Food structure: Its formation and relationships with other properties

Food materials are complex in nature as it has heterogeneous, amorphous, hygroscopic and porous properties. During processing, microstructure of food materials changes which significantly affects other properties of food. An appropriate understanding of the microstructure of the raw food material and its evolution during processing is critical in order to understand and accurately describe dehydration processes and quality anticipation. This review critically assesses the factors that influence the modification of microstructure in the course of drying of fruits and vegetables. The effect of simultaneous heat and mass transfer on microstructure in various drying methods is investigated. Effects of changes in microstructure on other functional properties of dried foods are discussed. After an extensive review of the literature, it is found that development of food structure significantly depends on fresh food properties and process parameters. Also, modification of microstructure influences the other properties of final product. An enhanced understanding of the relationships between food microstructure, drying process parameters and final product quality will facilitate the energy efficient optimum design of the food processor in order to achieve high-quality food.     

An improved mathematical model bidirectional coupling of heat-water and mechanics during vacuum pre-cooling

Vacuum pre-cooling is a multi-physics process coupling heat transfer, water transport, and shrinkage, the stresses caused by water evaporation and temperature variation in food interact with its deformation. However, the developed models usually assume that the shrinkage of food is insignificant so that it is ignored, which is inconsistent with the actual vacuum pre-cooling process and makes the simulation results inaccurate. Taking strawberry as an example, a multiphase porous media model with heat-water and mechanics (HWM) bi-directional coupling was developed for food vacuum pre-cooling. The accuracy of the HWM model was verified by comparing the heat-water (HW) model without considering shrinkage and the experiments. The results show that the development of the evaporation front predicted by the HWM model is more sensitive to the vacuum chamber pressure change compared with the HW model. The maximum average relative errors corresponding to the temperature and shrinkage of the HWM model are 0.27% and 6.95%, respectively, which are better than the HW model. In addition, the edge gradient effect that occurs in the middle stage of vacuum pre-cooling was observed. When the vacuum chamber pressure approached the lowest point, the evaporation region rapidly developed toward the core. The increase of evaporation driving force and the decrease of boundary moisture caused drastic temperature and shrinkage changes on the product surface. The model developed in this paper considering shrinkage provides technical support to optimize the vacuum pre-cooling process and improve product quality.     

预处理对冻干肉制品品质影响的研究进展

真空冷冻干燥技术能较好地改善干燥肉制品的品质和风味,但是由于真空冷冻干燥技术是一种较为昂贵的 加工方法,能耗大、处理时间长等特点使其在肉制品中的应用规模受到限制,而真空冷冻干燥前适宜的预处理能够 改善真空冷冻干燥食品的品质,减少能耗,进而拓宽其使用范围。本文综合分析了渗透脱水、超声波、微波、烫漂 和其他预处理方法在肉制品冷冻干燥中的应用现状、作用原理和研究进展,为肉品材料冻干预处理方法的选择提供参考。     

Machine learning-based modeling in food processing applications: State of the art

Food processing is a complex, multifaceted problem that requires substantial human interaction to optimize the various process parameters to minimize energy consumption and ensure better-quality products. The development of a machine learning (ML)-based approach to food processing applications is an exciting and innovative idea for optimizing process parameters and process kinetics to reduce energy consumption, processing time, and ensure better-quality products; however, developing such a novel approach requires significant scientific effort. This paper presents and evaluates ML-based approaches to various food processing operations such as drying, frying, baking, canning, extrusion, encapsulation, and fermentation to predict process kinetics. A step-by-step procedure to develop an ML-based model and its practical implementation is presented. The key challenges of neural network training and testing algorithms and their limitations are discussed to assist readers in selecting algorithms for solving problems specific to food processing. In addition, this paper presents the potential and challenges of applying ML-based techniques to hybrid food processing operations. The potential of physics-informed ML modeling techniques for food processing applications and their strategies is also discussed. It is expected that the potential information of this paper will be valuable in advancing the ML-based technology for food processing applications.     

油菜籽热风干燥传热传质与优化的研究进展

油菜是经济价值高、发展潜力大的油料作物,也是蛋白质、饲料、蜜源和能源作物,油菜籽的干燥和储存联系油菜高产栽培和油脂深加工综合利用。本文在分析油菜籽干燥特点和主要干燥技术的基础上,综述了油菜籽热风干燥传热传质与优化的研究进展,以期为油菜籽热风干燥装置设计、干燥工艺、参数和过程优化等的研究提供依据。目前,有关油菜籽热风干燥传热传质与优化的研究多限于实验层面,不具有广泛适用性。传统干燥理论和模型大多以Luikov理论和Whitaker理论为基础,对其适当简化或修正,由于假设多孔介质为均匀分布连续介质,无法揭示局部和整体之间的本质联系。将分形理论与孔道网络模型相结合是多孔介质干燥尺度综合的有效方法。数值研究有宏观、多尺度和微观三个层面,借助CFD技术可以有效获悉干燥速率、能量消耗和湿分分布等信息,以优化干燥装置和过程控制。油菜籽热风干燥实验研究主要集中在干燥特性、干燥品质及其测量技术等方面,为获得良好的干燥品质,应注意干燥工艺、参数和过程优化。     

基于离散多目标布谷鸟算法的食品拣取机器人协同路径规划

目的：提高大型食品加工仓储原材料拣取效率。方法：针对按食品加工配方比例拣取多货位原材料问题,建立以总移动距离、总能耗和周期拣取原材料总重量为指标的多目标食品拣取机器人协同路径规划模型。提出Pareto最优解离散多目标布谷鸟算法(discrete multi-objective cuckoo algorithm,DMCA),设计3层布谷鸟编码,重新定义突变、同类进化、异类进化更新策略,以提高DMCA全局优化能力。结果：该方法能够快速给出多机器人协同规划路径,相比于其他算法,总移动距离缩短了约6.3%,总能耗降低了约7.5%。结论：所提方法能够有效提高大型网格化仓储原材料拣取效率,规划路径平衡了移动距离和能耗。     

Model Building and Slicing in Food 3D Printing Processes: A Review

Three‐dimensional (3D) printing has been successfully applied to food processing, and widely appreciated by food science researchers. Recently, a lot of researches and review works have been done focusing on the ink's properties, printer design, and printing parameters. However, few articles specifically describe 3D models and slicing methods used in food printing. This work introduced the requirements for 3D printing models in some specific areas, discussed the critical parameter settings in the model slicing processes, and discussed the possible use of numerical techniques in the model building and printing of food 3D printing. The objective of this review is to increase researchers' focus on 3D printing models and slices in order to optimize the printing process and to provide some useful information for future research.     

高压脉冲电场技术在食品质量与安全中的应用进展

高压脉冲电场技术作为国际上最先进的非热加工技术之一,以其良好的应用特性如能耗低、省时、处理温度低、效率高和对食品原有品质保存效果好等特点,吸引了国内外广大研究者的关注。与其它食品加工技术相比,高压脉冲电场技术不仅具有更好的杀菌、钝酶效果,还能有效降解残留农药,减少食品添加剂的使用,而且基本不影响食品的原有品质和营养特性。因此,将高压脉冲电场技术有效应用于食品工业中,可大大提高食品质量与食品安全性,为食品行业的发展开辟新途径。作者介绍了高压脉冲电场的处理装置、加工机理以及在食品质量与安全中的应用途径,并对高压脉冲电场技术的应用前景进行了展望。     

超声波技术在中央厨房食品加工中的应用研究进展

中央厨房是餐饮和食品行业发展的必然趋势，但在中央厨房集中采购、加工、储运环节过程中，传统加工方式不能满足中央厨房工业化运作。因此，需要新的高效处理技术来提高中央厨房的运营效率和食品安全控制。超声波技术是一种非热物理加工技术，不仅可以对原辅料及产品进行无损检测，还可以实现加工过程的精确控制和更高程度的自动化。该综述概述了超声波技术的机理，系统地阐述了超声波技术在中央厨房的原辅料和厨房用具的清洗、冷冻和腌制等加工操作的应用、产品杀菌、产品储运以及加工过程及产品进行无损检测。通过文献综述发现，超声波技术在中央厨房加工过程中非常具有应用价值，可以有效解决中央厨房在低清洁效率、高营养损失、高能耗、产品保质期短和自动化运行带来的挑战等问题。     

Reaction kinetics in food extrusion: methods and results

Extrusion cooking is a highly efficient food processing technology. During the extrusion process, there are many desirable and undesirable reactions which will determine final product quality. While being heated and sheared simultaneously, food raw materials experience a non-isothermal process and their residence time in the extruder is distributed. All these factors contribute to the difficulties in determining the kinetic parameters for those reactions. Therefore, this paper attempts to review the reaction kinetics in food extrusion. First of all, the kinetic models for the reactions are outlined. After elucidating how to determine reaction time in an extruder, the methodological approaches for determining the reaction order, rate constant, and activation energy of a reaction under isothermal or non-isothermal conditions with or without residence time distribution (RTD) are presented. Then, different models relating the rate constant to its various impact factors, with especially focusing on shear stress, are reviewed. Subsequently, how shear stress is estimated in an extruder, is illustrated. In the last part of this paper, the reported data of rate constant, reaction order, and activation energy for the reactions occurring during food extrusion are summarized, with detailed impacts of temperature, moisture content, shear stress, and determination method on these kinetic parameters. Finally, future research needs are suggested.     

功率超声在热风干燥领域中的研究进展

热风干燥是农产品加工中的重要单元操作,但目前其能效利用低.近年来干燥领域向节能、高效,并能进一步提高产品质量的高标准要求方向发展.功率超声具有传播方向性强、介质质点振动加速度大等特点,可作为能量的一种有效载体,在强化传热和传质方面表现出突出的优势.论文介绍了气介式大功率超声的设计原理,阐述了超声强化热风干燥设备的系统构成及类型,综述了近年来气介式大功率超声强化热风干燥在含湿物料方面的研究进展,探讨了当前存在问题及今后发展方向.     

Dynamic Viscoelastic Characterization of Solid Food Materials

SUMMARY—There currently exists a large demand for objective methods to be used in the evaluation of food texture. A very logical approach to the evaluation of some of the parameters of texture would appear to be the use of engineering parameters for the characterization of mechanical response of materials used in processing or direct consumption. Considering the changeability of living materials, dynamic tests in which information is derived in a relatively short time appear to be highly desirable. Dynamic methods currently available include direct stress-strain measurements, transducer methods, resonance methods and wave propagation. Results from any of these tests may be presented in the form of storage and loss moduli. Interpretation of results is dependent upon the final use of the product. In most cases, a relation between the structural mechanics of the food material and the observed mechanical behavior appears to be desirable both as an aid in quality control and as a guide to the development of synthetic foods.     

新型加工食品果蔬纸研究进展

果蔬纸是一种新型的果蔬深加工产品,可作为休闲食品或可食性包装材料。果蔬纸能保留基料果蔬原有的香味、色泽和各种营养成分,是一种能提高果蔬附加值的新型加工产品。本文从果蔬纸原料配方和关键加工工艺方面论述果蔬纸研究的进展,从感官品质、营养品质、贮藏品质、抗菌特性等方面论述果蔬纸品质的研究状况,还就目前果蔬纸加工及品质研究中存在的问题(如新产品开发、纸质特性欠佳、制浆与护色关键工艺需要优化等)进行了分析,并提出了解决这些问题的建议,以期为果蔬纸的开发研究提供参考。     

我国食品及包装机械面临产业升级——访中国食品和包装机械工业协会副会长 何南至

<正> 我国食品工业和食品包装机械真正形成行业也就20年的时间。这20年是世界技术发展最快的时期,新技术不断在行业上应用,而我国食品工业整体基础薄弱,技术及科研力量不足,因而造成我国食品机械工业的发展相对滞后。大量技术含量高的成套食品机械设备仍依靠进口。要改变这种状况,我国食品机械面临产业升级。日前,记者特别专访了中国食品和包装机械工业协会副会长何南至,倾听他的独到见解。     

Migration of Chemical Compounds from Packaging Polymers during Microwave,Conventional Heat Treatment,and Storage

Polymeric packaging protects food during storage and transportation, and withstands mechanical and thermal stresses from high‐temperature conventional retort or microwave‐assisted food processing treatments. Chemical compounds that are incorporated within polymeric packaging materials to improve functionality, may interact with food components during processing or storage and migrate into the food. Once these compounds reach a specified limit, food quality and safety may be jeopardized. Possible chemical migrants include plasticizers, antioxidants, thermal stabilizers, slip compounds, and monomers. Chemical migration from food packaging is affected by a number of parameters including the nature and complexity of food, the contact time and temperature of the system, the type of packaging contact layer, and the properties of the migrants. Researchers study the migration of food‐packaging compounds by exposing food or food‐simulating liquids to conventional and microwave heating and storage conditions, primarily through chromatographic or spectroscopic methods; from these data, they develop kinetic and risk assessment models. This review provides a comprehensive overview of the migration of chemical compounds into food or food simulants exposed to various heat treatments and storage conditions, as well as a discussion of regulatory issues.     

营养安全视角下的食品加工应用研究

粮食和营养安全是当前全球关注的一项重要议题,预计到2050年全球人口将达到90亿,意味着需要通过继续增加粮食产量来解决日益复杂的粮食安全问题。与此同时减少从生产到消费整个供应链环节的食物损失浪费,以及通过食品加工为人类提高食品保存期限、营养质量以及食品安全也引起了极大的重视。本文通过文献梳理描述了初级食品生产系统的发展,以及食品加工对人类健康以及营养安全的作用。从未来的发展趋势来看,无论是农业生产部门还是食品加工部门都将面临用更少的资源来生产更多食品的问题。因而本文认为面对世界资源的日益紧张,必须对食品的能量和营养含量加以平衡,促进食品加工环节营养安全的提高,不失为一个良策。     

Influence of dielectric and sorption properties on drying behaviour and energy efficiency during microwave convective drying of selected food and non-food inorganic materials

The average energy efficiency of microwave convective drying is strongly related to drying time and thus to drying kinetics. This study investigates the energy efficiency of materials with different material properties and drying rates. Four solid, porous materials (swede, potato, bread, and lightweight concrete) were dried under the same microwave convective drying conditions. Drying behaviour, temperature development, hygroscopicity, dielectric properties, and specific energy consumption were studied. Despite differences in kinetics and product properties, the specific energy consumption (MJ/kg evaporated water) was approximately the same for all materials at intermediate to high moisture contents. When drying was pursued into the hygroscopic region, however, the specific energy consumption increased. The results indicate that a relationship between microwave penetration depth and water activity of the materials may be found. Drying of the food materials was limited by burning either due to temperature runaway in the hygroscopic region or due to development of hot spots, possibly induced by material structure.     

超声波技术在食品加工中的应用进展

在食品加工过程中,传统的加工方式已不能满足人们对食品质量的高需求。超声波技术是一种非热处理技术,可以减少传统加工给食品带来的损害,增强食品的营养价值与加工特性。本文主要讨论了超声波在干燥、冷冻、提取、过滤和乳化等加工操作中所产生的效应与作用,超声波产生的空化、机械、化学和生物效应能够通过复杂的关联对加工操作产生影响,例如能够提高传质传热效率、减少加工时间、降低加工试剂用量、增加产量、提高食品安全性、保留食品营养等。通过对文献的梳理与比较,超声波技术被证明在食品加工中非常具有应用价值,但是不适当的超声条件处理也会给食品品质带来负面影响。在未来的工作研究中,不仅需要建立超声波在食品加工中的动力学模型,还需在工业水平上的应用进行深入挖掘,以克服超声能源消耗大的短板。     

基于非支配排序遗传算法的细纱工艺参数优化

为了实现细纱生产工艺参数优化,解决细纱生产过程中高能耗问题,提出了一种基于非支配排序遗传算法的细纱工艺参数多目标优化方法.通过分析细纱生产工艺流程,确定了影响细纱成纱质量与能耗的工艺参数,提取了评价成纱质量的关键质量评价指标,结合灰色关联理论将质量评价指标转化为综合质量指标,利用二阶响应曲面法拟合工艺参数与综合质量指标...     

Polymers and Biopolymers with Antiviral Activity: Potential Applications for Improving Food Safety

Gastroenteritis and hepatitis, caused by human noroviruses (HuNoVs) and hepatitis A virus (HAV), respectively, are the most common illnesses resulting from the consumption of food contaminated with human enteric viruses. Food‐grade polymers can be tailor designed to improve food safety, either as novel food‐packaging materials imparting active antimicrobial properties, applied in food contact surfaces to avoid cross‐contamination, or as edible coatings to increase fresh produce's shelf life. The incorporation of antimicrobial agents into food‐grade polymers can be used to control the food microbiota and even target specific foodborne pathogens to improve microbiological food safety and to enhance food quality. Enteric viruses are responsible for one fifth of acute gastroenteritis cases worldwide and the development of food‐grade polymers and biopolymers with antiviral activity for food applications is a topic of increased interest, both for academia and the food industry, even though developments are still limited. This review compiles existing studies in this widely unexplored area and highlights the potential of these developments to improve viral food safety.