The Horace Brown Medal Lecture: Forty Years of Brewing Research

Horace Brown spent fifty years conducting brewing research in Burton‐on‐Trent, Dublin and London. His contributions were remarkable and his focus was to solve practical brewing problems by employing and developing fundamental scientific principles. He studied all aspects of the brewing process including raw materials, wort preparation, fermentation, yeast and beer stability. As a number of previous presenters of the Horace Brown Lecture have discussed Brown's achievements in detail, the focus of this paper is a review of the brewing research that has been conducted by the author and his colleagues during the past forty years. Similar to Horace Brown, fundamental research has been employed to solve brewing problems. Research studies that are discussed in this review paper include reasons for premature flocculation of ale strains resulting in wort underattenuation including mechanisms of co‐flocculation and pure strain flocculation, storage procedures for yeast cultures prior to propagation, studies on the genetic manipulation of brewer's yeast strains with an emphasis on the FLO1 gene, spheroplast fusion and the respiratory deficient (petite) mutation, the uptake and metabolism of wort sugars and amino acids, the influence of wort density on fermentation characteristics and beer flavour and stability, and finally, the contribution that high gravity brewing has on brewing capacity, fermentation efficiency and beer quality and stability.     

Quantitative assessment of antioxidant properties of natural colorants and phytochemicals: carotenoids,flavonoids, phenols and indigoids. The role of β‐carotene in antioxidant functions

Reactive oxygen species are potentially damaging molecules. An important function of antioxidants is to intercept harmful triplet states, in order to prevent the formation of singlet oxygen, or to quench singlet oxygen directly. However, antioxidants are also reactive towards other active oxygen species such as the hydroxyl radical, the superoxide anion and the non‐excited oxygen ground state in the presence of radical initiators. It is well known that flavonoids and carotenoids show strong antioxidant properties. Polyenes and carotenoids are the best known among the compounds that quench singlet oxygen by efficient energy transfer. A large number of modified, synthetic analogues and derivatives have been synthesised to prepare even better quenchers than the natural carotenoids. Phenols are also excellent chain‐breaking antioxidants. Recently, many indigoid dyes (including bacterial indigoids) were studied, with the remarkable result that most, but not all, members of this class of chromophores quench singlet oxygen at the diffusion limit and some of them are excellent radical traps. It has been shown in this study that a quantitative assessment of antioxidant properties of flavonoids, carotenoids, phenols and natural indigoids can be achieved using the following three assays: (1) oxygen pressure dependence; (2) peroxide formation; (3) singlet oxygen quenching. Reactivities towards both excited states and ground state radicals can be properly described by these assays. The remarkable role of β‐carotene as an ‘unusual antioxidant’ (Burton GW and Ingold KU, Science 224 : 569–573 (1984)) in reactions using various oxygen pressures becomes clearer. The so‐called ‘pro‐oxidant effects’ concern primarily the antioxidant itself and its degradation, since no or very little damage to the substrate occurs in this type of experiment. Three main categories of antioxidants may be classified: (1) excellent antioxidants that perfectly quench excited states as well as ground state radicals (eg actinioerythrol, astaxanthin); (2) good antioxidants that strongly inhibit peroxide formation but are less efficient in quenching excited states (eg flavonols, tocopherols) or lead to considerable degradation of the antioxidant itself (eg β‐carotene, lycopene); (3) moderate antioxidants that fail to excel in both reactivities (eg ζ‐carotene, flavone). © 2001 Society of Chemical Industry     

Biochemical changes during ripening of some sudanese date varieties

Changes in the chemical composition of three popular Sudanese varieties of date (Jawa, Bentamoda and Mishrig Wad Laggai) during ripening are described and are related to changes in texture and in the activities of various degradative enzymes in the fruit. Total invertase levels were high throughout maturation of the three varieties. Although the proportion of soluble enzyme increased during ripening solubilisation did not appear to influence the relative amounts of sucrose and reducing sugars in the ripening fruit. Both cellulase and polygalacturonase were absent or at low levels in the green fruit but displayed large increases in activity during ripening. This enhancement was reflected in a reduction in fruit firmness although little change in cellulose or pectin levels was apparent analytically until the final stage of ripening. Despite a considerable rise in pectinesterase activity during ripening no significant trend could be discerned in the degree of esterification of pectin suggesting that the enzyme is of minor importance in softening of these fruit.     

Influence of carding and drawing processes on orientation of fibers in slivers

The orientation of fibers is known to play a very important role in determining the quality of the carded and drawn slivers as well as the quality of the ultimate yarns produced from those slivers. Also, the orientation of fibers is considered to be a very useful parameter for evaluating the effectiveness of the carding and drawing processes in aligning the fibers. In addition, the orientation of fibers is known to determine the length utilization of the fibers in the slivers. This article reports on the influence of carding and drawing processes on the orientation of fibers in the carded and drawn slivers. A series of carded and drawn slivers were prepared by using polyester staple fibers and making various changes in the carding and drawing processes and the orientation of fibers in the slivers was evaluated based on Lindsley’s methodology in conjunction with a mathematical model of fiber orientation in slivers. It was observed that the increase in cylinder speed and the decrease in doffer speed resulted in more anisotropic fiber orientation distribution in the carded slivers and the degree of anisotropy was found to be more in the forward direction as compared to the backward direction of the carded slivers. The higher draft and doubling in the drawframe resulted in higher anisotropy in the orientation of fibers in the drawn slivers and the drawn slivers displayed more anisotropy in the backward direction as compared to the forward direction. The higher delivery speed of the drawframe resulted in higher anisotropy in fiber orientation in the drawn slivers and the drawn slivers exhibited more anisotropy in the backward direction as compared to the forward direction. The results of fiber orientation in the carded and drawn slivers obtained by using the mathematical model were compared to the fiber orientation parameters suggested by earlier researchers and a satisfactory correlation between them was observed.     

Effects of duration of moderate increases in grain feeding on endotoxins in the digestive tract and acute phase proteins in peripheral blood of yearling calves

Effects of duration of grain feeding on the concentration of endotoxic lipopolysaccharide (LPS) in digesta throughout the digestive tract and on acute phase proteins and LPS in peripheral blood were determined in Holstein yearling calves. Twenty-five Holstein yearling steer calves received either a forage-based diet containing 92% hay and 8% of a mineral and vitamin pellet on a dry matter basis (CON) or a moderate-grain diet, obtained by replacing 41.5% of the hay in the forage-based diet with barley grain, for 3 (MG3), 7 (MG7), 14 (MG14), or 21 d (MG21) before slaughter. Immediately before slaughter, blood samples were collected from the jugular vein. Immediately after slaughter, digesta samples were collected from the rumen, jejunum, ileum, cecum, colon, and rectum. Rumen liquid digesta, digesta from the intestines, and peripheral blood plasma were analyzed for LPS. Peripheral blood plasma and serum were analyzed for the acute phase proteins amyloid A, haptoglobin, and LPS-binding protein. Feeding the grain diet increased the LPS concentration in rumen fluid linearly from 15,488 endotoxin units (EU)/mL for CON to 70,146 EU/mL for MG7. Concentrations of LPS in rumen fluid in MG14 and MG21 were 61,944 and 56,234 EU/mL, respectively, and did not differ. The LPS concentrations in jejunal digesta were much lower than that in digesta elsewhere in the digestive tract, which suggests that ruminal LPS is broken down in the abomasum or proximal jejunum. The concentration of digesta LPS in the ileum was higher than that of digesta elsewhere in the intestines and similar to that in rumen fluid. The duration of grain feeding increased the LPS concentration in digesta in the ileum and cecum and tended to increase that in the colon cubically. Concentrations of LPS in this part of the digestive tract were highest in the MG3 and MG21 groups. The highest concentrations of LPS in digesta in the cecum, colon, and rectum were 3.7, 3.8, and 5.6 times higher than that in CON, respectively. Grain feeding and the increase in LPS in digesta were not accompanied by an acute phase response or a detectable concentration of LPS in peripheral blood. The absence of LPS in peripheral blood and the lack of increase in acute phase proteins indicated that the grain feeding protocol used in the current study and the accompanying changes in LPS concentrations of the digesta did not result in systemic inflammation.     

Distribution of hydrophilic and lipophilic antibacterial drugs in skim milk,cream, and casein

This study determined the distribution of drugs to different milk fractions according to their physicochemical properties. Hydrophilic drugs tend to concentrate in skim milk, whereas lipophilic drugs tend to concentrate in cream. The concentration of a drug in casein is related to its degree of binding to milk proteins. Thus, we aimed to determine whether withdrawal time in whole milk differs from that in cream, casein, and skim milk. Amoxicillin and tylosin were selected as prototype hydrophilic and lipophilic drugs, respectively. The study was conducted in vitro and in vivo to determine whether in vitro conditions reflect the distribution of drugs in the different milk fractions in vivo. The in vivo study was conducted using a crossover design on 6 healthy Holstein dairy cattle. First, amoxicillin (i.m., single dose, 14 mg/kg) was administered to cows. Following a 1-wk washout period, tylosin (i.m., single dose, 15 mg/kg) was administered. Concentrations of amoxicillin and tylosin in milk and milk fractions were measured using HPLC-UV. In the in vitro study, 0.04 to 400 μg/g of amoxicillin and 0.05 to 50 μg/g of tylosin were spiked to drug-free milk and the concentrations in milk and milk fractions were measured. In addition, the percentage of total protein in milk and milk fractions was determined. Amoxicillin accumulated more in skim milk than in cream and casein, both in vitro (92%) and in vivo (73%, skim milk-to-whole milk ratio). The distribution of tylosin in whole and skim milk was similar to that of amoxicillin in the in vitro study, in contrast to the accumulation of tylosin in cream seen in vivo. However, the accumulation ratio of tylosin in cream was lower than expected. By either method, tylosin was less concentrated in casein than in skim milk and cream. The percentage of total protein was similar in skim milk and whole milk and higher than in cream. Thus, amoxicillin accumulates less in cream and casein, suggesting that these fractions would pose a lower risk to the consumer. Tylosin was still present at the maximum residue limit (50 μg/kg) 24 h after injection in the casein fraction and 48 h after injection in the cream fraction.     

The uptake of na and its redistribution between leaves during the development and alleviation of K deficiency

Changes in the concentration of Na in the shoot dry matter and in the petiole sap of individual leaves of lettuce were measured in order to determine the extent to which Na was able to replace K within the plants during K deficiency. The results were used to estimate changes in the distribution of the total ionic concentration between leaves and to make deductions about likely variations in osmotic potential within the shoots and their effect on plant growth. Measurements of Na concentration revealed both a pronounced delay in the uptake of additional amounts of Na and in its translocation within the K-deficient plants. Sodium concentrations increased most rapidly in the young expanding leaves during the onset of K deficiency but the changes in its concentration were ultimately larger in the middle to older ones. Elevated Na concentrations in the younger leaves of K-deficient plants also declined more rapidly than those in any of the other leaves following reintroduction of the K supply. Although the pattern of these changes broadly mirrored the corresponding changes in K concentration within the shoots there were significant reductions in the combined K+Na concentrations during the onset and development of K deficiency. The deficit in K+Na was initially greatest in the young leaves but subsequently disappeared more quickly when either the uptake of Na was increased or the K supply was resumed. Since the combined concentrations of K+Na were directly related to the changes in total ionic concentrations within the shoots, the results suggest that during K deficiency, plants adopt a strategy which reduces the effects of a decline in ionic strength at the most actively growing sites in order to minimise the damage to normal growth processes from changes in the internal osmotic pressure.     

Evaluation of arterial digital blood flow in dairy cows with claw horn disruption lesions using Doppler ultrasonography

Vascular changes play an important role in the pathogenesis of claw horn disruption lesions in cattle. The aim of the study was to measure arterial blood flow in the hind limbs of German Holstein cows with claw horn disruption lesions. A 10-MHz linear transducer was used to assess blood flow in the interdigital artery in the dorsal pastern region in the hind limbs of 11 non-lame and 33 lame German Holstein cows in which lameness was scored clinically. Qualitative and quantitative blood flow parameters were compared in affected limbs and unaffected contralateral hind limbs in lame cows and in the hind limbs of lame cows and non-lame cows. A pulsed-wave Doppler signal suitable for analysis was obtained in 78 of 88 limbs (33 affected and contralateral limbs, 22 limbs of control cows). Blood flow curve types 1 and 2 were predominant in the hind limbs of lame cows. Vessel diameter, end-diastolic velocity, and blood flow rate were significantly greater in lame cows than in non-lame cows and were numerically greater in moderately lame cows than in mildly lame cows. The differences in the qualitative and quantitative parameters between lame and non-lame cows were most likely caused by inflammation of the pododerm. The role of weight distribution between the paired hind limbs and the existence of claw horn disruption appeared to have an effect on the differences in local circulation in the affected and unaffected contralateral hind limbs in lame cows.     

Reproductive and neurobehavioural effects of thiabendazole administered to mice in the diet

Thiabendazole was given in the diet to provide levels of 0 (control), 0.031, 0.125, and 0.5% from 5 weeks of age of the F₀ generation to 9 weeks of age of the F₁ generation in mice, and selected reproductive and neurobehavioural parameters were measured. The average litter size and weight were significantly reduced in the high-dose group at birth. No adverse effects were observed in the sex ratio at birth. The average body weight of offspring was significantly increased in the low-dose group during the late lactation period, and was significantly reduced in the high-dose group during the lactation period. In the assessment of neurobehavioural parameters, surface righting at postnatal day (PND) 7 was significantly delayed in a dose-related manner in both sexes. Swimming limb movement at PND 14 and olfactory orientation at PND 14 were significantly depressed in the high-dose group in both sexes. In movement activity at 3 weeks of age in the F₁ generation, vertical time and number of defaecations were significantly decreased in the high-dose group in female offspring. Several adverse effects on reproductive and neurobehavioural parameters were produced at the highest dose level of thiabendazole used in the present study (equivalent to 700-1800mg/kg bw/day). Slight, dose-related delays were also seen in surface-righting ability at the two lower dose levels. The lowest dose level (equivalent to 50-180mg/kg bw/day) is 500     

气候变化背景下鄂西烟草种植气象风险评价与区划

为了确定湖北西部植烟区的气象灾害风险程度,根据灾害学系统理论,从致灾因子、孕灾环境、承灾体和防灾减灾能力4个子系统出发,综合考虑气候条件、地理地形、社会经济状况等多个因素,利用GIS平台对鄂西烟草种植气象灾害风险进行评价与区划。结果表明,鄂西北地区气象灾害危险性东高西低,南北向无明显规律,而鄂西南地区是南高北低;鄂西南巴东和恩施烟草易损性较小,而鄂西北的枣阳和丹江口市易损性较大;鄂西南北部地区的气象风险低于南部地区,而鄂西北南部地区气象风险较小,东部气象风险最大;神农架局部地区和鹤峰、丹江口市东部等地的气象风险最严重。总体而言,鄂西地区适宜种植烟草,尽管存在风险,但是大部分地区风险等级在中等及中等以下,这对指导当地合理规划烟草种植和生产具有重要意义。     

棉纺细纱后区牵伸型式的演变与发展(三)

为说明后区牵伸运用原则,从后区牵伸中纱条紧密度测定、有捻粗纱的匀伸作用、牵伸力与输出纱条不匀关系测定、不同牵伸分配、不同粗纱捻系数下前区牵伸力测定等方面分析,指出后区牵伸为前区主牵伸创造良好的牵伸条件;其实质是使喂入前区的牵伸纱条具有较均匀结构和必要紧密度,它产生的内摩擦力场强度与前区外摩擦力场强度分布相配合,共同形成胶圈牵伸良好而稳定的总摩擦力场强度分布,有利于成纱质量的提高;表明在此前提下,后区适当承担总牵伸的一部分可以减轻前区牵伸过大的负担,这就是后区牵伸运用原则。对罗拉直线牵伸、罗拉曲线牵伸和胶圈牵伸等各种后区牵伸型式进行了摩擦力场强度分布分析比较,指出单控制辊式VC型曲线牵伸是后区牵伸型式的重大突破和发展,可发挥前、后区牵伸潜力,其总牵伸能力达50倍～150倍,成为第三代大牵伸新水平,是后区牵伸型式技术进步的标志。     

Origin and fate of 2,4,6-trichloroanisole in cork bark and wine corks

2,4,6-Trichloroanisole (TCA), which is a major cause of cork taint in bottled wine, is already present in the bark of living cork trees to the extent that it can account for the majority of incidences of cork taint in bottled wine. Other post-harvest sources of TCA are known and may add to the forest-derived TCA in cork. Both the origin of TCA in the bark in the forest, and the means by which additional TCA can accumulate in the corks during manufacture, have been examined. TCA can originate from 2,4,6-trichlorophenol (TCP) produced from naturally-occurring phenol and chlorine from sanitisers and cleaning products, and town water. Also, chlorophenol biocides have accumulated in the environment due to the large quantities used in previous times – TCP has been a minor impurity in pentachlorophenol biocides and a major ingredient in other preparations. There is some evidence that chlorophenols were used in pest management in the forest prior to restrictions on the use of these materials. The factors affecting the uptake and loss of TCA by the bark on the tree and by corks during production, and through to their use in the bottling of wine have been considered in this review.     

Effects of applying sodium and sulphur fertilisers on the concentrations of elements in water leached from permanent pasture

The element composition of water leached from a perennial ryegrass pasture to which isonitrogenous quantities of sodium nitrate, ammonium nitrate or ammonium sulphate fertilisers had been applied in an experiment lasting 2 years is described. The experimental design also allowed a comparison of the immediate effects of sodium nitrate in the grazing season in which the fertiliser was applied with the residual effects of applying it in the previous year. Applying sodium fertiliser in either 1992 or 1993, but not both years, increased the concentrations of sodium, potassium, magnesium, calcium and cobalt and reduced those of phosphorus and molybdenum in leachate. The application of sulphur fertiliser reduced the concentrations of zinc, copper, iron and molybdenum in leachate. It also reduced the concentrations of sodium, potassium and magnesium, but only when sodium fertiliser was applied in 1992, and not when it was applied in 1993. It is concluded that sulphur fertiliser reduces the leaching of trace elements from the soil and that, in the long term, sodium fertiliser can amplify the effect of applying sulphur fertiliser. Sodium fertiliser in moderate quantities increased the leaching of the major divalent cations but reduced the phosphorus and molybdenum concentrations in leachate. © 2002 Society of Chemical Industry     

Eucalyptus increases ceramide levels in keratinocytes and improves stratum corneum function

The objectives of this study were to identify a plant extract that would improve stratum corneum functions and to elucidate the mechanism(s) involved. Based on the information that stratum corneum functions depend on the level of ceramide in the stratum corneum, we identified a Eucalyptus extract that was able to increase the level of ceramide in human keratinocytes in culture and in human stratum corneum and that improves the stratum corneum water holding and barrier functions. Addition of the Eucalyptus extract to human keratinocytes in culture increased the level of ceramide in a dose-dependent manner and also increased the biosynthesis of ceramide, glucosylceramide and sphingomyelin. Topical application of the Eucalyptus extract on the dry skin of human subjects induced by acetone and diethylether treatment resulted in a significant increase in ceramide level in the stratum corneum, a significant improvement in its water-holding function and an improvement in its barrier function. The addition of macrocarpal A, one of the main components of the Eucalyptus extract, to human keratinocytes in culture increased the level of ceramide and the mRNA expression of serine palmitoyltransferase, acid sphingomyelinase, neutral sphingomyelinase, glucosylceramide synthase and glucocerebrosidase in a dose-dependent manner. Our results indicate that the increased content of ceramides in the stratum corneum may underlie the therapeutic effect of the Eucalyptus extract. Our results also indicate the possibility that macrocarpal A is the key component that stimulates the synthesis of ceramide in the stratum corneum.     

我国不同生态区云烟97烟叶主要品质性状差异分析

为掌握云烟97在我国不同生态区烟叶的主要品质性状差异,系统分析了云南曲靖（清香型烟区）、贵州毕节（中偏清香型烟区）和重庆武隆（中间香型烟区）3个烤烟种植生态区云烟97烟叶的外观质量、化学成分、风格特征和烟气品质。结果表明,贵州毕节烟叶烟气品质综合得分最高,中部叶干草香香韵、香气质、香气量和透发性得分显著高于云南和重庆,还原糖含量和烟气浓度显著高于重庆;云南曲靖烟叶外观质量最好,中部叶总氮含量、氮碱比值以及烟气飘逸感得分均显著高于贵州和重庆,烟气浓度和劲头得分居中,清香型特点显著;重庆武隆烟叶外观质量居中,中部叶总植物碱含量、烟气刺激性、干燥感和悬浮感得分均显著高于云南和贵州,而糖碱比和余味得分则显著低于云南和贵州,中间香型特点显著。由云南经贵州向重庆方向,云烟97烟叶清甜香韵和烟气飘逸感逐渐减弱,木香香韵和烟气悬浮感逐渐加强。     

巧克力起霜研究进展

巧克力起霜导致产品品质下降,成为困扰糖果工业的一个世界性难题。基料油种类不同,起霜的机理显著不同。从基料油性质出发,详细阐述基料油组成、加工条件以及储存条件对巧克力起霜的影响。在此基础上,对各类巧克力起霜的机理进行总结,为解决起霜问题提供理论支持。参考国内外文献报道,对巧克力起霜的研究方法进行总结,并详细阐述具有延缓起霜作用的措施,为巧克力生产提供参考。     

红车轴草不同部位中异黄酮含量的测定

采用反相高效液相色谱法对红车轴草不同部位(花、茎和叶)中四种主要异黄酮(鸡豆黄素A、芒柄花黄素、染料木素和大豆黄素)的含量进行了测定,结果表明:以占干物质计,4种异黄酮总量,叶中含量最高(0.856%),茎次之(0.403%),花中含量较低(0.258%)。鸡豆黄素A和芒柄花黄素是红车轴草中两种最主要的异黄酮,主要分布在叶中,其次是茎,花中含量较低。染料木素和大豆黄素,无论是花、茎还是叶,含量均较低。     

连续蒸煮器内洗涤结合器外扩散洗涤的应用

连续蒸煮器内洗涤结合器外扩散洗涤，具有洗涤时间长、洗涤效率高、提取黑液浓度高、浆层厚度均匀、浆层结构组织和浓度一致等特点，运行可靠，易于自动化控制，实现了洗涤用水的封闭循环。     

Amounts of glycosides in grapevine organs during berry development

Whole berries, leaf blades and petioles from Muscat Gordo Blanco (syn. Muscat of Alexandria), Sultana and Flame Seedless vines were sampled at intervals from three weeks after flowering to fruit ripeness. The glycosidically-bound constituents present in the samples were quantified through a determination of the glycosyl glucose. At the stage of berry ripeness, the concentration of glycosides per gram fresh weight in the leaf blades was 10–30 times higher than in the fruit. During berry development glycoside concentrations increased in leaf blades and petioles but decreased in fruit. However, when expressed on a per berry basis, the levels of glycosides in the fruit increased as ripening progressed; the levels in ripe fruit were high in Muscat Gordo Blanco and low in Sultana. Further experimentation will be needed to establish whether the glycosides are synthesised in the leaves and transported to the berries or synthesised independently in both organs.     

Assessment of endogenous androgen levels in meat,liver and testis of Iranian native cross-breed male sheep and bull by gas chromatography-mass spectrometry

Androgenic steroids always exist in different animal tissues at trace level, with significant numbers of interfering compounds, which makes their determination difficult. To solve some of the problems in quantification of the natural steroids in those tissues, a new GC-MS method was developed in this study. By using a surrogate analyte approach, which was developed in the authors’ previous studies, and extensive sample preparation procedure, which successfully eliminates many of the interfering compounds and resulting in a cleaner extract, accuracy, precision, sensitivity and selectivity of the method for the determination of steroids in complex matrices such as meat, liver and testis were improved. By aid of this method, the levels of androgens in different tissues of Iranian native cross-breed bulls and male sheep were determined. According to the results obtained in the present study, although the androgenic profile (contents and ratios of precursors and metabolites to the main hormones) is similar between the same tissues of both animals, the total androgenic content of each tissue is higher in the bull than the same tissue in male sheep. In addition, in both animals higher amount of androgens were found in liver in comparison with meat and testis.