Nanotechnology and Food Digestibility
One of the important and modern developments in the field of material sciences is the development of nanoscience and nanotechnology. This technology increases the area of material science, to a level of the nanostructure of scientific and engineering materials. Since material sciences cover a broad area of scientific process, by controlling the properties, changing the structures and compositing the producing materials, a deep structural, as well as physical and chemical characteristics of the material, are required in order to control the process. Multiple fields of material sciences cover and govern by structural and physical features of solid materials, but covering the chemical and physical properties of biological ingredients is the important one in terms of structural properties, performance, and processing of food (Loveday, Rao and Singh, 2012).
The application of nanotechnology in the food sector depends upon its functionality. The main areas of effectiveness of nanotechnology in the food industry are bioavailability of food particles and enhancement of nutritional values of food particles. Since the biological properties of nanoparticles depend majorly on their chemical and physical characteristics, therefore, nanotechnology can be used for extending the shelf life of food, increased nutrients, improved flavours, detection of pathogens and toxins along with several other security functioning, related to food (He and Hwang, 2016). In the article “Applications and implications of nanotechnologies for the food sector”, Chaudhry et al. (2008), classifies applications of nanotechnology in food science and technology into four main parts.
- Nanostructure formation and processing, especially for food ingredients.
- Bioengineering and encapsulation of food-related nanoparticles
- Nanotechnology used in developing new packaging materials
- And the use of nanoparticle-based instruments and technology like nano-water filtration and treatment and sensors for the detection of nanoparticles in food.
The largest category for the use of nanotechnology in the food industry is of the nanomaterials used for packaging of food. Nanotechnology is the use and handling of matter at the molecular and sub-molecular level. It is the most prominent technologies of the time. It has the potential to improve the digestion process by delivering the bioactive compound and micronutrients. Nanotechnology has application in the encapsulation of micronutrients along with enzymes in order to hydrolyse antinutrient particles. Protection against biological decay, chemical intoxicants, and enhancing the physical properties of the food are some of the other key benefits of nanotechnology (He and Hwang, 2016).
Food Microstructure and Digestibility
The primary part of food structure in perceiving the behaviour of foods during eating and processing is well established (Troncoso, Aguilera and McClements, 2012). It is seen that the food structure is a major factor for humans to understand the digestion of foods and the behaviour of it (Aguilera, 2005). We consume nutrients in the simplest form of called microstructures that exists in size ranging from nanometers to a few millimetres. The food microstructure mainly depends on the processing, post-processing storage, and composition and has an important function in determining the speed of digestibility in different edibles (Singh, Kaur and Singh, 2013).
The natural food microstructures like beans, rice, potato which also include the attributes of the cell wall polymers like: nature of pectic materials, parenchyma cell size, etc has been observed as a significant factor, which influences the deformation that occurs during mechanical processing or mastication (Singh, Kaur and Singh, 2013) The microstructural features of natural foods (like raw potatoes, etc) such as cell wall composition, thickness, and parenchyma cell size, have been said to possess a substantial effect on the last texture of the food like waxy, mealy, etc, after cooking which has an impact on digestion (Singh, Kaur and Singh, 2013) There is a new interest that has arisen concerning the role of food structure that it may participate in our health, nutrition, and well-being when the food is inside our body.
This interest is supported additionally by the increase in belief that foods are the basic unit of nutrition and not nutrients (Singh, Kaur and Singh, 2013). Therefore, the excretion of any nutrient from the food matrix (the complex that contains the nutrients in any food) and also the meeting between restructuring phenomena and food components through the transit in the digestive system turns out to be far more vital than the original nutrients. According to Lundin there is a rising interest in the effect of food structure on the relationship of digestive behaviour with human nutrition, as the interaction among individual macronutrients like fat, carbohydrate, and protein, manage in several situations the pace of processes of digestion, such as lipolysis and proteolysis, influence condition and satiety the nutrient (Troncoso, Aguilera and McClements, 2012). Since foods become the key consideration wellbeing and better health instead of nutrients, the food structure role is not even more important (Troncoso, Aguilera and McClements, 2012). Hence, it can be observed that the microstructure of food, whether created or natural, plays a very important role for the human body, and in the overall digestion of food (Singh, Kaur and Singh, 2013).
Phase Transition and Digestibility
The basic determinants of the uses and behaviours of all materials are the basic states of materials that are solid, liquid and gases. A modification in phase is often a need for structural modifications of systems, for example like melting followed by cooling to form a desired solid structure of a material. After Ehrenfest’s principles phase transitions can be primarily classified as first-order, second-order and higher-order transitions. The first-order phase transitions are those who at the transition temperature show a discontinuity of the first derivative of Gibbs chemical or energy potential. First-order transitions include condensation, evaporation, crystallisation, and melting and these are phase transitions which comprise of latent heats of the transitions and show a lack of continuity for the heat capacity at exact temperature and pressure conditions at which minimum two of the three fundamental states of matter (solid, liquid and gas) can co-exist in equilibrium. Second-order transitions, at the transition temperature, show lack of continuity of the second derivative of Gibbs chemical or energy potential moreover they show a step change in thermal expansion coefficient heat capacity.
Lipids comprise of an important and diverse group of biomolecules. Most lipids behave as lyotropic liquid crystals. They assemble on their own in a variety of phases with different geometry and structure, in the presence of water. The lipid mesomorphic and polymorphic behaviour makes them able to form several ordered, gel, liquid-crystalline or crystalline phases as a utility of water temperature, and composition, content, is one of the most fascinating characteristics of lipid-water systems (Koynova and Tenchov, 2008).
Lipids are molecules which are amphiphilic, and they self-assemble in a diversity of various phases depending on their molecular shape and structure (branching and unsaturation, backbone and head, chain length, and group structure) and on external variables such as water temperature, content, pressure, aqueous phase, and lipid mixture compositions. With the aggregation process being driven by the hydrophobic outcome the lipid phases are made of aggregates of unique architecture. The physical rules that administer the lipid self-organization in aqueous media are the same for all surfactants.
The small intestine absorbs dietary fats. The ingested triacylglycerols are changed from insoluble fat particles into thinly dispersed microscopic micelles to be absorbed through the intestinal wall. Bile salts are synthesized from cholesterol in the liver and transferred into the small intestine for this function. They change dietary fats into mixed micelles of bile salts and triacylglycerols and perform as biologic detergents. The fraction of lipid molecules available to the action of water-soluble lipases is increased by the change of the solid lipid particles into micelles.
Gel Structures and Digestibility
Food gels are said to be a three-dimensioned continuous polymeric arrangement that holds a huge quantity of an aqueous component which shows mechanical inflexibility in the observation period. Proteins capability to produce emulsions and gels lets them be a perfect matter for keeping in control the digestion rate and releasing the bioactive compounds at particular places in the GIT. No doubt that protein gels are the most suitable and extensively used compound in food applications.
Protein gel behaves as a pH-sensitive matrix through the presence of basic (ammonium) or acidic (carboxylic) groups in a chain of protein, which either releases protons in to counteract the changes in pH of the medium or accepts it. This action can influence the pace of molecule excretion strongly by gels revealed to either intestinal medium (neutral pH) or gastric (low pH) by reducing the interaction of polypeptide chain and so taking the water in the system and permitting the diffusion of molecules outer by osmotic pressure.
Protein matrix experiences alleged the first-order degradation in intestinal enzyme digestion and gastric. The action of the films was recognized for a greater entanglement and more rigid structure of the polypeptide chain present in the SPI films because improved cross-linking, hence leading to a decrease in diffusion of digestive enzymes into the system (Chen et al., 2008).
Micro-beads of protein gel have been used lately to microorganisms with probiotic action quality in a capsule. The major challenge for this particular technique is enhancing the rate of survival of probiotics in the human digestive system. Hébrard et al., (2006) is the manufacturer of whey protein isolate (WPI) beads that contain yeasts from cold-integrated gelatine. Throughout the simulated human gastric digestion, beads were resistant to pepsin attack and acidification. Initially trapped yeasts recovered in the gastric medium were approximately 2%.
Protein gel microstructures are highly effective in the release of bioactive compounds and the digestion of proteins. When a digestive enzyme would degrade the gel component, then high-pour interconnectivity and a large porosity would increase the digestion rate over time. Additionally, to that, gels should be gastro-resistant in order to make competent systems for specific intestinal absorption of probiotics or bioactive compounds. Therefore, the control of tailoring the porous structure of protein gels and microstructure, it would provide more opportunities for release or protection of a nutrient or a physiologically bioactive constituent inside the GIT.
Interfacial Properties of Food Systems and Digestibility
All objects or materials are surrounded by some other materials and have the interface with them. The characteristic of the materials at the boundary surface or interface is dissimilar every time from the bulk, either due to contamination during their manufacturing or due to rearrangement of the interface forming components to reduce the energy. A property change like this, on a nanometre scale, could be at a single molecular layer (monolayer). Interfacial science includes the behaviour of surface-active materials at fine particle dispersion, molecular level, thin films and fibres and other systems that are strongly influenced by their interfaces. Interfacial properties are Surface energetics, adhesion and surface tension. Solid, liquid and gas can be these interfaces. The particles are solid, liquid or gas and the continuous phase could also be solid, liquid and gas if it is a particulate dispersed system. The interfaces could be solid-liquid (equipment surface-food liquid), liquid-liquid (oil-water), liquid-gas (water-air), gas-solid (air-equipment surface), or solid-solid (glass-plastic). The application of interfacial science is involved in the most common engineered food systems called Emulsions. While a number of food products are made by emulsification, some natural emulsions like milk also exist. By increasing repulsion of particles and reducing the surface energy, Surfactants are used in food systems to stabilize the emulsions.
By trapping gas bubbles in a liquid or solid, the foam is formed. It is also known as the dispersal of a hydrophobic gas (air) in a hydrophilic liquid. Oil-in-water type emulsions and Foams have similarities. Colloids are fine foams. Foamed structure is found in a number of food systems. They can be solid or liquid foams. Few products like those are bread, ice-cream, whipped cream, and some confectionery products. The foam contributes to lightness (cream and butter), froth (cappuccino), brittleness and crunchiness (extruded food), scoopiness (ice cream), softness (bread, cakes) and improves the increase in volume (bread).
In a fluid, Colloids are submicron or micron size particle dispersions. The diameter of the particle ranges from some nanometers to up to 1 millimetre. Many foods are in the colloidal form: like the casein present in milk is in colloidal form. Many water pollutants can be in colloidal form. Colloidal suspensions are usually used in the cosmetic, paint, and pharmaceutical industries. In comparatively concentrated food systems like cream, topping, ice cream, and other desserts, the stability to emulsions is provided by colloidal proteins, like casein present in milk acts which exist in a colloidal form, acts as the main stabiliser.