β-glucosidase Activity in Juice-Processing Enzymes Based on Anthocyanin Analysis

A screening procedure utilizing boysenberry juice as a substrate, which combined HPLC and spectrophotometric analyses, was used to measure β-glucosidase activity of enzyme preparations used for juice processing. Enzyme preparations (n = 26) were evaluated at two dosage rates. At the mean recommended dosage, one preparation produced a decrease in total monomeric anthocyanin and cyanidin-3-glucoside, relative to a control, indicating β-glucosidase activity. At 0.1% dosage, 4 enzymes produced a significant decrease in cyanidin-3-sophoroside and 2 enzymes caused an increase in cyanidin-3-rutinoside, indicating β-1,2-glucosidase activity. Such activity in juice processing enzymes was much lower and less prevalent than found previously for β-galactosidase. Botrytis cinerea also degraded anthocyanins in boysenberry juice.     

Uncovering Hierarchical Regulation among MYB-bHLH-WD40 Proteins and Manipulating Anthocyanin Pigmentation in Rice

Anthocyanins accumulate in various organs of rice, and the regulatory genes involved in pigmentation of specific organs, such as pericarp, hull, leaf, apiculus, and stigma have been elucidated. However, the corresponding gene for rice culm pigmentation has not been clarified. The well-known MYB-bHLH-WD40 (MBW) complex plays vital role in regulating the anthocyanin biosynthesis pathway in plants. However, the core members of MBW and the hierarchical regulation between these members are not fully elucidated in rice. Here, by map-based cloning, we identified the culm-specific pigmentation gene S1 whose alleles are also known for hull/pericarp pigmentation. We also clarified that one WD40 protein encoding gene, WA1, is indispensable for anthocyanin biosynthesis in rice. In the cascading regulation among MBW members, S1 (bHLH) acts as the master gene by activating the expression of C1 (MYB), and then C1 activates the expression of WA1 (WD40), which is unique in plant species. This enables MBW members to be coordinated in a common way to efficiently regulate anthocyanin biosynthesis genes. Based on these studies, we explored the minimal gene set required for anthocyanin biosynthesis in rice. These findings will help us design new rice varieties with anthocyanin accumulation in specific organs as needed.     

ESR法对蓝莓提取物清除自由基能力的测定

目的:比较并分析蓝莓果与蓝莓叶提取物清除自由基的能力。方法:采用电子自旋共振波谱法(ESR),对不同浓度蓝莓果实与蓝莓叶提取物的瞬时清除羟基自由基(·OH)能力及在3~45 min清除DPPH自由基能力进行了测定。结果:当蓝莓叶提取物浓度在2.500 mg/L,反应2 min时,其清除·OH自由基的能力达到87%,高于蓝莓果提取物;当蓝莓果提取物浓度在2.500 mg/L,反应时间为30 min时,其清除DPPH自由基的能力达到80%以上,且高于蓝莓叶提取物。结论:蓝莓提取物均具有良好的清除自由基的能力,其能力与提取物中总酚含量和组成多酚的成分有关。      

加压溶剂法提取紫色马铃薯中花色苷的工艺优化

以紫色马铃薯粉为原料,使用加压溶剂提取的方法萃取紫色马铃薯中的花色苷。探讨提取时间、提取温度、料液比和提取剂的浓度对花色苷提取率的影响,并通过响应面法确定了最佳提取工艺参数为乙醇浓度为77%,提取温度为67℃,提取时间为25 min,料液比为1∶58,在最优条件下的花色苷提取量为200.13 mg/100 g。超声波辅助提取法提取紫色马铃薯中的花色苷,其最佳工艺条件下提取花色苷量为139.30 mg/100 g,加压溶剂法提取量高于超声波辅助提取法。      

冰温结合ε聚赖氨酸对贮藏期间蓝莓生理品质的变化影响

通过研究对经ε-聚赖氨酸处理的蓝莓在冰温贮藏期间的生理品质的变化,探讨冰温结合ε-聚赖氨酸处理对蓝莓的保鲜效果。实验选取浓度为100、300、500μL/gε-聚赖氨酸处理蓝莓,在70d贮藏期中每10d测一次相关指标。结果表明,与直接冰温贮藏蓝莓相比,冰温结合ε-聚赖氨酸的处理对延缓蓝莓的腐烂、抑制VC和花色苷的减少、保护蓝莓果霜均有明显效果,并且抑制了蓝莓的呼吸强度和乙烯生成速率,对过氧化氢酶CAT活力也有很明显的抑制效果。其中经300μL/gε-聚赖氨酸处理的效果最优。说明冰温结合ε-聚赖氨酸处理贮藏的效果优于直接冰温贮藏。      

全谷物抗氧化活性研究进展

全谷物的胚芽与皮层富含酚酸、花色苷、原花青素、γ-谷维素、烷基间苯二酚等,因其独特的抗氧化活性已被世界各国所推崇。越来越多的研究表明,全谷物体外和离体抗氧化活性并不一定与它们体内抗氧化活性一致,生理环境、消化吸收和生理代谢是决定其体内抗氧化活性的三个关键因素。最新研究表明,有色全谷物的体外、离体和体内抗氧化活性比普通全谷物的高,且其体内抗氧化效果和体外、离体的具有一致性。本文主要针对全谷物中常见的抗氧化成分及其作用机理,体外、离体和体内抗氧化活性研究方法的特点,普通全谷物和有色全谷物的体外、离体和体内抗氧化活性的最新研究进展做一综述,以期客观地评价全谷物的抗氧化活性,为全谷物抗氧化资源开发提供理论依据,同时也为合理摄入全谷物食品和平衡膳食结构提供参考。      

蓝莓籽瓜果酒酿造工艺优化及其抗氧化功能研究

本实验选取蓝莓、籽瓜为原料制备果酒,分别对酵母接种量、蓝莓籽瓜比、固形物含量进行单因素实验,并以酒精度为指标,确定果酒的最佳工艺参数。选取羟基自由基、抗超氧自由基、总抗氧化三种试剂盒分别进行果酒清除自由基能力、清除超氧自由基、总抗氧化能力的测定,并利用Folin-Ciocalteu法进行总酚含量的测定。确定果酒的最佳工艺参数:调至固形物含量为200 g/L、酵母接种量添加量为0.3 g/L、蓝莓籽瓜质量百分比为55∶45,该果酒的酒精度为11.63%±0.04%。发酵过程中,蓝莓籽瓜果酒具有很强的抗氧化能力,随着发酵时间的延长,其抗氧化活性较稳定。抗超氧自由基、抑制羟基自由基、总抗氧化能力与总酚含量呈正相关,皮尔逊相关系数分别为0.916、0.976、0.922,抑制羟自由基能力与总酚含量关系最为密切。      

pH对紫甘薯色素呈色及紫外可见吸收光谱的影响

研究了常用食品酸碱度范围内,pH对紫甘薯色素呈色及紫外可见吸收光谱的影响。结果表明,在不同pH下,紫甘薯色素呈现不同的色调、不同的紫外可见吸收光谱,两者变化显著并表现出类似的趋势。在pH2.0~8.0范围内,随着pH的升高,色素溶液的颜色由红色逐渐过渡到紫色,最后变成蓝色。在紫外可见光区域,随着pH的升高,紫甘薯色素在237、530nm附近的特征吸收峰逐渐向长波方向移动。