How does tooth cusp radius of curvature affect brittle food item processing?

Tooth cusp sharpness, measured by radius of curvature (RoC), has been predicted to play a significant role in brittle/hard food item fracture. Here, we set out to test three existing hypotheses about this relationship: namely, the Blunt and Strong Cusp hypotheses, which predict that dull cusps will be most efficient at brittle food item fracture, and the Pointed Cusp hypothesis, which predicts that sharp cusps will be most efficient at brittle food item fracture using a four cusp bunodont molar. We also put forth and test the newly constructed Complex Cusp hypothesis, which predicts that a mixture of dull and sharp cusps will be most efficient at brittle food item fracture. We tested the four hypotheses using finite-element models of four cusped, bunodont molars. When testing the three existing hypotheses, we assumed all cusps had the same level of sharpness (RoC), and gained partial support for the Blunt Cusp hypotheses. We found no support for the Pointed Cusp or Strong Cusp hypotheses. We used the Taguchi sampling method to test the Complex Cusps hypothesis with a morphospace created by independently varying the radii of curvature of the four cusps in the buccolingual and mesiodistal directions. The optimal occlusal morphology for fracturing brittle food items consists of a combination of sharp and dull cusps, which creates high stress concentrations in the food item while stabilizing the food item and keeping the stress concentrations in the enamel low. This model performed better than the Blunt Cusp hypothesis, suggesting a role for optimality in the evolution of cusp form.     

Liposomes as carrier vehicles for functional compounds in food sector

Liposomes are attractive encapsulation systems that provide enhanced stability of encapsulated materials against a range of environmental, enzymatic, and chemical stresses, including the presence of enzymes or reactive chemicals, and exposure to extreme pH, temperature, and ionic strength changes. Liposomes have been widely used in the pharmaceutical and food industries because of their biocompatibility, biodegradability, absence of toxicity, small size, and ability to carry a wide variety of bioactive compounds due to the amphiphilicity of the phospholipid encapsulating material. In the food industry, liposomes have recently been used to deliver different functional compounds in food systems. In this paper, the food application of liposomes and nanoliposomes as emerging carrier vehicles of vitamins, enzymes, food antimicrobials, essential oils, and polyphenols is discussed in detail.     

Mass transport studies of different additives in polyamide and exfoliated nanocomposite polyamide films for food industry

The development of new food packaging films through the incorporation of nanoparticles, and the effect of the nanoparticles on the process of migration of the substances used in manufacturing the new films is expected to lead to an improvement in the shelf life of food and thus, consumer safety and health. In recent years, attention has focused on nanocomposites because these compounds often exhibit unexpected hybrid properties derived from synergistic reactions between nanoparticles and the polymeric matrix. The exfoliation of nanoclays in polyamide film provides a film with better barrier properties than that obtained through the intercalation of nanoclays. Migration of chemicals from food packaging into food may produce potential adverse health effects because of exposure to toxic compounds. The present study addressed the migration of caprolactam, 5‐Chloro‐2‐(2,4‐dichlorophenoxy)phenol (triclosan) and trans,trans‐1,4‐diphenyl‐1,3‐butadiene (DPBD) from polyamide and polyamide‐nanoclays to different types of food simulants. The values for limit of detection (LOD) obtained for caprolactam, triclosan and DPBD was 0.5 mg/L, 0.02 mg/L and 0.01 mg/L, respectively. Furthermore, instrumental precision was evaluated through repeatability injections, resulting in relative standard deviations lower than 3.08%. Diffusion coefficients were calculated according to a mathematical model based on Fick's Second Law, and the results were discussed in terms of the parameters that may have the greatest effect on migration. The presence of polymer nanoparticles was found to slow down the rate of migration of substances from the matrix polymer into the food up to six times. Copyright © 2009 John Wiley & Sons, Ltd.     

Optimal shape remodelling of linearly elastic plates using finite element methods

The optimality conditions for the optimal shape remodelling of linearly elastic plates are obtained by introducing the total variation of a function defined on a variable domain, although the variation of a function has been taken on a fixed domain in most literature on calculus of variations. Using these optimality conditions, a solution scheme involving an iterative algorithm is proposed, together with several numerical examples.     

How to best smash a snail: the effect of tooth shape on crushing load

Organisms that are durophagous, hard prey consumers, have a diversity of tooth forms. To determine why we see this variation, we tested whether some tooth forms break shells better than others. We measured the force needed with three series of aluminium tooth models, which varied in concavity and the morphology of a stress concentrating cusp, to break a shell. We created functionally identical copies of two intertidal snail shells: the thicker shelled Nucella ostrina and the more ornamented Nucella lamellosa using a three-dimensional printer. In this way, we reduced variation in material properties between test shells, allowing us to test only the interaction of the experimental teeth with the two shell morphologies. We found that for all tooth shapes, thicker shells are harder to break than the thinner shells and that increased ornamentation has no discernible effect. Our results show that for both shell morphologies, domed and flat teeth break shells better than cupped teeth, and teeth with tall or skinny cusps break shells best. While our results indicate that there is an ideal tooth form for shell breaking, we do not see this shape in nature. This suggests a probable trade-off between tooth function and the structural integrity of the tooth.     

不同冷却方式对冷鲜鸡肉品质的影响

目的 探究不同冷却方式对鸡肉水分分布、蛋白质变性等理化性质的影响.方法 分析风冷、真空冷却和浸没式真空冷却对鸡肉的冷却速率、pH、色差、质构等指标的影响,通过低场核磁共振和差式扫描量热技术分析冷却后鸡肉中水分分布和肌蛋白的变化.结果 风冷的冷却速率最慢,肉色暗沉,且质量损失率高,硬度和剪切力也较大;真空冷却的冷却速率最快,肉色较为鲜艳,其质量损失率、硬度和剪切力也最大;浸没式真空冷却能有效减小鸡肉的质量损失率(P<0.05),肉色最鲜艳,弹性和回复性也最好.通过差式扫描量热法分析可知,3种冷却方式下肌蛋白的变性焓均减小,风冷组的肌球蛋白、肌浆蛋白和肌动蛋白降解最多,真空冷却组的蛋白降解较风冷组更好,浸没式真空冷却组的蛋白降解最小,与对照组无显著差异;由低场核磁共振分析可知,风冷组不易流动水组分显著降低(P<0.05),自由水显著增加(P<0.05),真空冷却自由水组分显著降低(P<0.05),浸没式真空冷却后鸡肉中水分分布与对照组无显著差异.结论 浸没式真空冷却弥补了真空冷却不足,在一定程度上提高了鸡肉品质.     

超声技术在食品工业中的应用

超声作用的物理机制有热机制、机械机制和空化机制。它能加速质量、热量传递，缩短单元操作时间，提高操作效率；还能促进结晶成核、控制晶粒体粒径分布，改善食品的品质等。超声技术不仅可应用于食品的加工过程，如食品的提取、干燥、过滤、结晶、乳化、灭菌，还可应用于食品体系的检测、分析。文章简要介绍了超声作用的物理机制，重点论述了超声技术在食品加工及食品检测分析中的应用。     

Effect of item redundancy on Rasch item and person estimates

One of the assumptions of many latent trait models is local independence. This assumption specifies that, after controlling for the underlying trait, item responses are independent. Given the lack of studies of model robustness against such violations, it appears that this assumption is frequently taken for granted. Therefore, this study investigated the robustness of Rasch item and person estimates with simulated data under varying number of items, sample sizes, and levels of item redundancy. Item and person reliabilities, the standard deviations of the person and item estimates, the root mean squared differences and mean signed differences among person and item estimates, the correlations between person estimates, and the percentage of person estimates shifting by more than .50 logits were used to evaluate the impact of item redundancy. Both norm and criterion-reference interpretations may be influenced by the imputation of redundancy into the data. However, it appears that the amount of redundancy needs to be considerable before such interpretations would be adversely impacted. Suggestions for further simulation research are provided.     

Optimal pricing strategy for the perishable food supply chain

This research investigates the optimal pricing strategy for the perishable food supply chain. Using the setting of a two-echelon supply chain including a supplier and a retailer, we apply the game theory approach to derive the equilibriums for both a single pricing strategy and a two-stage pricing strategy. Through a comparison of the equilibriums, we explore how the two pricing strategies affect the supply chain’s decisions and supplier’s and retailer’s performance individually and collectively. The results of the analysis show that the optimal choice of pricing strategy depends on the price markdown cost and its relationship with the two critical thresholds that are determined by a combination of factors including the potential market size, the price and quality sensitivity factors, the initial quality, the unit product cost, and the quality deterioration rate.     

A Constraint Programming model for food processing industry: a case for an ice cream processing facility

This paper presents a Constraint Programming (CP) scheduling model for an ice cream processing facility. CP is a mathematical optimisation tool for solving problems either for optimality (for small-size problems) or good quality solutions (for large-size problems). For practical scheduling problems, a single CP solution model can be used to optimise daily production or production horizon extending for months. The proposed model minimises a makespan objective and consists of various processing interval and sequence variables and a number of production constraints for a case from a food processing industry. Its performance was compared to a Mixed Integer Linear Programming (MILP) model from the literature for optimality, speed, and competence using the partial capacity of the production facility of the case study. Furthermore, the model was tested using different product demand sizes for the full capacity of the facility. The results demonstrate both the effectiveness, flexibility, and speed of the CP models, especially for large-scale models. As an alternative to MILP, CP models can provide a reasonable balance between optimality and computation speed for large problems.     

Identification of problems arising during manual handling of food packaging by older consumers in Poland

The ageing population all over the world requires much greater attention than it receives from many businesses, including packaging industry. Therefore, it is essential to investigate the specific needs, requirements, and expectations of older consumers, particularly those related to the labelling and ergonomics, so as to shape the food packaging characteristics. In this way, consumers' satisfaction and hence the brand loyalty can be built. The aim of the study was to analyse the needs of older consumers related to food packaging handling and other corresponding issues, as well as to develop guidelines for food producers. The research consisted of two stages: a survey that covered a group of 600 consumers aged 60 and older in southern Poland and individual in‐depth interviews (IDIs) carried out among 60 people over the age of 60 in southern Poland. The outcomes of this consumer research indicated the need for changes in food packaging designed for older consumers, especially in consideration of the physical limitations for its handling before and after the product purchase. Food producers should also pay particular attention to the problems connected with packaging as a source of information. Moreover, they should make modifications in packaging ergonomics, especially in terms of size, shape, and opening and closing features. According to respondents, packaging material should be safe for health but not necessarily environmentally friendly.     

Analysis of Photothermal Characterization of Layered Materials – Design of Optimal Experiments

In this paper numerical calculations are presented for the steady-periodic temperature in layered materials and functionally-graded materials to simulate photothermal methods for the measurement of thermal properties. No laboratory experiments were performed. The temperature is found from a new Green's function formulation which is particularly well-suited to machine calculation. The simulation method is verified by comparison with literature data for a layered material. The method is applied to a class of two-component functionally-graded materials, and results for temperature and sensitivity coefficients are presented. An optimality criterion, based on the sensitivity coefficients, is used for choosing what experimental conditions will be needed for photothermal measurements to determine the spatial distribution of thermal properties. This method for optimal experiment design is completely general and may be applied to any photothermal technique and to any material with spatial variation of thermal properties.     

Novel model and kernel search heuristic for multi-period closed-loop food supply chain planning with returnable transport items

Closed-loop supply chain (CLSC) is of utmost importance to sustainable development and has received increasing attention in recent decades. However, food CLSC with returnable transport items (RTIs) has been rarely studied although its growing applications in practice. This paper aims to investigate a multi-period CLSC planning problem that coordinates the flows of perishable food products and RTIs considering food quality. The objective is to maximise the total profit of the holistic supply chain over a finite planning horizon. To this end, a novel mixed integer linear programming model is first formulated. As the problem is proven NP-hard, an improved kernel search-based heuristic is then developed. A real case study deriving from a food manufacturer in China shows the applicability of the proposed model and method. The results indicate that the manufacturer’s profit can be improved by more than 10% with our method. Numerical experiments on randomly generated instances demonstrate that the proposed heuristic can yield high-quality solutions with much less computation time compared with the commercial solver CPLEX and an existing heuristic.     

傅立叶变换红外光谱法分析市售食品中反式脂肪酸

建立了一种快速测定食品中反式脂肪酸含量的方法,用索氏提取法或氯仿—甲醇提取法提取食品中脂肪,经甲醇-BF3快速甲酯化后,采用Avatar 370傅立叶变换红外光谱对反式脂肪酸进行定性定量分析,回收率为89.5%~103.3%,相对标准偏差为1.80%,重复性好,准确度高,适用于一般食品营养标签的测定。对我国市场上的涂抹奶油、派和蛋糕、饼干、巧克力、冰淇淋、薯片和薯条等6大类食品中20种样品中反式脂肪酸进行测定。结果表明,16种检出样品中反式脂肪酸含量在0.18%~10.34%之间,反式脂肪酸含量随食品种类不同存在显著差异,涂抹奶油、蛋黄派、威化饼干是反式脂肪酸含量较高的食品类别。     

A simple model for the interaction between water vapour and oxygen transmission in multilayer barrier materials intended for food packaging applications

The low oxygen permeability of the ethylene‐vinyl alcohol copolymer, EVOH, is outstanding, but is also known to be very sensitive to moisture uptake and cannot be used as a monolayer packaging material. In this paper, theory is presented in order to calculate the average water activity of the EVOH layer at steady state and the corresponding oxygen barrier for different multilayer structures using various polymer types and layer thicknesses. Multilayer materials can be designed for different food packaging applications and storage conditions, in order to keep the relative humidity of the barrier below recommended 75%, by varying the thickness of the outside versus the inside protective layers and/or varying the water vapour transmission rate of the outside versus the inside layer. The conclusion reached is that to retain the optimal barrier properties and thereby the optimal protection of the food, asymmetric multilayer structures are necessary. Copyright ©2007 John Wiley & Sons, Ltd.     

An examination of exposure control and content balancing restrictions on item selection in CATs using the partial credit model

The purpose of the present investigation was to systematically examine the effectiveness of the Sympson-Hetter technique and rotated content balancing relative to no exposure control and no content rotation conditions in a computerized adaptive testing system (CAT) based on the partial credit model. A series of simulated fixed and variable length CATs were run using two data sets generated to multiple content areas for three sizes of item pools. The 2 (exposure control) X 2 (content rotation) X 2 (test length) X 3 (item pool size) X 2 (data sets) yielded a total of 48 conditions. Results show that while both procedures can be used with no deleterious effect on measurement precision, the gains in exposure control, pool utilization, and item overlap appear quite modest. Difficulties involved with setting the exposure control parameters in small item pools make questionable the utility of the Sympson-Hetter technique with similar item pools.     

Optimal markdown policy of perishable food under the consumer price fairness perception

Markdown policies are widely used by retailers to sell perishable food. Consumers purchase food at different prices during different sales periods. Some consumers may compare their experience with others who purchase the same items. Price unfairness or inequity is perceived when different prices are quoted without reasonable explanations. This study develops an optimal markdown model for perishable food pricing to optimise the food retailer revenue and enable a maximum aggregated consumer utility considering individuals’ price fairness perception. The model serves as the first step in evaluating trade-offs between food retailer revenue and consumer utility. In addition, it enables consumer utility to be depicted through perceived price fairness by including the effects of food perishability and scarcity. Another innovative feature is the equalisation of the consumer average aggregated utility during different sales periods as a condition of intertemporal price fairness perception. The proposed model is compared with two benchmark models to justify the effectiveness and advantages in the example. Finally, a sensitive analysis based on the food deterioration rate, consumer food desire rate and consumer average reservation price is conducted to justify the manner in which these factors influence the optimal pricing policy, and managerial insights are suggested for food retailers.     

A review of packaging-related studies in the context of household food waste: Drivers,solutions and avenues for future research

Packaging has the potential to reduce food waste and contribute to the United Nations sustainable development goal 12.3. Yet packaging is also a household food waste (FW) driver, necessitating packaging improvements. Through a review of primary consumer studies on household FW and packaging published 2006–2020, this study mapped the effects of packaging functions on different food categories to identify packaging-related FW drivers, solutions and research opportunities. Relevant studies are increasing, yet packaging yields less attention than factors including domestic routines. Many studies limit packaging discussion to the aspects attributed to wasted food, with date-labels and overly large pack sizes the most mentioned. Suggested solutions by extant literature include clearer date-labels and more pack size variety. However, research showing the effectiveness of these suggested solutions in households is lacking. Packaging formats and materials may affect packaging functionality and therefore household FW, but studies are lacking. There is therefore scope for household studies to collect more packaging related FW data. In particular, focussing on the effects of specific packaging functions on domestic food practices, with an effort to gather food-group-specific data. More studies in Africa, Asia, the Americas, Middle East and the Pacific/Oceania will provide insights beyond the current Eurocentric focus. These findings contribute to theory and practice within the focus of household FW and packaging literature, helping to extend existing research to support the development and implementation of packaging that considers regional differences in food systems, food routines and preferences for a better chance at reducing FW.     

Fracture mechanisms and particle shape formation during size reduction of a model food material

The importance of particle shape to powder properties warrants examination of the effect of size reduction on particle shape formation. In this study, a model food material (dried gelatinized starch) was comminuted in an impact breakage gun, a hammer mill (with and without a screen) and in a blender. After sieving, particle shape at selected sizes was assessed as deviation from sphericity. Generally, particle shapes were elongated at smaller size, except for those produced by unscreened hammer milling. Particle shapes were unaffected by impact velocity in the gun, but were rounded by increased milling. Fractography was used to demonstrate how elongated particles formed. During fracture, fracture fronts were disturbed by air holes in the material, creating cleavage steps. Subsequent undercutting of the steps as fracture planes spread released the elongated particles. Such particle formation mechanisms may account for anomalous size distribution results at early stages of grinding. Particle shape differences between mills and single impact breakage were ascribed to particle selection mechanisms surmised to be operating in the mill. Both material properties and the size reduction method were shown to affect particle shape, thus fracture progress in a given material should be studied if particles of specific shapes are to be produced by comminution.     

Refrigeration and world food requirements

In discussions relating to the world food supply system and to global nutritional problems, much attention is often paid to food losses. A special concern is expressed as regards losses of perishable foods, especially milk, meat and fishery products where losses at times may be extremely high, for fish as high as 50% of the catch.Chilling or freezing appear to be the preferred methods of preservation especially for meat, milk, poultry and fish. Much effort is exerted to erect or expand refrigeration and freezing facilities with the object of accommodating more of these products, and also, to a more limited extent, for the storage of fruit and vegetables.