Food emulsions as delivery systems for flavor compounds: A review

Food flavor is an important attribute of quality food, and it largely determines consumer food preference. Many food products exist as emulsions or experience emulsification during processing, and therefore, a good understanding of flavor release from emulsions is essential to design food with desirable flavor characteristics. Emulsions are biphasic systems, where flavor compounds are partitioning into different phases, and the releases can be modulated through different ways. Emulsion ingredients, such as oils, emulsifiers, thickening agents, can interact with flavor compounds, thus modifying the thermodynamic behavior of flavor compounds. Emulsion structures, including droplet size and size distribution, viscosity, interface thickness, etc., can influence flavor component partition and their diffusion in the emulsions, resulting in different release kinetics. When emulsions are consumed in the mouth, both emulsion ingredients and structures undergo significant changes, resulting in different flavor perception. Special design of emulsion structures in the water phase, oil phase, and interface provides emulsions with great potential as delivery systems to control flavor release in wider applications. This review provides an overview of the current understanding of flavor release from emulsions, and how emulsions can behave as delivery systems for flavor compounds to better design novel food products with enhanced sensorial and nutritional attributes.     

Emulsion gels: The structuring of soft solids with protein-stabilized oil droplets

Many food products can be categorized as emulsion gels. This is especially the case for protein-based oil-in-water emulsions which can be converted into soft-solid-like materials by common food processing operations such as heating, acidification, and enzyme action. This review article outlines how the rheological and structural properties of protein-stabilized emulsion gels are influenced by the dispersed oil volume fraction, the oil–water interfacial composition, and the colloidal interactions of the constituent emulsion droplets. For model systems of variable oil content and containing different food proteins, some general trends of rheological behaviour at small and large deformations are identified. Experimental rigidity data are considered in relation to: (i) material science theories of the reinforcement of solid materials by active and inactive filler particles, and (ii) Brownian dynamics simulations of aggregated particle networks containing bonded and non-bonded particles. Influences of interfacial composition and particle–matrix interactions on microstructure and rheology are explained with particular reference to the role of small-molecule surfactants. Compositional and structural factors affecting the large-deformation rheology and fracture properties are described. Finally, the practical relevance of the model system studies to the behaviour of real food products is critically assessed.     

Advances in the Design and Production of Reduced-Fat and Reduced-Cholesterol Salad Dressing and Mayonnaise: A Review

Reducing fat and cholesterol content is currently one of the primary trends in food product innovation. Fat plays an important role in maintaining food quality, particularly the texture, flavor, and stability of food emulsion products. The food industry faces major challenges in seeking to produce reduced-fat and low-cholesterol mayonnaise and dressings that have attributes similar to full-fat products. Efficient monitoring of products to ensure desirable quality requires knowledge of their physicochemical characteristics, including appearance, rheology, emulsion stability, microstructure, and flavor, as well as particle size and charge distribution. The purpose of this paper is to provide a comprehensive overview of trends in the development of reduced-fat and low-cholesterol dressings. The effects of reducing fat content or using various fat replacers on the physicochemical properties of dressing and mayonnaise products are detailed with supporting experimental results. The possibility of using plant-based ingredients or reduced-cholesterol egg yolk in the formulation of such products is also examined.     

Impact of Fat Replacers on the Rheological,Tribological, and Aroma Release Properties of Reduced-Fat Model Emulsion Systems and Processed Cheese

Due to the increasing prevalence of overweight and obesity and their associated health problems, the demand for low-calorie and low-fat foods is growing worldwide, especially in the fast food and convenience sectors. However, fat- or calorie-reduced products are often accompanied by sensory deficiencies. Although fat reduction in foods has been addressed in literature, an ideal fat replacer has not been identified due to the variety of fats, their multifarious functions in foods, and the wide range of food products. The aim of this work was to investigate the influence of selected fat replacers on the properties of reduced-fat model emulsion systems and processed cheese. The use of dietary fibers as fat replacers was of particular interest due to their intrinsic health benefits. In addition, both new and established methods of measurement of sensory attributes were applied and compared to determine correlations of findings between different methods of measurement. Chapter 1 addresses the influence of fat replacers on attributes such as energy density, flowability, and firmness in a real food product, processed cheese. To this end, microparticulated whey protein (MWP), which has been widely used as a fat replacer, and three dietary fibers (corn dextrin (CD), inulin, and polydextrose), were used in reduced-fat processed cheese slices. A reduction in energy density of about 30 to 40% was achieved using a fat replacer compared to standard commercial full-fat processed cheese. Higher CD and inulin concentrations reduced the flowability of the cheese slices upon heating, but only had a minor impact on the firmness of the unheated cheese. The addition of MWP resulted in firmer cheese slices with higher flowability compared to the other fat replacers. However, changes in the MWP concentration had little effect on either property. The results demonstrated that different fat replacers with varying concentrations need to be applied to achieve desired attributes for specific conditions of use, e.g., unheated cheese in sandwiches or heated cheese in cheeseburgers. To evaluate newly developed reduced-fat foods, the impact of fat replacers on sensory properties and aroma release also needs to be investigated, which is addressed in chapters 2 to 4. Due to the complex composition of cheese, systematic investigation of the mode of action of fat replacers is difficult. Therefore, emulsion-based model foods were used to eliminate interfering factors and natural variations of ingredients. The second study (chapter 2) focused on developing and validating appropriate methods to investigate the effects of fat, fat reduction and the use of fat replacers on emulsion systems. Tribology, a comparatively new method in food research, was used to instrumentally analyze selected aspects of food mouthfeel. Reduced-fat salad mayonnaises were prepared as separate samples containing different CD concentrations, and characterized using textural, rheological and tribological analyses together with measures of spreadability and human-sensory analysis. The results showed a very high correlation between tribological measurements and the sensory evaluation of the attribute stickiness. In addition, it was shown that some correlations between instrumental and sensory data were best described by a non-linear correlation (Stevens’ power law), such as the relationship between Texture Analyzer measurements and sensory sensations of firmness. Furthermore, the Kokini oral shear stress correlated very well with the sensory attribute creaminess. Hence, the instrumental analytical methods used showed the potential to predict elements of the sensory analysis and reduce the overall analytical effort. While aroma release plays a key role in consumer acceptance, the influence of fat replacers on this attribute has rarely been studied. The third study (chapter 3) therefore investigated not only techno-functional properties but also the release of typical cheese aromas using a liquid emulsion as a model food. While both MWP and CD exhibited a retarding effect on the release of lipophilic aroma compounds, MWP also reduced the release of hydrophilic aroma compounds. It was also shown that aroma release is not only influenced by a change in viscosity, but also by interactions between aroma compounds and fat replacers. In this context, CD exhibited a similar ability to interact with aroma compounds as fat, which is desirable for the development of low-fat foods. In the final study (chapter 4), the findings and methods developed in chapters 1-3 of this work, supplemented with additional methods, were used to investigate the effect of fat reduction and CD concentration on a model processed cheese spread (PCS). By replacing 50% of fat completely with CD, the fat content of the PCS could be reduced without causing any significant changes in properties compared to the full-fat version, e.g. in firmness, flowability upon heating and aroma release. CD was determined to be a promising fat replacer, mimicking important properties of fat. Additional correlations, such as those between the parameters of Winter's critical gel theory (gel strength and interaction factor) and spreadability and lubrication properties were identified and can help to further reduce the analytical effort. In conclusion, CD has been confirmed as a promising fat replacer in both liquid and semi-solid food emulsion products. Furthermore, this work contributes to closing the research gap in the instrumental measurement of sensory attributes by outlining correlations, for example, between tribological methods and mouthfeel sensations. Thus, the evaluation tools of this work can help to assess the potential applications of new fat replacers without extensive application and sensory testing which significantly shortens the development time for food manufacturers. In addition, the results contribute to a better understanding of the interactions between fat, fat replacers and aroma compounds in food matrices. This facilitates the systematic development of reduced-fat processed cheese and other dairy- and emulsion-based products which meet consumer preferences and accelerate the trend towards healthy eating.     

Review on the Stability Mechanism and Application of Water‐in‐Oil Emulsions Encapsulating Various Additives

Water‐in‐oil (W/O) emulsions can be used to encapsulate and control the release of bioactive compounds for nutrition fortification in fat‐based food products. However, long‐term stabilization of W/O emulsions remains a challenging task in food science and thereby limits their potential application in the food industry. To develop high‐quality emulsion‐based food products, it is essential to better understand the factors that affect the emulsions’ stability. In real food system, the stability situation of W/O emulsions is more complicated by the fact that various additives are contained in the products, such as NaCl, sugar, and other large molecular additives. The potential stability issues of W/O emulsions caused by these encapsulated additives are a current concern, and special attention should be given to the relevant theoretical knowledge. This article presents several commonly used methods for the preparation of W/O emulsions, and the roles of different additives (water‐ and oil‐soluble types) in stabilizing W/O emulsions are mainly discussed and illustrated to gain new insights into the stability mechanism of emulsion systems. In addition, the review provides a comprehensive and state‐of‐art overview of the potential applications of W/O emulsions in food systems, for example, as fat replacers, controlled‐release platforms of nutrients, and delivery carrier systems of water‐soluble bioactive compounds. The information may be useful for optimizing the formulation of W/O emulsions for utilization in commercial functional food products.     

Reduced Fat Food Emulsions: Physicochemical,Sensory, and Biological Aspects

Fat plays multiple important roles in imparting desirable sensory attributes to emulsion-based food products, such as sauces, dressings, soups, beverages, and desserts. However, there is concern that over consumption of fats leads to increased incidences of chronic diseases, such as obesity, coronary heart disease, and diabetes. Consequently, there is a need to develop reduced fat products with desirable sensory profiles that match those of their full-fat counterparts. The successful design of high quality reduced-fat products requires an understanding of the many roles that fat plays in determining the sensory attributes of food emulsions, and of appropriate strategies to replace some or all of these attributes. This paper reviews our current understanding of the influence of fat on the physicochemical and physiological attributes of food emulsions, and highlights some of the main approaches that can be used to create high quality emulsion-based food products with reduced fat contents.     

Future trends of processed meat products concerning perceived healthiness: A review

The 21st-century consumer is highly demanding when it comes to the health benefits of food and food products. In the pursuit of attracting these consumers and easing the rise in demand for high-quality meat products, the processed meat sector is intensely focused on developing reformulated, low-fat, healthy meat products. Meat and meat products are considered the primary sources of saturated fatty acids in the human diet. Therefore, these reformulation strategies aim to improve the fatty acid profile and reduce total fat and cholesterol, which can be achieved by replacing animal fat with plant-based oils; it could be performed as direct inclusion of these oils or pre-emulsified oils. However, emulsions offer a viable option for incorporating vegetable oils while avoiding the multiple issues of direct inclusion of these oils in meat products. Processed meat products are popular worldwide and showing a gradually increasing trend of consumption. Various types of plant-based oils have been studied as fat replacers in meat products. This review will focus on possible methods to reduce the saturated fatty acid content in meat products.     

Atomic force microscopy as a nanoscience tool in rational food design

Atomic force microscopy (AFM) is a nanoscience tool that has been used to provide new information on the molecular structure of food materials. As an imaging tool it has led to solutions to previously intractable problems in food science. This type of information can provide a basis for tailoring food structures to optimise functional behaviour. Such an approach will be illustrated by indicating how a basic understanding of the role of interfacial stability in complex foods systems can be extended to understand how such interfacial structures behave on digestion, and how this in turn suggests routes for the rational design of processed food structures to modify lipolysis and control fat intake. As a force transducer AFM can be used to probe interactions between food structures such as emulsion droplets at the colloidal level. This use of force spectroscopy will be illustrated through showing how it allows the effect of the structural modification of interfacial structures on colloidal interactions to be probed in model emulsion systems. Direct studies on interactions between colliding soft, deformable droplets reveal new types of interactions unique to deformable particles that can be exploited to manipulate the behaviour of processed or natural emulsion structures involved in digestion processes. Force spectroscopy can be adapted to probe specific intermolecular interactions, and this application of the technique will be illustrated through its use to test molecular hypotheses for the bioactivity of modified pectin molecules. Copyright © 2011 Society of Chemical Industry     

Sensory Analysis: Relevance for Prebiotic,Probiotic, and Synbiotic Product Development

Abstract: Sensory analysis represents a decisive step during the various stages of food product development. For probiotic, prebiotic, and synbiotic foods, which have shown continuous and significant consumption in the functional food category, the choice of an appropriate technique allows obtaining relevant sensory information that contributes to consumer acceptance. This review focuses on the importance of sensory analytical techniques in prebiotic and probiotic food product development. Examples of the most known sensory methodologies applied to these important functional foods are presented, as well as some considerations about consumer attitudes that can influence acceptance of these products. Moreover, applications of such techniques on functional product evaluation are provided.     

采用METHOCEL MXTM技术开发低脂肪香肠和肉制品

由于消费者希望降低对脂肪特别是动物脂肪的摄取,诸如香肠类的肉制品已经逐步从消费者的日常饮食中降低使用量.METHOCELTMMX的脂肪替代技术可以使低脂肪的肉制品保持如全脂肉制品一样的优异的风味,提供良好的质构和柔嫩多汁的口感.这项技术使用健康的植物油来替代饱和脂肪酸或氢化植物油,形成形如"矩阵"的乳状液.将METHOCEL MXTM,冷水和植物油结合制成这个乳状液系统,植物油的含量可以是2%60%.本文中描述了一个用METHOCELTMMX的脂肪替代技术制作的10%脂肪含量的香肠,在保持良好质量的前提下,降低脂肪含量27%.     

Invited review: Authentication of milk by direct and indirect analysis of triacylglycerol molecular species

Milk, milk-based products, and milk derivatives represent an important group of food commodities, with high nutritional value and widely consumed by large segment of consumers, including pregnant women, newborns, children, and the elderly. Food authentication is a rapidly growing field because of increasing consumer awareness regarding food quality and safety. This review attempts to critically summarize the status of direct and indirect analysis of the molecular species of triacylglycerols (TAG) used to assess the authenticity of milk. Identification and quantification of TAG molecular species in milk fat can be accurately performed even though analytical approaches focused on fraud evaluation should be developed. Recent analytical breakthroughs and novel techniques are discussed, along with their applications in milk authentication.     

Factors Influencing the Freeze‐Thaw Stability of Emulsion‐Based Foods

Many of the sauces used in frozen meals are oil‐in‐water emulsions that consist of fat droplets dispersed within an aqueous medium. This type of emulsion must remain physically and chemically stable throughout processing, freezing, storage, and defrosting conditions. Knowledge of the fundamental physicochemical mechanisms responsible for the stability of emulsion‐based sauces is needed to design and fabricate high‐quality sauces with the desired sensory attributes. This review provides an overview of the current understanding of the influence of freezing and thawing on the stability of oil‐in‐water emulsions. In particular, it focuses on the influence of product composition (such as emulsifiers, biopolymers, salts, and cryoprotectants), homogenization conditions, and freezing/thawing conditions on the stability of emulsions. The information contained in this review may be useful for optimizing the design of emulsion‐based sauces for utilization in commercial food products.     

Food Technological Applications for Optimal Nutrition: An Overview of Opportunities for the Food Industry

Abstract: An increasingly important determinant in food choice is the growing consumer concern about nutrition and health. This focusing of consumer interest on the food supply, and also extensive research and technological developments in food science will provide further opportunities for new product development. The Food‐Based Dietary Guidelines of the World Health Organization (WHO) and European Union (EU) legislation on health claims play an important role in regulating information to the public about a wholesome diet and for improving the availability and affordability of nutritious food choices to consumers. More specifically, the food industry can contribute by reducing the number of energy‐dense products; by improving the nutrient profile of processed food through the reduction of salt, added sugar, trans‐fatty acid, and saturated fat content. As a result, food science and technology are prompted to create a new framework for these food‐based dietary guidelines, principally in the areas of food physics, methods of food storage and preservation, nutrient restoration and fortification of foods, and the development of health‐focused designer foods and functional foods. The aim of this review is to provide an overview of some further opportunities for new product development and nutrition research. Some topics related to the energy reduction of foods include: dilution and structure design, carbohydrate and/or fat substitutes, and inhibition of enzymes in carbohydrate and/or fat digestion; additionally, regulation of some metabolic functions with food‐derived bioactive peptides and probiotics, and enrichment of foods with bioactive compounds are reviewed in this overview as the most promising issues.     

Reduction of Sodium and Fat Levels in Natural and Processed Cheeses: Scientific and Technological Aspects

ABSTRACT: The various types of cheese are nutrient‐dense foods that are good sources of calcium, phosphorus, and protein. They are also important ingredients in many highly consumed foods such as pizza, cheeseburgers, and sauces. However, they are also perceived as being high in fat and sodium. Consumers have indicated that they would like to continue utilizing cheese in their diet but would prefer to have lower‐fat and lower‐sodium products. Fat and salt are important elements in the flavor, texture, food safety, and overall acceptability of cheese. Alternatives to fat and salt are being investigated but have not been found to be acceptable, especially in those products that meet the FDA's definition of low‐fat and/or low‐sodium. This review is primarily a report on the current status of research to develop desirable cheeses with low‐fat and/or low‐sodium, their regulatory and labeling status, consumer acceptability, and challenges for further efforts.     

鱼油在食品领域中的应用技术综述

对鱼油在食品领域中的应用技术进行综述。由于具有独特的营养功能,鱼油的应用十分广泛。中国居民目前对二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)摄入不足,因而鱼油在食品中的应用十分必要。目前市场上已有多种鱼油应用于各类食品中。在应用过程中,鱼油的氧化稳定性问题一直是研究热点,选择不同的添加形式(纯鱼油、乳状液和微胶囊)并采用某些新工艺可有效提高氧化稳定性。鱼油应用于食品在技术和商业方面的发展前景均十分广阔。     

Analytical methods combined with multivariate analysis for authentication of animal and vegetable food products with high fat content

BackgroundFood fraud is described as a violation of food law, which is intentionally committed to get an economic or financial gain through the consumer's swindle resulting in multi-million business and posing a public health threat. The main fraudulent practices are mislabelling of composition, certificates of origin, health claims, and artificial increases in weight or volume caused by replacement, dilution, addition or removal of some ingredients. Hardly 68% of the food fraud violations are produced in animal and vegetable products with high fat content (27% meat, 13% fish, 11% oils, 10% dairy products, 4% nuts and seeds and 3% animal by-products) becoming a crucial issue for food processing industries.Scope and approachThe present review focuses on the main authentication techniques and methods employed to clarify the authenticity of both animal and vegetable fat food products emphasizing the importance of the use of robust and reliable analytical techniques combined with multivariate analyses.Key findings and conclusionsTargeted approaches, such as chromatography and DNA-based methods, combined with multivariate analysis have shown high accuracy, sensitivity and selectivity, allowing the simultaneous evaluation of multiple analytes. In addition, non-target methods, such as those based on spectroscopic techniques, have been used to establish the geographic origin of food products with quick response, low cost, non-destructive character and also offering the possibility to be miniaturized.     

Optimization of a gelled emulsion intended to supply ω-3 fatty acids into meat products by means of response surface methodology

The optimization of a gelled oil-in-water emulsion was performed for use as fat replacer in the formulation of ω-3 PUFA-enriched cooked meat products. The linseed oil content, carrageenan concentration and surfactant–oil ratio were properly combined in a surface response design for maximizing the hardness and minimizing the syneresis of the PUFA delivery system. The optimal formulation resulted in a gelled emulsion containing 40% of oil and 1.5% of carrageenan, keeping a surfactant–oil ratio of 0.003. The gel was applied as a partial fat replacer in a Bologna-type sausage and compared to the use of an O/W emulsion also enriched in ω-3. Both experimental sausages contributed with higher ω-3 PUFA content than the control. No sensory differences were found among formulations. The selected optimized gelled oil-in-water emulsion was demonstrated to be a suitable lipophilic delivery system for ω-3 PUFA compounds and applicable in food formulations as fat replacer.     

Cereal starch nanoparticles—A prospective food additive: A review

Starch is one of the most abundant biopolymers in nature and is typically isolated from plants in the form of micro-scale granules. Raw starch has limited applications due to its innate disadvantages such as poor solubility in cold water, tendency to retrograde and high viscosity once it is gelatinized. Therefore, some degree of modification is required to enhance its functionality. Starch nanoparticle is one of the products of such modification. Chemical, enzymatic, and physical treatments are used for the preparation of starch nanoparticles and to study their granular and molecular structures. Characterization of starch nanoparticles on the size distribution, crystalline structure, and physical properties in relation to the starch sources and preparation methods can be done using various characterization tools e.g. Scanning Electron Microscopy, Transmission Electron Microscopy, Atomic Florescence Microscopy, etc. Starch nanoparticles can be used as a food additive as it has adverse range of uses in food such as emulsion stabilizer, fat replacer, Thickener, or rheology modifier etc.     

The nutrition and health benefits of yoghurt

Yoghurt is one of the most popular fermented milk products worldwide and has gained widespread consumer acceptance as a healthy food. It provides an array of nutrients in significant amounts, in relation to its energy and fat content, making it a nutrient-dense food. In particular, yoghurt can provide the body with significant amounts of calcium in a bioavailable form. Furthermore, yoghurt has many health benefits beyond the basic nutrition it provides, such as improved lactose tolerance, a possible role in body weight and fat loss, and a variety of health attributes associated with probiotic bacteria.     

Effects of composition and processing variables on the oxidative stability of protein-based and oil-in-water food emulsions

Because many common foods are emulsions (mayonnaise, coffee creamers, salad dressing, etc.), a better understanding of lipid oxidation mechanisms in these systems is crucial for the formulation, production, and storage of the relevant consumer products. A research body has focused on the microstructural and oxidative stability of protein-stabilized oil-in-water emulsions that are structurally similar to innovative products that have been recently developed by the food industry (e.g., non-dairy creams, vegetable fat spreads, etc.) This review presents recent findings about the factors that determine the development of lipid oxidation in emulsions where proteins constitute the stabilizing interface. Emphasis is given to “endogenous” factors, such as those of compositional (e.g., protein/lipid phases, pH, presence of transition metals) or processing (e.g., temperature, droplet size) nature. Improved knowledge of the conditions that favor the oxidative protection of protein in emulsions can lead to their optimized use as food ingredients and thereby improve the organoleptic and nutritional value of the related products.