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.     

Effects of wheat and rye bread structure on mastication process and bolus properties

Chemical composition, baking process and structure of breads influence their degradation in digestion leading to different postprandial responses. Rye bread has a very different structure as compared to wheat bread, and rye breads are known to induce lower postprandial insulin responses than wheat bread. The aim of this study was to find out potential differences in mastication and initial starch hydrolysis rate of rye and wheat breads. Three rye breads (wholemeal rye, endosperm rye and endosperm rye with gluten) and wheat bread were masticated by fifteen participants and the process was monitored using electromyography. The particle size distribution and initial in vitro starch hydrolysis of the bread boluses were analysed. Specific volume correlated negatively and closed porosity of breads correlated positively with work required for mastication. When compared to wheat bread, wholemeal rye bread required more work for mastication process (p = 0.004). Rye breads were degraded to smaller particles than wheat bread during mastication. There was a trend (p = 0.098) towards slower in vitro starch hydrolysis rate in rye bread boluses than in wheat bread boluses. The results indicate that the digestion process of rye breads differs from that of wheat bread already in the early phase of digestion. This may be one reason behind the unique postprandial responses reported for rye breads.     

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 and lipid composition of skim milk lipid material

Skim milk lipid material was characterized in terms of particle size distribution and lipid composition, and compared with other milk fat particle distributions. Whole milk, skim milk, large fat globules, small fat particles and skim milk lipid material were prepared using centrifugation and/or filtration, and the particle size distributions measured by laser diffraction. The lipid composition was determined using a combination of thin layer chromatography and gas chromatography–mass spectrometry. There were significant compositional differences between each fraction for both particle size distribution and fatty acid composition. The most distinguishing feature of the skim milk lipid material was the increased percentage of long chain sphingomyelin species compared with the other milk fat fractions.     

Impact of varying food hardness on mastication/swallowing

Food Science and Biotechnology - The purpose of this study was to analyze mastication and swallowing in the elderly and confirm the association with dysphagia characteristics. A questionnaire was...     

The potential effects of demands for natural and safe foods on global food security

There are a number of intersecting and conflicting issues that may require greater oversight than is currently evident:

1. Global food security as defined by FAO, requires that all people have access to adequate supplies of safe, nutritious food of their own choice for healthy living. There is evidence that such amounts of suitable food are being produced in the world today, but not available to all (FAO, 2006).

2. Demands for natural and safe foods and ingredients are expanding and people in the new and developed countries can afford to pay premium prices.

3. Relatively inexpensive air freight allows rapid deliveries of “fresh” and minimally processed food items along extensive supply chains. There are no calculations of environmental costs in evidence.

4. Minimum food processing is demanded, placing a heavy reliance on local safety standards at point of origin and in transit. This can and has created conflict of priorities between improving local safety standards and maintaining profitability. Recent events in China are an important case study.

5. Risks to consumers can escalate as increasing sales demand an expanding range of suppliers and a sometimes expanding supply chain. Failure of any one link can be critical for the chain and its end-user.

6. Opportunities for international suppliers and demands on the production potential of many developing countries can reduce the availability of basic foods to local markets.

7. A new phenomenon has arisen of obesity and starvation occurring simultaneously in the same country (The Australian, 2007), an example of national wealth divergence.

Conclusions

Natural does not mean Safe, particularly with regard to food. Disturbing outcomes during interviews for a local television programme, Catalyst (www.abc.net.au/catalyst, 16 August, 2007), were the extent to which not only the members of the public, but also a General Medical Practitioner, interviewed believed that natural products must be safe. This is an ongoing concern for the food industry and others.Safe food is a term relative to local customs and standards and the further the foods travel from a culture, the greater the need for compliance with accepted international food safety and quality standards. Economic pressures are always likely to compromises in meeting stringent requirements.The demands and freedom of food choice emanating from the growing affluence of some can severely limit the possibilities of food security for others.The International Council for Science (ICSU, www.icsu.org) has a number of programmes in place looking at issues such as Global Environmental Change and Food Systems (GECAFS) and Health and Wellbeing in the Changing Urban Environment (SHWB). Both projects deserve attention.Ultimately, it will depend on each of us and our attitudes as consumers as to how a balance can be obtained between free choice and food security for all. Last month we reached the mid-term of the Millennium Development Goals to reduce the world's hunger by half. We have not met our targets so far and there are signs of harvest difficulties ahead. A more engaging strategy is needed with greater international cooperation. Are we up to the challenge?Free Trade, Fair Trade and Safe Trade are not, after all, equivalent.Food security “Food Security exists when all people, at all times, have physical and economic access to sufficient, safe and nutritious food to meet their dietary needs and food preference for an active and healthy life.”FAO, 1996.“All substances are poisons: there is none which is not a poison. The right dose differentiates a poison and a remedy.”Paracelsus, 1493–1541.World Food Summit (WFS) and Millennium Development Goals (MDGs) Despite disappointing performances in reducing the number of hungry people, a smaller percentage of the populations of developing countries is undernourished today compared with 1990–92: 17 percent against 20 percent. FAO's projections suggest that the proportion of hungry people in developing countries in 2015 could be about half of what it was in 1990–92: a drop from 20 to 10 percent.Thus the world is on a path to meeting the MDG 1 on hunger reduction but will miss the WFS target by 170 million people.FAO, 2006.

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.     

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.     

动态光散射法研究降度白酒的粒径及其分布

在白酒原酒加浆降度生产低度白酒的过程中酒体会失光、浑浊,用感官或浊度计评价酒体的浑浊程度难以准确指导后处理工艺的合理设计。该研究用动态光散射法测定了不同酒精度的降度白酒的粒径及其分布。结果表明,40%vol、30%vol、20%vol和10%vol降度白酒的粒径分别集中在800～1 300 nm、430～550 nm、235～260 nm和180～215 nm范围内,且降度白酒产生最大粒径时的酒精度与其出现最大浊度时的酒精度明显不同。气相色谱（GC）法的分析结果表明,降度白酒的粒径分布主要取决于酒体中部分酯类、醇类、醛酮类成分,特别是高级脂肪酸乙酯的析出情况。用动态光散射法快速检测降度白酒得到的粒径分布可以为更精准地选择降度白酒的后处理工艺参数提供指导。     

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 homogenisation efficiency in high-pressure homogenisation of wheat germ oil-water system

Wheat germ oil (WGO) is well-known as a good source of vegetable oil due to its nutrients and health benefits. Emulsification is a process that improves the incorporation of oil into food. High-pressure homogenisation (HPH) is a nonthermal and soft technique with enormous potential in oil-in-water emulsification. This paper focussed on the application of HPH for emulsification of WGO-in-water system. Influences of homogenisation pressure (100–300 bar), oil fraction (10–20% v/v) and lecithin adding (0–0.2% w/v of content) on the homogenisation were evaluated based on distribution of particles diameter and homogenisation efficiency. The increase in operating pressure and lecithin ratio decreased the particle size and increased the emulsion stability, and vice versa for oil fraction. The findings imply that the investigated factors significantly influenced particle size and emulsion system stability. The regression model between mean particle diameter and technical conditions of emulsion was established. With HPH treatment conditions of 300 bar operating pressure, 10% (v/v) oil fraction and 0.2% (w/v) lecithin created an emulsion system with a mean particle size of 3.32 µm, more than 50% of the volume of particles smaller than 1.5 µm of diameter and the homogenisation efficiency of 98.61%. HPH exhibits high efficiency and potential in WGO-in-water emulsification application.     

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.