Emerging drying techniques for food safety and quality: A review

The new trends in drying technology seek a promising alternative to synthetic preservatives to improve the shelf-life and storage stability of food products. On the other hand, the drying process can result in deformation and degradation of phytoconstituents due to their thermal sensitivity. The main purpose of this review is to give a general overview of common drying techniques with special attention to food industrial applications, focusing on recent advances to maintain the features of the active phytoconstituents and nutrients, and improve their release and storage stability. Furthermore, a drying technique that extends the shelf-life of food products by reducing trapped water, will negatively affect the spoilage of microorganisms and enzymes that are responsible for undesired chemical composition changes, but can protect beneficial microorganisms like probiotics. This paper also explores recent efficient improvements in drying technologies that produce high-quality and low-cost final products compared to conventional methods. However, despite the recent advances in drying technologies, hybrid drying (a combination of different drying techniques) and spray drying (drying with the help of encapsulation methods) are still promising techniques in food industries. In conclusion, spray drying encapsulation can improve the morphology and texture of dry materials, preserve natural components for a long time, and increase storage times (shelf-life). Optimizing a drying technique and using a suitable drying agent should also be a promising solution to preserve probiotic bacteria and antimicrobial compounds.     

Nanoencapsulation Techniques for Food Bioactive Components: A Review

The protection and controlled release of bioactive compounds at the right time and the right place can be implemented by encapsulation. Nanoencapsulation remains to be the one of the most promising technologies having the feasibility to entrap bioactive compounds. Nanoencapsulation of bioactive compounds has versatile advantages for targeted site-specific delivery and efficient absorption through cells. However, researches in the application of nanotechnology in the food industry have been very limited and there are only a few review articles that explored the nanoencapsulation technology. This review focuses on the various nanoencapsulation techniques such as emulsification, coacervation, inclusion, complexation nanoprecipitation, emulsification–solvent evaporation, and supercritical fluid for food ingredients. Drying techniques such as spray drying and freeze drying for stabilization of nanoparticles are also discussed. Current state of knowledge, limitations of these techniques, and recent trends are also discussed. Finally, safety and regulatory issues in the nanoencapsulation of bioactive compounds are also highlighted.     

益生菌微胶囊的制备及其在食品中应用的研究进展

益生菌对人体健康有益而被广泛应用于食品领域,但其易受温度、氧气、湿度、压力、胃酸和胆汁盐等不良环境因素影响。为使益生菌在加工、储藏、消化过程中保持高存活率,人们利用不同的微胶囊技术对益生菌进行包埋和保护。益生菌微胶囊技术通过创建一种物理屏障来提高益生菌对不良环境的抗性力,减少保护基质中益生菌的损伤,从而使其到达目标部位顺利释放并发挥作用。文章概述了益生菌的起源、种类及益生功效,重点总结了益生菌微胶囊常用制备方法的基本原理及优缺点,包括挤压法、乳化法、喷雾干燥法、冷冻干燥法、喷雾冷却法、复凝聚法、静电纺丝、电喷雾和撞击气溶胶法,进而重点讨论了益生菌微胶囊技术在乳制品、肉制品、非乳饮料及焙烤制品等食品中的应用优势和可能性。虽然众多研究进行体外模拟消化,但仍存在一定局限性,对于现有的问题,未来仍然需要通过扩大包埋方法、开展体内实验、建立系统性数据库等方法来满足益生菌食品的工业化生产需求,以为开发新型益生菌食品提供理论借鉴和参考。     

Influence of functional food components on gut health

Intestinal epithelial cells (IECs) lining the gastrointestinal tract establish a barrier between external environments and the internal milieu. An intact intestinal barrier maintains gut health and overall good health of the body by preventing from tissue injury, pathogen infection and disease development. When the intestinal barrier function is compromised, bacterial translocation can occur. Our gut microbiota also plays a fundamentally important role in health, for example, by maintaining intestinal barrier integrity, metabolism and modulating the immune system, etc. Any disruption of gut microbiota composition (also termed dysbiosis) can lead to various pathological conditions. In short, intestinal barrier and gut microbiota are two crucial factors affecting gut health. The gastrointestinal tract is a complex environment exposed to many dietary components and commensal bacteria. Dietary components are increasingly recognized to play various beneficial roles beyond basic nutrition, resulting in the development of the functional food concepts. Various dietary modifiers, including the consumption of live bacteria (probiotics) and ingestible food constituents such as prebiotics, as well as polyphenols or synbiotics (combinations of probiotics and prebiotics) are the most well characterized dietary bioactive compounds and have been demonstrated to beneficially impact the gut health and the overall well-being of the host. In this review we depict the roles of intestinal epithelium and gut microbiota in mucosal defence responses and the influence of certain functional food components on the modulation of gut health, with a particular focus on probiotics, prebiotics and polyphenols.     

Effectiveness of probiotics,prebiotics, and prebiotic‐like components in common functional foods

The bioactive ingredients in commonly consumed foods include, but are not limited to, prebiotics, prebiotic‐like components, probiotics, and postbiotics. The bioactive ingredients in functional foods have also been associated with beneficial effects on human health. For example, they aid in shaping of gut microflora and promotion of immunity. These functional components also contribute in preventing serious diseases such as cardiovascular malfunction and tumorigenesis. However, the specific mechanisms of these positive influences on human health are still under investigation. In this review, we aim to emphasize the major contents of probiotics, prebiotics, and prebiotic‐like components commonly found in consumable functional foods, and we present an overview of direct and indirect benefits they provide on human health. The major contributors are certain families of metabolites, specifically short‐chain fatty acids and polyunsaturated fatty acids produced by probiotics, and prebiotics, or prebiotic‐like components such as flavonoids, polyphenols, and vitamins that are found in functional foods. These functional ingredients in foods influence the gut microbiota by stimulating the growth of beneficial microbes and the production of beneficial metabolites that, in turn, have direct benefits to the host, while also providing protection from pathogens and maintaining a balanced gut ecosystem. The complex interactions that arise among functional food ingredients, human physiology, the gut microbiota, and their respective metabolic pathways have been found to minimize several factors that contribute to the incidence of chronic disease, such as inflammation oxidative stress.     

Spray Drying for the Production of Nutraceutical Ingredients—A Review

Contributions of spray drying to food processing applications are increasing as compared to other conventional drying methods. Spray drying has not only contributed in drying of fluids but also has played a vital role in encapsulation and microencapsulation of valuable foods and functional–nutraceutical ingredients. Microencapsulation by spray drying is a cost-effective one-step process as compared to other encapsulation methods. Encapsulation using spray drying is mainly used in the food sector to protect bioactive compounds or functional foods from light, temperature, oxidation, etc. This paper reviews the work done in past years in the functional food and nutraceutical sector using spray drying. The paper focuses on the role of spray drying in vitamins, minerals, flavouring substances, antioxidant compounds and fatty acids encapsulation.     

大豆活性组分和肠道菌群相互作用研究进展

目前食品组分与肠道菌群的相互作用及其对健康的影响已成为膳食与健康领域的研究热点。存在于动物体内的肠道菌群对大豆活性组分的分解代谢、转化吸收有着重要作用,大豆活性组分在体内肠道菌群作用下发生生物转化,导致其结构改变,从而形成新的活性成分,进而影响人体健康。同时,大豆活性组分的肠道菌群代谢产物又能够调节肠道菌群结构、保护肠黏膜屏障、维护肠道微生态平衡。本文对大豆活性组分如何在菌群作用下进行有效生物转化、肠道菌群在外源组分的扰动下如何进行菌群结构和丰度调整以及大豆组分的菌群代谢产物对人的健康影响等方面进行了综述,以期为深入研究大豆活性成分对人体健康作用的机理提供参考。     

Development of functional ingredients for gut health

Microbial reactions in the gut have an essential role not only in gut health, but in general human health. The gut is the site of active fermentation of non-digestible diet components, as well as bioconversions and absorption of plant-derived compounds, such as phenolics. When developing nutritionally designed foods that promote health through gut microbial reactions, three different types of food ingredients can be used: living micro-organisms (probiotics), non-digestible carbohydrates (dietary fiber and prebiotics) and bioactive plant secondary metabolites (e.g. phenolics).     

Release and antilisterial properties of nisin from zein capsules spray-dried at different temperatures

Nisin is an effective antimicrobial against a broad spectrum of Gram-positive bacteria. It has been proposed that reduced efficacy of nisin in foods can be improved by technologies such as encapsulation to protect it from interferences by food matrix components. The potential of spray drying, a practical technology, was studied in this work for encapsulation of nisin in zein microcapsules at four inlet temperatures between 75 and 120 °C. At 95 °C and above, no apparent loss of nisin activity was observed after spray drying. At pH 6.0, burst release of nisin was impacted by spray drying temperature more than equilibrium release, possibly due to influences on capsule structures. At pH 2.0, complete release of nisin in 30 min was observed, contrasting to limited release over 8 d at pH 8.0. Capsules produced at an inlet temperature of 105 °C showed the most sustained release of nisin at pH 6.0. For these capsules, sustained release of nisin to >80% was observed at pH 6.0 and 8.0 when NaCl was used at 0.5 mol/L. Finally, at 400 IU/mL, the encapsulated nisin demonstrated slightly improved antilisterial properties than free nisin in reduced fat (2g/100g) milk but much work is still needed to enhance the antimicrobial effectiveness.     

Issues deserve attention in encapsulating probiotics: Critical review of existing literature

Probiotic bacteria are being increasingly added to food for developing products with health-promoting properties. However, the efficacy of probiotics in commercial products is often questioned due to the loss of their viability during shelf storage and in human gastrointestinal tracts. Encapsulation of probiotics has been expected to provide protection to probiotics, but not many commercial products contain encapsulated and viable probiotic cells owing to various reasons. To promote the development and application of encapsulation technologies, this paper has critically reviewed previous publications with a focus on the areas where studies have fallen short, including insufficient consideration of structural effects of encapsulating material, general defects in encapsulating methods and issues in evaluation methodologies and risk assessments for application. Corresponding key issues that require further studies are highlighted. Some emerging trends in the field, such as current treads in encapsulating material and recently advanced encapsulation techniques, have also been discussed.     

Encapsulation of Probiotic Bacteria in Biopolymeric System

Encapsulation of probiotic bacteria is generally used to enhance the viability during processing, and also for the target delivery in gastrointestinal tract. Probiotics are used with the fermented dairy products, pharmaceutical products, and health supplements. They play a great role in maintaining human health. The survival of these bacteria in the human gastrointestinal system is questionable. In order to protect the viability of the probiotic bacteria, several types of biopolymers such as alginate, chitosan, gelatin, whey protein isolate, cellulose derivatives are used for encapsulation and several methods of encapsulation such as spray drying, extrusion, emulsion have been reported. This review focuses on the method of encapsulation and the use of different biopolymeric system for encapsulation of probiotics.     

Flavor release from spray-dried amorphous matrix: Effect of lactose content and water plasticization

Glass-forming carbohydrates are widely used as matrix for encapsulation of nutrients and bioactive compounds. In this study, encapsulation systems with lactose/whey protein isolate (WPI) mixtures (4:1, 1:1, and 1:4), or WPI as wall materials and ethyl butyrate as core material were prepared by spray drying. The effects of lactose content and water plasticization on encapsulation efficiency and flavor release were investigated. Wall material consisting of lactose/WPI (4:1) mixture had significantly (P < 0.05) higher encapsulation efficiency. The flavor retention in powders did not have significant decrease with equilibration at 0.33 a_w, while it was dramatically decreased at 0.54 a_w and 0.65 a_w as a result of lactose crystallisation. Mechanical property study showed that the molecular mobility and free volume of encapsulation systems with higher lactose content increased more significantly with increasing water content, which accelerated the diffusion of flavor molecules. Those results may use in the assessment of protection and release characteristics of flavor components in formulated systems.     

Encapsulation of orange oil in a spray dried double emulsion

Encapsulation is an important technique being used to protect sensitive food materials like flavours from deterioration. The capsule wall isolates them from the atmospheric oxygen, moisture, temperature and light. Encapsulation also masks some objectionable flavours, e.g. fish oil and some bitter antibiotics. In this study orange oil was encapsulated in the inner compartment of a double emulsion belonging to the type O1-W-O2 where O1 is orange oil, W is water and O2 is vegetable oil. In order to make orange oil double emulsion suitable for use in dry mixes, it was secondarily coated with wall materials of lactose and caseinate using spray drying technique. Entrapment of orange oil in such structure is also expected to slow down the release of volatiles and guarantee more protection for orange oil against atmospheric conditions. This method may have a potential application in different types of food or pharmaceutical products where maximum protection for flavours or slow release are required. This study includes detailed preparation of the spray dried double emulsion, evaluation of the encapsulation efficiency using light and scanning electron microscope and calculation of the yield percent of the encapsulated oil. In a separate paper we will examine the efficiency of spray dried double emulsion to control the release of orange oil by GC.     

Legume proteins are smart carriers to encapsulate hydrophilic and hydrophobic bioactive compounds and probiotic bacteria: A review

Encapsulation is a promising technological process enabling the protection of bioactive compounds against harsh storage, processing, and gastrointestinal tract (GIT) conditions. Legume proteins (LPs) are unique carriers that can efficiently encapsulate these unstable and highly reactive ingredients. Stable LPs-based microcapsules loaded with active ingredients can thus develop to be embedded into processed functional foods. The recent advances in micro- and nanoencapsulation process of an extensive span of bioactive health-promoting probiotics and chemical compounds such as marine and plant fatty acid-rich oils, carotenoid pigments, vitamins, flavors, essential oils, phenolic and anthocyanin-rich extracts, iron, and phytase by LPs as single wall materials were highlighted. A technical summary of the use of single LP-based carriers in designing innovative delivery systems for natural bioactive molecules and probiotics was made. The encapsulation mechanisms, encapsulation efficiency, physicochemical and thermal stability, as well as the release and absorption behavior of bioactives were comprehensively discussed. Protein isolates and concentrates of soy and pea were the most common LPs to encapsulate nutraceuticals and probiotics. The microencapsulation of probiotics using LPs improved bacteria survivability, storage stability, and tolerance in the in vitro GIT conditions. Moreover, homogenization and high-pressure pretreatments as well as enzymatic cross-linking of LPs significantly modify their structure and functionality to better encapsulate the bioactive core materials. LPs can be attractive delivery devices for the controlled release and increased bioaccessibility of the main food-grade bioactives.     

肠道菌群与食物过敏性疾病研究进展

食物过敏作为食品安全的热点问题在全球引起了广泛关注,食物过敏发病率的不断增加与肠道菌群结构和功能的变化密切相关。生活环境和膳食结构的改变、抗生素的使用等诸多因素都可引起肠道菌群失衡,而肠道菌群丰度和多样性的变化可导致肠道菌群与宿主免疫系统相互作用的变化,从而破坏口服耐受增加食物过敏的发病率。近年来随着肠道菌群-宿主相互作用等相关研究的不断深入,调整肠道菌群结构为过敏性疾病的防治提供了新的思路,因而益生菌在预防和治疗食物过敏中的作用开始备受关注。本文首先从细胞和分子水平总结了口服耐受和食物过敏的产生的相关机理,进一步综述了目前对于肠道菌群通过与宿主黏膜免疫系统相互作用调节食物过敏的相关机制研究,并探讨益生菌防治食物过敏的潜在机理,以期为益生菌在预防和治疗食物过敏中的应用提供理论依据。     

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.     

Modeling the release of food bioactive ingredients from carriers/nanocarriers by the empirical,semiempirical, and mechanistic models

The encapsulation process has been utilized in the field of food technology to enhance the technofunctional properties of food products and the delivery of nutraceutical ingredients via food into the human body. The latter application is very similar to drug delivery systems. The inherent sophisticated nature of release mechanisms requires the utilization of mathematical equations and statistics to predict the release behavior during the time. The science of mathematical modeling of controlled release has gained a tremendous advancement in drug delivery in recent years. Many of these modeling methods could be transferred to food. In order to develop and design enhanced food controlled/targeted bioactive release systems, understanding of the underlying physiological and chemical processes, mechanisms, and principles of release and applying the knowledge gained in the pharmaceutical field to food products is a big challenge. Ideally, by using an appropriate mathematical model, the formulation parameters could be predicted to achieve a specific release behavior. So, designing new products could be optimized. Many papers are dealing with encapsulation approaches and evaluation of the impact of process and the utilized system on release characteristics of encapsulated food bioactives, but still, there is no deep insight into the mathematical release modeling of encapsulated food materials. In this study, information gained from the pharmaceutical field is collected and discussed to investigate the probable application in the food industry.     

Addressing the gut microbiome and implications for obesity

Identification of the gut microbiota as an environmental factor that modulates obesity and metabolic diseases has provided the medical and functional food industry with new targets to treat metabolic diseases. However, only limited knowledge about the mechanisms by which the gut microbiota contributes to these lifestyle diseases are known. The gut microbiota is involved in energy harvest from the diet, modulation of endocrine signalling, and promoting metabolic inflammation. This review will discuss how the gut microbiota is altered in obesity, some of the mechanisms by which it promotes disease development, and how pre- and probiotics may be used to improve metabolic diseases.     

Food protein-based materials as nutraceutical delivery systems

Incorporation of bioactive compounds–such as vitamins, probiotics, bioactive peptides, and antioxidants etc.–into food systems provide a simple way to develop novel functional foods that may have physiological benefits or reduce the risks of diseases. As a vital macronutrient in food, proteins possess unique functional properties including their ability to form gels and emulsions, which allow them to be an ideal material for the encapsulation of bioactive compounds. Based on the knowledge of protein physical–chemistry properties, this review describes the potential role of food proteins as substrate for the development of nutraceutical delivery systems in the form of hydrogel, micro-, or nano- particles. Applications of these food protein matrices to protect and delivery-sensitive nutraceutical compounds are illustrated, and the impacts of particle size on release properties are emphasized.     

Ways and Means for the Infusion of Bioactive Constituents in Solid Foods

The development and consumption of functional food, or foods that promote health not merely basic nutrition, is on rise. In recent years, industrial and consumer interests have focused on developing foods supplemented with bioactive constituents that provide greater physiological benefits. The direct addition of these components to liquid or fabricated solid foods has led to a wide range of new products appearing on the market. Osmotic dehydration, an operation in which food stuff is soaked in solution of low water activity, has been reported as a suitable technology for formulating new products because of the twofold effect that it has on food where it partially removes water and impregnates the food pieces (solid food matrix) with solutes from the osmotic solution. The article focuses on the impregnation of bioactive constituents having added advantage to human health such as antioxidants, minerals, vitamins, and probiotics. The infusion of enzymes and aroma also has been discussed. Application of ultrasound, vacuum, high pressure, and/or atmospheric impregnation techniques appears to be the feasible technologies for impregnation of solid food matrix for the incorporation of bioactive ingredients.