Thermal markers arising from changes in the protein component of milk

Classification of heat load applied to milk requires the detection of parameters appropriately related to the intensity of the heat treatment. Current analytical methods based on heat-induced changes in the protein component of milk have been directed either to determine the amount of protein-derived products arised from heat treatments or to evaluate the extent of thermal denaturation of milk proteins. Lately, a new analytical strategy has been developed according to the occurrence of three major whey proteins, namely bovine serum albumin (BSA), beta-lactoglobulin (βlg) and alfa-lactalbumin (αla), normally soluble at pH 4.6 in raw milk, in the pH 4.6 insoluble protein fraction recovered from heat-treated milk. The results have shown that pH 4.6 insoluble BSA, βlg and αla, as detected by ELISA in milk, can be regarded as thermal markers suited for either dairy process control or regulation purposes.     

Review of the structural characterization,quality evaluation,and industrial application of Lycium barbarum polysaccharides

BackgroundLycium barbarum polysaccharides (LBPs) are considered to be the major bioactive components in L. barbarum. Due to the considerable health benefits of LBPs, and the significant research interest in LBPs, quality evaluation of LBPs and their related products is imperative for ensuring their efficacy and safety. The bioactivities of polysaccharides are closely associated with their physicochemical properties, which can be easily monitored via chemical techniques. Therefore, analysis of physicochemical properties is a more straightforward and viable approach for the quality control of polysaccharides.Scope and approachIn this review, special techniques for the structural characterization of LBPs are summarized and discussed. In addition, quality evaluation approaches of LBPs that have never been emphasized are highlighted herein. Furthermore, industrial applications of LBPs are reviewed and discussed.Key findings and conclusionsHigh-performance anion-exchange chromatography coupled with pulsed amperometric detection is one of the most effective techniques for analysis of both acidic and neutral LBPs. Size-exclusion chromatography coupled with multi-angle laser light scattering and refractive index detection is able to determine absolute molecular weights, chain conformations, and contents of LBPs. Fingerprinting analysis and saccharide mapping analysis are effective approaches for quality evaluation of LBPs. However, the lack of appropriate quality evaluation approaches indicates an unreliable regulation of LBPs and their related products. This reveals the deficiency in the quality control of commercial products. Thus, the development of reliable approaches for pharmacological activity-based quality control of LBPs and their related products must be extensively investigated.     

Flavour formation in meat and meat products: a review

The characteristic flavour of cooked meat derives from thermally induced reactions occurring during heating, principally the Maillard reaction and the degradation of lipid. Both types of reaction involve complex reaction pathways leading to a wide range of products, which account for the large number of volatile compounds found in cooked meat. Heterocyclic compounds, especially those containing sulfur, are important flavour compounds produced in the Maillard reaction providing savoury, meaty, roast and boiled flavours. Lipid degradation provides compounds which give fatty aromas to cooked meat and compounds which determine some of the aroma differences between meats from different species. Compounds formed during the Maillard reaction may also react with other components of meat, adding to the complexity of the profile of aroma compounds. For example, aldehydes and other carbonyls formed during lipid oxidation have been shown to react readily with Maillard intermediates. Such interactions give rise to additional aroma compounds, but they also modify the overall profile of compounds contributing to meat flavour. In particular, such interactions may control the formation of sulfur compounds, and other Maillard-derived volatiles, at levels which give the optimum cooked meat flavour characteristics.     

Fault diagnosis of an industrial plant using a Monte Carlo analysis coupled with systematic troubleshooting

Efficiently troubleshooting a fortification issue at an industrial milk powder plant is a complex undertaking given the myriad of possible causes. Multiple causes, even when simple, are not easy to diagnose, however every single cause needs to be addressed in order to consistently meet product quality specifications. This paper uses statistical modelling in the form of Monte Carlo simulations to investigate the probable causes for unexpected excessive product variation. This approach alone, refines but does not completely solve, the production issues, so a systematic approach was required to definitively solve other root causes. This two-step fault diagnosis approach ensured that all of the differing causes proposed by plant personnel could be addressed, and sound recommendations for good manufacturing operations could be made and adopted.     

Presence of mycotoxins in animal milk: A review

Mycotoxins can cause toxicity when ingested by humans and animals. Although the rumen is supposed to be a barrier against mycotoxins, some studies demonstrate that carry-over of mycotoxins to milk is possible. Different studies have found mycotoxin levels in animal milk, mainly related to contaminated feed for ruminants. Aflatoxin M1 is the most studied mycotoxin in milk and levels exceeding the EU maximum level for this mycotoxin in this matrix (0.050 μg/kg) have been found. Maximum levels in milk for other mycotoxins have not been established; however ochratoxin A, aflatoxins G1, G2, B1, B2 and M2, fumonisin B1, cyclopiazonic acid, zearalenone and its metabolites and deepoxy-deoxynivalenol have also been found in milk samples. Taking into account that multi-exposure to mycotoxins is the most likely scenario and co-occurrence of mycotoxins could affect their toxicological effects in humans and animals, there is a need to determine the co-occurrence of mycotoxins in milk.     

Network and vulnerability analysis of international spice trade

The spice trade network is one of the oldest and substantially vulnerable systems of the agri-food supply chains. Based on statistical analysis of spice paprika (chilli red pepper) and black pepper trade flows within the EU member states, stochastic simulation models have been developed for prognosis of the proliferation of contaminated products between the member states as a function of the source-state of the contaminated products. Results highlight the rapidity of proliferation, and offer a simple, but robust tool for prediction of contamination patterns among states, serving the formation of a targeted defence strategy and policy Traditional geostatistical methods (e.g. Morens’ I of spatial autocorrelation) in most cases are not suitable to predict the geographic distribution of contaminated products among countries, due to complexity and inter-connectedness of the European spice network. The pattern of proliferation of contaminated products between member states was analysed using a dyadic network of relational data, applying additive and multiplicative effects model. Results of analysis prove the importance of long-distance, international trade in distribution of contaminated products.     

Quality predictive models of grass carp (Ctenopharyngodon idellus) at different temperatures during storage

To study quality changes in cold chain circulation, kinetic models were developed to predict the freshness changes of grass carp at different temperatures during storage. Sensory assessment, total aerobic count (TAC), K value, total volatile basic nitrogen (TVB-N) and 2-Thiobarbituric acid (TBA) at ?3, 0, 3, 9 and 15 °C were accessed to investigate the relation between the freshness changes and temperature. The kinetic models of sensory assessment, TAC, K value, TVB-N and TBA with respect to storage time and temperature were developed based on Arrhenius equation. The high regression coefficients (R² > 0.9) indicated the acceptability of the first-order reaction and Arrhenius model for predicting the quality changes of grass carp. Activation energies (E_A) of sensory assessment, TAC, K value, TVB-N and TBA are 114.38, 75.88, 57.11, 111.55, 63.09 kJ mol^?1, and corresponding rate constants (k₀) are 2.97 × 10²⁰, 1.12 × 10¹³, 8.30 × 10⁹, 8.34 × 10¹⁹, 9.06 × 10¹⁰ respectively. Relative errors between predicted and observed freshness indictors values of TAC, K value and TVB-N are all within ±10%. Therefore the quality changes of grass carp can be predicted based on the prediction model of TAC, K value and TVB-N within ?3–15 °C.     

The effects of interfacial interactions on lamellar morphologies in thin and ultrathin films and nanocomposites of LLDPE

The transition from edge-on to flat-on morphology under confinement in spin-cast pristine and carbon nanofiber (CNF) or nanoclay (NC) filled linear low-density polyethylene thin films is investigated with emphasis on the surface interaction component. The morphology transition is observed by scanning probe microscopy and is linked to melting point depression and shear modulus decrease at the corresponding transition. A thermodynamic model, based on Gibbs’ free energy of crystallization according to Hoffman’s crystallization theory, is proposed to account for these phenomena. Particularly, the model can predict the confined film thickness at the morphology transition and, in part, the extent of melting point downshifting.     

液相色谱-串联质谱法同时测定食用植物油中5种香料

为有效提高食用植物油中麦芽酚、乙基麦芽酚、香兰素、甲基香兰素和乙基香兰素的检测效率,建立同时测定食用植物油中麦芽酚、乙基麦芽酚、香兰素、甲基香兰素和乙基香兰素的液相色谱-串联质谱(HPLC-MS/MS)检测方法。样品经乙腈提取,正己烷脱脂后,采用甲醇-0.1%甲酸水溶液作为流动相进行梯度洗脱,质谱电喷雾离子源在正离子模式下进行多反应监测扫描,对5种香料进行定量测定。结果表明,5种香料质量浓度与峰面积线性关系良好,相关系数均大于0.998,方法检出限为2.3～19.5μg/kg,定量限为7.7～65.0μg/kg,回收率在85.0%～107.8%之间,相对标准偏差均小于5.0%。该方法操作简便、定性定量准确、灵敏度高,适用于食用植物油中麦芽酚、乙基麦芽酚、香兰素、甲基香兰素和乙基香兰素的同时测定,可有效提高检测效率。