Lactic acid bacteria refers to sugar fermentation, the main products are a kind of lactic acid no spores, bacterium of positive of dyeing the floorboard of the bacteria. Those who could glucose or the lactose from fermentation process of lactic acid bacteria produce the bacteria collectively referred to as lactic acid bacteria. This is a group of quite a large bacteria, except a few outside, among them the majority is essential to the human body and has important physiological functions of microbes, which are widely exist in the human body in the intestinal tract. Bulgaria lactobacillus and streptococcus thermophilus cultured is people through the yogurt the earliest known health lactic acid bacteria. And \"probiotics\" means to get to the human body bowel and produce the effect of health living organisms. The current fermentation on common dairy market probiotics are: long colon bacillus, colon bacillus, animal youth colon bacillus, lactobacillus casei, eosinophilic acid lactobacillus, rat lee sugar lactobacillus, etc. Because they can fermenting sugar produce lactic acid, so also belongs to the health of lactic acid bacteria. Can say, probiotic products is paying more attention to the activity of lactic acid bacteria in the intestines and the survival rate of health effect.
Lactic acid bacteria from the main form classification ball and lever two kinds big. According to the biochemical taxonomy, lactic acid bacteria can be divided into the milk of bacteria, streptococcus stem of, Ming beads of bacteria, colon bacillus and juice of coccus of 5 genera, and each is had so many strains, some strains also included several subspecies. These microbes are related with lactic acid fermented, including lactobacillus and colon bacillus and human body health care is more close relationship. Lactobacillus genera of the lactic acid bacteria are generally thin stem form, mostly for the chain arrangement. They are no spores gram-positive bacteria, micro need oxygen. In fermentation industry application in the mainly has: the same type fermented milk stem bacteria, such as Germany's lactobacillus, Bulgaria, lactobacillus, Swiss milk stem bacteria, eosinophilic yoghurt stem, bacteria and lactobacillus casei; Alien lactobacillus fermentation, such as short stem and milk fermented milk coli bacteria. Native to Lactobacillus (Lactobacillus) is the most important, most industry, especially in food industry commonly used strains. Colon bacillus genera of the bacteria because its bacteria tipped with branching named, they are no spores gram-negatie organisms, especially sexual anaerobic. At present known stem normally antibacterial 24, used in the production of only five fermentation dairy products, which normally other vertebrates stem bacteria, long colon bacillus, normally short stem bacteria, baby stem normally bacteria and youth colon bacillus, they all exists in the gut. Piece of coccus is four league shape arrangement lactic acid
bacteria. Commonly used: lactic acid piece of coccus and a pentose sugar piece of coccus.
Biological activity bacteria in the body (lactic acid bacteria) reduce the cholesterol while, can reduce the triglycerides, make increase HDL, so as to achieve the purpose of improving blood fat. The intestinal flora lactic acid bacteria (including added in the intestinal tract in biological activity bacteria (lactic acid bacteria)) but by adjusting the intestinal inhibiting these bacteria of the enzyme activity, to reduce the risk of deeloping cancer, have the antitumor effect.
Lactic acid bacteria in the human body is often in the intestinal bacteria. Can change the intestinal environment, restrain harmful bacteria breeding (e. coli,
salmonella and other harmful bacterium group), adjust the balance of gastrointestinal tract flora. Lactic acid bacteria through the adhesion element and the intestinal mucosa cells closely, in the bowel glues the film surface planting sites, become the main components of the physical barrier, so as to restore the host resistance, repair, intestinal barriers, and heal intestinal disease role. Many years research shows that, biological activity bacteria (lactic acid bacteria) for some corruption bacteria and low temperature bacteria have better inhibition action. Can be used for prevention and control of diarrhea, dysentery, enteritis, constipation and bowel function disorder due to a variety of diseases and skin inflammation.
The modern medical science thinks, because the human body aging free radicals accumulation and cause. If can be reduced in the level of free radicals, they can slow down the aging process. Lactic acid bacteria can remove the body produces of free radicals, which has the slow cell ageing prolong life role.
Lactic acid bacteria in its unique advantages to be concerned and biological preservatives used in food as fresh. Lactic acid secretion streptococcus often produce Nisin (Nisin,), it to animals have no toxic effect, has been American FDA approved the application in the food to control easy to cause the food born diseases microbes. Use as a meat can reduce lactic acid bacteria culture nitrite residue. Lactic acid bacteria high efficiency degradation nitrite ability is through the lactic acid bacteria produce nitrite reductase ability and produce ability of common effect of lactic acid, lactic acid bacteria can produce nitrite reductase, make nitrite degradation, and to
reduce product nitrite content. Meat products in the fermentation process of lactic acid bacteria, along with the pH value of down, the decomposition of nitrite or nitrate accelerated, produce NO, NO and muscle red protein (Mb), the hemoglobin (Hb) formation and the nitro muscle red protein (NO-Mb) and the nitro hemoglobin (N0 a Hb), make the meat is beautiful cherry red or rose red, reduce the nitrite residues.
Due to the cultivation of high value added difficulty lactic acid bacteria, foreign resistance is poor, in the transport, storage and application process large number of death, serious impact on the overall value of the microbial agents. Therefore, how to develop high concentration and strong vitality of lactic acid bacteria, become the microbial scientists pursuing dreams.
α-amylase
Amylase exist widely in animals, plants and microbes, in food, fermentation, textiles and paper industries are in application, especially in starch processing industry, microbial amylase is widely used and has successfully replaced the chemical degradation; At the same time, they also can be used in the pharmaceutical and chemical industry, etc.
According to the hydrolysis of amylase on starch in different ways, it can he divided into alpha amylase, beta amylase, glucose amylase and different amylase, etc. Among them, the alpha amylase (alpha 1, 4-glucan-4-Portugal gathered indican enzyme) is exocellular enzyme, its role in starch from molecular internal randomly cut the chain starch alpha 1, 4 glycosidic bond, and the generated dextrin and reducing sugars, at the end of the product, the carbon atoms configuration for alpha configuration, it is called alpha amylase.
Alpha amylase source widely distributed in animals (saliva, pancreas, etc), plant (malt, behenic food) and microbial, main existing sprout grain aleurone cells, of course, from the microorganisms to higher animals and plants, all can be isolated, is a kind of important starch hydrolysis enzyme, also is the most widely used in industrial production of one of the enzyme preparation. It can be made by microorganism fermentation preparation, also can be extracted from plants and animals. Different sources of the nature of the alpha amylase has a certain difference, industry of the main application is fungi and bacteria alpha amylase.
At present, the alpha amylase has been widely used in modified starch and starch sugar, baking industry, beer brewing, alcohol industry, fermentation and textile and the many industries, it is a kind of important industrial YongMei. As in starch processing industry, microbial alpha amylase has successfully replaced the chemical degradation; Alcohol can significantly improve the industrial wine rate. The applied in all kinds of industries to shorten the production cycle, improve the product yield and the utilization rate of raw materials, improve product quality and saving food resources, all has the extremely vital role.
In recent decades, malt alpha amylase and microbial alpha amylase is widely used in baking industry. These enzymes for bread industry, make these products bigger, better color, more soft particles. So far, the baking industry alpha amylase has been from malted barley and bacteria, fungi leaf extract. Modern continuous baking process, in the flour add alpha amylase can not only increase rate, reduce the dough fermentation viscosity (improve the volume of products and quality of a material), increase the
dough in the sugar content, improve the taste of bread baking, skin color and quality, but also can extend the baking food preservation of the time. In the storage process, bread particles become dry, hard, skin no longer and crisp, lead to the taste of bread to become poor. These changes collectively referred to as bad. Every year for only bread metamorphic the loss caused by more than $100 million. Various traditional additives are used to prevent bad food, in order to improve the quality of a material of baking food and taste.
Recently, people begin to pay close attention to the enzyme as a preservative, BaoXianJi dough improvement in the role, such as a chain of amylase and alpha amylase cooperate can effectively used for corrosion protection. However excessive alpha amylase can lead to bread sticky. Therefore, the recent trend is to use temperature stability (ITS) alpha amylase, they in starch after liquefaction activity is high, but in the baking process finished before the deactivation. Although that has found a large number of microbes can produce alpha amylase, but has the temperature stability properties of alpha amylase only in several microorganisms were found.
Alpha amylase's main market is the product of the hydrolysis of starch, such as glucose and fructose. Starch was transformed into high fructose corn syrup (HFCS). Because of their high sweetness, be used to drink soft drinks industry of sweeteners. The liquefaction process is used in high temperature heat stability good alpha amylase. Alpha amylase in starch on the application of liquefied art has quite mature.
Relatively, about the alpha amylase inhibitors also has a lot of study reported at home and abroad. Alpha amylase inhibitors) is a kind of hydrolysis enzyme. It can effectively suppress the intestinal saliva and the activity of pancreatic amylase, obstruction of food carbohydrates in hydrolysis and digestion, reduce the human body sugar absorption, reduce blood glucose and blood fat content, reduce the fat synthesis, reduce weight. Reports have suggested that, alpha amylase can help improve the resistance of sugar diabetes patients. This research since s O s 2 O and 9 O s very active, but the alpha amylase inhibitors research work is still at the stage of foundation, have so far not been effective and reasonable development application. Alpha amylase, as a kind of important industrial YongMei, has been used widely in starch and starch based industry, and has been a good use effect. To shorten the production cycle, improve the product yield and the utilization rate of raw materials, improve product quality and saving food resources, all has the extremely vital role. But due to the different source of alpha amylase the nature of the difference, lead to its application by certain limitations, such as high temperature resistant alpha amylase in high temperature condition to give play to the greatest energy, and the low temperature and temperature in the use efficiency is very low, limiting its application scope. In addition, different alpha amylase used in the food, the safety of some have not fully affirmation. Therefore, in the later study, can through the chemical method or biological method with alpha amylase on modification, expand the use of the scope, improving efficiency. However, with the development of science and technology, the development of research, alpha amylase will get more extensive application.
Valency, Oxidation State and Bonding
A knowledge of valency and bonding theory serves as the key to correct formulas. In general, the writing of formulas with elements and radicals that have a fixed valence (or oxidation state) is easy, if a knowledge of electrostatics is applied. The real difficulty stems from elements that can assume several oxidation states, from which a variety of ions, molecules, and radicals can result, and a lack of knowledge of nomenclature, which is not always consistent.
Molecules, some ions, and radicals consist of two or more atoms bonded together in some definite manner. In general, the bonds may be ionic or covalent. An ionic bond is formed by the transfer of electrons from one atom to the other. One atom then takes on a positive charge (the cation) and the other a negative charge (the anion). The ion pair that results is held together loosely by electrostatic attraction. In other cases, electrons are not transferred, but are shared between atoms. In elementary molecules with identical atoms, such as Cl2, N2, and O2, the electrons are shared equally to form a covalent bond. On the other hand, in heteronuclear molecules which consist of unlike atoms, the electrons forming the bond are shared unequally. For this case the bonding is termed polar covalent.
The valency or oxidation number of an atom is determined by the number of electrons that it can take on, give up, or share with other atoms. According to valency theory, most atoms consist of neutrons, protons ( + ), and electrons ( - ). The neutrons and protons are contained within the nucleus, and a number of electrons, corresponding to the number of protons (atomic number) in the nucleus, are arranged in orderly rings outside. The outer ring contains the valence electrons. If electrons are lost, the atom becomes a positively charged ion, and if electrons are gained, the atom becomes a negatively charged ion.
Except for inert elements (such as argon) that already have complete rings, atoms tend to gain or lose electrons so as to assume or approach complete rings. To do this, they must team up with another atom in some manner. In the formation of ions, atoms of two elements undergo reduction and oxidation: one gains electrons and the other loses electrons. In the exchange, the metal or metal-like element loses electrons to gain or approach a stable condition with no electrons in its outer ring. The nonmetal steals electrons from the metal to complete its outer ring to eight electrons, a stable configuration. This exchange is normally accomplished by the release of a great deal of energy.
The chlorine atom also serves as an example of polar covalent bonding in its various possible combinations with oxygen. The chlorine atom contains several electrons in its outer ring. Oxygen has six electrons in its outer ring and needs two more to complete the ring. These it can obtain in various ways by sharing electrons with the chlorine atom, forming various molecular species which may or may not be charged as illustrated in Fig.
The electrons contained in the outer shells are represented by dots for simplicity. With oxygen, chlorine tends to share one, three, four, five, or seven of its electrons, to form Cl2O, ClO2- , ClO2, ClO3-, and Cl2O7. The oxides from which ClO2- and ClO3- are derived have never been isolated. However, compounds of chlorine with oxidation numbers of l + , 3 + , 4 + , 5 + , and 7+ are well defined. Sulfur, nitrogen, and the halogens are nonmetals that are capable of exhibiting a wide range of oxidation numbers because of their ability to take on or share electrons to complete the outer shell to eight or to give up one or more electrons to reach a stable configuration. Manganese, chromium, copper, and iron are examples of metals that can obtain several oxidation states by yielding or sharing one or more electrons. Manganese is an extreme case in that it can yield or share two, three, four, six, or seven electrons.
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