PLS methodology to study relationships between hedonic judgements and product characteristics

This paper depicts a methodology devoted to a situation where a few products are described by many physico-chemical and sensory characteristics, and are evaluated by consumers on a preference scale. The objective is to relate the block of hedonic variables to the physico-chemical and to the sensory blocks. The analysis of the link between the responses and the predictors using PLS regression allows to cluster the consumers in homogeneous groups with respect to their tastes, and in such a way that their behaviour can be related to the characteristics of the products. For each group, PLS regression allows obtaining a graphical display of the products with their characteristics, and a mapping of the consumers based on their preferences. Moreover, PLS path modelling allows a detailed analysis of each group by building a causal scheme: each block of consumers is related to the physico-chemical and the sensory blocks, and the sensory block is itself related to the physico-chemical block. Finally this PLS path modelling is compared with hierarchical multi-block PLS model.     

Comparison between linear and nonlinear PLS methods to explain overall liking from sensory characteristics

The influence of sensory characteristics on overall liking can be statistically studied with Partial Least Squares (PLS) regression methods. To correctly model nonlinear dependence relationships, some nonlinear PLS extensions are useful. The purpose of the present paper is to compare performances and results of three PLS methods, using a real data set: regular PLS with sensory attributes as explanatory variables; PLS with attributes and their respective squares; and a new nonlinear PLS extension, called ASPLS. In case of a nonlinear dependence relationship between sensory characteristics and hedonic responses, this last method is shown to be worth considering.     

类胡萝卜素肠道吸收及生物利用度研究进展

类胡萝卜素是一种自然界中分布广泛的食品成分,具有多种生物学活性,受到诸多学者关注。文章主要从类胡萝卜素生物学功能、食品成分对类胡萝卜素吸收利用的影响及提高其生物学利用三方面综述其研究进展。类胡萝卜素具有特异性调控相关基因及蛋白的功能,进而具有多种生物活性。文章从机制的角度归纳总结类胡萝卜素的功能特性,整理了食品成分间相互作用对类胡萝卜素生物利用率的影响,总结了纳米载药系统技术、异构化处理技术以及通过食品加工方式三种提高类胡萝卜素生物利用率的方法,为类胡萝卜素功能性产品研发提供一定的理论参考。     

Portion size selection as related to product and consumer characteristics studied by PLS path modelling

Expectations of satiation and satiety have been increasingly investigated because of the interest in how they, along with liking, can modulate portion-size selection. Consumer characteristics can also be important when consumers select their portion size. However, the contribution and interaction of consumers and product aspects to portion size selection has not been unveiled. This study aims to better understanding these complex relations by simultaneously assessing the relative influence of consumer characteristics and product related properties on portion size selection utilizing PLS-Path Modelling (PLS-PM) approach.In this study, consumers (n = 101) answered questions regarding attitudes to health and hedonic characteristics of foods, and completed hunger and fullness questions. In an evaluation step, they tasted eight samples of yogurt with different textures and rated liking, expected satiation, expected satiety and portion size. The consumers were also classified on their mouth behaviour by using the JBMB™ tool.Results showed that liking, satiation, satiety and portion size depended firstly on the thickness, and then on the particle size of samples. PLS-PM was used to generate a model, indicating that liking was a direct predictor of portion size, with a stronger effect than satiation or satiety. The relationship between liking and satiety was observed both in direct direction (liking-satiety) and also indirect direction throughout satiation (liking-satiation-satiety). The former was negative effect and the latter was positive effect depending on the criteria which consumers used.These findings implied that liking is a main factor in the prediction of portion size however the relations are complex.     

薄膜透气性测试的两种方法比较——压差法与等压法

从测试原理上论证了由于氮气逆向渗透的存在,使得压差法与等压法存在本质的区别.     

蜜环菌菌粉中甘露醇测定方法的比较与优化

目的:比较对蜜环菌菌粉的不同预处理方法和甘露醇含量测定方法,筛选更有效的方法对蜜环菌菌粉中甘露醇含量进行测定。方法:用醇提取、水提取和超声波破碎法对蜜环菌菌粉进行甘露醇提取比较,并选出最优者;使用浓盐酸与样品液共热去除果糖干扰;采用碘量法和分光光度法分别对蜜环菌菌粉进行甘露醇含量测定比较。结果:以水为溶剂,80℃下对蜜环菌菌粉进行超声波破碎,相对醇提取法和水提取法能有效提高甘露醇测定值;浓盐酸与样品液沸水共热可有效去除果糖干扰;在存在葡萄糖等单糖对甘露醇干扰的情况下,分光光度法测定值相对碘量法更准确。结论:以超声波破碎预处理、浓盐酸去除果糖干扰,采用分光光度法为具体测定方法的组合方式为最佳测定方法。      

Time required to determine performance variables and production efficiency of lactating dairy cows

Thirty-five lactating dairy cows throughout weeks of lactation (WOL) 16 to 30 were used to determine optimal time needed for reliable measurement of performance variables, and to classify the cows into high-, medium-, and low-efficiency groups. Individual performance variables [body weight (BW), dry matter intake (DMI), and milk production] were measured daily with a computerized monitoring system. Body condition was visually scored weekly and used to calculate retained or depleted body energy as a result of fat content change (RE_F). Milk composition was analyzed weekly. Body weight, DMI, and total recovered energy (RE), which represents energy in milk production plus RE_F, were summarized weekly. Efficiency was calculated as RE/DMI and as residual feed intake (RFI; i.e., the difference between actual and expected DMI), which was calculated from multiple linear regression of DMI dependence on BW^0.75 and RE. Unexpectedly, it was found that BW did not affect DMI and RE/DMI. Changes and relative changes in phenotypic coefficient of variation and correlations among data from shortened tests ranging from 1 wk (WOL 16) to a sequence of 15-wk tests were used to determine optimal test period durations for 5 traits: BW, DMI, RE, RE/DMI, and RFI. Traits were fitted into a mixed model with repeated measures. For each week, the traits were summarized as a sequence of cumulative data, starting from WOL 16 and cumulated over periods that increased in 1-wk steps up to WOL 16 to 29. Weekly cumulations were compared with those for entire test period (WOL 16 to 30). Consistency of each cow’s efficiency classification as high, medium, or low was tested by the total-agreement procedure; the kappa index P-value was used. Throughout WOL 16 to 30, the effects of increasing test period duration on between-animal coefficient of variation differed with respect to the various performance variables and RE/DMI: it tended to change with respect to BW, did not change with respect to DMI, and decreased with respect to RE and RE/DMI. In conclusion, compared with a 15-wk study, a 2-wk study can classify RFI and RE/DMI to 3 efficiency levels, with an individual correlation coefficient of 0.6. When the study was carried out over 3 wk or more, the lowest significant index of the classification was P < 0.004, the lowest individual correlation coefficient was 0.65, and its lowest significance was P < 0.01. The current study indicated that the insignificant effect of the BW of dairy lactating cows on their DMI should be validated in more studies.     

一种测定枸杞鲜果中总类胡萝卜素含量的方法

研究的目的是建立一种应用四氢呋喃-癸酸反胶束溶液作为样品萃取溶媒测定枸杞鲜果中总类胡萝卜素含量的方法。在实验中,比较了四氢呋喃、癸酸和四氢呋喃-癸酸反胶束溶液对枸杞鲜果中总类胡萝卜素的萃取效率,测定了四氢呋喃-癸酸反胶束溶液萃取玉米黄素酯的重复性和加样回收率,确定了样品萃取方法。同时测定玉米黄素酯在癸酸反胶束溶液中的吸光系数,建立了以四氢呋喃-癸酸反胶束溶液为样品液在UV-VIS上检测枸杞鲜果中总类胡萝卜素含量的方法。实验结果表明:四氢呋喃-癸酸反胶束溶液对枸杞鲜果样品具有良好的萃取效率和重复性(CV=6.24%)以及94.7%的玉米黄素棕榈酸双酯加样回收率。玉米黄素棕榈酸双酯在四氢呋喃-癸酸反胶束溶液中的吸光系数(A11%cm)为1221。可用来计算样品中的总类胡萝卜素含量。     

A model to determine the optimal sampling schedule of diet components

Various recommendations have been issued regarding the sampling schedule of diet components, especially forages. Their basis is unclear and none are justified from an economic standpoint. The objective of this research was to derive a general method for determining the optimal sampling design for forages. The process of forage removal from storage can be conceptualized as a quality control issue that can be monitored using a Shewhart X-bar chart. This procedure requires 3 control parameters: number of samples (n), sampling interval (h), and control limits (L). A quality cost function made of 4 parts is proposed: cost per cycle while the process is in-control (I); cost per cycle while the process is out-of-control (O); cost per cycle for sampling and analyses (A); and expected duration of a cycle (D). Thirteen inputs enter the cost function: the mean time that process is in control, the number of animals in the herd, the unit price of milk, the milk production loss due to white noise, the milk production loss from an abrupt change in forage composition, the time to sample and analyze one item, the expected time to discover the assignable cause, the expected time to fix the diet, the cost per false alarm, the cost to fix the diet, the fixed cost of sampling at each sampling time, the cost for each unit sampled, and the number of standard deviation slips when forage changes. The total quality cost per day C = (I + O + A)/D. The C function can be optimized with respect to n, h, and L to yield an optimal sampling schedule. Because n and h are discrete variables in a highly nonlinear function, parametric optimization algorithms cannot be used to optimize the function. A genetic algorithm was used for the minimization of C. Results showed that the optimal sampling designs are close to current practices in small herds of 50 cows, but very different in large herds of 1,000 cows, resulting in reduced total quality costs of $250/d. Total sensitivity of C was greatest for the number of cows in the herd, the shift in milk production when forage changes, the mean time that the process is in control, the price of milk, and the time to sample and analyze one item. Total sensitivities of n, h, and L were greatest for the mean time that the process is in control, the extent of the change in composition when there is a change in forage composition, the number of cows in the herd, the shift in milk production when forage changes, and the cost per unit sampled.     

The analysis of sensory and chemical–physical variables via multivariate additive PLS splines

When the information given by a panel of judges on wine sensory characteristics is resumed in a three-way table, Y, and the objective is to extract knowledge from a chemical data-set, X, which has a predictive power for wine sensorial variables, the study of the relationships between chemical–physical variables and sensorial data sets is really complex. In this paper after resuming the information in Y, we propose to consider multivariate additive partial least squares via splines, recently presented in literature, to predict Y by X.     

婴幼儿奶粉中维生素C检测方法的研究

目的 应用荧光分光光度计对婴幼儿乳品中维生素C的含量进行测定。方法 以婴幼儿奶粉为例, 依据国家标准GB 5413.18-2010《食品安全国家标准 婴幼儿食品和乳品中维生素C的测定》, 应用日立F-4600型荧光分光光度计测定婴幼儿乳品中维生素C的含量。结果 线性方程为Y=457.79X 28.877, 相关系数为0.9993, 方法检出限为0.1 mg/100 g。在50 mg/100 g、100 mg/100 g 两个加标水平下, 加标回收率为91.8%~101.8%, 相对标准偏差为0.36%~0.85%(n=6)。结论 此方法操作简便, 线性良好是测定食品中维生素C含量的理想方法。     

Effects of different objective functions on optimal decision variables: a study using modified complex method to optimize hamburger cooking

Hamburger patties are prepared from ground beef and cooked to obtain a safe product before consumption. Cooking process eliminates microbial hazards and results in certain quality changes (e.g., cooking loss, textural changes). All these changes can be used as an objective function to achieve an optimum cooking process, but their effects on decision variable (e.g. process temperature profiles) of the optimization should be known. The use of different objective functions (minimization of cooking losses, hardness, chewiness, and shear to work) was compared to see their effects on plate temperature profiles for double-sided contact cooking. Modified Complex Method was applied as the optimization procedure. Lower and higher limits of grill temperatures (177–220°C) were explicit constraints while lethality and temperature at the patties center (F₀⩾15 s; T_c⩾71°C) were implicit constraints. The objective functions and implicit constraints were determined using a previously developed numerical heat transfer simulation model. Constant temperature profiles (decision variables) for different objective functions at different processing times (121 and 130 s) were determined. Same decision variables were found regarding the different objective functions (198.3°C and 184.1°C) for the given processing times.     

An economic spreadsheet model to determine optimal breeding and replacement decisions for dairy cattle

The aim of this paper is to describe a user-friendly spreadsheet culling model that was constructed to support economical, optimal breeding and replacement decisions on dairy farms. The model was based on the marginal net revenue technique. Inputs for the model can be entered for specific farm conditions, and the output is easily accessible. In the model, the retention pay-off (RPO) value of individual dairy cows was calculated. The RPO value of a cow is equal to the total additional profits that a producer can expect from trying to keep the cow until her optimal age, taking into account the changes of involuntary removal compared with her immediate replacement. To calculate the RPO values, the future production, revenues, and costs of dairy cows at different levels of milk production with different numbers of days open (DO) were determined. Furthermore, the ranges of carcass value, calf revenues, and the range of involuntary disposal rates of cows within and across lactations were taken into account. To illustrate the model, parameters in the model were chosen to represent a typical Holstein dairy herd in Pennsylvania. The results of this model are very comparable with earlier, more complex models that are more difficult to use on the farm. In addition to using the RPO values to evaluate the decision to breed or replace a cow, the costs per additional DO were estimated. Early conception was most profitable with the costs per additional DO varying from $0 to more than $3/d. The model can be used as a decision-supporting tool for producers, extension personnel, veterinarians, and consultants. In addition, researchers, economists, and government organizations can use the model to determine the costs of culling dairy cows in a disease control program. The model and manual are available at http://cahpwww.vet.upenn.edu/software/econcow.html.     

Canonical correlation: a multivariate technique to determine the contribution of various dependent and independent variables

Composite flour chapaties were prepared by blending wheat, guar gum, lentil and chickpea flours in different proportions to evaluate their hypoglycaemic and hypocholesterolaemic worth because of their fibre content. Stepwise regression analysis revealed that dietary fibre and intestine length contributed negatively, while peroxide value (POV) contributed positively to the serum cholesterol and glucose. Likewise, for total chapati scores, dough stability and phytic acid showed inverse contribution, while folding ability, dough development time, dietary fibre, POV, crude fibre and texture performed positively. The canonical correlation was applied to develop a model between two groups of variables, where the first group comprised three dependent variables, i.e. total chapati scores, cholesterol and glucose and the second set comprised thirteen independent variables, i.e. crude fibre, POV, phytic acid, dietary fibre, dough development time, dough stability, feed intake, intestine length, low‐density lipoprotein, triglycerides, albumin, texture and folding ability. The selection of independent variables was based on the significant chemical, rheological, sensory and efficacy characteristics in a multiple stepwise regression. The value of coefficient of determination for dietary fibre of the flour samples was observed to be 0.99749 indicating that 99.74% of the variation in dietary fibre can be explained by all other variables in the second set. However, 17.35% and 4.83% of variation in total chapati scores and cholesterol levels, respectively, can be explained by the entire variables in the first group, while 17.20% of variation in glucose can be explained by all other variables of the first group. The squared multiple regression of each variable in the first set with all the variables in the second set indicated that a 99.97% variation in total chapati scores, cholesterol and glucose is explained by the variables in the second set. The F‐values were significant for total chapati scores, cholesterol and glucose. The results substantiated that all the variables in the second set are important to account for the significant variation for the variables tested in the first set. Canonical analysis revealed the existence of a high correlation between dependent variables and other independent variables.     

直接进样快速测定葡萄酒中白藜芦醇及其甙的HPLC方法

1 前言饮用红葡萄酒有益于健康的报道不断增加，这一方面是由于适量饮用酒精；更重要的是由于红葡萄酒中含有丰富的酚类物质。经国内外专家大量研究表明，酚类物质中的白藜芦醇及其葡萄糖甙具有很强的药理活性，这些药理活性包括：阻止LDL氧化、抗血小板凝聚、抑制肿瘤等作用。作为衡量红葡萄酒质量好坏的成分指标之一，如何将其准确测定就显的十分重要。至今国内外已建立了HPLC、GC/MS等多种测定白藜芦醇及其甙的方法，总结这些方法发现存在诸如样品处理方法复杂、分析所用时间较长、应用了复杂的梯度洗脱等影响分析精确度和准确度的…     

A multispectral imaging technique to determine concentration profiles of myoglobin derivatives during meat oxygenation

We have designed a multispectral imaging acquisition system to measure the relative concentration values of myoglobin forms inside meat during oxygenation. Images at 474, 525, 572 and 610 nm are used to compute the concentration of reduced myoglobin, oxymyoglobin and metmyoglobin with a spatial resolution of 0.0125 mm/pixel. From these images, pigment concentration profiles as a function of oxygenation time and depth beneath the surface were obtained. A model describing the diffusion of oxygen and the consumption of reduced myoglobin is numerically tested versus the measured concentration profiles. The model accurately fits the data with a Mean Root Squared Error equal to 0.253%. Precise definitions for position and width of pigment layers based in concentration profiles are given. The results suggest that multispectral imaging techniques combined with precise control and measurement of sample temperature and oxygen partial pressure will permit detailed studies of the myoglobin chemistry during oxygenation.     

Comparison of polarimetry and crown ether-based HPLC chiral stationary phase method to determine (L)-amino acid optical purity

Although various pharmacopoeias provide titration methods to assay (L)-amino acid content, none of these methods distinguish between (L)- and (D)-amino acids and do not consider the presence of enantiomeric impurities. Consequently, these methods are limited in scope to describe the relationship between content and specific rotation, [α]. In this study, the US Pharmacopoeia method was compared with the crown ether-based high performance liquid chromatographic (HPLC) chiral stationary phase (CSP) method to determine (L)-amino acid content and specific rotation. The (L)-amino acid content specified by the US Pharmacopoeia method was not consistent with the specific rotation in the presence of enantiomeric impurities, whereas the HPLC-CSP method was very effective for determining the (L)-amino acid content and the optical purity. The other advantage is that the HPLC-CSP method requires amino acid samples of quite low concentration (as low as 1 μg/mL), whereas the pharmacopoeia method requires higher concentrations (20-110 mg/mL).