Particle breakdown dynamics of heterogeneous foods during mastication: Peanuts embedded inside different food matrices

Heterogeneous foods are widely consumed but little is known about the dynamics of their breakdown during mastication. To investigate these dynamics the particle size and bolus mass at regular stages of the chewing sequence were investigated using a single subject, who was carefully selected according to strict mastication and dental criteria. A standardized volume of both a gelatine gel and chocolate matrix containing roasted peanuts was chewed and expectorated after a specified number of chews or at the point of swallowing. The mass of various components of the bolus was determined along with peanut particle parameters (d₅₀, broadness (b), and specific surface area) at each interval.Results showed that for this subject the type of matrix influenced the pathway that the peanut particles (embedded inside each matrix) were broken down. The d₅₀ of peanut particles within the bolus of the gelatine gel were greater than within the bolus of the chocolate throughout the chewing sequence until the point of swallowing. At the point of swallowing, the d₅₀ of peanut particles inside the bolus of the gelatine gel and chocolate were the same. The broadness value (b) and specific surface area of the peanut particles in the bolus of the chocolate were greater than those in the bolus of the gelatine gel throughout the chewing sequence. The matrices also induced different dynamic trends in the mass of bolus components during the chewing sequence.     

Viscoelastic and fragmentation characters of model bolus from polysaccharide gels after instrumental mastication

Model bolus from polysaccharide gels was investigated by the stress-relaxation tests and particulate size analyses. Using two gelling agents, gellan gum and a composite of gellan/psyllium seed gums, gels with different physical properties (i.e., elastic gellan single gels and plastic composite gels) and gel hardness were prepared. Gels were masticated instrumentally in the presence or absence of artificial saliva to prepare model bolus. Data from the stress-relaxation tests analyzed by 5-element mechanical model showed that difference between two Maxwell-bodies in the elasticity for the composite gels was generally smaller than that for gellan single gels when compared at equivalent gel hardness and was less influenced by the addition level of saliva. For each gel sample, cumulative particulate size distribution of model bolus was reduced logarithmically with a normal curve regardless of the addition level of saliva. Mean particulate size of model bolus from the composite gels was generally larger than that for gellan single gels when compared at equivalent gel hardness and was less influenced by the addition level of saliva. Based on the particulate size distribution of model bolus, coefficients of skewness and kurtosis calculated for the composite gels tended to be larger than those for gellan single gels when compared at equivalent gel hardness. Results indicated higher structural homogeneity of model bolus from the composite gels, which is related to higher miscibility with saliva. Structural homogeneity should be the key for texture design of nursing-care foods, particularly for dysphagia.     

Constituent of natural food additive hokosshi extract and an analytical method for the additive in foods

Hokosshi extract is obtained by ethanol extraction from the seeds of hokosshi (Psoralea corylifolia), which is used as a Chinese medicine. The constituents of hokosshi extract were analyzed. The main constituent was isolated using column chromatography, and identified as bakuchiol by TLC, LC/MS and NMR. Bavachinin A was also detected. In order to prepare a marker substance for hokosshi extract, bakuchiol was isolated from seeds of hokosshi using Sep-Pak cartridges. An analytical method for hokosshi extract in foods based on detection of bakuchiol was developed. Bakuchiol was extracted from food with 60 vol% ethanol. The extract was cleaned up using a Sep-Pak plus C18 cartridge, and bakuchiol was determined by HPLC. Seasoning and juice were spiked with hokosshi extract at 500 micrograms/g and analyzed by the proposed method. The recoveries of bakuchiol were 72-99%. The detection limit for the assay was 25 micrograms/g.     

丙烯酸酯皮革填充乳液的粒径及其分布

采用不同的聚合方式和预乳化工艺 ,合成了丙烯酸酯皮革填充乳液。系统研究了聚合方式、复合乳化剂的用量和配比、聚合温度、官能团单体含量和搅拌强度对丙烯酸酯共聚物乳液粒径及其分布的影响     

Particle size distribution effects on gas-particle mass transfer within electrostatic precipitators

Varying degrees of mercury capture and transformation have been reported across electrostatic precipitators (ESPs). Previous analyses have shown that the dominant mass transfer mechanism responsible for mercury capture within ESPs is gas-particle mass transfer during particulate collection. Whereas previous analyses assumed dispersions of uniform size, the present analysis reveals the effects of polydispersity on both gas-particle mass transfer and particle collection within an ESP. The analysis reveals that the idealized monodisperse particle size distribution provides the highest gas-particle mass transfer but results in the lowest particle collection efficiency (% mass). As the particle size distribution broadens, gas-particle mass transfer decreases and particle collection efficiency increases. The results suggest that more than just reporting mean particle diameter provided by the sorbent manufacturer, pilot- and field-tests of sorbent injection for mercury emissions control need to experimentally measure the particle size distribution of the sorbent as it is injected in order to facilitate interpretation of their results.     

Core foods of the US food supply

The core food dietary intake/exposure model may be used to assess the average intake of nutrients, contaminants and other food components by a population group and various subgroups of the population. The core food model is a mechanism that allows for the selection of the most important foods in a population's food supply so that these foods can be obtained and analysed in the laboratory. The core foods for a population change over time as food consumption patterns are altered by changes in the food supply and/or changes in the demographics of the population. Core foods of the US diet were selected using food consumption data from the 1994-96 US Department of Agriculture (USDA) Continuing Survey of the Food Intake of Individuals (CSFII). The 304 core foods were identified by placing the 5722 foods consumed by survey participants into about 300 groups. The groupings were based on food type, food use and similarity of nutrient composition. The foods within each grouping were ranked in terms of frequency of use and weight of intake, and one food item within each group was selected to become a core food and represent its group. In the model, each core food assumes the full dietary intake (by weight) for all the foods in its group. Daily mean intakes of the 304 selected core foods are presented for women and men of 19-30 years of age. If the food components of interest to investigators using this model are found in selected foods or food types, then only these foods need be analysed. The list of 304 core foods may be shortened by further aggregation to match the needs of different investigators. For example, limited data on food composition may warrant use of a shorter core food list. A shortened food list with average daily intakes of 78 core foods for women and men of 19-30 years of age is provided as an example.     

Measuring nanoparticles size distribution in food and consumer products: a review

Nanoparticles are already used in several consumer products including food, food packaging and cosmetics, and their detection and measurement in food represent a particularly difficult challenge. In order to fill the void in the official definition of what constitutes a nanomaterial, the European Commission published in October 2011 its recommendation on the definition of 'nanomaterial'. This will have an impact in many different areas of legislation, such as the European Cosmetic Products Regulation, where the current definitions of nanomaterial will come under discussion regarding how they should be adapted in light of this new definition. This new definition calls for the measurement of the number-based particle size distribution in the 1-100 nm size range of all the primary particles present in the sample independently of whether they are in a free, unbound state or as part of an aggregate/agglomerate. This definition does present great technical challenges for those who must develop valid and compatible measuring methods. This review will give an overview of the current state of the art, focusing particularly on the suitability of the most used techniques for the size measurement of nanoparticles when addressing this new definition of nanomaterials. The problems to be overcome in measuring nanoparticles in food and consumer products will be illustrated with some practical examples. Finally, a possible way forward (based on the combination of different measuring techniques) for solving this challenging analytical problem is illustrated.     

Measuring nanoparticles size distribution in food and consumer products: a review

Nanoparticles are already used in several consumer products including food, food packaging and cosmetics, and their detection and measurement in food represent a particularly difficult challenge. In order to fill the void in the official definition of what constitutes a nanomaterial, the European Commission published in October 2011 its recommendation on the definition of ‘nanomaterial’. This will have an impact in many different areas of legislation, such as the European Cosmetic Products Regulation, where the current definitions of nanomaterial will come under discussion regarding how they should be adapted in light of this new definition. This new definition calls for the measurement of the number-based particle size distribution in the 1–100?nm size range of all the primary particles present in the sample independently of whether they are in a free, unbound state or as part of an aggregate/agglomerate. This definition does present great technical challenges for those who must develop valid and compatible measuring methods. This review will give an overview of the current state of the art, focusing particularly on the suitability of the most used techniques for the size measurement of nanoparticles when addressing this new definition of nanomaterials. The problems to be overcome in measuring nanoparticles in food and consumer products will be illustrated with some practical examples. Finally, a possible way forward (based on the combination of different measuring techniques) for solving this challenging analytical problem is illustrated.     

Particle size distribution and polycyclic aromatic hydrocarbons emissions from agricultural crop residue burning

Laboratory measurements were conducted to determine particle size distribution and polycyclic aromatic hydrocarbons (PAHs) emissions from the burning of rice, wheat, and corn straws, three major agricultural crop residues in China. Particle size distributions were determined by a wide-range particle spectrometer (WPS). PAHs in both the particulate and gaseous phases were simultaneously collected and analyzed by GC-MS. Particle number size distributions showed a prominent accumulation mode with peaks at 0.10, 0.15, and 0.15 μm for rice, wheat, and corn-burned aerosols, respectively. PAHs emission factors of rice, wheat, and corn straws were 5.26, 1.37, and 1.74 mg kg(-1), respectively. It was suggested that combustion with higher efficiency was characterized by smaller particle size and lower PAHs emission factors. The total PAHs emissions from the burning of three agricultural crop residues in China were estimated to be 1.09 Gg for the year 2004.     

Particle size distribution of break,sizing and middling wheat flours by laser diffraction

The particle size distributions of wheat flours collected along a milling diagram were assessed. Nine wheat varieties from the genetic trait Triticum aesticum vulgare and differing in hardness were studied for two consecutive years. Break, sizing and middling flours were collected for each wheat at different stages in an experimental mill, with all the milling conditions being kept constant. The particle size distributions were measured from 1·5 to 600 μm by using a laser light diffraction apparatus. The distributions were compared by principal component analysis. The method provided a global and synthetic comparison of all the flour fractions. In the case of the soft varieties, the distributions exhibited a first mode around 25 μm, corresponding mainly to isolated starch granules. The distribution of this mode was very low or non-existent for the hard varieties. As the milling conditions were the same for all the wheats, the different proportions measured for this mode were interpreted as being directly representative of the wheat hardness. The proportion of the 25 μm mode was considered as a measure of the ability of the wheat to release starch granules and could be used to follow a grinding or milling process. © 1998 Society of Chemical Industry     

Aluminium content in foods with aluminium-containing food additives

The aluminium (Al) content of 105 samples, including bakery products made with baking powder, agricultural products and seafoods treated with alum, was investigated. The amounts of Al detected were as follows (limit of quantification: 0.01 mg/g): 0.01-0.37 mg/g in 26 of 57 bakery products, 0.22-0.57 mg/g in 3 of 6 powder mixes, 0.01-0.05 mg/g in all three agricultural products examined, 0.03-0.90 mg/g in 4 of 6 seafood samples, 0.01-0.03 mg/g in 3 of 11 samples of instant noodles, 0.04-0.14 mg/g in 3 of 4 samples of vermicelli, 0.01 mg/g in 1 of 16 soybean products, but none in soybeans. Amounts equivalent to the PTWI of a 16 kg infant were detected in two samples of bakery products, two samples of powder mixes and one sample of salted jellyfish, if each sample was taken once a week. These results suggest that certain foods, depending on the product and the intake, might exceed the PTWI of children, especially infants.     

Swallowing profiles of food polysaccharide gels in relation to bolus rheology

Swallowing profiles of food polysaccharide gels were investigated in relation to bolus rheology. Polysaccharide gel from either gellan gum or a mixture of gellan gum and psyllium seed gum was used as a model food. Acoustic analysis and sensory evaluation were carried out to investigate the swallowing profiles using the same human subjects. Model bolus was prepared through instrumental mastication using a mechanical simulator to mimic the action of the human jaw in the presence or absence of artificial saliva and was subjected to dynamic viscoelasticity measurements to investigate the rheological properties. Bolus from the binary gel was shorter in time required to transfer through the pharyngeal phase due to mass flow and was scored higher in sensory perceived cohesiveness (bolus forming) than that from gellan gum gel. Model bolus from the binary gel showed a rheologically weak gel (or structured fluid) behavior and was higher in structural homogeneity than that from gellan gum gel. Also, dynamic viscoelasticity parameters of the binary gel were less dependent on the addition level of saliva. Results indicate that the viscoelasticity balance is a key for texture design of dysphagia foods in relation to the saliva miscibility.     

天然食物对自由基的作用

提取了绿豆中的超氧化物歧化酶(SOD),测定了其清除邻苯三酚自氧化法产生的O2-自由基的作用.用乙醇沉淀法提取了银耳的多糖,初步认为它可能有促进自由基生成的作用.经网上检索,未见类似报导.     

天然食物链中的类胡萝卜素

类胡萝卜素是生物体中一类细胞次生代谢产物,是人类膳食中的健康功能因子。在自然界中,人类食物中的类胡萝卜素可以在一种生物体内合成,也可以经过多种生物体一起加工而合成。本文在阐述类胡萝卜素在自然界中不同生物体(如藻类、细菌、酵母、真菌、高等植物和低等动物)内组成特点的基础上,根据各生物体在天然食物链上的位置,详细描述了类胡萝卜素的起始合成、中间产物转移和后期加工。在这些过程中,各生物体对类胡萝卜素的选择性吸收和代谢修饰对最终产物的形成具有重要影响。本文最终得出的结论对更好地认识人类膳食中的类胡萝卜素资源具有一定的意义。     

Aluminium content of some foods and food products in the USA, with aluminium food additives.

The primary objective was to determine the aluminium (Al) content of selected foods and food products in the USA which contain Al as an approved food additive. Intake of Al from the labeled serving size of each food product was calculated. The samples were acid or base digested and analysed for Al using electrothermal atomic absorption spectrometry. Quality control (QC) samples, with matrices matching the samples, were generated and used to verify the Al determinations. Food product Al content ranged from <1-27,000 mg kg(-1). Cheese in a serving of frozen pizzas had up to 14 mg of Al, from basic sodium aluminium phosphate; whereas the same amount of cheese in a ready-to-eat restaurant pizza provided 0.03-0.09 mg. Many single serving packets of non-dairy creamer had approximately 50-600 mg Al kg(-1) as sodium aluminosilicate, providing up to 1.5 mg Al per serving. Many single serving packets of salt also had sodium aluminosilicate as an additive, but the Al content was less than in single-serving non-dairy creamer packets. Acidic sodium aluminium phosphate was present in many food products, pancakes and waffles. Baking powder, some pancake/waffle mixes and frozen products, and ready-to-eat pancakes provided the most Al of the foods tested; up to 180 mg/serving. Many products provide a significant amount of Al compared to the typical intake of 3-12 mg/day reported from dietary Al studies conducted in many countries.     

国外天然食品防腐剂的研究进展

食品防腐剂是防止因微生物的作用引起食品腐败变质,延长食品保存期的一种食品添加剂。本文就天然食品防腐剂的分类进行了简要介绍,重点阐述了天然食品防腐剂的发展现状,此外,还简要说明了食品防腐剂的安全使用问题。     

Determination of acrylonitrile monomer in food packaging materials and in foods

An automated headspace gas chromatographic method is described using nitrogen specific detection for the quantification of acrylonitrile monomer (AN) in acrylonitrile-butadiene-styrene (ABS) food packaging tubs and in the contained foods. For a limited number of retail foods, levels of AN in ABS tubs (ranging from 2 to 10 mg/kg) and their contents (soft margarine, butter and shortening) are reported (ranging from 0.01 to 0.05 mg/kg), the results being confirmed by mass spectrometry (low and medium resolution selected ion monitoring). The latter technique was also used to quantify the levels of AN in the coatings of retail packaging films on a range of substrates, which were found to be between <0.001 and 0.02 mg/m².