented medium was shown to improve the growth of beer spoiling L. backi and L. brevis, and is thereby suggested for faster detection of these strains at the breweries.     

老年人肠道乳酸菌的分离与鉴定及其来源发酵乳杆菌的遗传进化分析

首先对湖北襄阳和恩施地区的健康老年人肠道乳酸菌进行分离与鉴定,然后从中选择发酵乳杆菌（Lactobacillus fermentum）进行多位点序列分型（multilocus sequence typing,MLST）分析。结果显示,基于可培养方法,湖北襄阳与恩施地区老年人肠道乳酸菌可以鉴定为以乳杆菌属（Lactobacillus）为主的5 个菌属,15 个种。总的来说,发酵乳杆菌和唾液乳杆菌（L. salivarius）占老年人肠道源乳酸菌分离株总量的55%左右,表明人体肠道可以作为发酵乳杆菌的重要分离来源。基于8 个持家基因的MLST分析表明,25 株来源于肠道的发酵乳杆菌可以划分为25 个序列型,具有极高的遗传多样性;基于选择压力分析与phi-test,选用的8 个持家基因均受到纯化选择作用,且其中仅基因rpoB显著经历了基因重组事件;另外,基于Prim’s和goeBURST的进化分析表明,一半左右的肠道源发酵乳杆菌倾向于形成单独的分支,表明它们具有一定的宿主特异性,可能的原因是为适应肠道环境,这些发酵乳杆菌经历了有异于发酵食品生境的进化历程。     

A novel esterase from Saccharomyces carlsbergensis,a possible function for the yeast TIP1 gene

An extracellular esterase was isolated from the brewer's yeast, Saccharomyces carlsbergensis. Inhibition by diisopropyl fluorophosphate shows that the enzyme has a serine active site. By mass spectrometry, the molecular weight of the enzyme was 16·9 kDa. The optimal pH for activity was in the range of four to five. Esterase activity was found in beer before pasteurization, and a low level of activity was still present after pasteurization. Caprylic acid, which is present in beer, competitively inhibited the esterase. The substrate preference towards esters of p-nitrophenol indicated that the enzyme prefers esters of fatty acids from four to 16 carbon atoms. The esterase has lipolytical activity; olive oil (C-18:1), which is a classical substrate for lipase, was hydrolysed. N-terminal sequence analysis of the esterase yielded a sequence which was identical to the deduced amino acid sequence of the S. cerevisiae TIP1 gene. The esterase preparation did not appear to contain significant amounts of other proteins than Tip1p, indicating that the TIP1 gene is the structural gene for the esterase. © 1998 John Wiley & Sons, Ltd.