Contributions of Amino-carbonyl Reaction,Caramelization and Some Other Reaction to Browning of Saké

In the previous report, it has been concluded that the browning of Saké involves three kinds of browning reactions which are the amino-carbonyl reaction, the caramelization and some other browning reaction by components other than glucose. In the present work, the extents of contributions of the three kinds of reactions to the browning of Saké were actually estimated, respectively, by analysing its dependence on the glucose concentration. It was concluded that the browning by components other than glucose was the major factor while the amino-carbonyl reaction and the caramelization were the minor ones in the browning of Saké. In addition, the change in pH value, as well as in temperature, was observed to influence exponentially on the browning rate of Saké. An empirical equation was proposed to elucidate the way in which the three kinds of reactions contributed to the overall browning in Saké.     

The lack of enzymic browning in the wild potato species Solanum hjertingii compared with commercial Solanum tuberosum varieties

Enzymic browning of tuber tissue was evaluated quantitatively for 50 genotypes, representing seven accessions, of Solanum hjertingii, a wild potato species from north-east Mexico, together with five commercial varieties of Solanum tuberosum with a known range of enzymic browning. Ninety-four percent of S. hjertingii clones examined showed less browning than the commercial varieties, with 66% exhibiting half the ‘potential browning’ (a measure of the total enzymic browning resulting from disruption of cellular compartmentalisation in that system) of cv. Maris Piper, a low enzymic browning cultivar. Of these clones, 18 showed no visual discoloration when sliced. Results clearly indicate that the lack of enzymic browning in S. hjertingii is a ‘true’ character. The efficiency of one subjective and two objective methods for obtaining different measures of enzymic browning was assessed. Potential browning of a rehydrated freeze-dried powder was adopted as the most efficient technique for screening enzymic browning.     

Effects of Chemical Components on the Browning of Tomato Juice

The effects of eleven components in tomato juice on browning by heating were examined at the concentrations found in juice, About 70% of the browning of tomato juice was attributable to three constituents; fructose, galacturonic acid and glutamic acid. The interaction between glutamic acid and galacturonic acid or fructose was also found to accelerate the browning of tomato juice. The browning by heating of galacturonic acid with or without amino acids was larger than that of sugars or amino acids. The browning mechanism of galacturonic acid on heating at high temperature was discussed.     

The dark side of browning

The induction of brown-like adipocyte development in white adipose tissue (WAT) confers numerous metabolic benefits by decreasing adiposity and increasing energy expenditure. Therefore, WAT browning has gained considerable attention for its potential to reverse obesity and its associated co-morbidities. However, this perspective has been tainted by recent studies identifying the detrimental effects of inducing WAT browning. This review aims to highlight the adverse outcomes of both overactive and underactive browning activity, the harmful side effects of browning agents, as well as the molecular brake-switch system that has been proposed to regulate this process. Developing novel strategies that both sustain the metabolic improvements of WAT browning and attenuate the related adverse side effects is therefore essential for unlocking the therapeutic potential of browning agents in the treatment of metabolic diseases.     

Decoupled trophic responses to long‐term recovery from acidification and associated browning in lakes

Increases in the concentration of dissolved organic matter (DOM) have been documented in many inland waters in recent decades, a process known as “browning”. Previous studies have often used space‐for‐time substitution to examine the direct consequences of increased DOM on lake ecosystems. However, browning often occurs concomitant with other ecologically important water chemistry changes that may interact with or overwhelm any potential ecological response to browning itself. Here we examine a long‐term (~20 year) dataset of 28 lakes in the Adirondack Park, New York, USA, that have undergone strong browning in response to recovery from acidification. With these data, we explored how primary producer and zooplankton consumer populations changed during this time and what physical and chemical changes best predicted these long‐term ecosystem changes. Our results indicate that changes in primary producers are likely driven by reduced water clarity due to browning, independent of changes in nutrients, counter to previously hypothesized primary producer response to browning. In contrast, declines in calcium concomitant with browning play an important role in driving long‐term declines in zooplankton biomass. Our results indicate that responses to browning at different trophic levels are decoupled from one another. Concomitant chemical changes have important implications for our understanding of the response of aquatic ecosystems to browning.     

Contribution of 3-Deoxyglucosone as an Intermediate to Browning of Saké

The behaviour of 3-deoxyglucosone (3-D-G) was investigated in the process of browning of Saké, and it was concluded that the browning of Saké involved at least three kinds of browning reactions which were the amino-carbonyl reaction, the caramelization and some other browning reaction by components other than glucose in Saké. The active dicarbonyl compound of 3-D-G was confirmed to act as an important intermediate in both the amino-carbonyl reaction and caramelization. The caramelization was the browning of glucose by itself via 3-D-G, while the amino-carbonyl reaction was the browning of glucose via 3-D-G by the interaction with the amino compounds in Saké. The remainder was, however, independent of glucose and 3-D-G. The temperature coefficient for the rate of the overall browning of Saké was estimated to be 2.8 to 2.9 of Q₁₀ value.     

柠檬酸和抗坏血酸对蝴蝶兰叶外植体褐变发生的影响

目的:探究柠檬酸和抗坏血酸对蝴蝶兰叶片外植体褐变发生的影响以及对PPO活性变化影响的作用机理.方法:以褐变率和褐变指数为参考数据,分析柠檬酸和抗坏血酸对外植体PPO活性和PPO反应产物积累的影响以及与外植体褐变发生的关系.结果:分别用100mg/L柠檬酸共培养和50mg/L抗坏血酸浸泡处理叶片外植体,经离体培养3d,褐变率分别比对照降低94.9%和54.9%,离体培养6d,褐变指数低于对照的0.53,分别为0.46和0.36,同时PPO活性降低.结论:推测柠檬酸抑制褐变的原因是直接与酶蛋白作用,抗坏血酸则与新生醌类物质结合.     

几种培养基及光照对蝴蝶兰叶片外植体褐变的影响

蝴蝶兰叶片外植体在MS纸桥培养基上培养10 d发生褐变率较低,1/2 MS次之,MS、B₅和N₆培养基外植体褐变率最高。MS培养基中铁盐加倍或微量元素缺乏造成外植体严重褐变,培养基积累很多褐色物质;减少琼脂含量,外植体褐变加重;添加柠檬酸可减轻外植体褐变;而添加活性炭、抗坏血酸或PVP对减轻外植体褐变无显著作用。光照强度增加外植体褐变严重。     

Low accumulation of chlorogenic acids represses reddening during flesh browning in Japanese peach “Okayama PEH7”

In peaches, fruit flesh browns unattractively after peeling or cutting. A recently developed cultivar, Okayama PEH7, was distinct from other Japanese cultivars, including Okayama PEH8, with respect to its reduced browning potential. Homogenate prepared from Okayama PEH7 flesh had significantly less reddening during the browning reaction. Okayama PEH7 had less soluble phenolic compounds and higher polyphenol oxidase activity than Okayama PEH8. Reduced browning was observed even when phenols prepared from Okayama PEH7 were incubated with crude extract from Okayama PEH8, suggesting that phenols lower the browning potential of Okayama PEH7. In Okayama PEH7, contents of chlorogenic acid and its isomers were about one-tenth compared to Okayama PEH8. Exogenous addition of chlorogenic acid to Okayama PEH7 homogenate increased the browning potential and visibly enhanced reddening. These results indicate that the reduced browning of Okayama PEH7 flesh is due to a defect in chlorogenic acid accumulation.     

A single genetic locus in chromosome 1 controls conditional browning during the induction of calli from mature seeds of Oryza sativa ssp. indica

Being the crucial step for rice transgenic manipulation, callus culture from mature seeds is severely restricted by browning of induced calli, especially in the case of indica (Oryza Sativa L.) rice. Once this browning occurs, the callus will die and no embryonic calli can be obtained for regeneration. Here we report an induction procedure that overcomes callus browning was found. To clarify the inheritance pattern of callus browning, two reciprocal crosses F₂ and two backcrosses BC₁ were made between indica cultivar inbred lines 93-11 and YueTaiB (YTB) which produced normal and browning respectively in the same induction medium. The ratio of browning to normal in the reciprocal F₂ and backcross (BC₁) populations tested was approximately 1:3 and 1:1, respectively, these results indicate that callus browning is controlled by one single chromosomal locus which is tentatively named Ic1 (Induced callus 1). The genetic mapping of this locus was carried out using microsatellite markers (SSR) in a 216 extremely browning F₂ seed callus. The analysis of genetic linkage indicated that one single locus that mapped to chromosome 1 was correlated to callus browning, and the closest marker in this study was mapped within 1.9 cM from the target locus.     

Changes in morphology and biochemical indices in browning callus derived from <Emphasis Type="Italic">Jatropha curcas</Emphasis> hypocotyls

Callus browning is a typical feature of callus cultures derived from the hypocotyl of Jatropha curcas. Brown callus results in decreased regenerative ability, poor growth and even death. In this study, we investigated the effect of browning on callus morphology and biochemical indices. Light microscopy and scanning electron microscopy showed striking differences in callus morphology. During browning, chlorophylls and carotenoids concentrations decreased steadily. Polyphenol oxidase (PPO) and peroxidase (POD) enzymatic activities patterns were similar during callus culture with a higher activity level at week 3 compared to week 2 or later weeks. Grey relation degree analysis indicated that PPO played a more important role than POD in enzymatic callus browning. Polyacrylamide gel electrophoresis results showed differences between browning and non-browning callus. Gas chromatography–mass spectrometry results showed that saturated and unsaturated fatty acid quantities differed significantly but there was little difference in fatty acid composition between non-browning and browning callus. Differences in 17, 18.4 and 25 kDa protein concentrations were also observed in browning and non-browning callus using sodium dodecyl sulfate–polyacrylamide gel electrophoresis.     

不同激素对青钱柳外植体和愈伤组织褐化的影响

以青钱柳(Cyclocarya paliurus)叶片为研究材料, 采用单因素完全随机试验法比较不同激素(6-BA、GA₃和NAA)浓度组合对叶片外植体褐化的影响; 在此基础上, 分别采用二因素、单因素完全随机试验法比较6-BA+NAA不同浓度组合、不同基本培养基对愈伤组织褐化的影响。结果表明, 改良MS+1.0 mg∙L ^-1 6-BA+1.0 mg∙L ^-1 GA₃+0.3 mg∙L ^-1 NAA是抑制青钱柳叶片外植体褐化的最佳培养基, 其褐化率为0, 愈伤组织诱导率100%; 改良MS+0.5 mg∙L ^-1 6-BA+0.2 mg∙L ^-1 NAA是抑制愈伤组织褐化的最佳培养基, 其褐化率为0, 愈伤组织增殖倍数达4.80倍, 愈伤组织呈黄绿色或黄色, 颗粒状, 颗粒小而紧密、质硬且表面干燥。该方法有效解决了青钱柳叶片外植体和愈伤组织褐化问题, 为青钱柳组织培养褐化控制提供了一条简单高效的离体培养途径, 也为青钱柳叶片离体再生体系的建立奠定基础。     

不同激素对青钱柳外植体和愈伤组织褐化的影响

以青钱柳(Cyclocarya paliurus)叶片为研究材料, 采用单因素完全随机试验法比较不同激素(6-BA、GA₃和NAA)浓度组合对叶片外植体褐化的影响; 在此基础上, 分别采用二因素、单因素完全随机试验法比较6-BA+NAA不同浓度组合、不同基本培养基对愈伤组织褐化的影响。结果表明, 改良MS+1.0 mg?L ^-1 6-BA+1.0 mg?L ^-1 GA₃+0.3 mg?L ^-1 NAA是抑制青钱柳叶片外植体褐化的最佳培养基, 其褐化率为0, 愈伤组织诱导率100%; 改良MS+0.5 mg?L ^-1 6-BA+0.2 mg?L ^-1 NAA是抑制愈伤组织褐化的最佳培养基, 其褐化率为0, 愈伤组织增殖倍数达4.80倍, 愈伤组织呈黄绿色或黄色, 颗粒状, 颗粒小而紧密、质硬且表面干燥。该方法有效解决了青钱柳叶片外植体和愈伤组织褐化问题, 为青钱柳组织培养褐化控制提供了一条简单高效的离体培养途径, 也为青钱柳叶片离体再生体系的建立奠定基础。     

植物组织培养外植体褐变的研究进展

外植体的褐变是组织培养过程中的主要障碍。目前一般认为影响褐变的因素主要有外植体材料、培养基和培养条件。为了防止褐变的发生,主要可以从外植体和培养条件、进行细胞筛选和材料的预处理、抑制剂或吸附剂的加入等方面入手。酚、酚酶的区域性分布假说、自由基伤害假说、保护酶系统假说是褐变机理方面较为成熟的3种假说。     

Relationship between the enzymatic browning and phenylalanine ammonia-lyase activity of cut lettuce, and the prevention of browning by inhibitors of polyphenol biosynthesis.

Cut lettuce stored at 4 degrees C gradually turned brown on the cut section after several days of storage. Three factors for enzymatic browning, the polyphenol content, polyphenol oxidase activity, and phenylalanine ammonia-lyase (PAL) activity, were examined during the cold storage of cut lettuce. A relationship between the browning and PAL activity was apparent. We tried to prevent this browning by using the two enzyme inhibitors, 2-aminoindane-2-phosphonic acid (AIP), an inhibitor of the phenylpropanoid pathway, and glyphosate, an inhibitor of the shikimate pathway. AIP and glyphosate significantly inhibited the browning of cut lettuce. The polyphenol content and PAL activity were both reduced by the treatment with AIP. These results show that regulating the biosynthesis of polyphenols is essential to prevent the browning of cut lettuce.     

Browning and decomposed products of model orange juice

A model solution of orange juice containing sugars, ascorbic acid, and citric acid was prepared and its browning during storage was examined. The solution gradually turned brown. Ascorbic acid (AsA) most contributed to the browning. Citric acid and such amino acids as Arg and Pro promoted the browning. DTPA, a strong chelator, inhibited the browning. 3-Hydroxy-2-pyrone (3OH2P), 5-hydroxymethylfurfural (HMF), furfural, 5-hydroxymaltol, and 2-furoic acid were identified as decomposed products in the stored solution. When 3OH2P was stored, the solution turned slightly brown. Furfural solution added with amino acids turned yellow. 3OH2P showed a positive relation with the browning of retail orange juice during storage.     

Brown and beige fat: From molecules to physiology

The recent re-discovery of brown adipose tissue (BAT) and even more recent discovery of the browning of white adipose tissue (WAT) in humans have generated intense scientific interest in the role of adipose tissue as potential target against obesity and its metabolic complications. The purpose of this review is to: i) critically evaluate the current evidence on the physiological significance of BAT and the browning of WAT in metabolic function in humans and ii) discuss factors that have been reported to regulate BAT and/or the browning of WAT in humans. The current literature supports that BAT and the browning of WAT constitute promising emerging targets for interventions aiming to prevent and/or treat of obesity and its metabolic complications. Further research is needed to better understand the physiological significance of BAT and browning of WAT in health and disease along with the factors modulating their metabolic function in humans.     

Browning of chitooligomers and their optimum preservation

Chitooligomers have attracted much interest due to their unique biological activities. However, chitooligomers easily turn brown during shelf life. The factors influencing the browning of chitooligomers were investigated. The results indicated that the browning was attributed to the structure change of chitooligomers. The water-solubility, thermal stability and moisture–adsorption of chitooligomers decreased with the increase of browning. The time, temperature, pH, moisture, oxygen and reductant all had effect on the browning of chitooligomers. The optimal preservation condition for chitooligomers should be at low temperature and humidity, at pH below 4 or above 10, and in absence of oxygen.