Advanced Modeling of Food Convective Drying: A Comparison Between Artificial Neural Networks and Hybrid Approaches

In the present paper, three different approaches are proposed to model the convective drying of food. The performance of thin-layer, pure neural network and hybrid neural model is compared in a wide range of operating conditions, with two different vegetables, available either as cylinders or as slabs with different characteristic dimensions. It was found that the thin-layer model was adequate to describe food drying behavior, but it could be applied only as a fitting procedure. Pure neural models gave accurate predictions in some situations, but exhibited poor performance when tested outside the range of operating conditions exploited during their development. Finally, it was shown that hybrid neural models, formulated as a combination of both theoretical and neural network models, are capable of offering the most accurate predictions of system behavior with average relative errors never exceeding 10%, even in operating conditions unexploited during the definition of the neural part of the model. The results obtained proved that the hybrid neural paradigm is a novel and efficient modeling technique that could be used successfully in food processing, thus allowing drying process optimization to be achieved, and efficient and fast on-line controllers to be implemented.     

基于直线截距直方图的Arimoto熵或Arimoto灰度熵的食品图像分割

食品生产中涉及到的食品种类繁多且必须满足国家相关食品安全标准,为此要求食品图像分割方法必须速度快、准确性高、普适性强。利用基于二维Arimoto熵或二维Arimoto灰度熵的阈值选取方法对食品图像进行分割,算法复杂度高,难以满足实时性要求。针对这一问题,提出基于直线截距直方图的Arimoto熵或Arimoto灰度熵的食品图像分割方法。首先给出直线截距直方图的定义,然后根据此定义建立图像的直线截距直方图,最后计算基于此直线截距直方图的不同灰度级的Arimoto熵或Arimoto灰度熵,当该熵达到最大时,对应的灰度级即为图像的最佳分割阈值。针对此方法,对多种食品图像进行了大量的试验,通过与现有的基于一维和二维Arimoto熵、Arimoto灰度熵的分割方法对比,发现本文方法在综合提升算法速度和改善分割效果上,性能更优。     

ESTIMATING FOOD TEMPERATURES DURING VARIOUS PROCESSING OR HANDLING TREATMENTS

SUMMARY— A procedure was developed for predicting the transient temperature of a solid food exposed to time variable ambient temperatures. Duhamel's theorem was applied to the empirical formulas used for calculating the temperature of a food subjected to a step change in its ambient temperature. The formulas contain two constants: f, the slope index of a heating or cooling curve of a food; and j, the intercept coefficient of the heating or cooling curve. With the procedure developed transient temperature can be estimated without regard to the geometric shape of the food provided the f and j values are known. A table is presented to reduce computations involved in the procedure. Sample calculations are given for a fresh orange, a fresh carrot and a canned food product.     

Shrinkage During Convective Drying of Whole Rose Hip (Rosa Rubiginosa L.) Fruits

Volume and area shrinkages occur during food dehydration. The food behaviour must be characterized not only for using in process and equipment simulation models but also to evaluate the final quality of the product. No literature reports were found on the rose hip behaviour. After removing the peduncles, whole fruits were dehydrated in heated air at temperatures of 50, 55, 60, 65, and 75°C, air velocities of 1, 2, 3, 5 m/s, and air relative humidities of 5 and 50%. Volume changes were evaluated by picnometric techniques and with geometric measurements by micrometer and superficial area from geometric measurements. In agreement with previous reports on other foods, volume and area changes do not depend on dehydration operating variables. A linear relationship was found between the dimensionless volume change and the moisture content of the partially dehydrated fruits. The area depended on moisture according to a third-grade polynomial.     

基于小波域多尺度Markov随机场的织物印花图案分割

织物印花图案的分割是纺织印染工艺中一个非常重要的过程,为了提高纺织印花图案的分色精度,本文采用小波域的多尺度Markov随机场模型实现了织物印花图案的分割。该方法首先对图像进行预处理,然后对图像进行小波“金字塔”分解,在每一尺度的分割过程中利用了各尺度上的有关信息:特征场建模通过描述小波系数之间的相关性反映每一像素位置的特征属性,标记场建模通过考虑邻域标记间的相互作用反映图像分割的区域性。两种随机场建模以联合概率乘积的形式相互约束,共同作用于该尺度的分割过程。在分割过程中,从最低分辨率尺度到原始分辨率尺度逐次进行图像分割,低分辨率尺度的分割结果通过直接投影作为相邻的更高分辨率尺度的初始分割,最高分辨率尺度上的分割结果作为本文方法的分割结果。     

Application of elements of microbiological risk assessment in the food industry via a tiered approach

Food safety control is a matter for concern for all parts of the food supply chain, including governments that develop food safety policy, food industries that must control potential hazards, and consumers who need to keep to the intended use of the food. In the future, food safety policy may be set using the framework of risk analysis, part of which is the development of (inter)national microbiological risk assessment (MRA) studies. MRA studies increase our understanding of the impact of risk management interventions and of the relationships among subsequent parts of food supply chains with regard to the safety of the food when it reaches the consumer. Application of aspects of MRA in the development of new food concepts has potential benefits for the food industry. A tiered approach to applying MRA can best realize these benefits. The tiered MRA approach involves calculation of microbial fate for a product and process design on the basis of experimental data (e.g., monitoring data on prevalence) and predictive microbiological models. Calculations on new product formulations and novel processing technologies provide improved understanding of microbial fate beyond currently known boundaries, which enables identification of new opportunities in process design. The outcome of the tiered approach focuses on developing benchmarks of potential consumer exposure to hazards associated with new products by comparison with exposure associated with products that are already on the market and have a safe history of use. The tiered prototype is a tool to be used by experienced microbiologists as a basis for advice to product developers and can help to make safety assurance for new food concepts transparent to food inspection services.     

立体几何褶皱织物的成型与织造

为拓宽立体几何褶皱织物的设计思路,设计具有立体几何效果的褶皱织物,对立体几何褶皱织物的成型原理进行了研究和探讨。提出了在二维织物面料铺设折叠线,形成一定规律的几何图案,并将几何图案按折叠线划分成上凸折叠区、下凹折叠区及非折叠区,在不同折叠区填充不同组织并以弹性纱和非弹性纱交替引纬,以此作为设计立体几何褶皱织物的基础。结果显示:设计好几何图案,选择不同的纬二重组织填充不同折叠区域,选用蚕丝为经纱、涤纶低弹丝与氨纶丝包覆的弹力丝与涤纶全拉丝为纬纱进行织造,所得的织物能形成具有明显立体几何形状的褶皱。     

Mass Transfer and Nutrient Absorption in a Simulated Model of Small Intestine

Abstract: There is an increasing need to understand how food formulations behave in vivo from both food and pharma industries. A number of models have been proposed for the stomach, but few are available for the other parts of the gastrointestinal tract. An experimental rig that simulates the segmentation motion occurring in the small intestine has been developed. The objective of developing such an experimental apparatus was to study mass transport phenomena occurring in the lumen and their potential effect on the concentration of species available for absorption. When segmentation motion was applied the mass transfer coefficient in the lumen side was increased up to a factor of 7. The viscosity of the lumen, as influenced by guar gum concentration, had a profound effect on the mass transfer coefficient. The experimental model was also used to demonstrate that glucose available for absorption, resulting from starch hydrolysis, can be significantly reduced by altering the lumen viscosity. Results suggest that absorption of nutrients could be controlled by mass transfer. Practical Application: To address health-related diseases such as obesity, novel foods that provide advanced functions are required. To achieve the full potential offered by the latest developments in the field of food material science, a fundamental understanding of the behavior of food structures in vivo is required. Using the developed gut model we have demonstrated that absorption of nutrients can be controlled by mass transfer limitations.     

Determination of Optimum Concentrations of a Food Ingredient Using Survival Analysis Statistics

ABSTRACT:  For desirable attributes in food products such as red color in a strawberry yogurt, the color can be too light, okay, or too dark, leading to 2 events of interest: the transition of too light to ok, and the transition of ok to too dark. The objective of the present work was to develop a model using survival analysis statistics to allow modeling these 2 events and thus allow prediction of the optimum color based on acceptance or rejection data obtained from consumers. Concepts and calculations were applied to a data set obtained from 60 consumers who each looked at 7 yogurt samples with different red color intensities, answering whether they found the samples too light, okay, or too dark. From this censored data set parametric models were obtained which allowed optimum color estimation and segmentation of consumers in groups according to whether they liked lighter or darker colored yogurts. Applications of the model to other food ingredients and to the ripening and spoilage of fruit are discussed.     

ESTIMATION OF PARAMETERS FOR MOISTURE TRANSPORT IN FOODS1

The problem of estimation of transport parameters in food processing models is examined. A procedure is presented which consists of controlled experiments, application of theory to model the process and estimation of parameters by comparing the experimental and predicted data by the use of nonlinear optimization technique. The optimization program estimates a set of parameters in a food processing model which gives a minimum value of the sum of squares of the deviation between the observed and estimated values. The processes considered are drying, soaking and parboiiing of rice and peanut drying. Depending on the complexity of the process, the solution of the mathematical model is given in the form of analytical, finite difference or finite element approximations. The precision of transport parameters determination is also discussed.     

High-pressure shift freezing: recrystallization during storage

High-pressure shift freezing has been proposed as a method to produce frozen food with smaller ice crystal size and, consequently, with reduced tissular damage and higher overall quality. The fate of this initially improved crystal size distribution, decisive for the long-term value of this procedure, is unclear. The recrystallization behaviour of partially frozen aqueous solutions, as food models, is here compared with that of similar classically frozen samples. A microscopic observation cell has been specially designed for this purpose. The temporal evolution of high-pressure shift frozen ice crystals has been fitted to different mechanism models and is found to be similar within experimental error to that of classically frozen samples. However, differences in the shape evolution of crystals have been detected, which can be ascribed to small differences in the initial distribution. The implications of these observations for the long-term storage of frozen food are discussed.     

Optimization of energy consumption during the heat processing of canned foods

A procedure was developed which enables the energy consumption of batch food sterilizing processes to be minimized. Application of the procedure is illustrated for pea puree packed in 307 × 409 (mm) cans and heat processed in a pilot-scale retort at six different time-temperature combinations providing the same lethal value. The total energy requirement was calculated for each process and plotted as a function of the processing temperature. An optimum value of 121·8°C for 64·8 min was found for processing conditions, corresponding to a minimum energy requirement.     

CENTERPOINT NUTRIENT DEGRADATION IN HEAT PROCESSED CONDUCTION HEATING FOOD MODEL

A methodology was developed for the evaluation of centerpoint nutrient degradation in conduction heating canned food subjected to thermal processing. the methodology involved sealing of 75μL aliquote of test solution in a leakproof pressure-stable stainless steel capsule, placing the capsule at the geometric center of a can filled with a conduction heating simulated food prior to the closure, and recovering the capsule and analyzing the contents following a given thermal treatment. Experiments carried out using aqueous solutions of ascorbic acid and thiamine indicated good reproducibility of the results. Employing kinetic data for thermal destruction of the nutrients and center temperature-time history of the food simulant obtained from several simultaneously processed cans, the centerpoint nutrient retention predicted by several models agreed favorably with the experimental results.     

Experimental determination of the dynamics of vacuum impregnation of apples

ABSTRACT:  Vacuum impregnation (VI) is a food processing method by which air and native solution are removed from porous spaces within a food and replaced by an external solution. In this study, an experimental device based on a previous design was built, including some modifications, in order to investigate the dynamics of the VI process. The device measured the net force exerted by a food sample submitted to the VI process using a load cell. The influence of the vacuum level and sample geometry was well quantified by the experimental procedure and the modified equipment using apple samples (Fuji var.) as a food model. The results indicated that the experimental device proposed in this study, together with the suggested procedure, is a useful tool to investigate the dynamics of VI processes. It is robust and versatile, and has the advantage of not requiring the determination of the water evaporated during the VI process in a separate experiment, which represents an increase in the accuracy of the results.     

Estimation of microbial growth using population measurements subject to a detection limit

In this paper we develop a maximum likelihood estimation procedure for determining the mean and variance in microbial population size from microbial population measurements subject to a detection limit. Existing estimation methods generally set non-detectable measurements equal to the detection limit and are highly biased. Because changes in the mean and variance in the microbial population size are typical in industrial processes we also outline statistical tests for detecting such changes when measurements are subject to a detection limit, which is critical for process control. In an industrial process there may also potentially be variability in the microbial growth rate due to variation in the microbial strain, environment, and food characteristics. Accordingly, we also present a maximum likelihood procedure for estimating microbial growth model parameters and their variance components from microbial population measurements subject to a detection limit. Such information can be used to generate the mean and variance through time of the microbial population size, which is vital for the application of predictive microbiological models to risk assessment and food product shelf-life estimation.     

Effect of Satureja thymbra essential oil on growth-no growth interfaces of Listeria monocytogenes Scott A and Salmonella Enteritidis PT4, at various temperatures, pH, and water activities

Antimicrobial efficacy of Satureja thymbra essential oil against Listeria monocytogenes Scott A and Salmonella ser. Enteritidis PT4 was evaluated in vitro by modeling the growth boundaries at various temperatures, pH, and NaCl concentrations. Growth-no growth (turbidity) data were modeled by logistic polynomial regression. The concordance indices and the Hosmer- Lemeshow statistics of both logistic models indicated a good fit to the observed data. Salmonella Enteritidis was more sensitive at increasing salt content as compared with L. monocytogenes. On the other hand, pH changes had greater effect on growth initiation of L. monocytogenes than they had on growth initiation of Salmonella Enteritidis. Presence of essential oil up to 0.06% (vol/vol) had no or little effect on growth initiation of both microorganisms tested, while the concentration of 0.1% (vol/vol) essential oil exhibited great inhibition on growth initiation, especially when it was combined with increased salt content and low temperatures. The antimicrobial potency of S. thymbra essential oil was more pronounced when multiple hurdles were applied. Modeling the growth boundaries offers a useful tool to food microbiologists for assessing the antimicrobial activity in a range of food preservation conditions as compared with the conventional MIC determination.     

Preference data analysis using a paired comparison model

Ranking procedures are very suitable for measuring consumer preference. This paper deals with the segmentation of a consumer panel after a ranking trial. A latent class approach is used to estimate segments from the preference data. The statistical analysis is based on the Bradley-Terry-Luce model, classically used to interpret paired comparison data. This segmentation procedure provides configurations of the stimuli in the different classes and the weights of these segments. A likelihood ratio test can be performed in order to determine the adequate number of latent classes. An application of this segmentation model on preference data is presented.     

采用色纺纱图像的真实感色织物模拟

为解决色织物产品设计周期长,试织打样耗时费力的问题,提出一种采用色纺纱图像的真实感色织物的模拟方法。首先采集彩色纱线图像,运用阈值分割、形态学处理得到纱线主体,获取纱线主体的上、下边界和中心线,进而得到原始纱线图像的主体部分;接着根据椭圆模型和正弦曲线模型对纱线主体图像进行处理,得到纱线在二维织物表面中的形态;最后根据色纱循环和织物组织变换模型来改变经纬纱的覆盖关系,实现了真实感条纹型和格子型色织物的模拟。模拟结果表明：本文算法能够模拟不同种类色织物的织造过程,真实地反映织物的外观效果,且能够调整织物组织和色纱循环参数,提高了现有模拟算法的真实性和适应性。     

三维膳食调查辅助工具箱的设计及制作

目的:设计并制作国内首套便携式三维膳食调查辅助工具箱,提高回顾法膳食调查时食物份量估计的准确性。方法:根据文献资料及上海市和南通市长途汽车司机经常就餐的食堂及菜市场调查,设计并制作三维膳食调查用模型,将市场购买的蔬菜按相同方法烹调后,计算出100g模型所代表实际食物的熟重和生重。结果:制作了膳食调查用工具箱,该工具箱除含常见水果和馒头模型外,还有20多种不同食物原料模型;该套模型基本满足了长途汽车司机膳食调查的需要。结论:三维食物模型形象逼真,激发了调查对象参与的兴趣,可有效提高调查对象的依从性和对食物份量估计的准确性。     

螺杆挤压过程食品流动能力计算与综合修正

螺杆挤压推料是食品加工过程中完成食品的输送、挤压与混合的常用工序,确定螺杆挤压过程食品流动能力,是为研究食品加工工艺及设备提供必要的条件。本文针对具有幂律非牛顿流体特性的一类食品,对前人的螺杆挤压流动模型及公式进行了简化与扩展,并提出了一种模型修正法--综合系数修正法。