发酵豆粕中异黄酮(FSMI)抗菌活性的研究

研究了发酵豆粕中异黄酮(FSMI)对食品中常见污染菌的抗菌活性及热处理对其抗菌活性的影响。结果表明,FSMI具有较强的抗菌活性,对食品中常见的细菌和真菌的最低抑制浓度分别为0.24%和0.56%,优于豆粕中的异黄酮(SMI)和化学合成防腐剂苯甲酸钠;FSMI的抗菌活性具有热稳定性,能忍受高温短时的热处理。本研究为FSMI开发成多功能天然食品防腐剂提供了实验依据。     

发酵豆粕中异黄酮的抗氧化性研究

为开发利用发醇豆粕中异黄酮(FSMI)天然食品抗氧化剂，主要研究了FSMI在植物油中的抗氧化作用。研究结果表明：FSMI对大豆油和菜籽油具有抗氧化作用，其抗氧化性高于未发酵豆粕中的异黄酮(SMI)和化学合成抗氧化剂BHT。     

发酵豆粕中异黄酮热稳定抗氧化性的研究

为开发利用发酵豆粕中异黄酮(FSMI)天然食品抗氧化剂,采用烘箱贮藏法,以过氧化值为指标,研究了高温(120℃)下FSMI对猪油和菜籽油的抗氧化作用.结果表明:在高温下,FSMI具有良好的抗氧化稳定性,并且随着FSMI添加量的增加,其抗氧化作用显著增强;对猪油和菜籽油的抗氧化效果优于同浓度的SMI(从豆粕中提取的异黄酮)、茶多酚和BHT;并对由金属离子(Cu2+、Fe2+)引起的促氧化作用有明显的抑制效应.     

发酵豆粕中异黄酮对细菌抑制作用的研究

发酵豆粕中的异黄酮具有较强的抗菌活性，对人体常见的致病细菌和食品腐败细菌的最低抑菌浓度为0．24％，比豆粕中的异黄酮的抗菌活性明显增强。将大肠杆菌和鼠伤寒沙门氏菌接种到发酵基质中，结果发现两菌在豆粕发酵环境中不能存活。本研究为发酵豆粕中异黄酮在功能性成分和食品天然防腐剂领域的开发利用提供实验依据。     

拓木的防腐作用及其在薄片中的应用

拓木是我国的药食两用物种,具有多种生物活性。对拓木树叶作为食品防腐剂和抗氧化剂来源的再利用潜力进行评估。评价拓木树叶中黄酮、多糖和皂苷的抗氧化和抗真菌活性,并将拓木黄酮类作为防腐剂应用于薄片中。结果表明,黄酮质量浓度5 mg/mL时,其对6种供试真菌的抑制率达100%,作为天然防腐剂在薄片中的防腐效果明显优于合成防腐剂苯甲酸钠(0.1%),抗氧化试验也显示良好的抗氧化活性。该试验为从拓木树叶中开发天然食品防腐剂和抗氧化剂提供潜在创新应用。     

木犀草素生物活性研究

该文报道对木犀草素抗氧化活性及抗菌活性研究,结果表明:木犀草素添加量以0．02％为宜,其效果与同剂量BHT相当,比同剂量茶多酚抗氧化效果好,还原能力和消除羟自由基能力均比茶多酚和 BHT强;且对食品中常见供试四种茵具有高效抗菌活性,并随浓度增加而增强,对金黄色葡萄球菌、枯草杆菌、啤酒酵母和大肠杆菌完全抑制浓度分别为300mg／L、200mg／L、250mg／L、300mg／L,具有高效抗菌活性;表明木犀草素作为食品天然防腐剂和天然抗氧化剂具有开发潜力。     

银杏叶提取物(EGb)抗菌特性的研究

测定了银杏叶提取物(EGb)对食品常见污染菌的抗菌活性,探讨了热处理和pH值对EGb抗菌活性的影响,阐明了银杏叶提取物(EGb)的抗菌特点以及作为食品天然防腐剂的开发价值。结果表明:银杏叶提取物的抑菌作用显著,其抗菌活性随着其浓度增加而增强,对细菌和真菌的最低抑菌浓度(MIC)为1.25%和5.0%;EGb的抗菌活性具有热稳定性,能忍受高温短时的热处理;EGb在pH5～9的范围内均具有抗菌活性。本研究为EGb在食品天然防腐剂领域中的开发利用提供实验依据。     

天然防腐剂研究进展

为预防微生物腐败带来的产品品质下降以及对人类健康和世界经济带来不利影响,防腐剂在食品、化妆品、医药等行业得到广泛应用。化学合成防腐剂在安全方面具有局限性,而来源天然的抗菌物质具有安全、稳定、广谱抗菌活性等特点逐步成为研究热点。本文介绍了具有抗菌性的天然防腐剂,包括酚类和非酚类物质。酚类物质具有抗菌、抗氧化、抗褐变、防止酸败等作用,应用更加广泛,而非酚类物质主要表现出抗菌性。     

灵芝固态发酵豆渣的抗氧化特性变化研究

以灵芝作为固态发酵豆渣的菌种,对发酵过程中的活性成分(多酚、异黄酮、三萜)及抗氧化特性(总还原力、羟自由基清除力、DPPH自由基清除力、ABTS+自由基清除力)进行研究。结果显示:豆渣经灵芝发酵后,三萜及多酚含量升高;糖苷型异黄酮在发酵前期(第1天～第5天)转化为苷元型异黄酮,发酵中后期(第5天～第11天),4种异黄酮含量降低;发酵后,菌质的抗氧化能力发生变化,其中发酵后菌质的DPPH自由基清除力、羟自由基清除力、总还原力提高,ABTS+自由基清除力下降。灵芝发酵豆渣后,豆渣的活性成分及抗氧化活性得到提高,可以作为一种天然的抗氧化剂。     

加工方式对外施天然抗氧化剂面制品抗氧化能力的影响

本文研究了发酵+焙烤、发酵+蒸制、直接焙烤3种烘焙方式对添加天然抗氧化剂面制品的抗氧化能力的影响。通过在面食中添加5种天然抗氧化剂(大豆异黄酮、茶多酚、花青素、植酸、V_C/V_E),测定面食制品在加工前后的丙酮提取液对各种自由基的清除率,通过变异系数法全面评价面制品的抗氧化能力。结果表明:加工方式和添加的抗氧化剂种类是影响小麦面制品抗氧化能力的重要原因。添加大豆异黄酮的面制品用于直接焙烤能提高抗氧化性能的3.85%,添加茶多酚的面制品用于直接焙烤时抗氧化损失率最低为-3.39%,添加花青素的面制品应用于发酵+焙烤可以更好地保留其抗氧化活性,损失率为-1.77%,添加植酸和V_C/V_E的面制品应用于发酵+蒸制可以更好地保留其抗氧化能力,损失率分别为-4.66%、-5.14%。在天然抗氧化剂作为面制品添加剂时,针对不同的抗氧化剂选择最适的加工方式,能够在一定程度上改善面制品的抗氧化能力。     

Simultaneous enhancement of free isoflavone content and antioxidant potential of soybean by fermentation with Aspergillus oryzae

In order to determine the fungal strain and fermentation period which produce the highest antioxidant activity of fermented soy product, soybean was fermented with Aspergillus oryzae NL 5 isolated from Korean traditional meju produced in Sunchang Yeastopia Land in Korea, and was subjected to analyzing isoflavone profiles and assaying antioxidant activity. Antioxidant potential of the samples was evaluated by ferric reducing antioxidant power assay, 2,2'-azinobis (2-ethylbenzthiazoline-6-sulfonic acid) radical scavenging activity and total phenolic contents. In addition, antioxidant assay using fluorescent probes, 2',7'-dichlorofluorescin diacetate and dihydroethidium, in HepG2 cells was conducted for the samples. The results showed that both high isoflavone variety Aga 3 and medium isoflavone variety Daewon of soybean fermented with Asp oryzae NL5 for 4 to 5 d showed the highest increase in free isoflavone contents, together with the highest antioxidant activity. In conclusion, the antioxidant activity of fermented soy was proportional to the concentration of free isoflavones, and was significantly influenced by total isoflavone content of soybean variety and fermentation period. Practical Application: Isoflavone profile and antioxidant capacity of soybean were widely variable during fermentation with Asp oryzae, and thereby it is recommended that meju (or koji) preparation condition, in particular, fermentation time is carefully optimized to maximize the antioxidant capacity of soy products fermented by Asp oryzae.     

Effect of fermentation time on the antioxidant activities of tempeh prepared from fermented soybean using Rhizopus oligosporus

The objective of this study was to evaluate the effect of fermentation time on the antioxidant activity of tempeh, a fermented product from soybean. Rhizopus oligosporus was used to ferment soybean for 0, 1, 2, 5 and 10 days. Lyophilised tempeh powder was extracted with hexane followed by petroleum ether, ether, 95% ethanol and water. Antioxidant activities of the extracts were evaluated with various models including α,α-diphenyl-β-pricryl-hydrazyl (DPPH) and superoxide-scavenging activities, reducing power and inhibitory activity towards lipid peroxidation. The results revealed that tempeh showed greater antioxidant activities than unfermented soybean. On behalf of a DPPH scavenger, water extracts were as good as 95% ethanol extracts. In comparison of superoxide anion-scavenging activity, inhibition of lipid peroxidation and reducing power, 95% ethanol extracts were superior to water extracts. Tempeh fermented with R. oligosporus for 10 days exhibited the highest antioxidant activities than the others.     

Effect of biotic elicitors on enrichment of antioxidant properties and induced isoflavones in soybean

ABSTRACT:  The antioxidant properties of methanolic extracts from soybean obtained with germination, wounding, and application of biotic elicitors were evaluated. Also, the relationship between observed antioxidant properties and compositional changes in isoflavone content was determined. The 2 biotic elicitors used in this study were the food-grade fungus Aspergillus sojae and A. sojae cell wall extract. Isoflavone content was determined by C₁₈ reverse phase high-performance chromatography coupled with a photodiode array detector. Antioxidant activities of the extracts were measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and β-carotene cooxidation in a linoleate system. Higher antioxidant activities were observed in wounded and elicitor-treated extracts when compared with nonwounded control extracts. In addition, the phenolic content was higher in extracts from wounded and elicitor-treated soybean. Germination for 3 d slightly decreased total isoflavone content (–4.3%); however, wounding increased total isoflavone content (25.8%). The soybean extracts from seeds treated with A. sojae biotic elicitors had the highest total isoflavone contents (9.8 to 11.6 mg/g extract) and displayed the highest antioxidant activities in both the DPPH and β-carotene assays. Also identified in the wounded and elicitor-treated extracts were the induced isoflavones glyceollins that contributed to the higher isoflavone contents observed.     

Effect of Lactic Acid Fermentation on Enrichment of Antioxidant Properties and Bioactive Isoflavones in Soybean

ABSTRACT: The antioxidant properties of 80% ethanolic extracts from soybean obtained with lactic acid fermentation using ABTS•⁺ [2,2'-azinobis (3-ethylbenzothiazoline-6-sulphonicacid) diammonium salt] free radical decolorization assay and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay were measured, and the relationship between the observed antioxidant properties and the compositional changes in the isoflavone isomers was evaluated. Fermentation of soybean with 4 bacterial strains producing β-glucosidase for 48 h at 37°C— Lactobacillus plantarum KFRI 00144, Lactobacillus delbrueckii subsp. latisKFRI01181, Bifidobacteriathermophilum KFRI00748, and Bifidobacteria breve K-101—resulted in a significant increas (P < 0.05) in the antioxidant capacity expressed as Trolox equivalent antioxidant capacity (TEAC) (mM) and % scavenging activity. The significant bioconversion (P < 0.001) of the isoflavone glucosides (daidzin + genistin) into their responding bioactive aglycones (daidzein + genistein) during soy fermentation was observed. There was a good linear correlation between the concentration of isoflavone aglycones and the scavenging activity of ABTS ( R = 0.9045) assay, and DPPH ( R = 0.8299) assay in each extract. Among each extract, B. thermophilum KFRI 00748 showed a particularly high antioxidant activity (19.8 mM TEAC) and increased by 4.1 times compared with that of the control (4.8 mM TEAC), which fermented without strains. These results indicated that fermented soybean could be regarded as a potent antioxidant and radical scavenging dietary source due to their remarkable content of bioactive isoflavones.     

Improved functionality of soft soybean curd containing Monascus fermented soybean ethanol extract

Monascus fermented soybeans (MFS) were produced by solid state fermentation and ethanol extractions were carried out to recover monacolin K (MK) and isoflavones from the MFS. About 99 and 87% of monacolin K (891 mg/kg) and isoflavones (895 mg/kg) were recovered by 80%(v/v) ethanol extraction. The 80% ethanol extract also showed significantly higher antioxidant activities (DPPH, ABTS radical scavenging activity, and ferric reducing antioxidant power) than the other ethanol extracts prepared by either 40 or 60% ethanol. The 80% Monascus fermented soybeans extract (MFSE) also contained significant α-glucosidase inhibitory activity (2.7 acarbose g equivalents/g MFS). Based on the results, MFSE can be used to enrich bioactive MK and isoflavone aglycones in soft soybean curd products.     

Enhancements of isoflavone aglycones, total phenolic content, and antioxidant activity of black soybean by solid-state fermentation with Rhizopus spp.

In the present study, a solid-state fermentation process of black soybean was developed. Three filamentous fungi including Rhizopus oligosporus (BCRC 31996), R. oligosporus (NTU-5), and Rhizopus oryzae (BCRC 30894) were cultivated with steam-cooked intact and dehulled black soybeans. It was found that fermentation enhanced the total phenolic and isoflavone aglycone content as well as antioxidant activity of the black soybean methanol [80 % (v/v)] extracts. Among the three candidates, R. oligosporus BCRC 31996 was chosen as the working strain, and dehulled Tainan NO.3 black soybeans were used as the substrate based on the relatively high total phenolic content, isoflavone aglycone accumulation, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging effect of the fermented extracts. In a 6-day fermentation, extracts of the fermented dehulled black soybeans yielded higher total phenolic content (2,876.2 μg/g) which was 1.16 times of the result from the intact soybean extracts. The DPPH scavenging effect of the fermented dehulled black soybean extract reached its maximum on the third day. The activity of β-glucosidase of dehulled black soybean samples increased with time and resulted in accumulation of isoflavone aglycones. The product of solid-state black soybean fermentation serves as a functional ingredient in the products of nutritional supplements and health foods.     

利用高温豆粕生产醇洗大豆浓缩蛋白的研究

分别以高温豆粕和低温豆粕为原料采用醇洗工艺制取大豆浓缩蛋白。测定高温豆粕和低温豆粕醇洗浓缩蛋白的蛋白质含量、NSI以及乙醇萃取液糖蜜中皂甙、异黄酮、总糖、蛋白质含量。结果显示:高温豆粕(蛋白质含量47.16%)醇洗浓缩蛋白的蛋白质含量(59.64%)虽然低于低温豆粕(蛋白质含量51.83%)醇洗浓缩蛋白的蛋白质含量(67.71%),但已接近60%,且高温豆粕乙醇萃取液糖蜜中皂甙、异黄酮含量(分别为8.04%、2.67%)与低温豆粕乙醇萃取液糖蜜中的含量接近(8.53%、2.13%)。表明利用高温豆粕生产饲用大豆浓缩蛋白应该是可行的,且副产物糖蜜是提取大豆皂甙、异黄酮、低聚糖的优质原料。     

不同品种大豆异黄酮组分及体外抗氧化活性分析

为研究不同品种大豆异黄酮组分和含量以及抗氧化活性,测定了50个特色大豆品种的百粒重、色泽（L*、a*、b*）,通过高效液相色谱法（HPLC）测定异黄酮组分,评估不同品种大豆甲醇提取物的DPPH、ABTS自由基清除能力,并用相关性分析、主成分分析及聚类分析法对样品进行分析。结果表明:大豆的百粒重范围为7.05~47.46 g。不同种皮色大豆L*、a*和b*呈现显著差异（P<0.05）。HPLC分析结果发现糖苷型异黄酮含量是大豆中主要的异黄酮组分,占总异黄酮含量的90%以上。其中染料木苷含量最高。安豆115品种的大豆异黄酮的总含量最高,为2500.78 μg/g;靖江丝瓜青品种的大豆异黄酮含量最低,为888.86 μg/g。安豆115品种的DPPH和ABTS自由基清除能力较强,分别为（16.11±0.25）和（8.12±0.04）μmol V_C/g。糖苷型异黄酮含量与DPPH和ABTS自由基清除能力有较高的线性相关性（R2分别为0.903和0.867）。主成分分析表明6项指标可用2个主成分来表示（累计贡献率达66.3%）。聚类分析将50个品种的大豆分为4类:第一类中黄豆黄素和黄豆黄苷含量较高;第二类中大豆苷、大豆苷元、染料木苷和染料木素含量较高;第三类和第四类中其大豆异黄酮含量基本处于中等水平和较低含量。综上所述,不同大豆品种的异黄酮组成、含量和抗氧化能力存在较大差异,可为其进一步综合开发利用提供一定理论基础。     

乳酸菌发酵黄浆水的抗氧化研究

应用鼠李糖乳杆菌和嗜酸乳杆菌发酵豆腐黄浆水,分析了黄浆水和发酵黄浆水还原三价铁、清除DPPH和ABTS+自由基以及螯合二价铁的能力.结果表明,嗜酸乳杆菌发酵黄浆水的还原力最强,显著高于鼠李糖乳杆菌发酵的黄浆水和未发酵的黄浆水;经过发酵的黄浆水清除DPPH和ABTS+自由基的能力明显大于未发酵黄浆水,但是菌种和发酵时间影响不大;螯合二价铁的能力依次为鼠李糖乳杆菌发酵的黄浆水＞嗜酸乳杆菌发酵的黄浆水＞未发酵黄浆水,且延长发酵时间能提高其螯合二价铁的能力.