Functional Foods

1.About Functional Foods
In the past two years, functional food has become the industry’s new wind mouth, you may not be clear about what “functional food” is, but it is undeniable that the functional food on the market has become more and more abundant ……

2.How to Define Functional Food
According to the provisions of the Food Safety Law, China’s food category can be divided into two categories: ordinary food and special food, special food includes health food, and there is no name of “functional food” in the classification. So what is this functional food that is widely mentioned in the industry?

National Functional Food Engineering Technology Center, deputy director of the Jiangnan University School of Food Professor Lu Wenwei said, functional food in the country is not a legal concept, in a particular concept, functional food is a specific nutritional health care function of food. Functional food is a bridge between food and medicine in the industry, which can meet the individual’s demand for health. This type of food is actually called dietary supplements or functional food in foreign countries.

In the opinion of nutrition experts, there is no accurate definition of functional food, but in most cases it refers to food with specific nutritional and health care functions, i.e., food suitable for consumption by specific groups of people, with the function of regulating the organism, and not for therapeutic purposes.

Production Technology of Functional Foods

The development of functional foods provides consumers with the best way to choose healthy foods. The substances that play a functional role in functional foods are called bioactive substances, which have the functions of delaying aging, improving immunity, anti-tumor, anti-radiation, etc. Most of the bioactive substances are heat-sensitive, and it is crucial to retain the bioactivity and stability of the bioactive substances in their extraction and separation.

Functional food production technology mainly includes bioengineering technology (including fermentation engineering, enzyme engineering, genetic engineering, cell engineering, etc.), separation and purification technology, ultra-micro pulverization technology, freeze-drying technology, microcapsule technology, cold sterilization technology.

The current research on functional foods focuses on:

Active polysaccharide and its processing technology, active polysaccharide including dietary fiber, fungal active polysaccharide, plant active polysaccharide;
Active peptides and their processing technology, casein phosphopeptide (enzyme-precipitation method, enzyme-ion exchange method), glutathione (extraction method, fermentation method), blood pressure-lowering peptide functional fats and their processing technology;
Polyunsaturated fatty acids, phospholipid active trace elements and their processing technology;
Free radical scavengers and their processing technology (superoxide dismutase, preparation by precipitation method, ion exchange chromatography);
Active bacteria and their processing technology;
Functional sweetener and its processing technology.

I. Traditional separation technology

1.Preliminary separation and purification
From the solid-liquid separation out of the extract needs to be initially separated and purified, and further remove impurities. Commonly used preliminary separation and purification techniques include extraction separation, precipitation separation, adsorption clarification, molecular distillation technology, membrane filtration, resin separation methods.

1.1 Extractive separation
Extractive separation is an important extraction method, but also from a mixture of preliminary separation and purification of an important common separation method. This is because the solvent extraction has a fast mass transfer rate, short operating time, easy to continuous operation, easy to automate the control, separation and purification efficiency and other advantages.

Extraction separation method: a water-organic solvent extraction, that is, using an organic solvent to extract the target product from the aqueous solution, to achieve the purpose of concentration and purification; two aqueous phase extraction, which is the recent emergence of the compelling and promising new separation and purification technology.

When two different properties, immiscible water-soluble polymers mixed, and reach a certain concentration, will produce two phases, two polymers were dissolved in the immiscible two phases. The commonly used two-phase aqueous extraction system is polyethylene glycol ( P E G ) a dextran ( eD x t ar n ) system.

1.2 Precipitation purification
Precipitation separation and purification using the addition of reagents or change the conditions so that the functional active ingredients (or impurities) to generate insoluble particles and precipitation precipitation method is the most commonly used and the simplest method of separation and purification, due to its concentration is often greater than the purification effect, so it is usually used as a method of preliminary separation.

Precipitation separation and purification methods mainly include salting out method, isoelectric point method, organic solvent precipitation method, non-ionic polymer precipitation method, polyelectrolyte precipitation method, high-valent metal ion precipitation method and other precipitation methods.

1.3 Adsorption clarification technology
Adsorption clarification is through the adsorption of adsorption clarifying agent, bridging, flocculation, and inorganic salt electrolyte particles and surface charge flocculation, etc., so that a number of unstable particles linked into flocs, and constantly grow larger to increase the radius of the particles, accelerate the rate of settling, and improve filtration rate.

1.4 Molecular distillation technology
Molecular distillation is the use of liquid mixtures of molecules heat will escape from the liquid surface, and in the liquid surface is less than the average free range of light molecules and greater than the average free range of heavy molecules set up a condensing surface, so that light molecules continue to escape, and heavy molecules can not reach the condensing surface, thus breaking the dynamic equilibrium of the mixture and the separation of light and heavy molecules.

1.5 Membrane filtration
Membrane filtration method is to pressure as the driving force, relying on the selective permeability of the membrane for the separation and purification of substances, including microfiltration, nanofiltration, ultrafiltration, reverse osmosis and electrodialysis and other types. Membrane filtration method has more prominent advantages than ordinary separation methods, due to the separation, the material is not subjected to heat heating, and does not occur phase changes, the functional active ingredients will not be lost or destroyed, easy to maintain the original function of the active ingredients.

2. High separation and purification
After the initial separation and purification of functional active ingredients, the purity may not meet the requirements, but also contains some impurities, and requires a high degree of further separation and purification, in order to meet the nature of the functional active ingredients, structure and activity of the research. High separation and purification methods include crystallization and chromatographic separation and purification.

2.1 Crystallization
Crystallization is the process of precipitation of solutes from solution in a crystalline state. Because the first precipitation of the crystallization will always be more or less with some impurities, so you need to repeat the crystallization in order to get a more pure product. From the relatively impure crystals and then through the crystallization of the purer crystals, this process is called recrystallization.

The regular structure within the crystal provides that the formation of crystals must be the same ions or molecules, which can be arranged periodically according to a certain distance, so the substances that can form crystals are relatively pure.

2.2 Chromatography
Separation and purification paper chromatography is a liquid chromatographic method using paper and adsorbed water as stationary phases, and is mainly applied to the separation of hydrophilic compounds. Usually paper chromatography is normal-phase chromatography, but sometimes the filter paper with less polar liquid treatment as a stationary liquid, while the polarity of the aqueous solvent as the mobile phase, which is the reversed-phase paper chromatography. The sample size of paper chromatography is small, and the amount of pure product after separation is small, so it is difficult to collect a large number of functional active ingredients for further research.

Thin layer chromatography (TLC) is a liquid chromatographic method in which an adsorbent is coated on a thin plate as a stationary phase. Thin-layer chromatography sample volume than paper chromatography, separation and purification effect is also better than paper chromatography, can be used for purity identification; can also be separated from the spot scraped, dissolved to collect the pure product, but the amount of collection is still too small, in addition to special circumstances, generally do not need to do the collection of the pure product method.

Second, modern extraction technology
Separation is a major operation in food processing, it is based on certain physical and chemical principles of an intermediate product in the separation of different components.

The production of functional food, often using some of the efficacy of high content of functional plant and animal substrates, such as ginkgo biloba, lotus leaves, tea, tea tree flowers, yam, etc., to extract flavonoids, phenols, alkaloids, polysaccharides and other functionally active components of Chuan.

The classical extraction method is mainly organic solvent extraction method, this extraction method often does not require special equipment, so the application is more common. Modern extraction methods are based on the development of new extraction methods based on advanced instruments, mainly water vapor distillation technology, ultrasonic extraction technology, microwave extraction technology, biological enzymatic extraction technology, solid phase extraction technology.

1. Water vapor distillation technology
Water vapor distillation is the use of distilled substances and water insoluble, so that the separated substances can be lower than the original boiling point of the temperature of the boiling, the steam and water vapor generated with the escape, after condensation, cooling, collected to the oil-water separator, the use of extracts are insoluble in water and the relative density difference with water will be separated out to achieve the purpose of separation.

2. Ultrasonic extraction technology
Most of the active ingredients of natural plants exist in the cell wall, the structure and composition of the cell wall is the main obstacle to the extraction of active ingredients of plant cells, the existing mechanical or chemical methods are sometimes difficult to achieve the desired effect of fragmentation.

Ultrasonic extraction technology is the use of ultrasound has a mechanical effect, cavitation effect and thermal effect, strengthen the release of intracellular material, diffusion and dissolution, accelerate the leaching of active ingredients, greatly improving the extraction efficiency.

3. Microwave extraction technology
Microwave extraction technology is to use microwave energy to improve the extraction rate of a new technology. Microwave extraction process, microwave radiation leads to polar substances within the plant cell, especially water molecules absorb microwave energy, generating a large amount of heat, so that the temperature inside the cell rises rapidly, the pressure generated by the vaporization of liquid water will be the cell membrane and the cell wall rupture, the formation of tiny holes; further heating, resulting in a reduction in the water inside the cell and the cell wall, the cell shrinkage, cracks on the surface. The existence of holes and cracks so that the extracellular solvent can easily enter the cell, dissolve and release the intracellular products.

4.Bio-enzymatic extraction technology
Bio-enzymatic extraction technology is the use of enzyme reaction has a high degree of specificity and other characteristics, according to the composition of plant cell walls, select the appropriate enzyme, the cell wall components of hydrolysis or degradation, destruction of the cell wall structure, so that the active ingredient is fully exposed, dissolved, suspended or colloidal solvent, so as to achieve the extraction of the active ingredients within the cell of a new type of extraction method.

Due to the plant extraction process of the barrier – the cell wall is destroyed, so the enzymatic extraction is conducive to improve the extraction efficiency of the active ingredients. In addition, because many plants contain proteins, so the conventional extraction method, in the process of decoction, proteins coagulate with heat, affecting the dissolution of the active ingredients.

5. Solid phase extraction
Solid phase extraction (SPE) is based on the principle of liquid chromatography, the use of components in the solvent and adsorbent selective adsorption and selective elution process, to achieve the purpose of extraction and separation, enrichment, i.e., the sample through the column equipped with adsorbent, the target product is retained in the adsorbent, the first appropriate solvent to wash away the impurities, and then under certain conditions, the selection of different solvents, will be the target product elution down.

Membrane separation technology

1. Overview of membrane separation technology
Membrane separation technology has been applied to the desalination of seawater since 1950, and has become one of the most promising high-tech, widely used in chemical, pharmaceutical, biological and food industries.

Membrane separation technology uses selectively permeable membrane as the separation medium, and with the help of external driving force, two or more components are graded, separated and enriched. Compared with other separation technologies, membrane separation is a physical process, without the introduction of exogenous substances, saving energy at the same time, reducing the pollution of the environment; secondly, membrane separation is carried out at room temperature, there is no phase change in the process, and it is suitable for separating and concentrating biologically active substances in the food industry.

Membrane separation technology applied to the food industry concentration, clarification and separation, can better maintain the original color, aroma, taste and a variety of nutrients. In addition, membrane separation equipment has a simple structure, easy to operate, easy to maintain the characteristics of the chemical, pharmaceutical, biological and food industry and other fields of application more widely.

2. Application of membrane separation technology in functional foods
The development of functional food provides consumers with the best way to choose healthy food. Functional foods play a functional role in the substances known as bioactive substances, with the function of delaying aging, improve immunity, anti-tumor, anti-radiation, etc. Most of the bioactive substances are heat-sensitive, and it is crucial to retain the bioactivity and stability of bioactive substances in the extraction and separation of bioactive substances. Membrane separation technology is operated at room temperature, and it is a more ideal separation technology for the separation of bioactive substances.

Loginov et al. used ultrafiltration membranes to separate proteins and polyphenols from flaxseed peel extract, by adjusting the pH value of 4.4, so that the protein agglutination, centrifugation, and then use the molecular weight cut-off 30 KDa polyethersulfone ultrafiltration membranes for filtration of the supernatant. After centrifugation, the supernatant was filtered using a MWCO of 30 KDa polyethersulfone ultrafiltration membrane. Xu Fuping et al. combined membrane separation with alcohol precipitation to purify soybean isoflavones. Tested using 20 nm and 50 nm two pore size membrane on the ethanol extract of defatted soybean meal for ultrafiltration.

Fourth, ultra-micro pulverization technology

1. Overview of ultra-micro-grinding technology
Microcrushing technology is in recent years with the modern chemical, electronics, biology, materials and mineral development and other high-tech development and the rise of food processing at home and abroad, high-tech cutting-edge technology.

In foreign countries, the United States, Japan, marketed fruit-flavored herbal tea, freeze-dried fruit powder, ultra-low-temperature frozen turtle powder, kelp powder, pollen and placenta powder, etc., are processed using ultra-micro-grinding technology; and our country is also in the 1990s this technology is applied to pollen wall-breaking, followed by a number of taste, nutritional ratios are reasonable, easy to digest and assimilate functional foods (such as hawthorn powder, konjac powder, mushroom powder, etc.) came into being.

Ultra-micro pulverization technology is the use of mechanical or hydrodynamic methods, the material particles will be crushed to micron or even nano-scale micro-powder process. Micro-powder is the final product of ultra-fine crushing, with general particles do not have some special physical and chemical properties, such as good solubility, dispersion, adsorption, chemical reaction activity. The particle size limit so far there is no uniform standard, it is generally agreed that the particle size of micropowder defined as less than 75μm is more reasonable.

The principle of ultra-micro pulverization and ordinary crushing the same, only higher fineness requirements, it uses the addition of mechanical force, so that the mechanical force into free energy, partially destroying the cohesion between the molecules of the material to achieve the purpose of crushing.

Ultra-fine crushing technology is the use of a variety of special crushing equipment, through a certain processing technology, grinding, impact, shear, etc., the material will be crushed in the particle size of more than 3 mm to the particle size of 10 μm below the micro-fine particles, so that the product has interface activity, presenting a special function of the process.

Compared with the traditional crushing, crushing, grinding and other processing technologies, the particle size of the ultra-fine pulverized products is even smaller. Ultra-micro pulverization is based on the principle of micron technology. With the ultramicrofabrication of substances, its surface molecular arrangement, electron distribution structure and crystal structure are changed, resulting in a block (particle) material does not have the surface effect, small size effect, quantum effect and macroscopic quantum tunneling effect, which makes the ultramicro products compared with the macro-particles have a series of excellent physical, chemical and surface interface properties.

2.Application of Ultra-micro pulverization technology in functional foods
Zhu et al. prepared bitter melon ultramicro powder, and used in the treatment of diabetic patients, found that after 1 week of consumption, the patient’s blood glucose from 21.40 mmol / L down to 12.54 mmol / L, indicating that the bitter melon ultramicro powder has a better inhibition of diabetes performance, can be developed and utilized as a hypoglycemic functional food.

Sun et al. prepared apricot mushroom ultramicro powder, and studied its immunomodulatory and antioxidant effects in mice, and found that apricot mushroom ultramicro powder has good antioxidant, antiviral and antitumor functions. Kurek et al. added oat fiber ultramicro powder into wheat flour dough at a certain mass ratio, and as the proportion of the ultramicro powder increased, the volume of the dough became smaller, and its water content and elasticity increased, which provided a reference for the development of breads with high dietary fiber content. With the increase of the proportion of ultra-micro-flour, the volume of dough became smaller, the water content and elasticity increased, which provided a reference for the development of high dietary fiber content bread.

3. Prospects for the application of ultra-micro-grinding technology
Research on the application of ultra-micro-grinding technology in functional health food, both at home and abroad are in progress, but the research is still preliminary.

With the deterioration of the human living environment, water resources and air pollution phenomenon has intensified. The rising incidence of various malignant diseases stimulates people to pay more attention to their health. Therefore, people have placed great hopes on functional health food. Including ultra-micro pulverization technology, including a variety of new food processing technologies, will be more in-depth and extensive application of functional health food.

In short, with the continuous development of the modern food industry, there will be more, more advanced high-tech, ultra-fine pulverization technology in food processing is still only in a beginning stage, ultra-fine powder technology, because there are other general crushing methods do not have the advantages and characteristics of the future in the production of soups, medicinal herbs will certainly play a more prominent role in the production of energy saving, I believe that in the near future, the energy-saving, high-efficiency products of high quality new technologies will be more effective and efficient. I believe that in the near future, this energy-saving, high-efficiency products of high quality of the new technology will be more perfect.

V. Microencapsulation technology

1. Microencapsulation technology overview
Nanocapsules (nanocapsule), that is, microcapsules with nano-size, its particles are small, easy to disperse and suspended in water, the formation of a uniform and stable colloidal solution, and has a good targeting and slow release.

In the field of functional foods, the use of nano-microcapsule technology to encapsulate functional factors in functional foods can both reduce the loss of functional factors during processing or storage and effectively deliver functional factors to the gastrointestinal tract location of the human body.

The specific targeting of nanocapsules can make the functional factors change the distribution state and concentrate in specific target tissues to achieve the purpose of reducing toxicity and improving therapeutic efficacy, as well as to improve the bioavailability of the functional factors by controlling the release of the functional factors, while maintaining the texture and structure of the food as well as its sensory appeal. Therefore, nano-microencapsulation technology for the research and development of functional food provides a new theory and application platform, very conducive to the development of functional food.

Microencapsulation (microencapsulation) refers to the use of natural or synthetic polymer encapsulation materials, solid, liquid or even gaseous capsule core material encapsulation to form a kind of diameter in the range of 1 to 5000 μm, with semi-permeable or sealed capsule membrane microcapsule technology.

Nano-microcapsule technology is a new technology that uses nanocomposite, nanoemulsification, and nanostructuring technologies to encapsulate the nucleus of a vesicle to form a microcapsule in the nanoscale range (1 to 1,000 nm). Among them, the coated substance is called the core material of the microcapsule, and the substance used for coating is called the wall material of the microcapsule.

2. Application of microencapsulation technology in functional foods
2.1 Nano-microencapsulation of functional fats and oils
Zambrano-Zaragoza et al. prepared nano-microcapsules with food-grade fats and oils (safflower oil, sunflower oil, soybean oil, β-carotene, and α-tocopherol) as the core material by using the emulsion dispersion method, and investigated the properties of the nano-microcapsules to determine the optimal conditions for the preparation of the nano-microcapsules, and the average size of the food-grade fats and oils produced was about 300 nm, the The study is of some significance for the preservation and storage of fatty foods.

Zimet et al. prepared nanomicrocapsules of docosahexaenoic acid (DHA) from ω-3 series polyunsaturated fatty acids by using β-lactoglobulin and low-methoxy pectin as the carrier, the average particle size of the nanoparticles was 100 nm, and the nanomicrocapsules showed a good colloidal stability, and were able to effectively inhibit the oxidative decomposition of DHA, and the DHA product was placed in an environment of 40°C for For 100 h, only 5% to 10% of the nanomicroencapsulated DHA was oxidatively decomposed, while 80% of the untreated DHA was lost.

This study has some guiding significance for the nano-microencapsulation of long-chain polyunsaturated fatty acids before applying them to clarified acidic beverages.Gkmen et al. used spray-drying method to nano-microencapsulate the ω-3 series of unsaturated fatty acids flaxseed oil with high straight-chain corn starch, and added them to the raw dough in different amounts to study their effects on the quality of bread.

2.2 Nano-microencapsulation of antioxidant class
Antioxidants applied in functional foods mainly include phenolics, flavonoids (mainly flavonols, flavonoids, flavonoids, flavanones, flavanone alcohols, etc.), alkaloids, etc., as well as β-carotene, lycopene, lutein, curcumin, etc., which are natural antioxidants in food coloring. The use of nano-microcapsules to encapsulate antioxidants can improve their stability and bioavailability to the human body in food applications and enhance their health benefits to the human body.

Epigallocatechin gallate (EGCG) is a catechin-like monomer isolated from tea and is the most effective water-soluble polyphenolic antioxidant with biological activities such as antioxidant, anticancer and antimutagenic.

In 2010, Shpigelman et al. embedded EGCG in nano-microcapsules with thermally denatured β-lactoglobulin, and obtained nanoparticles with a size of less than 50 nm, and the product has a very good protective effect against the oxidative decomposition of EGCG, which is a good guide for the development of clarified beverages, a type of fortified food.

In 2012, Shpigelman et al. remodeled the nanoparticles by changing the ratio of β-lactoglobulin and EGCG and using freeze-drying method, and investigated the stability, size change, embedding rate, sensory properties, and experiments simulating gastrointestinal tract digestion of colloidal solutions composed of nanoparticles.

2.3 Nano-microencapsulation of Vitamins and Minerals
Vitamins are indispensable nutrients to maintain normal physiological functions of the human body and promote various metabolic processes. Vitamins can hardly be synthesized by the human body and must be obtained from food, which mainly includes water-soluble vitamins (VC, VB series, folic acid, pantothenic acid, etc.) and fat-soluble vitamins (VA, VD, VE, etc.). Making vitamins into microcapsules can greatly improve their stability. Minerals used as efficacy components in functional foods mainly include calcium, iron, zinc, selenium, etc. Microencapsulation of minerals mainly solves the problems of minerals’ own instability, the tendency to produce undesirable flavors in foods, and the reduction of toxic side effects.

Semo et al. successfully prepared nano-microcapsules of VD2 with an average particle size of about 150 nm by embedding fat-soluble VD2 with rCM as the wall material. This study showed that the concentration of VD2 in the microcapsules was 5.5 times higher than that in serum, and the morphology and average particle size of the rCM microcapsules were similar to that of naturally occurring casein. rCM microcapsules could partially protect VD2 from degradation induced by UV irradiation. rCM can be used as a nanocarrier for the embedding, protection and delivery of sensitive hydrophobic nutrients, which is of great significance for the development and production of food products enriched with lipid-poor or low-fat food products.Haham et al. prepared VD3 nanomicrocapsules (VD3-rCM) with rCM as wall material and an average particle size of (91±8) nm on the basis of the above studies.They also investigated the effect of ultrahigh-pressure homogenization on the properties of the microcapsules, and evaluated the protective effect of rCM/CM against thermal and photodegradation of VD3, and evaluated the VD3 by clinical experiments. bioavailability.

Prospects for the application of microencapsulation technology

Nano-microencapsulation technology, which is a multi-intersecting discipline involving physical and colloid chemistry, polymer physics and chemistry, dispersion and drying technology, nanomaterials in nanotechnology and nanofabrication.

As the development and extension of microencapsulation technology, the application of nano-microencapsulation technology in the processing and production of functional food has received more and more attention, especially the attention to the retention and bio-availability of the efficacy components in functional food, and in view of the problems of the efficacy components in functional food, such as low solubility, poor functional targeting, low bio-activity, and poor bio-availability, etc., the nano-microencapsulation technology has been adopted to encapsulate various efficacy components in functional food. To address the problems of low solubility, poor functional targeting, low bioactivity and poor bioavailability of functional food ingredients in the application process, nano-microcapsules are used to encapsulate various functional ingredients to enhance their functional targeting release performance in organisms, improve bioavailability and prolong the period of storage stability.

As a kind of composite phase functional materials, the development trend of nano-microcapsule will be toward the small particle size of the capsule, narrow distribution, good dispersion, high selectivity, and a wide range of applications.

Some progress has been made in the application and development of nano-microcapsule technology in the field of functional food, but for the nano-microcapsule technology itself, it has just started in both theory and application, and more in-depth research is needed.