Effect of relative humidity on the migration of benzophenone from paperboard into the food simulant Tenax® and modelling hereof

The aim of this study was to investigate the effect of relative humidity on the migration of benzophenone from paperboard into the food simulant Tenax®. Kinetic migration investigations were carried out with three relative humidities in the interval between 39% and >73%. All investigations were carried out at a constant temperature of 34°C. It was found that the migration of benzophenone after more than 30 days was 4.8 times higher at a relative humidity of 64%–71%, and 7.3 times higher at a relative humidity of >73%, compared with that at a relative humidity of 39%–49%. Diffusion and partition coefficients were derived from the results by using a software for modelling migration in multilayer materials. Both the diffusion coefficient and the partition coefficient, between paperboard and Tenax®, decrease with increasing relative humidity. The experimental results were correctly modelled only when the paperboard was regarded as a one-layer system as compared with a two-layer system: where the main part of the paperboard (B1) has a high diffusion rate and a thin part of the paperboard (B2) in contact with the foodstuff has a lower diffusion rate.     

纳米金属/金属氧化物-聚烯烃食品包装膜中纳米成分迁移的扩散系数估算

为探讨Fick第二定律是否符合聚烯烃食品包装膜中纳米成分向食品模拟物的迁移规律,根据已有实验数据,基于Crank模型进行拟合,估算纳米金属/金属氧化物-聚烯烃食品包装膜中纳米成分的扩散系数,并分析温度、聚烯烃、纳米成分和食品模拟物对扩散系数的影响。结果表明：纳米成分向食品模拟物的迁移符合Fick第二定律。温度升高促进纳米成分的迁移,且温度与纳米成分扩散系数的关系符合Arrhenius公式。不同聚烯烃结构对扩散系数的影响不同;聚丙烯3 种结构中,纳米铜和纳米氧化锌在均聚共聚聚丙烯中的扩散系数最大。不同纳米成分质量分数对其扩散系数的影响不同。纳米成分与食品模拟物、聚烯烃之间的溶解度差异也会影响其向食品模拟物迁移。     

微生物预测模型技术研究进展及其在食品工业中的应用

为了更好的了解微生物预测模型与食品微生物生长、残存、死亡的量化关系。本文简要的概述了微生物预测模型技术的基本内容和初级、二级和三级模型的形成与发展。并在此基础上,分别介绍了食品腐败微生物和食品致病微生物预测模型的研究进展及其在食品工业中的应用,并对目前存在的问题和研究方向进行分析,旨在为推广微生物预测模型技术,并将其应用在实际生产,提高食品工业加工技术水平。     

Study of silver ion migration from melt-blended and layered-deposited silver polyethylene nanocomposite into food simulants and apple juice

Colloidal silver nanoparticles were prepared via chemical reduction using polyethylene glycol (PEG) as a reducing agent, stabiliser and solvent. Silver polyethylene nanocomposites were produced via two methods, namely: melt blending and layer-by-layer (LBL) deposition of silver nanoparticles onto a polyethylene film. The silver ion release from either melt-blended or LBL-deposited nanocomposites into a food simulant and apple juice during 30 days at 4°C and 40°C was determined by atomic absorption spectroscopy. The effects of incorporating or coating of silver nanoparticles, silver concentration, contact media, temperature and time on silver ion migration were evaluated using factorial design. The diffusion coefficients of silver ions into the food simulants and apple juice were calculated using the Miltz model. The results indicated that the production method of nanocomposite, silver concentration, temperature, time and contact media showed a significant effect (p < 0.05) on silver ion migration. The quantity of silver ion migration from the nanocomposites into the food simulants and apple juice was less than the cytotoxicity-level concentration (10 mg kg^?1) in all cases over 30 days. The coating of silver nanoparticles, higher silver concentration in the nanocomposite, higher temperature and acidic property of contact liquid all promoted the silver ion release from the nanocomposite films. The migration of silver ions from nanocomposites obeyed first-order diffusion kinetics.     

水产品腌制过程中NaCl传递的模拟方法及应用进展

NaCl作为腌制料中必不可少的组成成分;其在水产品肌肉中的传递会对水产品微生物、质地与风味等质量特性产生重要的影响。因此;为了提升腌制效率并改善产品品质;研究者就如何控制与预测NaCl的传递过程进行了广泛研究。本文从理论模型、预测模型与有限元分析3 个方面介绍当前NaCl传递过程的模拟方法;并详细阐述3 种模拟方法在水产品腌制过程中的应用现状与优缺点;以期为腌制类水产品的创新发展与智能生产提供一定的理论和技术参考。     

食品包装污染物双酚类物质在食品模拟体系中的迁移规律研究

采用4 种食品模拟物包括超纯水、30 g/L乙酸水溶液、10%乙醇水溶液和异辛烷对食品金属罐中4 种双酚物（包括双酚A、双酚F、双酚A二缩水甘油醚和双酚F二缩水甘油醚）迁移情况进行研究,并建立半经验的双酚物迁移规律数学模型。结果表明：4 种双酚物同时在10%乙醇溶液中出现最大迁移,且贮存温度和时间对迁移量变化有显著影响。根据模拟实验得到的迁移数据和Fick第二定律建立数学模型,初步确定扩散系数DP,再根据DP估计得到包材的特征参数AP的范围为35.38～48.48。     

快餐包装纸中矿物油向固体食品模拟物的迁移

研究从市场上收集到的24种快餐包装纸中的矿物油向固体食品模拟物Tenax的迁移规律.在多个不同的迁移条件(40℃/0.5、1、2、3h,40℃/10 d和70℃/2 h),探究矿物油的迁移行为及其影响因素,以评价其安全性.选择正己烷-乙醇(1∶1,V/V)混合溶液对Tenax进行过夜萃取,采用质量分数0.3％硝酸银固相...     

Predictive modeling of microbial single cells: A review

In practice, food products tend to be contaminated with food-borne pathogens at a low inoculum level. However, the huge potential risk cannot be ignored because microbes may initiate high-speed growth suitable conditions during the food chain, such as transportation or storage. Thus, it is important to perform predictive modeling of microbial single cells. Several key aspects of microbial single-cell modeling are covered in this review. First, based on previous studies, the techniques of microbial single-cell data acquisition and growth data collection are presented in detail. In addition, the sources of microbial single-cell variability are also summarized. Due to model microbial growth, traditional deterministic mathematical models have been developed. However, most models fail to make accurate predictions at low cell numbers or at the single-cell level due to high cell-to-cell heterogeneity. Stochastic models have been a subject of great interest; and these models take into consideration the variability in microbial single-cell behavior.     

食品包装纸中紫外吸收剂向固态模拟物的迁移行为

研究4种紫外吸收剂,即2-(2’-羟基-3’,5’-二叔丁基苯基)-5-氯代苯并三唑(UV-327)、2-(2-羟基-5-甲基苯基)苯并三氮唑(UV-P)、2-羟基-4-甲氧基二苯甲酮(UV-9)和2-羟基-4-正辛氧基二苯甲酮(UV-531)在50、75℃和100℃3个温度条件下从食品包装牛皮纸迁移到固态食品模拟物Tenax~?中的迁移规律和影响因素。结果表明:随着温度的升高,紫外吸收剂的迁移速度加快,迁移量增加。此外,不同紫外吸收剂本身的物理化学性质(相对分子质量、油水分配系数等)也对其迁移规律和平衡迁移率产生了重要影响。在上述实验的基础上建立数学模型,以达到预测迁移量的目的。数据证明,所构建的模型可很好地预测在达到迁移平衡前,紫外吸收剂从牛皮纸迁移到Tenax~?中的迁移量。     

食品包装材料中有害物质迁移行为的研究进展

食品包装材料在食品安全中发挥了重要的作用。食品包装能有效地保护食品,防止变质,但其中化学物质的迁移,又会给食品质量和安全带来负面影响。因此,对食品包装材料中化学物质的迁移进行研究显得非常必要。本文综述了近几年食品包装材料中有害物质的检测分析、迁移规律以及传质模型;对主要被检物质所采用的检测方法进行了总结,并对塑料与纸基材料中物质的迁移规律和传质模型进行了对比;最后对食品包装材料未来的发展方向进行展望。     

低温肉制品微生物控制与预测模型应用研究进展

低温肉制品营养丰富,是我国肉制品未来的发展方向。本文介绍了低温肉制品中的主要微生物来源、种类以及控制措施;综述了低温肉制品中微生物预测的各级模型,分析了其优缺点;简述了预测模型在实际生产中的应用。     

Mathematical modeling of swelling in high moisture whey protein gels

Gels prepared from whey proteins can be used for controlled release of nutrients or active ingredients in food systems. The objective of this study was to characterize the water uptake by these hydrophilic gels to aid in the design of release systems. Whey protein isolate (WPI) gels (17% w/w protein) of different aspect ratios were submersed in aqueous solution at pH 7.0. Modeling of mass uptake is presented in terms of Case I (Fickian diffusion) and Case II (kinetic) models. Due to the extent of swelling, the Fickian diffusion with moving boundaries provided the most realistic reflection of the physics. An optimization routine provided the best fit values for the diffusivity. The average diffusivity for the smaller gels (with an initial radius of 6.7 mm) was 1.40 × 10⁻¹⁰ m²/s. The average diffusivity of the larger gels (with an initial radius of 8.5 mm) was 0.79 × 10⁻¹⁰ m²/s. The average diffusivities differed due to the slight variation in the composition of the gels. The model also yielded instantaneous values of the radius and sample length. The functionality of moisture uptake and total surface area was linear. The Fickian diffusion with moving boundary model can be extended to evaluate different geometries for controlled release systems.     

MRI Observation and Mathematical Model Simulation of Water Migration in Wheat Flour Dough During Boiling

Existing cooking rate equations fail to describe the change of moisture content profile in starchy foods during cooking. There is a need for a new model. In this paper, an experiment on water migration during boiling was performed using a slab of wheat flour dough. The moisture content profile was measured by an MRI method. The result was compared with predictions made using mathematical models. The existing mathematical model was found to predict a much more rapid change than that measured by experiment. The accuracy of the prediction was considerably improved when a new model was applied: a mathematical model based on a new concept that water migration is driven by water demand.     

非渗透包装下双组分食品间水分扩散模型研究

采用Fick第二定律,结合食品等温吸湿模型和水分有效扩散理论,建立了非渗透包装下双组分食品间水分扩散模型;以饼干和琼脂凝胶包装为研究对象,基于实验表征等温吸湿模型和有效扩散系数,得到研究对象间水分扩散数值解并与实验结果进行对比分析。结果表明,理论模型与实验数据的吻合度高。     

Updated evaluation of the migration of styrene monomer and oligomers from polystyrene food contact materials to foods and food simulants

Due to the 2011 labelling of styrene monomer as “reasonably anticipated to be a human carcinogen” by the National Institutes of Health’s National Toxicology Program (NTP) and the controversy over whether styrene oligomers mimic the physiological effects of estrogen, an updated review of styrene monomer and oligomers in food and food contact materials (FCMs) was performed. The concentrations of styrene monomer and oligomers were determined in 24 polystyrene (PS) products and ranged from 9.3 to 3100 mg kg^–1 for the styrene monomer, 130–2900 mg kg^–1 for the sum of three styrene dimers, and 220–16,000 mg kg^–1 for the sum of six styrene trimers. Foods in contact with PS packaging had styrene monomer concentrations ranging from 2.6 to 163 ng g^–1; dimer concentrations from the limit of quantitation (LOQ) to 4.8 ng g^–1 and trimer concentrations were all below the LOQ (2 ng g^–1). Diffusion coefficients (D_p) and partition coefficients (K) were also calculated for styrene dimers and trimers. The results presented here indicate that styrene monomer concentrations in foods have not significantly changed since the 1980s and monomer concentrations in food packaging quantified in this study were all below USFDA limits. Although styrene dimers and trimers are present in higher concentrations in PS FCMs than the monomer, their migration to food is limited because of their high K values (4 × 10² to 2 × 10⁶) and their low diffusion coefficients in PS products. Additionally, diffusion coefficients calculated using USFDA-recommended food simulants and Arrhenius plots describing the temperature dependence of styrene dimers and trimers can be used in future calculations of dietary intake of the styrene oligomers.