Stress, poor diet, and antibiotic treatments upset the balance of intestinal bacteria and increase the ratio of harmful to beneficial bacteria in the gut. Increased harmful bacteria reduce the body’s resistance to disease, intestinal disorders, inflammatory diseases, infections, damage to the integrated structure of the intestinal mucosa, and weight loss. In this situation, how can the microbial condition of the intestine be regulated and general health be improved?
One of the most important and newfound solutions is diet intervention at three levels:
- Receiving beneficial bacteria (probiotics)
- Intake of indigestible oligosaccharides (prebiotics)
- Receiving both components (synbiotics)
According to the FDA, WHO probiotics are living microorganisms, including bacteria and yeasts, that play a role in health if they are present in sufficient numbers in the host intestine. What is certain is that the gut contains a lot of useful and useless bacteria. Under the conditions of the disease, the useless bacteria multiply and the balance between these two categories is disturbed.The word probiotic comes from Greek, but the word is made up of the Latin prefix “Peru” and the ancient Greek word “bios”, a linguistic combination meaning “for life”. It is commonly used for bacteria that have beneficial effects on humans and animals. The term probiotic was technically defined by a committee of experts as “living microorganisms that, when consumed in certain numbers, have a health-enhancing effect in addition to other common nutritional effects.” Each product should have the minimum amount needed daily to create health effects to improve the growth and proliferation of beneficial bacteria in the digestive system. The minimum for probiotics is 106. In 1899, pediatrician Henry Tissier discovered a small number of Y-shaped bacteria in the feces of children with diarrhea. On the other hand, the number of these “Bifid” bacteria was very high in healthy children. He suggested that the bacteria could be used by patients with diarrhea to restore the gut microbial flora. In 1906 ELIE METCHNIKOFF proposed a hypothesis that the lactic acid bacteria could be replaced or destroyed by lactic acid bacteria. He considered these bacteria to increase longevity and wrote the scientific basis of this hypothesis in the book (Long Life). Over time, other changes were made in the definition as well as the discovery of other effects of the consumption of living microorganisms. In 1974, PARKER announced that these microorganisms were involved in the microbial balance of the gut. In 1989, Fuller called probiotics living food microorganisms. And the last definition was the FAO committee, which we discussed earlier. Fermented dairy products now make up the bulk of the probiotic market. Because a large part of dairy products from previous periods for the survival of fermenting bacteria have been tested and organized to some extent, the current knowledge can be evidence of adequate survival of probiotic cultures. On the other hand, dairy products are a good carrier for such cultures.
Key steps in selecting probiotic cultures
One of the most important steps that has been taken in the case of probiotic bacteria over time is the selection of a bacterium as a probiotic culture. There are considerations to be considered in these choices.
- The genus of bacteria is of human origin
- It is non-toxic and non-pathogenic
- They are resistant to acid-bile and oxygen conditions
- Has the ability to produce antimicrobial inhibitory compounds and has antagonistic activity against pathogenic bacteria
- Has the ability to stick and connect to the intestinal mucosa
- Have observable efficiency and effectiveness
- Has the ability to reproduce and accumulate in the human digestive system
- Be able to withstand the conditions of the production process and the possibility of survival during the life of the product
- The ability to survive in a high population (preferably 106 to 108) bacteria
- No negative effects during fermentation and storage time on product quality (such as taste, aroma, and texture)
Probiotic cultures
Most commercially available probiotic cultures are either in the form of frozen concentrated cultures or in the form of frozen freezing powders. And they are often prepared for direct applications or DVS. Cultures commonly used to produce probiotic products include Lactobacillus, Streptococcus, and Saccharomyces. Research into other types of probiotics is ongoing. Many questions have been raised about the identity and potential effects of probiotic cultures on consumer health, such as comparing the nutritional value of foods containing probiotics with traditional fermented foods, and the effect of production and storage methods on the shelf life of probiotic bacteria. The main reason for using probiotics is to take advantage of the desired clinical properties, but in the meantime, to produce the products that can be offered, some essential needs must be met. The most important of these needs is the survival of sufficient probiotic cultures in the product, their endurance during production, and maintenance of the product.
Some of the factors that determine the effects of probiotic cultures on dairy products are as follows:
- Ambient temperature plays an important role in the shelf life, viability, stability, and endurance of probiotic cultures.
- Environmental compounds such as oxygen content, carbohydrate content, aqueous activity, acidity or alkalinity of the environment, the number of degraded proteins that provide essential amino acids for bacteria, The amount of broken-down fats that supply short-chain fatty acids, Communication, and the effect of probiotic microorganisms and cultures due to the production of substances that can directly or indirectly increase or decrease the activity of bacteria or even inactivate them.Bacteriocins have antibiotic properties that disrupt the composition of normal gut bacteria as a result of consumption and antibiotic therapy and are a reducing parameter for starter activity and probiotic cultures.
- Substances derived from the activity of lactic acid bacteria such as lactic acid, hydrogen peroxide, benzoic acid, and amines from the carboxylation of amino acids are also effective factors in reducing the activity of probiotic bacteria.
- The timing of inoculation of probiotic cultures is also very important. When these cultures are added to the product after fermentation and before or after cooling, at 8°C, the interactions between probiotic bacteria and dietary performance are probably lower. Although these exchanges continue during long-term storage and storage, these reactions occur less frequently with proper temperature principles.Another case is the physical condition of probiotic cultures. Studies show that bacteria in the logarithmic growth phase are more sensitive to nutrients than in the stable growth phase.
- Hydrolysis of caseins is a contributing factor in the rate of fermentation and ultimately the stability of probiotic cultures.
Mechanism or how probiotics play a role in the human digestive system
Some probiotic microorganisms produce substances that are inhibitory in the laboratory. However, their antimicrobial action is not just due to the production of acid. Lactobacilli are well established in the early parts of the small intestine and adhere to receptors on the surface of its mucosal cells. By absorbing nutrients and excreting lactic acid and possibly antimicrobial compounds, they metabolize and consume a significant portion of the available lactose. The concentration of lactose that reaches the large intestine is so low that it does not cause destructive symptoms. It also improves the strength and frequency of defecation. In addition to the above two effects, from 1989 to 1991, a scientist named Sellars showed that the presence of this bacterial population was enough to stimulate the immune system and protect against some cancers. Unlike lactobacilli, bifidobacteria accumulate and multiply on the lining of the large intestine and, by absorbing nutrients and producing lactic acid and antimicrobial compounds, make the conditions unfavorable for the growth and multiplication of undesirable bacteria. The dominance of bifidobacteria on the wall of the large intestine facilitates the passage of feces due to the ability to metabolize a polysaccharide called mutin. Accumulation of these bacteria prevents the multiplication and accumulation of undesirable bacteria such as Escherichia coli or yeasts and protects the person from diarrhea related to the overgrowth and proliferation of these microorganisms. Accumulation and growth of probiotic bacteria affect the growth of bacteria that break down the protein in the stool and this restriction appears to reduce the risk of producing and releasing carcinogenic compounds during microbial fermentation in the rectum. The health effects of probiotics are related to the activity and presence of their living cells in the gastrointestinal tract, secretory metabolites, and even the remnants of their dead cells.
Also, probiotic products are not limited to dairy products and in recent years have been used in other food industries, food-medicine, dietary supplements, and even fodder.
References:
Sodini, I., Lucas, A., Oliveira, M.N.D., Remeuf, F. and Corrieu, G., 2002. Effect of milk base and starter culture on acidification, texture, and probiotic cell counts in fermented milk processing. Journal of Dairy Science, 85(10), pp.2479-2488. DOI: 3168/jds.S0022-0302(02)74330-0
Heller, K.J., 2001. Probiotic bacteria in fermented foods: product characteristics and starter organisms. The American journal of clinical nutrition, 73(2), pp.374s-379s. DOI: 1093/ajcn/73.2.374s
Tripathi, M.K. and Giri, S.K., 2014. Probiotic functional foods: Survival of probiotics during processing and storage. Journal of functional foods, 9, pp.225-241. DOI: 1016/j.jff.2014.04.030
