Water transport in starchy foods: Experimental and mathematical aspects

BackgroundThe availability and movement of water inside the food materials play essential roles for food stability by affecting their physical and chemical properties, and microbiological activity. Understanding the moisture sorption behavior is a necessary step to control food properties. Food processing unit operations like drying and cooking influence the behavior of starch since such systems trigger swelling or shrinkage as a result of moisture sorption or desorption mechanisms. Also, these processes alter many aspects of starch-containing foods such as acceptability, nutritional value, quality, and shelf-life.Scope and approachTherefore, understanding the water transport in starchy foods and the changes occurring in functional properties of starch has a great importance to describe and model their sorption and drying behavior. First, the primary mechanisms occurring during water transport such as moisture sorption, swelling, gelatinization, and glass transition are discussed using experimental results presented in the literature. Additionally, the hybrid mixture theory (HMT) and its potential for predicting transport mechanisms in starchy foods is discussed.Key findings and conclusionsIn addition to experimental considerations, the mathematical modeling provides complementary information to predict the heat and fluid transfer. The hybrid mixture theory based multiscale models are able to describe the physico-chemical changes and general transport mechanisms occurring within a porous food matrix. This theory can also be used to predict the quality changes in food products during processing.     

The food matrix: implications in processing,nutrition and health

Abstract

The concept of food matrix has received much attention lately in reference to its effects on food processing, nutrition and health. However, the term matrix is used vaguely by food and nutrition scientists, often as synonymous of the food itself or its microstructure. This review analyses the concept of food matrix and proposes a classification for the major types of matrices found in foods. The food matrix may be viewed as a physical domain that contains and/or interacts with specific constituents of a food (e.g., a nutrient) providing functionalities and behaviors which are different from those exhibited by the components in isolation or a free state. The effect of the food matrix (FM-effect) is discussed in reference to food processing, oral processing and flavor perception, satiation and satiety, and digestion in the gastrointestinal tract. The FM-effect has also implications in nutrition, food allergies and food intolerances, and in the quality and relevance of results of analytical techniques. The role of the food matrix in the design of healthy foods is also discussed.     

Diagnostics of plasma reactive species and induced chemistry of plasma treated foods

Cold plasma is a promising technique that has been tested as a process technology for a range of food commodities, mainly to destroy microorganisms, but also aimed at toxin degradation, enzyme inactivation, residual pesticide degradation and functionalization of food properties. Plasma has already been employed by industry for food packaging material sterilization and surface modification. As most of the current literature on cold plasma in the field of food science is focused on microbial inactivation efficacy, the information about its chemical influences on food is sparse. To better understand the chemical interactions of with plasma, this review focuses on plasma chemistry diagnostics techniques available to characterize the plasma reactive species generated. Equally important is the detection of induced chemistry in the food and here we present approaches to analyze likely reactions with key food bio-molecules. Such analysis will support mechanistic insights involved in these complex chemical reactions (i.e., DNA, lipid and protein) along with potential physical modifications of the food structure. For successful adoption of plasma as a food processing aid it is critical to elucidate these interactions as they have an important role in demonstrating the technology’s safety as a food processing technique along with understanding any effect on food nutrients.     

Multiresponse modelling of the caramelisation reaction

Multiresponse modelling is a powerful tool for studying complex kinetics of reactions occurring in food products. This modelling technique uses information of reactants and products involved, allowing insightful kinetic parameters estimation and helping in clarifying reaction mechanisms. One example of a complex reaction that occurs in food processing is the caramelisation reaction. Caramelisation is the common name for a group of reactions observed when carbohydrates are exposed to high temperatures.The objective of this work was to apply multiresponse regression in developing a mathematical mechanistic model that describes sucrose thermal degradation and caramelisation products formation in highly concentrated sucrose solutions, with different water contents and under various temperatures.Results demonstrated the usefulness of multiresponse modelling in understanding reaction mechanisms in food matrices. A mechanistic model for the caramelisation reaction was proposed, which successfully described the experimental data of concentrated solutions in the 30.03 to 12.20% (w/w) water content range. Furthermore, good predictions of temperature and water content effects were achieved. For extremely low water content systems (3.58% (w/w)), the proposed mechanistic model failed to describe experimental data, indicating different reaction pathways.Industrial relevanceCaramelisation is one reaction occurring during heat treatment in high sugar content food products. Understanding the mechanism of caramelisation reaction and the effect of the environmental conditions on different reaction steps may help in the design of products and processes, in order to prevent or promote such occurrence. This work also uses an advanced modelling technique that can be used in any food system for any reaction occurring during processing.     

Water Mobility in Glassy and Rubbery Solids as Determined by Oxygen-17 Nuclear Magnetic Resonance: Impact on Chemical Stability

Although chemical reactivity in solid food systems has been studied as a function of water activity and glass transition, the possible effects of water mobility on chemical reactions have not been investigated. The effect of the glass transition on water mobility at constant temperature and water content was determined. The relationship between the experimentally determined water mobility in polyvinylpyrrolidone (PVP) systems and chemical reactivity data from the same PVP systems was evaluated. Water mobility, as determined via ¹⁷O-NMR, was not affected by the glass transition; PVP systems at constant water activities and water contents, but different physical states (glassy and rubbery), had the same water mobility. An evaluation of four chemical reactions showed no relation between water mobility and kinetic data. The effect of water on chemical reactions is multidimensional and cannot be reduced to a single physicochemical parameter.     

Application of PLSR in correlating physical and chemical properties of pork ham with different cooling methods

Partial least squares regression (PLSR) was applied to understand the relationship between physical and chemical properties of pork leg ham with different cooling treatments, i.e., cold room, air blast and vacuum cooling. The results indicated that overall 69.8% variation of physical matrix was explained by chemical matrix. For the univariate analysis of physical attributes, the results showed that gumminess (88.1%) and hardness (86.5%) were best explained by chemical matrix, followed by springiness (78.7%), Warner–Bratzler Shear force (61.3%), and a* (60.0%). Graphical display of the regression coefficients indicated that different cooling treatments had different effects on the physical property of pork ham. Therefore, to predict the physical quality with chemical attributes, separate regression formulations should be adopted for different cooling methods. These findings have practical importance in attempts to predict physical properties from chemical components. In addition, they can also be used to control the physical properties by adjusting the components in the meat system.     

Physical approaches for the delivery of active ingredients in foods

Encapsulation systems in food applications are typically employed to solve formulation problems arising from a limited chemical or physical stability of the active ingredient, an incompatibility between active ingredient and food matrix, or to control the release of a sensorially active compound or the bioavailability of a nutrient. However, the use of encapsulation systems in complex food matrices often fails because their application is mostly based on trial and error. The present article introduces a conceptually new approach in which the target application is analyzed based on physical principles, including materials science, physical chemistry and biophysics in order to develop a range of solution strategies from which the most promising may be selected for final application. The approach is illustrated with two case studies on the stability of active ingredients in glassy carbohydrates.     

Analytical capabilities of mass spectrometry imaging and its potential applications in food science

BackgroundMass spectrometry imaging (MSI) is an untargeted and label-free chemical imaging technique that allows for the analysis of hundreds to thousands of molecules in a single experiment. Over the last two decades, MSI has become common in the medicinal, pharmaceutical, and botanical research communities, but has been applied less frequently in food science research. As an emerging “molecular microscope”, MSI offers unparalleled advantages for exploration of the spatio-chemical information from various food materials. It allows researchers to localize biomarkers of food origin and authenticity, characterize nutrients or chemical contaminants affecting human health, and ultimately, extend our understanding of food factors at the molecular level.Scope and approachThis review focuses on the predominant MSI ionization technologies and summarizes their application to studies involving food science, including the imaging of food metabolites, elements, naturally occurring toxic constituents, and exogenous contaminates. Technical considerations associated with sample preparation, MALDI matrix choice and application, data processing, analyte identification, and spatial resolution are discussed, as are the future outlooks for MSI in food science.Key findings and conclusionsMSI offers unparalleled chemical specificity for multiplexed analysis of the spatial distribution of nutrients, elements, and contaminants in food; information that is difficult or impossible to acquire with traditional staining or label-based methodologies. The unique spatio-chemical insights acquired with MSI have proven essential for understanding metabolic origin and change, and for visualization of exogenous substances having relevance to food quality and safety.     

Microencapsulation of bacteria: A review of different technologies and their impact on the probiotic effects

Probiotic based products are associated with many health benefits. However, the main problem is the low survival of these microorganisms in food products and in gastrointestinal tract. Providing probiotics with a physical barrier is an efficient approach to protect microorganisms and to deliver them into the gut. In our opinion, microencapsulation is one of the most efficient methods, and has been under especial consideration and investigation. However, there are still many challenges to overcome with respect to the microencapsulation process. This review focuses mainly on the methodological approach of probiotic encapsulation including materials and results obtained using encapsulated probiotic in food matrices and different pathologies in animal models.Industrial relevanceThe inclusion of probiotics into food matrices is one of the most challenging lines of research in food technology. Probiotics in general, and some strains in particular, have a low resistance to different environmental conditions, such as oxygen, light or temperature. Thus, the protection and isolation of the microorganism from the food matrix and the environmental condition are crucial for the development of new probiotic food. In this sense, microencapsulation has gained an increasing interest, since it has been demonstrated that it could protect the bacteria not only during its production process but also during its incorporation into the food matrix, also with protective effects during storage. In conclusion, microencapsulation is of great interest since it could allow a wider application of probiotics in the food market, actually restricted to fresh or powder products.     

The effect of cooking on the phytochemical content of vegetables

Cooking induces many chemical and physical modifications in foods; among these the phytochemical content can change. Many authors have studied variations in vegetable nutrients after cooking, and great variability in the data has been reported. In this review more than 100 articles from indexed scientific journals were considered in order to assess the effect of cooking on different phytochemical classes. Changes in phytochemicals upon cooking may result from two opposite phenomena: (1) thermal degradation, which reduces their concentration, and (2) a matrix softening effect, which increases the extractability of phytochemicals, resulting in a higher concentration with respect to the raw material. The final effect of cooking on phytochemical concentration depends on the processing parameters, the structure of food matrix, and the chemical nature of the specific compound. Looking at the different cooking procedures it can be concluded that steaming will ensure better preservation/extraction yield of phenols and glucosinolates than do other cooking methods: steamed tissues are not in direct contact with the cooking material (water or oil) so leaching of soluble compounds into water is minimised and, at the same time, thermal degradation is limited. Carotenoids showed a different behaviour; a positive effect on extraction and the solubilisation of carotenes were reported after severe processing. © 2013 Society of Chemical Industry     

Modification of cassava starch by acetylation and pulsed electric field technology: Analysis of physical and functional properties

A dual pulsed electric field (PEF)-acetylation method to modify cassava starch was optimized. Also, the independent effect of each method on the functional properties of the starch was investigated. A PEF pre-treatment of 40 J/g (9.48 kV/cm) increased the acetylation degree by 47%. The dually modified starches presented the highest water solubility index (39.3%), a decrease of gelatinization enthalpy (5.4 J/g d.b.) and temperature (60.8 °C), and a better tolerance to refrigerated storage. A reduction of ordered structures was evidenced by FTIR. The PEF-modified starch also showed changes in its rheological profile, increments of the hydration properties and decreased retrogradation in comparison to the native sample, suggesting the potential of this physical method to modify starches. This work studied for the first time the effect of dual modifications by PEF and acetylation performed sequentially and not simultaneously. The results showed that the proposed scheme was efficient to improve the acetylation process.Industrial relevanceStarch is widely used in the food industry to modify texture, water retention and film making properties of products. Yet, because native starches rarely meet all the specific requirements for certain applications, physical and chemical modifications are applied to improve their functional properties. Acetylation is one of the most common chemical modifications for food uses. However, the pursue to minimize costs and environmental impact has motivated the search for complementary treatments to reduce the use of reagents and processing times. In the present study, a novel PEF-assisted acetylation process is proposed in which applying the physical and chemical treatments independently showed to be efficient to improve the acetylation process. This work scheme could enable the use of a common PEF system to assist different starch chemical modifications, offering a more versatile alternative for its industrial implementation.     

Chemical composition,health effects,and uses of water caltrop

BackgroundWater caltrop (Trapa spp.) has been cultivated for food and traditional medicine in Asia for thousands of years. It is, however, considered as a pest in North America due to the adverse effects on ecological systems. Thus, a better understanding of the chemistry and potential applications of water caltrop may suggest strategies to utilize this aquatic plant.Scope and approachThis review summarizes the chemical composition, nutritional benefits, processing, and food and industrial uses of different parts of water caltrop from diverse species. The relationships between the components and potential uses of water caltrop are discussed.Key findings and conclusionsPeels and kernels of water caltrop are rich in starch, dietary fiber, essential amino acids, and certain types of phenolics and minerals, and showed a range of bioactivities such as anti-cancer and antioxidant capacities. Water caltrop has been utilized in diverse food and non-food sectors. There is great potential of water caltrop for various applications due to the unique chemical composition and abundance of supply.     

Effect of Food Matrix on Saltiness Perception—Implications for Sodium Reduction

Enhancing sodium release from the food matrix, thus increasing saltiness perception, is a promising strategy to reduce the amount of salt needed in foods. However, the complex nature of the effect of the food matrix on saltiness perception makes it difficult to control saltiness perception when designing food products. The aim of this review is to provide an overview of the food matrix effects on saltiness perception of sodium chloride. The effects are discussed in the order of 3 stages in saltiness perception: release of sodium from food matrix into oral cavity (1st stage), delivery of sodium within oral cavity (2nd stage), and detection of sodium by the taste receptor cells (TRCs) (3rd stage). In the 1st stage, the food matrix affects the initial availability of sodium to be released, and also affects the spontaneous and facilitated migration of sodium from the matrix into the oral cavity. In the 2nd stage, the food matrix affects the availability of sodium and the mixing efficiency of sodium with saliva. The relationship between food matrix and oral processing of food that may affect the sodium release (1st stage) and the delivery (2nd stage) is also discussed. In the 3rd stage, the food matrix affects the physical availability of sodium for the TRCs, the physiological activity of TRCs, and the central activities involved in the perception process. Based on the understanding of complex nature of the matrix effects on saltiness perception discussed in this review, the properties of food matrix may be controlled effectively to enhance saltiness perception and achieve sodium reduction.     

Thermal Treatments for Fruit and Vegetable Juices and Beverages: A Literature Overview

Fruit and vegetable juices and beverages are generally preserved by thermal processing, currently being the most cost‐effective means ensuring microbial safety and enzyme deactivation. However, thermal treatments may induce several chemical and physical changes that impair the organoleptic properties and may reduce the content or bioavailability of some nutrients; in most cases, these effects are strongly dependent on the food matrix. Moreover, the efficacy of treatments can also be affected by the complexity of the product and microorganisms. This review covers researches on this topic, with a particular emphasis on products derived from different botanical sources. Technologies presented include conventional and alternative thermal treatments. Advances toward hurdle‐based technology approaches have been also reviewed.     

Food oral processing: Mechanisms and implications of food oral destruction

BackgroundFood oral processing is a simultaneous process of food destruction and sensory perception. How a food breaks down its structure inside the mouth and what mechanisms control this process are hugely important to our eating experience and sensory perception. A proper understanding of this process is urgently needed by the food industry for better design and manufacturing of quality tasty food.Scope and approachThis review article analyses research findings from literature and from author's own laboratory in order to identify main controlling mechanisms of food oral destruction. Appropriate experimental evidences are given wherever available to demonstrate the important implications of different destruction mechanisms to sensory perception.Key findings and conclusionsThree major controlling mechanisms of food oral destruction are identified: the mechanical size reduction, the colloidal destabilisation, and the enzymatic interactions. These mechanisms may be applicable to different food materials either independently or collectively. They could also be applicable through the whole eating process or just at a certain stage of an eating process.     

Modeling of Hexanal Sorption Kinetic in an Aldehydes Scavenger Film Intended for Food Packaging Applications

A mathematical model aimed to predict the hexanal sorption kinetic into an aldehyde scavenger film is presented. The proposed model is based on the assumption that the sorbed hexanal molecules are in part randomly dispersed into the polymeric matrix and in part chemically bonded to the polymeric matrix. To validate the model hexanal sorption kinetics were determined at 25°C and at 3 different hexanal activity. The proposed model satisfactorily fits the experimental data suggesting that hexanal absorption by the active film is a complex phenomenon involving both chemical reaction and physical reversible absorption.     

Predicting the headspace oxygen level due to oxygen permeation across multilayer polymer packaging materials: A practical software simulation tool

The shelf life of a food product is largely determined by its chemical and microbiological stability. In this respect, the gas composition surrounding a packaged product plays a major role. Modified Atmosphere Packaging (MAP) is a packaging technique that usually reduces the headspace oxygen to a preferable minimum for most food products. Besides the residual oxygen, the O₂-permeability of the packaging material is also important, as it determines the amount of oxygen permeating into the package during storage. This paper describes the development of a practical software simulation tool to predict the amount of oxygen permeating into the headspace during storage for a variety of multilayer packaging configurations. The simulation tool gives access to simulation models for mono- and multilayer films, trays covered with top foils and bottles with caps. The user can compose his/her own (multilayer) packaging material and check the oxygen ingress over time for different temperature conditions for all packaging configurations.Industrial relevanceThe software simulation tool is of industrial relevance to food companies, as they can use it to select or compare different films, but also to underpin their choice for a certain packaging material with regard to the sensitivity of the food product to oxygen and the desirable shelf life. The simulation program also provides food companies with information about the influence of storage conditions, like time and temperature, on the ingress of oxygen in their food package throughout the storage-distribution chain. On the other hand, it can also be used by packaging suppliers to predict the oxygen permeability in the optimization process of new films and as a client support tool.     

Modeling the effects of initial nitrogen content and temperature on fermentation kinetics of hard cider

Hard apple cider manufactured as a value-added product will increase consumption of excess American apples and give impetus to local industry. For larger scale productions, a mechanistic model that could predict the fermentation kinetics would be a useful tool for understanding and designing processes. Hence, the objective of this study was to apply a simple mechanistic model to predict fermentation kinetics of hard cider from Michigan apples and study the combined effect of initial nitrogen and temperature on fermentation. Kinetic parameters of the primary mechanistic model based on Monod kinetics were estimated non-linearly via the Runge-Kutta method. Four coupled ordinary differential equations were used for each of the four dependent variables, yeast cell concentration, nitrogen, sugar and ethanol concentration. For the secondary model, it was proposed to model the effect of temperature and initial nitrogen content on the kinetic parameters of the primary model with an Arrhenius relationship. The current study is the first known application of a mathematical model to the hard cider fermentation process.     

From raw material to dish: pasta quality step by step

Pasta is a traditional Italian cereal‐based food that is popular worldwide because of its convenience, versatility, sensory and nutritional value. The aim of this review is to present a step‐by‐step guide to facilitate the understanding of the most important events that can affect pasta characteristics, directing the reader to the appropriate production steps. Owing to its unique flavor, color, composition and rheological properties, durum wheat semolina is the best raw material for pasta production. Although pasta is traditionally made from only two ingredients, sensory quality and chemical/physical characteristics of the final product may vary greatly. Starting from the same ingredients, there are a lot of different events in each step of pasta production that can result in the development of varieties of pasta with different characteristics. In particular, numerous studies have demonstrated the importance of temperature and humidity conditions of the pasta drying operation as well as the significance of the choice of raw material and operating conditions on pasta quality. © 2015 Society of Chemical Industry     

Towards an improved understanding of sweetener synergy

Sweetener synergy is of vital practical importance to the food manufacturer but its mechanistic explanation is impossible given the current limited understanding of sweet taste chemoreception. All current psychophysical models of response to sweet stimuli are probably incomplete, but some fit the experimental data better than others and can thus be used to predict the taste of sweetener mixtures. Some sweetener mixtures have been unequivocally reported as synergistic but such observations do not in themselves constitute evidence for the existence of multiple sweet taste receptors, and the interpretation of synergy demands analysis at the molecular level.