Global classification of human facial healthy skin using PLS discriminant analysis and clustering analysis

Today's classifications of healthy skin are predominantly based on a very limited number of skin characteristics, such as skin oiliness or susceptibility to sun exposure. The aim of the present analysis was to set up a global classification of healthy facial skin, using mathematical models. This classification is based on clinical, biophysical skin characteristics and self-reported information related to the skin, as well as the results of a theoretical skin classification assessed separately for the frontal and the malar zones of the face. In order to maximize the predictive power of the models with a minimum of variables, the Partial Least Square (PLS) discriminant analysis method was used. The resulting PLS components were subjected to clustering analyses to identify the plausible number of clusters and to group the individuals according to their proximities. Using this approach, four PLS components could be constructed and six clusters were found relevant. So, from the 36 hypothetical combinations of the theoretical skin types classification, we tended to a strengthened six classes proposal. Our data suggest that the association of the PLS discriminant analysis and the clustering methods leads to a valid and simple way to classify healthy human skin and represents a potentially useful tool for cosmetic and dermatological research.     

NIR spectral imaging with discriminant analysis for detecting foreign materials among blueberries

The visualization of foreign materials (leaves and stems) in frozen blueberries was achieved by near infrared (NIR) spectral imaging and discriminant analysis. As a preliminary experiment, NIR spectroscopy of a sample surface was carried out to determine the effective wavelengths for differentiating foreign materials from blueberries in the NIR region. The optimal illumination wavelengths for distinguishing foreign materials were determined to be 1268 and 1317 nm, according to the results of a discriminant analysis of absorbance spectra. Next, absorbance images of areas containing foreign materials and blueberries were acquired by NIR spectral imaging at these two wavelengths. Nine thousand eight hundred and fifty pixels of a blueberry area and 10,107 pixels of a foreign material area were picked randomly from the absorbance images. Discriminant analysis was applied to the absorbance of pixels within the area of interest to determine the discriminant function and threshold value for image binarization. Finally, binary images were obtained by applying the discriminant function and threshold value to each pixel of the absorbance images taken at 1268 and 1317 nm. Foreign materials were clearly distinguished from blueberries as black areas in the binary images.     

PLS法和PCA法在近红外光谱定量分析中的应用研究

利用啤酒的近红外光谱数据比较了 PLS(偏最小二乘法,partial-Squares)和 PCA(主成分回归法,principal componentregression)两种方法在近红外光谱定量分析中的应用。并应用所建模型预测了 21 个啤酒样品麦芽的含量,结论为两种方法均适合近红外光谱定量分析,PLS 法所得预测结果准确度更高。     

Quality of pilsner malt and roasted malt during storage

Malt is usually expected to be stable during 12 months of storage. However, in practice many brewers notice changes in malt aroma during storage. The oxidative stabilities of pilsner malt and roasted malt were evaluated during a 12 month storage at different temperatures (10 and 20 °C) and water activities (0.231 and 0.432). The radical content in malt kernels was measured by electron spin resonance spectroscopy and the volatile profile of the resulting sweet worts was measured by head‐space analysis followed by GC‐MS analysis. The storage of malt resulted in oxidative reactions and a large change of the volatile profile of the resulting worts. Roasted malt was much more unstable than pilsner malt, as illustrated by a higher initial radical intensity, larger radical decay during storage and a larger change in the volatile profile of the wort with increased amounts of lipid oxidation products. For both roasted malt and pilsner malt, good correlations were found between radical decay and changes in the volatile profile of the wort, where high temperature and high water activity resulted in the largest changes. During the 12 months of storage, the sugar extract of the wort made from the malts remained constant and was not affected by the chemical changes. This study suggests that chemical changes occurring in malts during less than 12 months of storage may potentially affect the aroma of beer, and that water activity and storage temperature should both be kept low in order to maintain a high malt quality. Copyright © 2014 The Institute of Brewing & Distilling     

Quantification of glucose,fructose and sucrose in bayberry juice by NIR and PLS

Bayberry plays an important role in the nutrition and is a very important fruit-product. It has a high economic and officinal value. In this study, glucose, fructose and sucrose in bayberry juice were detected and quantified using near-infrared (NIR) spectroscopy. The HPLC method was assumed to provide the reference value of the analyte for calibration. Partial least-squares regression (PLSR) was used to construct calibration models with different pre-processing methods. The number of PLS factors was optimised. The results show PLS models are good for predicting glucose, fructose and sucrose concentrations in bayberry juice, and their prediction accuracy can be improved by using derivative process with the exception of the glucose. The best models were mostly given by the second derivative processed spectra, especially for sucrose with the determination coefficient, R² of 0.9931. This demonstrates the potential of NIR spectroscopy to quickly detect these components simultaneously in bayberry juice with the reference method of HPLC.     

Effect of cold shock on the enhancement of β‐amylase activity during malting and malt processability for a red sorghum intended for brewing use

The low β‐amylase activity of sorghum malt is a major concern when malts are intended for use in brewing. Several studies have shown that the germination temperature plays an important role in β‐amylase synthesis. In this study, the cold shock treatment was envisioned as a means of improving β‐amylase synthesis during red sorghum malting. The results show that, when a high‐frequency decrease in the germination temperature is used, the obtained malt exhibits a significantly increased β‐amylase activity. This study shows that this increase is not sufficient to consider cold shock as a means of improving β‐amylase activity for red sorghum brewing use, as the processabilty of the malts is unsatisfactory. Copyright © 2015 The Institute of Brewing & Distilling     

微量农药溶液近红外光谱PLS模型的不同预处理方法对比研究

比较了常用的多种预处理方法对近红外光谱技术(NIR)检测微量农药溶液含量的影响,使用偏最小二乘法(PLS)分别对各预处理方法处理后的数据建立了数学模型,利用两种不同农药初步探讨了数据量对PLS建模结果的影响。结果表明:矢量归一化(SNV)对26个微量毒死蜱溶液样本的预处理效果综合参数最好,校正集参数为R=0.9957,RMSECV=0.182,预测集参数为R=0.9992,RMSEP=0.0802;减去一条趋势线对20个微量炔螨特溶液样本的预处理效果综合参数最好,校正集参数为R=0.9925,RMSECV=0.649,预测集参数为R=0.9952,RMSEP=0.646。26个样本的微量毒死蜱溶液PLS建模结果优于20个样本的微量炔螨特溶液。     

近红外光谱结合不同偏最小二乘法快速检测镇江香醋的浑浊度

利用近红外光谱(4000cm-1～10000cm-1)结合化学计量学方法快速检测了镇江香醋中的浑浊度。首先,用近红外光谱仪采集香醋样本的近红外光谱数据以及用离心法测定样本的浑浊度值;然后,采用间隔偏最小二乘法(iPLS)、反向区间偏最小二乘法(biPLS)、联合间隔偏最小二乘算法(siPLS)优选光谱特征区间;最后,采用全光谱(4000cm-1～10000cm-1)偏最小二乘法(PLS)对优选出来的区间建立香醋浑浊度近红外光谱模型。结果表明,采用siPLS将全光谱均匀划分30个子区间,选择4个子区间[4 10 18 27]联合时,建立的模型预测效果最佳,其RMSECV和RMSEP分别为0.173和0.208,校正集和预测集相关系数分别为0.9337和0.9004。因此,利用近红外光谱技术快速检测香醋中的浑浊度是可行的。     

Protein profile and malt activity during sorghum germination

BACKGROUND: The effect of germination time on major sorghum macromolecules was followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy. Sorghum flour was also incubated with sorghum malt to evaluate amylase and protease activities. RESULTS: The SDS‐PAGE results showed that levels of high‐molecular‐weight aggregates, β monomer and γ and α monomers increased by 120.5, 20.3 and 12.7% respectively during the first few days of germination. This behaviour shows the enhancement of prolamin extractability and concentration in sorghum as a result of starch degradation. After the third day, proteins suffered degradation by intrinsic proteases. FTIR spectroscopy showed a gradual decrease in lipid and protein levels and starch structural changes during the germination period. These modifications are due to intrinsic lipases, proteases and amylases. Sorghum flour was incubated with different malt samples resulting from 0–7 days of germination. It was found that a 5 day malt led to a sixfold increase in carbohydrate digestibility and a fourfold increase in free amino acid content. CONCLUSION: A 5 day sorghum malt is the best inoculum for porridge preparation, representing an inexpensive, effortless and culturally acceptable way to prepare weaning foods at domestic and industrial levels. Copyright © 2008 Society of Chemical Industry     

Protein content determination in Brassica oleracea species using FT‐NIR technique and PLS regression

Six fresh and one frozen vegetable cultivar groups possessing remarkably different morphology from the same Brassica oleracea species, including broccoli, Brussels sprouts, curly cabbage, white cabbage, red cabbage, cauliflower and white kohlrabi, were chosen to set up a Fourier transform near‐infrared spectroscopy (FT‐NIR)‐based method for the quantification of protein content. Sample preparation was based on lyophilisation and homogenisation. Calibration was set up with the help of the Kjeldahl method for the quantification of protein content in the range of 12.9–32.5 m/m%. Calibration model was developed using the spectral regions 1136–1334 and 1639–1836 nm, with partial least squares regression. This model was checked by cross‐validation. The performance of the final FT‐NIR estimation model was evaluated by root mean square of cross‐validation, root‐mean‐square error of estimation and the determination coefficient (R²). The final estimation function for the protein determination was characterised with the predictive error of 0.76 m/m% and R² value of 98.81.     

Composite malt with dark-purple rice malt improves the phenolic profile and antioxidant activity of malt extract

This research presents a modification of bioactive compounds of malt extract produced from Riceberry rice malt (RRM)–barley malt composite for malt-based beverage. Malt extract was produced by varying RRM at 20% w/w, 40% w/w, 60% w/w, 80% w/w, and 100% w/w and were analysed for total polyphenol content (TPC), phenolic acids constituent, and antioxidant activity. The 100% RRM extract was rich in TPC relative to 100% w/w barley malt extract. The composite malt extract containing 40% w/w–80% w/w RRM had enough TPC in the filtered malt extract (236–524 mg L⁻¹) and boiled hopped malt extract (216–485 mg L⁻¹) and were directly proportional to the antioxidant activity in the extract. Barley malt fraction in the malt extracts had a positive response on ferulic acid and sinapic acid, whereas RRM inclusion in malt extract increased p-coumaric acid, vanillic acid, rutin, and methyl coumarate concentration. Therefore, the cereal malt composite could provide strong oxidative stability to the malt extract and derived products.     

小麦麦芽替代大麦麦芽生产啤酒的工艺探讨

在我国的啤酒生产中,一般是以大麦麦芽为主要原料。但目前所用的进口大麦麦芽价格约为2700元/t,国产大麦麦芽价格也在2300元/t左右,均比前一二年有了较大的提高,从而导致啤酒产品的生产成本加大,企业盈利水平下降。并且,啤酒市场竞争激烈,产品雷同现象比较普遍。如何降低生产成本,开发新产品,提高市场竞争力,增强企业效益是当前我国众多啤酒生产厂家积极努力解决的问题。而用小麦麦芽替代部分大麦麦芽生产啤酒则可以在一定程度上满足上述需求,为此,本文拟对此产品的工艺情况作一探讨。一、小麦麦芽概述小麦麦芽是以小麦为原料生产的,小麦的…     

制麦过程中麦芽抗氧化性的研究

大麦和麦芽中存在的氧化还原酶类能催化氧化总多酚、不饱和脂类等物质,产生了一些风味老化前驱物和羰醛化合物等,从而降低啤酒的非生物稳定性和风味稳定性。研究了4个品种啤酒大麦在制麦过程中总多酚、老化前驱物及几种氧化还原酶酶活力的变化,分析了制麦过程中总多酚、老化物质含量的变化与氧化还原酶活力之间的关系,发现Prestige的抗氧化性最高,内蒙大麦的抗氧化性最低,且DPPH自由基清除率和总多酚、TBA和LOX相关系数分别0.930和0.784具有高度相关性。      

啤酒大麦制麦过程中淀粉酶活性变化动态的研究

以不同品种的大麦为材料,运用底物分析法检测3种淀粉酶的活性。不同品种的大麦中α-淀粉酶、β-淀粉酶和极限糊精酶活力差异较大,因此实际生产中可对不同品种大麦进行筛选,选用酶活较高的大麦来制备麦芽;在制麦过程中,浸麦可在一定程度卜抑制淀粉酶的活力;淀粉酶的总活力在发芽初期缓慢增加,2d～3d后急剧增加至最大值;焙焦可使3种酶酶活有不同程度地下降。     

结晶麦芽的制备工艺优化及其品质分析

结晶麦芽作为重要的特种麦芽,可以赋予啤酒多样的风味和独特的口感。该文选取不同发芽时间的绿麦芽为原料,比较糖化后还原糖和游离氨基氮含量的变化,确定用于制备结晶麦芽的绿麦芽,优化绿麦芽的预糖化与焙焦工艺,制备结晶麦芽,并分析其常规理化指标与风味特征。结果表明,选择发芽84 h的绿麦芽为原料,调节预糖化水的pH值为3.36,蛋白质休止温度为60℃,糖化温度为71.1℃,预糖化结束的绿麦芽游离氨基氮与还原糖含量分别达到142.4 mg/L与26.2 g/L。由此制备的结晶麦芽结晶率98%,且麦芽内部结晶均匀,风味物质含量达到1 265μg/L,比普通商品结晶麦芽提高了98.3%,主要风味物质为醛类。该研究为国产优质结晶麦芽的规模化生产奠定了基础。     

气相色谱-嗅闻-质谱分析浅色麦芽、焦香麦芽及黑麦芽中香气成分

通过采用同时蒸馏萃取和固相微萃取技术,结合气相色谱-嗅闻-质谱进行麦芽风味的定性分析,包括浅色、焦香、黑麦芽3种,采用现行保留指数和美国国家标准与技术局化学(The National Institute of Standards and Technology,NIST)数据库能够定性出100种以上。通过采用峰后强度法结合气相色谱-嗅闻-质谱嗅闻出61种化合物,探明3类麦芽中共有物质及各自特有的重要致香物质。风味轮显示2种萃取的定性结果差异较小,能够真实反映出其香气物质。采用芳香萃取物稀释分析法针对同时蒸馏萃取麦芽萃取液进行深入剖析,确定出高达40种的主要关键香气物质贡献强度。对3类麦芽所有化合物进行定性分析并归类,发现醛类比例在10.3%~48.5%;含氮杂环化合物对其浅色麦芽、焦香麦芽香气贡献小,但对黑麦芽香贡献极显著,高达11%;含氧杂环类对焦香、黑麦芽香贡献突出,分别为7.9%、4.4%。醇、酮、酯、苯、其他类对麦芽香贡献较小。此外,麦芽制备中的热处理程度越强,醛、含氧杂环、含氮杂环、酮类数量和含量都不断递增,而醇类不断减少。     

Application of NIR spectroscopy and image analysis for the characterisation of grated Parmigiano-Reggiano cheese

Grated Parmigiano–Reggiano cheese holds a valuable market segment and its quality strictly depends on the amount of rind, size, shape of cheese particles and original cheese properties. Textural properties of the rind and inner part of the cheese significantly affect size and shape of grated particles. Rind produces a higher amount of finer and less circular particles than the inner region. Rind content established by European regulation (maximum 18%) is a major issue and could be successfully predicted by multivariate models developed on near-infrared (NIR) spectra. Image analysis (IA) was a suitable method to estimate rind percentage that was found positively correlated to number of particles, total surface covered by particles and circularity. IA and NIR spectroscopy enabled characterisation of the distribution of the particle in dimensional classes and could be used to control the maximum limit of 25% of particles finer than 0.5 mm provided by European regulation.     

贮存条件对Gairdner大麦和麦芽的醛类物质的影响

利用固相微萃取与气相色谱-质谱联用检测醛类物质的方法跟踪了啤酒酿造大麦和麦芽Gairdner中的脂质氧化醛、Strecker醛、糠醛在10℃和35℃条件下的变化趋势。新鲜麦芽中的Strecker醛和糠醛含量高于大麦,而脂肪氧化醛含量和脂合氧化酶活力明显低于大麦。大麦和麦芽中脂质氧化醛和糠醛在贮存过程明显增加,具有指示大麦和麦芽新鲜度的可能性。10℃和35℃贮存5个月后,大麦的反-2-壬烯醛分别增加了1.01和1.62倍,而麦芽的反-2-壬烯醛分别增加5.12和17.74倍。由于反-2-壬烯醛的高风味活性特点,建议将反-2-壬烯醛作为大麦和麦芽新鲜度与品质优劣的关键性评价指标。本研究从脂质氧化醛等指标量化的角度,再次肯定了低温贮存相对于高温贮存更利于大麦和麦芽保持新鲜的事实。      

贮存条件对Gairdner大麦和麦芽的醛类物质的影响

利用固相微萃取与气相色谱-质谱联用检测醛类物质的方法跟踪了啤酒酿造大麦和麦芽Gairdner中的脂质氧化醛、Strecker醛、糠醛在10℃和35℃条件下的变化趋势。新鲜麦芽中的Strecker醛和糠醛含量高于大麦,而脂肪氧化醛含量和脂合氧化酶活力明显低于大麦。大麦和麦芽中脂质氧化醛和糠醛在贮存过程明显增加,具有指示大麦和麦芽新鲜度的可能性。10℃和35℃贮存5个月后,大麦的反-2-壬烯醛分别增加了1.01和1.62倍,而麦芽的反-2-壬烯醛分别增加5.12和17.74倍。由于反-2-壬烯醛的高风味活性特点,建议将反-2-壬烯醛作为大麦和麦芽新鲜度与品质优劣的关键性评价指标。本研究从脂质氧化醛等指标量化的角度,再次肯定了低温贮存相对于高温贮存更利于大麦和麦芽保持新鲜的事实。     

Effect of different analysis conditions on Rapid Visco Analyser malt viscograms in relation to malt of varying fermentability

Malt fermentability is a difficult and time consuming trait to measure. The Rapid Visco Analyser (RVA) was assessed as an alternative rapid method to indicate potential fermentability. This study evaluated changes in rheological profiles under different operational conditions and compared these changes with reference to malt fermentability from a limited number of samples. Viscosity measurements of samples were also made using different RVA (models 3D+ and 4) analysis conditions including a brewhouse time–temperature profile, heating/cooling rate, particle size and enzyme activity. Rheological measurements using the RVA‐3D + gave similar results compared with the RVA‐4, indicating adequate sensitivity of the RVA 3D+ for discriminatory purposes. Use of a time–temperature profile of a commercial brewery mashing process was unsuitable. When malt enzymes were inactivated with silver nitrate, differences in viscosities were observed. However, this eliminated the ability to discriminate on fermentability. Increasing or decreasing the heating rate influenced the time available for enzyme action, which affected the degree of discrimination. This also provided some insight into physical and biochemical processes affected by differences in particle size. RVA has the potential to be used as a tool to discriminate between poor and good fermentability barley malts. RVA conditions when using the ‘Kilned Malt’ method with an appropriate mashing malt–water ratio provided a fast and reliable indication of malt performance prior to conducting lengthy fermentability tests. Copyright © 2014 The Institute of Brewing & Distilling