Methods to determine the growth domain in a multidimensional environmental space

Data from a database on microbial responses to the food environment (ComBase, see www.combase.cc) were used to study the boundary of growth several pathogens (Aeromonas hydrophila, Escherichia coli, Listeria monocytogenes, Yersinia enterocolitica). Two methods were used to evaluate the growth/no growth interface. The first one is an application of the Minimum Convex Polyhedron (MCP) introduced by Baranyi et al. [Baranyi, J., Ross, T., McMeekin, T., Roberts, T.A., 1996. The effect of parameterisation on the performance of empirical models used in Predictive Microbiology. Food Microbiol. 13, 83–91.]. The second method applies logistic regression to define the boundary of growth. The combination of these two different techniques can be a useful tool to handle the problem of extrapolation of predictive models at the growth limits.     

对引进制粉生产线清粉系统的改造与分析

如何根据实际情况对引进制粉工艺进行改造与调整是每一个引进厂都要面临和解决的问题。结合潞河面粉厂对清粉工序成功改造的事例,论述了改造清粉系统的思路、方法、步骤以及评价清粉工艺效果的方法,同行业众多面粉厂家将会从中得到有益的启示。     

煎炸油净化助滤剂在油炸鸡块生产中的应用

综述了煎炸油净化助滤剂脱除煎炸油中的游离脂肪酸、色素、极性化合物等杂质的吸附处理性能,以及其在油炸鸡块生产中的应用。经过滤处理后的煎炸油色泽浅黄,酸价由1．12mgKOH／g降低到0．12mgKOH/g,同时除掉70％以上的色素和大部分极性物,无异味,不再起泡冒烟,过滤净化效果显著。     

超滤膜在味精母液提纯工艺中的应用

将超滤膜运用到味精末次母液进行脱色除杂,试验结果为:味精末次母液的三价铁离子的截留率为48.2%,对焦谷氨酸钠截留率为47.8%,但对影响质量的最大因素料液的透光率来说则可以上升近50%,比传统的板框加碳柱则透光高近10%;脱色最佳浓缩比为8～9;膜法的产品收率为98.52%.     

Criteria to determine food allergen priority

The emergent health issue of food allergens presents an important challenge to the food industry. More than 170 foods have been reported in the scientific literature as causing allergic reactions. Clearly, it would be impossible to deal with the presence of trace amounts of all these in the context of food labeling. If the decision to classify major allergens is based solely on the knowledge and experience of allergists and food scientists in the field, without scientifically defined criteria, it is likely to lead to a proliferation of lists. Such practices may lead to an unnecessary elimination of foods containing important nutrients. This paper defines food allergy, food intolerance, and food anaphylaxis and identifies criteria for classifying food allergens associated with frequent allergic reactions. A practical list of food allergens that may result in potentially life-threatening allergic reactions is provided. A mechanism-based (i.e., immunoglobulin E mediated), acute life-threatening anaphylaxis that is standardized and measurable and reflects the severity of health risk is proposed as the principal inclusion criterion for food allergen labeling. Where available, prevalence in the population and threshold levels of allergens should be used as an additional guide to identify possible future labeling needs.     

Invited review: Methods to determine body fat reserves in the dairy cow with special regard to ultrasonographic measurement of backfat thickness

As the dairy cow uses body energy reserves in early lactation, body condition scoring has become an integral part of dairy herd management. Several methods based on visual and tactile evaluation have been developed. Problems caused by the subjectivity of these techniques have been reported. Alternative approaches to predict energy reserves or energy balance in dairy cattle include metabolic profiling and measurement of live weight, heart girth, or skinfold thickness. A less common method to assess fat reserves in body tissues is measuring backfat thickness (BFT) by using ultrasound. An ultrasound technique has been established to predict carcass quality in beef cattle. A new aspect is the application of ultrasound as a monitoring tool in dairy herd management where another location has to be evaluated. This technique has been validated by relating BFT to total body fat (TBF) content and carcass BFT. Backfat thickness also has been related to other methods of body condition scoring. Target values for the development of BFT throughout lactation are available. The relationship between BFT and TBF content is highly significant although biased by multiple factors. A change in BFT of 1 mm equates to approximately 5 kg of TBF content. Measuring BFT by ultrasound is of added value compared with other body condition scoring systems because it is objective and precise. Changes in body condition can be detected and evaluated properly.     

竹叶黄酮的提取和纯化工艺研究

本文对竹叶黄酮的提取和纯化工艺进行研究。实验表明：以浸提剂、固液比、浸提温度、浸提时间为主要考察因素，作L9(34)正交实验；确定了黄酮的最佳提取工艺为：以50％的乙醇溶液，按1：15的固液比。在80℃水浴的条件下浸提3小时。采用AB-8大孔吸附树脂为层析柱填充料，对竹叶黄酮的提取液进行了纯化，确定其吸附流速为2BV／h；用100ml蒸馏水能有效洗涤除去树脂同时吸附的糖、水溶性半纤维素等杂质。而以70％的乙醇溶液为洗脱液。在洗脱体积为100ml，洗脱流速为1BV／h的条件下，竹叶黄酮能较好的被洗脱。还通过样品的紫外吸收光谱以及黄酮与FeC13、浓H2SO4等试剂的特征反应对所得提取物进行了定性分析，确定了所得提取物为黄酮类物质。     

Enzymatic assay to determine collagen thermal denaturation and solubilization

Analysis of collagen in fresh and cooked meat products typically separates the heat-solubilized portion from the insoluble. However, extensive changes in the insoluble portion can occur during heat treatment that greatly affect cooked meat texture. This study evaluated a method of determining the proportion of solubilized and heat-altered collagen using a nonspecific protease from Streptomyces griseus to digest heat-altered collagen. Bovine semitendinosus muscle was heated to either 50, 60, or 70°C. Warner–Bratzler shear forces, Ringer's-soluble and insoluble collagen, and enzyme-labile collagen (digested with pronase) were determined on all samples. The enzyme-labile fraction (ELF) increased as endpoint temperature increased, and a corresponding decrease occurred in the total unaltered fraction (TUF). The Ringers-soluble fraction (RSF) increased slightly. Correlations of peak shear force and peak energy with TUF (0.65 and 0.81) were stronger than those with RSF (0.53 and 0.57). Use of this method should provide further insights into the role of collagen in the development of cooked meat texture.     

年份酒“年份”真假不再难辨

<正> 我国首个鉴别白酒陈酿年份的方法——"挥发系数鉴别法"日前问世。这一鉴别法由四川剑南春酒厂研究发明,已申请国家发明专利。业内专家对该方法给予高度评价,认为其破解了年份酒鉴定的世界性难题,使白酒年份酒有了鉴定标准。现阶段国内年份酒鉴别主要依赖于感     

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…     

Low-frequency dielectric spectrum to determine pork meat quality

The use of dielectric spectra to determine meat quality classes (PSE, DFD, RFN) in porcine muscle during postmortem period was evaluated. The changes in dielectric properties during meat ageing were also analyzed for each meat quality class. For these purposes, dielectric spectra were measured from 100 Hz to 0.4 MHz in parallel and in perpendicular to muscle fiber directions. Significant differences (p < 0.05) in dielectric constant and loss factor among classes were observed at 24 and 48 h post-mortem. Thus, the use of dielectric properties to detect low meat qualities is more reliable at 24 h after slaughtering. Moreover, two indexes for evaluating meat ageing were developed from dielectric properties with good results. This research is the first step for developing a sensor based on electromagnetic waves at radio frequencies for controlling pork meat quality. The results are promising and some definite frequencies are demonstrated to be useful for these purposes.Industrial RelevanceThe results of this research article are demonstrated to be useful for discriminating low meat qualities (PSE and DFD meats). Thus, the industrial relevance is clear in this case because the detection of low meat qualities is identified as one of the most important challenges of meat industry nowadays. On the other hand, basing on the results of the present paper it is possible to develop a prototype for industrial applications. Moreover, two possible Indexes are developed in the present paper for determining meat freshness which also can be considered important from an industrial point of view. All this determinations were made by using dielectric spectroscopy which can be considered an emerging technology. For all these reasons we are sending to this journal “Innovative Food Science and Emerging Technologies” our results.     

分光光度法测定大蒜提取物中硫代亚磺酸酯

提供了一种利用L-半胱氨酸和DTNB检测新鲜大蒜及大蒜提取物中硫代亚磺酸酯的分光光度法，通过对Lawson法的进一步改良，不仅提高了测定的准确性和重现性，而且可应用于大蒜乙醇提取物中硫代亚磺酸酯的定量测定，也同样适用于其它大蒜提取物中总硫代亚磺酸酯的定量测定。     

Optical techniques to determine thermal effects on proteins

Optical rotation (OR) and transmitted light (TL) measurements were conducted on 1%, 2.5% and 5% (w/v) bovine serum albumin (BSA) in 0.01 m phosphate buffer at pH 7 and ionic strength 0.08. Denaturation temperatures (T_d) obtained from OR measurements were consistent with reported differential scanning calorimetry values. Protein concentration did not affect T_d in agreement with most reports. Changes in TL reflecting gel formation and protein aggregation were influenced by BSA concentration. Sugar concentration in the range used in this study (0–5%) did not affect the thermal stability of BSA. The lack of difference in sucrose, trehalose and sorbitol effects on the thermal stability of BSA was consistent with some but not all reports. The optical system used to study protein denaturation had acceptable accuracy (consistency with published T_d values) and precision (coefficient of variation under 3.5%) levels.     

螺旋藻中藻蓝蛋白的生理功能及其提取纯化研究进展

藻蓝蛋白是螺旋藻的主要组成成分,它的生理功能已经得到多方面的证实.对藻蓝蛋白的结构、抗氧化、抗炎等生理活性及其提取纯化工艺作了较为系统的综述,以期为藻蓝蛋白的进一步研究与开发利用积累完善的资料.     

Using 19F NMR spectroscopy to determine trifluralin binding to soil

Trifluralin is a widely used herbicide for the control of broad leaf weeds in a variety of crops. Its binding to soil may result in significant losses in herbicidal activity and a delayed pollution problem. To investigate the nature of soil-bound trifluralin residues, 14C-labeled herbicide was incubated for 7 weeks with four soils under anoxic conditions. As determined by radiocounting, trifluralin binding ranged between 10 and 53% of the initial 14C depending on the soil tested. 19F NMR analyses of the methanol extracts and different fractions of the extracted soil suggested that bound residue formation largely involved reduced metabolites of the herbicide. A 2,6-diamino product of trifluralin reduction with zero-valent iron (Fe-TR), and the standard of a 1,2-diaminotrifluralin derivative (TR6) formed covalent bonds with fulvic acid (FA), as indicated by the 19F NMR spectra taken periodically over a 3-week contact time. At short contact times, TR6 and Fe-TR formed weak physical bonds with FA, as the respective spin-lattice relaxation times (T1) decreased from the range 1300-1831 ms for TR6 or Fe-TR analyzed in the absence of FA to the range 150-410 ms for TR6/FA or Fe-TR/FA mixtures. In general, the results indicated that trifluralin immobilization involved a variety of mechanisms (covalent binding, adsorption, sequestration), and with time it became increasingly stable.     

Using sweeping-micellar electrokinetic chromatography to determine melamine in food

This study developed a sweeping-micellar electrokinetic chromatography (sweeping-MEKC) method for fast screening of melamine in food. In order to optimise parameters with multiple responses in parallel, face-centred cube central composite design (FCD) was employed to search for the optimum conditions of the sweeping-MEKC. The optimum background electrolyte was composed of 45 mM phosphoric acid and 175 mM sodium dodecyl-sulfate with the addition of 15% (v/v) methanol. Under such conditions, melamine content could be determined within 13 min with the limit of detection (S/N = 3) at 5 ng/mL. The developed method was validated by analysing melamine-spiked milk, gluten, chicken feed, and cookies. The proposed method was applied to determine melamine in different food products, with recoveries between 92.9 ± 3.3% and 108.4 ± 1.7%. The present study shows that the developed sweeping-MEKC method is sensitive, accurate, and efficient for fast screening of melamine in food.     

Peptide biomarkers as a way to determine meat authenticity

Meat fraud implies many illegal procedures affecting the composition of meat and meat products, something that is commonly done with the aim to increase profit. These practices need to be controlled by legal authorities by means of robust, accurate and sensitive methodologies capable to assure that fraudulent or accidental mislabelling does not arise. Common strategies traditionally used to assess meat authenticity have been based on methods such as chemometric analysis of a large set of data analysis, immunoassays or DNA analysis. The identification of peptide biomarkers specific of a particular meat species, tissue or ingredient by proteomic technologies constitutes an interesting and promising alternative to existing methodologies due to its high discriminating power, robustness and sensitivity. The possibility to develop standardized protein extraction protocols, together with the considerably higher resistance of peptide sequences to food processing as compared to DNA sequences, would overcome some of the limitations currently existing for quantitative determinations of highly processed food samples. The use of routine mass spectrometry equipment would make the technology suitable for control laboratories.