Although people often think of bacteria and other microorganisms as harmful “germs,” many are helpful. Some bacteria help digest food, destroy disease-causing cells, or produce vitamins. Many of the microorganisms in probiotic products are the same as or like microorganisms that naturally live in our bodies. Probiotics are part of a larger picture concerning microbes and our body—our microbiome. These microbes are a combination of bacteria, fungi (including yeasts), viruses, and protozoa. Everyone’s microbiome is unique, and two people have not the same microbial cells [1].

The most common place linked to beneficial microbes is our gut (mostly the large intestine). The human gut contains over 100–1000 microbial species, more or less than about 10¹¹–10¹² CFU/g [2], which modulates the host internal environment and thus, play a major role in host health. Specifically, these organisms play key roles in defense function, good digestion (catabolism and anabolism), and impact brain-gut responses [3]. So, the main acts of the microbiota can be categorised into three groups—metabolic, protective, and trophic functions [4]. Moreover, besides the human gut, several locations in and on our body host good microbes. These locations are in contact with the “outside world” and include the mouth, vagina, urinary tract, skin, and lungs.

Bacterial colonisation of the human gut evolves and transforms over a lifetime. It begins at birth when newborns are exposed to a non-sterile environment [3] which alters the gut microbiome to a predominance of anaerobes within a few weeks of life [5]. It changes over time, depending on a dynamic relationship between the diet, genome, lifestyle, and the composition and number of drugs used, such as antibiotics. It can shift according to age, mainly around the time that the immune system starts to decline ^[3][6][3,6].

In adults, the human gut microbiota appears to have a leading phylogenetic core [7]. It was possible, by using the 16S rDNA sequencing technique to identify Gram-negative Bacteroidetes, Gram-positive Firmicutes, and Gram-positive Actinobacteria as the dominant phyla [8]. Arumugam and collaborators [9] by applying direct metagenomic sequencing methods have identified and defined three clusters/enterotypes, each characterised by a specific set of networked bacterial genera—the Bacteroides-, the Prevotella- and the Ruminococcus. This research highlights this phenomenon as occurring worldwide; although, as it was mentioned before, everyone’s microbiota profile is unique, all humans share a common pattern of gut microbiota. Usually, however, the composition of the basic intestinal microflora is stable during adulthood ^[1][10][1,10], at least until the elderly age (those over 60 years). With advancing age, microbial diversity, and composition is primarily driven by dietary factors and the microbiota, may significantly influence the inflammatory tone and health status immune function, which declines, increasing the number of facultative anaerobes, shifting the ratio of Bacteroides to firmicutes species, and marked decrease in bifidobacteria ^[11][12][11,12].

The “colonisation resistance” or beneficial usage of intestinal microflora, is considered the “barrier effect”, a mechanism used by the autochthonous gut bacteria to maintain their existence and confer protection against ingested microorganisms, including pathogens [13]. So, manipulation of the gut microflora by increasing the relative number of “helpful bacteria”, will beneficially influence the immune function, digestion, metabolism, and brain-gut communication [14]. Alterations in gut microbiota diversity may result in several disorders and diseases that can be treated with several drugs, that do not always work and are cost-effective, and inconvenient for common use. Therefore, a simple, low-cost, friendly, and natural way to improve host health has become a critical issue in the present day. In this perspective, probiotics tend to serve as bio-supplement to the host microflora and provide protection against various enteric pathogens [15].

Probiotics—a word of the modern era, the denotation “for life”—are live microorganisms that are intended to have health benefits when consumed or applied to the human body [16]. They can be found, naturally, in yogurt and other fermented foods and beverages. The microbiota of fermented products is an intricate microbial community made of indigenous microorganisms inherently associated with the raw materials and/or those that are present on the equipment and surfaces of processing sites where chosen microorganisms may be used as starter cultures [17].

Supplementation with probiotics, prebiotics, and synbiotics has shown promising results against various enteric pathogens due to their unique ability to compete with pathogenic microbiota for adhesion sites, to alienate pathogens, or to stimulate, modulate and regulate the host’s immune response by initiating the activation of specific genes in and outside the host intestinal tract. Probiotics have also been shown to regulate fat storage and stimulate intestinal angiogenesis [3].

Probiotics are made of good live bacteria and/or yeasts that naturally live in our body [15]. So, for a microbe to be called a probiotic, it must have several characteristics. These include (i) survive in our intestine after ingestion (being eaten); (ii) have a proven benefit and (iii) be safely consumed. Probiotics are also able to improve gut barrier function, competing with pathogenic microbiota for adhesion to the gut and improving their colonisation [15].

Probiotics may contain a variety of microorganisms. The most common are bacteria that belong to groups called lactobacilli, lactococci, and bifidobacteria [18]. Other bacteria may also be used as probiotics, like Pediococcus and Streptococcus ^[19][20][19,20] and so may yeasts of the genera Saccharomyces like Saccharomyces boulardii [21].

2. Probiotics in Non-Dairy Fermented Beverages

The major source of probiotics is fermented dairy products, however, a study in 2014 published in Food Microbiology ^[22][34] isolated bacteria from red wine and tested them for probiotic characteristics. There were isolated and tested 11 strains of Lactic Acid Bacteria (LAB) belonging to Pediococcus pentosaceus, Lactobacillus casei, Lactobacillus plantarum, and Oenococcus oeni. More recently, Le Roy and co-workers ^[23][35] performed a study that corroborated the initial one by showing that the occasional glass of red wine could be beneficial for our gut health. The researchers found that our gut microbiomes can be affected by alcoholic beverages including beer, cider, spirits, and both red and white wine. The diversity of alcoholic, low-alcoholic, and non-alcoholic fermented beverages constitute an integral part of the food culture of many European countries. A diversity of fermented beverages is produced from both edible and inedible raw materials. A wide range of substrates, cereals, fruits, and vegetables are used for its production.

3. Prebiotics Derived from Wine and Other Fermented Beverages

Consumers worldwide are increasingly aware of the relation between nutrition and health. The major segment of this market includes foods designed to increase gut health such as prebiotics. Prebiotics are defined in 1995 by Gibson and Roberfroid ^[24][92] as “nondigestible food constituents that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacterial species already resident in the colon”. Later, Gibson et al. ^[25][93] defined prebiotics as “a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora, that confer benefits upon host well-being and health”. The International Scientific Association for Prebiotics and Probiotics (ISAPP) in 2010 extended the definition to contain also the functionality of the prebiotics: “a selectively fermented ingredient that results in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health” ^[26][94]. Prebiotic dietary fibers turn into carbon sources for primary and secondary fermentation pathways in the colon and maintain digestive health in several ways. Prebiotics are generally low or nondigestible oligosaccharides and particularly fructooligosaccharides and inulin are usually agreed-upon prebiotics. Other prebiotic dietary fibers are beta-glucans ^[27][95], isomaltooligosaccharides, guar gum, maltodextrin, xylooligosaccharides (XOS), and arabinooligosaccharides. Resistant starch can also promote health by producing a high level of butyrate; so, it has been suggested to be also classified as a prebiotic ^[28][96]. They are classified as prebiotics since they are not hydrolysed or absorbed in the upper part of the gastrointestinal tract, and affect beneficially the selective stimulation of the growth of bacterial present in the colon and may inhibit pathogens, and therefore they can have health benefits ^[24][29][92,97]. Prebiotics of several types occurs naturally in asparagus, leeks, onions, soybeans, wheat, oats, Jerusalem artichokes, garlic, barley, bananas, rye-flour, and chicory ^[30][31][98,99]. In most of these foods, the prebiotics concentrations range between 0.3% and 6% of fresh weight; for chicory, these values are between 5% and 10% while in Jerusalem artichoke they can reach up to 20%. Fructooligosaccharides are mainly present in asparagus, Jerusalem artichoke, chicory, sugar beet, onion, garlic, barley, wheat, honey, banana, tomato, and rye in a concentration ranging from 0.15% to 0.75% of FOS in natural food ^[32][33][34][100,101,102]. Chemically, fructooligosaccharides are short- and medium-length chains of β-D-D-fructans in which fructosyl units are bound by β-2-1 osidic linkage. Fructooligosaccharides are not digested by the human gastrointestinal tract, obtained from plant sources, and when they reach the colon, they beneficially stimulate the growth and strengthening of specific bacteria in the intestine ^[35][103]. Inulin is a heterogeneous blend of fructose polymers found in nature as plant storage polysaccharides (degree of polymerisation, DP < 10) ^[36][104] such as in wheat (1.0–3.8 g/100 g), raw onion pulp (1.1–7.5 g/100 g), garlic (9.0–16.0 g/100 g), Jerusalem artichoke tuber (16.0–20.0 g/100 g), chicory root (35.7–47.6 g/100 g), asparagus raw (2.0–3.0 g/100 g) and barley (0.5–1.0 g/100 g) ^[37][105]. Beta-glucans (β-glucans) are linear polysaccharides formed by D-glucopyranosyl units with a mixture of β-(1,3) and β-(1,4) glycosidic linkages. β-glucans are chemical, non-starch polysaccharides with repeating glucose residues in linear chains or multiply branched structures with the glucose units being branched in diverse ways depending upon the source of origin. Cereal β-glucans chains are linear, composed by consecutive linked (via β-1–3 linkages) of cellulosic oligomers, i.e., segments of β-1–4 linked glucose residues ^[38][39][106,107]. For microbial β-glucans, the β-D-glucopyranose units are linked together through β-(1,3) linkages to form a long backbone, whereas side chains mostly arise through β-(1,6) linkages ^[40][108]. β-glucans are soluble fibers in the cereal grains endosperm cell walls such as in oat and barley (up to 7%) or in mushrooms, algae, and other marine plants ^[27][41][42][95,109,110], they can also occur in rye and rice ^[43][111]. Isomaltulose is a naturally occurring disaccharide composed of α-1,6-linked glucose and fructose, and it is considered a prebiotic ^[44][112]. It occurs naturally in honey and sugarcane juice and products derived thereof ^[45][113]. Xylooligosaccharides is a prebiotic with health benefits ^[46][114] and they are composed of sugar oligomers of xylose units and are found naturally in fruits, honey, vegetables, and bamboo shoots ^[47][115]. Phenolic compounds are naturally occurring secondary metabolites of plants that comprise of several compounds that are classified mainly based on structure ^[48][116]. Plant-based beverages, comprising fruits, vegetables, and wine, are rich sources of dietary polyphenols. Preclinical and clinical studies suggest that polyphenols are also able to express prebiotic properties and exert antimicrobial activities against pathogenic gut microflora ^{[49][50][51][52]}[117,118,119,120]. Parkar et al. ^[53][121] showed the inhibitory effect of citrus polyphenols such as hesperetin, naringenin, poncirin, and diosmetin on the growth of the human gut bacteria. Also, wine phenolic compounds have been suggested to modulate gut microbiota inducing prebiotic-like effects of the growth of beneficial bacteria and the inhibition of pathogenic bacteria ^[54][55][56][122,123,124]. During wine consumption, for example, oligomeric procyanidins arrive in the colon ^[57][125]. The red wine phenolic compounds may modify the gut microbial composition by their antimicrobial properties inhibiting non-beneficial bacteria from the human microbiota and potentiate the growth of probiotic bacteria such as bifidobacteria, and this, in turn, may affect their functional relations with the host ^[58][126]. Likewise, intestinal bacteria metabolise wine polyphenols into specific bioavailable metabolites. The beneficial actions described for wine have been recognised to these phenolic microbial-derived metabolites rather than the initial precursors present in wine ^[58][59][126,127]. Non-dairy probiotic fermented beverages, using a variety of subtracts, such as cereals, soy milk, fruit and vegetable juices, have become known for their health-promoting qualities. These fermented beverages are principally attractive due to their absence of dairy allergens such as lactose, low cholesterol content, and vegan friendly ^[60][128]. To this end, cereal-based beverages have natural prebiotics due to the existence of indigestible fibers. Cereals such as oats, wheat, maize, rye, millet, sorghum, barley, or rice are used to produce cereal-based fermented beverages. Oats, a noteworthy wellspring of β-glucans which can lessen LDL cholesterol, are referred to work as a prebiotic by boosting bifidobacteria numbers in the gut. Processing conditions such as fermentation could support the development of a cereal beverage with high beta-glucan values ^[61][129]. Oat-fermented beverage with high β-glucans with banana was studied as an alternative from milk proteins or lactose-intolerant people ^[41][109]. Barley and malt have also been used as beverage substrates ^[62][130]. European barley beer is an example of a cereal-based fermented beverage ^[63][132]. In Africa traditional beers diverge from the western-type; they are frequently less carbonated, sour, and have no hop. Examples are pito and burukutu which are brewed simultaneously by fermenting malted or germinated single cereal grains or a mixture of them ^[64][134]. Cereal fermentation in Africa and Asia involves mainly the processing of maize, rice, sorghum, and millets ^[65][135]. For example, in Zambia and the Democratic Republic of Congo is produced a non-alcoholic spontaneously fermented cereal-based beverage called Munkoyo ^[66][136], in Tanzanian is also produced a fermented cereal grains beverage with sorghum, maize, and millet named Togwa ^[67][131], in West African is produced a fermented sorghum gruel named Ogi-baba ^[68][137]. In Africa and Asia, many types of opaque beers named Tchoukoutou are produced by malting red sorghum ^[69][138]. Water-soluble and insoluble arabinoxylans, β-glucan, oligosaccharides, and resistant starch are cereal indigestible but fermentable dietary carbohydrates, which are used as fermentation substrates for probiotic lactic acid bacteria and could be used to realise the beneficial effect of both the probiotic organisms and imparting prebiotic effects ^[70][139]. According to Jovanovic-Malinovskat et al. ^[71][140] that make an oligosaccharide profile of 32 fruits (total FOS ranged from nd-0.89 g/100 g fresh weight of edible sample) and 41 vegetables (total FOS ranged from nd-3.32 g/100 g fresh weight of edible sample) observed that in general fruits contained low amounts of total fructooligosaccharides. The content of total oligosaccharides of fruits in a descending order was nectarine > watermelon > pear > raspberry > blueberry and for vegetable was scallion > onion > garlic > leek > spring garlic. The highest content of fructooligosaccharides was found in nectarine (0.89 ± 0.031 g/100 g fresh weight). The vegetable with the highest quantity of fructooligosaccharides was scallion (3.32 ± 0.108 g/100 g fresh weight). According to several authors, beverages formulated with fruit and vegetable juices are promising food matrices to serve as carriers of probiotic bacteria ^[72][73][141,142]. There is a great diversity of fermented beverages produced with fruits from Asia, Africa, and Latin America. Grape/grape juice is perhaps the most fermented beverage (wine) from an economic point of view, there are other fruit fermented beverages such as pineapple in Latin America and jackfruit in Asia ^[74][143]. Fermented beverages from agave (Pulque), coconut palm (Taberna), or coyol palm (Tuba) are also produced in Mexico ^[75][76][77][144,145,146].