beverages

Article Technique of Mbege, a Produced in Northeastern

Ryosuke Kubo 1,* and Method Kilasara 2

1 Graduate School of Global Environmental Studies, Kyoto University, Kyoto 606-8501, Japan 2 Faculty of Agriculture, Sokoine University of Agriculture, Morogoro P.O. Box 3008, Tanzania; [email protected] * Correspondence: [email protected]; Tel.: +81-75-753-6101

Academic Editor: Shao Quan Liu Received: 16 May 2016; Accepted: 26 July 2016; Published: 3 August 2016

Abstract: Mbege is a beer made of banana ( spp.) and finger millet (Eleusine coracana). It is the most popular indigenous alcoholic beverage in northeastern Tanzania, and plays an important role in the economy of the region. In this study, we observed and recorded a detailed traditional technique for brewing mbege. We observed that mbege production was divided into three major steps: nyalu preparation, mso preparation, and mixing. Fermented porridge made of ripened banana, called nyalu, was used as a source of . As a source of fermentable sugars, a sweet porridge made of germinated finger millet called mso was used. In mso preparation, a brewing technique to enhance the effectiveness of saccharification was used. After the preparation, these two types of porridge were mixed. The ethanol concentration of the mixture increased when it was fermented for 6 h, and it then became mbege. It was supposed that yeasts in the nyalu converted fermentable sugars in the mso into ethanol. We found that the brewing technique used in the production of mbege in northeast Tanzania was similar to that used in southern Tanzania. We also demonstrated that the stem bark of Rauvolfia caffra, which was called msesewe and used as an additive in mbege production, accelerated the fermentation of nyalu and therefore increased the rate of ethanol production in the brewing of mbege. This result was consistent with the traditional knowledge in the field about the effect of msesewe on mbege production.

Keywords: Africa; alcoholic beverage; banana; brewing; food culture

1. Introduction Indigenous alcoholic beverages are alcoholic beverages produced with locally available ingredients, instruments, and techniques. Although the production of indigenous alcoholic beverages has decreased globally in recent years due to the spread of mass-produced alcoholic beverages, indigenous alcoholic beverages are still popular in regions of Africa south of the Sahara desert. Statistically, about half of the total alcohol consumption in sub-Saharan Africa is in the form of indigenous alcoholic beverages [1]. In this region, these beverages take on socially, economically, and nutritionally important roles. They are served when people gather for social meetings in order to facilitate communication, and are also known to accompany religious and royal ceremonies [2–4]. In the case of cooperative work such as opening a field, weeding, and home building, it is served as an incentive and as a reward for work [2,3,5,6]. Producing indigenous alcoholic beverages is one of the precious few opportunities for women to earn a cash income [6,7]. They are also used as a source of nutrition and clean water [2,8]. Indigenous alcoholic beverages are necessary for people living in sub-Saharan Africa. Therefore, we must learn more about these beverages in order to further our understanding of the region.

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Tanzania is one of the sub-Saharan African countries in which indigenous alcoholic beverages are most abundantly produced and consumed. According to a report by the WHO, 87% of the total alcohol consumption in Tanzania comes in the form of indigenous alcoholic beverages [1]. This proportion of total consumption is more than 1.5 times larger than the average percentage of alcohol consumption attributed to indigenous alcoholic beverages in all countries of sub-Saharan Africa. More than 20 varieties of indigenous alcoholic beverages are found in Tanzania [9]. Among them, mbege, a banana beer made of banana (Musa spp.) and finger millet (Eleusine coracana), is the most popular indigenous alcoholic beverage in northeastern Tanzania [10]. However, in spite of its popularity and importance in the region, detailed brewing techniques of mbege had not yet been investigated prior to this study. Therefore, we carried out this study in order to clarify and record the brewing techniques of mbege.

2. Materials and Methods

2.1. Field Field research activities such as recording observations, conducting interviews, taking measurements and performing on-site trials were carried out at Kilema kaskazini ward (9669 inhabitants divided into 2166 households) located in northeastern Tanzania [11]. The field research was carried out in July and November of 2015 and in January of 2016.

2.2. Details of Mbege Production The details of the brewing technique of mbege were clarified by observation and interview. During the heating process in mbege production, changes in the temperature of the samples were measured using a handy infrared thermometer (826-T3; Testo, Kanagawa, Japan).

2.3. Measurement of the Changes of Ethanol Concentration, Brix Value and pH in Mbege Production The changes in ethanol concentration, Brix value and pH during mbege production were measured as described below. Ethanol concentration was measured by using a kit for measuring ethanol concentration in saliva (Q.E,D® Saliva Alcohol Test; OraSure Technologies Inc., Bethlehem, PA, USA). We diluted samples with water as needed before taking the measurement. We determined the Brix value of samples by using an Abbe refractometer (FHR-1; TGK, Tokyo, Japan). The pH values were measured using a handy pH meter (B-212; Horiba Ltd., Kyoto, Japan). All treatments and experiments were carried out on location using instruments we brought with us.

2.4. On-Site Trial to Verify the Effect of Msesewe In northeastern Tanzania, stem bark of Rauvolfia caffra is used as an additive in mbege [12]. It is called msesewe in the Chagga language and used for mbege production (Figure1). Msesewe was dried and ground into powder before being used for mbege production. People working in this region believed that it accelerated fermentation and increased the final ethanol concentration of mbege. The effect of msesewe on mbege production had not been verified prior to our study. Therefore, we investigated its effect by conducting an on-site trial. In the trial, we prepared two types of mbege, one with and one without msesewe, each according to the brewing techniques we learned previously during the observation and interview phases of this study. Ethanol concentration, Brix value and pH of samples, which were measured during the brewing process, were obtained using the methods described above. These measured parameters of mbege batches brewed with and without msesewe were compared to verify the effect of msesewe on mbege production. Beverages 2016, 2, 21 3 of 10

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Figure 1. Msesewe. Figure 1. Msesewe. 3. Results and Discussion 3. Results and Discussion 3.1. Varieties of Cultivated in the Research Field 3.1. Varieties ofThe Bananas banana Cultivated is a fruit produced in the by Research several kinds Field of large herbaceous plants in the genus Musa. It is originally domesticated in southeastern Asia and brought into other parts of the world. In several The bananaparts of sub is a‐Saharan fruit produced Africa, it is eaten by several as a staple kinds food. ofIt is large the most herbaceous important crop plants as a staple in the food genus Musa. It is originallyfor the domesticated Chagga people in in southeastern northeastern Tanzania. Asia and We brought found that into there other were parts 18 varieties of the of world. banana In several being cultivated within the research field (Table 1). Among them, ndishi was most frequently used parts of sub-Saharan Africa, it is eaten as a staple food. It is the most important crop as a staple food for mbege production. According to the interview, the advantage of ndishi as an ingredient of mbege for the Chaggawas that people it was easily in northeastern broken into small Tanzania. particles and We became found smooth that when there it werewas cooked. 18 varieties If banana of banana being cultivatedwas broken within into thesmall research particles, field the enzymes (Table1 used). Among for saccharification them, ndishi andwas the yeasts most engaged frequently in used for mbege production.alcoholic fermentation According tocould the easily interview, access thethe advantagesubstrates of of thesendishi reactions.as an ingredient Therefore, ofthismbege was characteristic of ndishi might contribute to increasing the productivity of ethanol. Although ndishi that it was easily broken into small particles and became smooth when it was cooked. If banana was was suitable for mbege production, it was not used for cooking purposes because of its unpleasant broken intotaste. small In addition particles, to ndishi the, enzymes other types used such as for kimalindi saccharification, kipungara, kisukari and the, mchare yeasts, mrarao engaged, and ndizi in alcoholic fermentationn’gombe could were easily also used access for thembege substrates production of (Table these 1). reactions. Mchare, which Therefore, was the most this popular characteristic variety of ndishi might contributefor cooking to purposes increasing in the the field, productivity was not used for of mbege ethanol. production Although frequently.ndishi The wasreason suitable was that for mbege mchare required a lot of time and energy to cook if it was used for brewing, because it was not easily ndishi production,broken it was into not small used particles. for cooking However, purposes people believed because that the of itsquality unpleasant of mbege could taste. be In enhanced addition if to , other typesmchare such were as kimalindi used for its, kipungaraproduction,, becausekisukari it ,containedmchare, amrarao larger amount, and ndizi of sugar n’gombe than ndishiwere. also used for mbege production (Table1). Mchare, which was the most popular variety for cooking purposes in the field, was not used for mbegeTable 1.production Names and usage frequently. of banana varieties The reason found in was the research that mchare field. required a lot of time and energy to cook if it was usedLocal for Name brewing, because it wasUsage not easily broken into small particles. However, people believed thatBokoboko the quality of mbege couldCooking be enhanced if mchare were used for its Irongo Cooking production, because it containedKimalindi a larger amount of sugarFruit, thancooking,ndishi brewing. Kinguruwe Fruit, cooking, brewing Table 1. NamesKipungara and usage of banana varieties foundBrewing in the research field. Kisasa Cooking KisukariLocal Name UsageFruit, brewing Kitarasa Cooking Bokoboko Cooking ya Bukoba Cooking Irongo Cooking Matoke yaKimalindi Mbeya Fruit, cooking,Cooking brewing MchareKinguruwe Fruit, cooking,Cooking, brewing brewing MkonosiKipungara BrewingCooking MnyenyeleKisasa CookingCooking Kisukari Fruit, brewing Kitarasa Cooking Matoke ya Bukoba Cooking Matoke ya Mbeya Cooking Mchare Cooking, brewing Mkonosi Cooking Mnyenyele Cooking Mrarao Fruit, brewing Mzuzu Cooking Ndishi Brewing Ndizi n’gombe Brewing Ndizi Uganda Cooking Beverages 2016, 2, 21 4 of 10

Mrarao Fruit, brewing Mzuzu Cooking Ndishi Brewing Ndizi n’gombe Brewing Ndizi Uganda Cooking Beverages 2016, 2, 21 4 of 10 3.2. Details of the Brewing Technique of Mbege 3.2.The Details scheme of the of Brewingmbege production Technique of Mbegeis shown in Figure 2. The production of mbege involved three major steps:The schemenyalu preparation, of mbege production mso preparation, is shown in Figureand mixing.2. The production Details of of thesembege threeinvolved steps three are as follows.major steps: nyalu preparation, mso preparation, and mixing. Details of these three steps are as follows.

FigureFigure 2. 2. SchemeScheme of mbege production. production.

MbegeMbege productionproduction began began with with the the preparation preparation of nyalunyalu. .Nyalu Nyaluwas was fermented fermented porridge porridge prepared prepared withwith ripened ripened banana. banana. It was It was prepared prepared as asfollows. follows. First, First, 36 36 L Lof of ripened ripened banana banana was was mixed withwith the samethe volume same volume of water of waterin an in oil an drum. oil drum. The The mixture mixture was was cooked cooked overover a a high high flame flame until until its color its color becamebecame red redand and all allthe the lumps lumps were were thoroughly thoroughly broken down down (Figure (Figure3). 3). After After cooking, cooking, the mixture the mixture was wastransferred transferred from from the the oil oil drum drum to to a a wooden wooden barrel (Figure(Figure4). 4). It wasIt was then then left left to stand to stand for 12 for days 12 days at ambientat ambient temperature temperature without without covering. covering. According According to thethe brewer, brewer, the the length length of timeof time required required to to fermentferment the cooked the cooked banana banana mixture mixture varies varies with with the the season. Generally, Generally, the the mixture mixture is left is left to stand to stand for for nine to 10 days in the hot season and 12 to 13 days in the cold season. If the brewer uses msesewe for nine to 10 days in the hot season and 12 to 13 days in the cold season. If the brewer uses msesewe for mbege production, a handful of it is added into the mixture after cooking. In this case, the mixture mbege production, a handful of it is added into the mixture after cooking. In this case, the mixture with msesewe will be ready after five days of fermentation. After a sufficient period of spontaneous withfermentation, msesewe will thebe ready mixture after was five filtered days using of fermentation. a nylon bag (Figure After a5 ).sufficient The mass period leftover of afterspontaneous the fermentation,filtration step the wasmixture called wasmakati filtered, and wasusing utilized a nylon as feed bag for (Figure pigs. The5). The obtained mass filtrate leftover was after the the filtrationnyalu step(Figure was6), called a red porridge makati, and that was had autilized slightly as sour feed odor. for Accordingpigs. The obtained to our analysis, filtrate the was ethanol the nyalu (Figureconcentration, 6), a red Brixporridge value andthat pH had of nyalua slightlywere 1.2%,sour 5.6 odor. and 4.5,According respectively. to our The presenceanalysis, of the ethanol ethanol concentration,in nyaly indicated Brix value that yeasts and werepH presentof nyalu in were the mixture 1.2%, and 5.6 spontaneous and 4.5, respectively. alcoholic fermentation The presence had of ethanoloccurred. in nyaly We observed indicated bubbling that yeasts at the surface were ofpresent the cooked in the banana mixture mixture and during spontaneous the fermentation alcoholic fermentationstage. Its pHhad value occurred. suggested We thatobservednyalu could bubbling provide at suitablethe surface conditions of the for cooked yeasts tobanana proliferate. mixture duringBy takingthe fermentation these facts into stage. account, Its pH it was value supposed suggested that nyalu that wasnyalu the could medium provide for suitable cultivation conditions in mbege production. for yeasts to proliferate. By taking these facts into account, it was supposed that nyalu was the medium for yeast cultivation in mbege production.

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Figure 3. The mixture of ripened banana cooked on a high flame. Figure 3. The mixture of ripened banana cooked on a high flame. Figure 3. The mixture of ripened banana cooked on a high flame. Figure 3. The mixture of ripened banana cooked on a high flame.

Figure 4. The wooden barrel to keep the cooked mixture. Figure 4. The wooden barrel to keep the cooked mixture. Figure 4. The wooden barrel to keep the cooked mixture. Figure 4. The wooden barrel to keep the cooked mixture.

Figure 5. Filtering the fermented mixture using a nylon bag to obtain nyalu. Figure 5. Filtering the fermented mixture using a nylon bag to obtain nyalu. Figure 5. Filtering the fermented mixture using a nylon bag to obtain nyalu. Figure 5. Filtering the fermented mixture using a nylon bag to obtain nyalu.

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Figure 6. NyaluNyalu..

After the nyalu was prepared, mso preparation began. Mso was porridge made of germinated After the nyalu was prepared, mso preparation began. Mso was porridge made of germinated finger millet. Mso was prepared according to the following process. First, 35 L of water was poured finger millet. Mso was prepared according to the following process. First, 35 L of water was poured into a metal barrel, and then 5 L of germinated finger millet flour was added into the water. The into a metal barrel, and then 5 L of germinated finger millet flour was added into the water. The barrel barrel and its contents were heated over a fire for a few minutes, and once the temperature of the and its contents were heated over a fire for a few minutes, and once the temperature of the water water had increased, 15 L of the warm, thin mixture was removed and put aside. This warm, thin had increased, 15 L of the warm, thin mixture was removed and put aside. This warm, thin mixture mixture was used later to adjust the thickness of the main mixture. According to the brewer, the was used later to adjust the thickness of the main mixture. According to the brewer, the warm, warm, thin mixture was used to thin out the main mixture instead of cold water so as to prevent a thin mixture was used to thin out the main mixture instead of cold water so as to prevent a drop in drop in temperature throughout the course of cooking. After removing the thin mixture, an temperature throughout the course of cooking. After removing the thin mixture, an additional 15 L of additional 15 L of germinated finger millet flour was added into the main mixture cooking over the germinated finger millet flour was added into the main mixture cooking over the fire. The mixture fire. The mixture was then stirred vigorously using a wooden rod with the occasional addition of the was then stirred vigorously using a wooden rod with the occasional addition of the thin mixture thin mixture (Figure 7). The mixture was cooked for 25 min with intermittent stirring after the (Figureincorporation7). The of mixture the second was cooked addition for of 25 germinated min with intermittent finger millet stirring flour. after The the temperature incorporation of the of themixture second was addition checked of carefully germinated throughout finger millet the process, flour. The and temperature was adjusted of the by mixture adding wasor removing checked carefullyfirewood. throughout The brewer thesaid process, that mso and preparation was adjusted could by not adding be successful or removing if the mixture firewood. was The cooked brewer at mso saidtoo‐high that temperatures.preparation The could change not bein successfulthe mixing if temperature the mixture during was cooked cooking at too-high is shown temperatures. in Figure 8. The change in the mixing temperature during cooking is shown in Figure8. The result shows that The result shows that the temperature was kept around 50–70 °C. The amylase activity of finger ˝ themillet temperature is maximized was at kept 50–60 around °C, but 50–70 it is denaturedC. The amylase beyond activity70 °C [13]. of Therefore, finger millet in mso is maximized preparation, at ˝ ˝ mso 50–60the effectivenessC, but it is of denatured saccharification beyond was 70 maximizedC[13]. Therefore, by keeping in the temperaturepreparation, of the the effectiveness mixture in the of ˝ saccharificationrange of 50–70 °C. was The maximized same brewing by keeping technique the was temperature also observed of the in mixture southern in theTanzania range [14]. of 50–70 Finally,C. Thethe cooked same brewing mixture technique was transferred was also into observed several in containers southern Tanzania to let it cool. [14]. Finally,The obtained the cooked mixture mixture was mso Mso wasmso. transferredMso was a thick into several brown containersporridge with to let a itsweet cool. taste The obtained(Figure 9). mixture The ethanol was concentration,. was a thick Brix brownvalue and porridge pH of with mso were a sweet 0%, taste 25.0% (Figure and 5.4%,9). The respectively. ethanol concentration, It did not contain Brix value ethanol. and However, pH of mso it wereshowed 0%, a 25.0% high andBrix 5.4%,value. respectively. This meant Itthat did the not mso contain was ethanol.rich in fermentable However, it sugars, showed which a high were Brix value.generated This by meant the action that the of amylasemso was during rich in cooking. fermentable The sugars, high amylase which wereactivity generated of germinated by the actionfinger ofmillet amylase compared during to cooking. other cereals The high cultivated amylase in activity Tanzania of germinatedmight contribute finger to millet the comparedhigh Brix value to other of cerealsmso [15]. cultivated It was suggested in Tanzania that might mso was contribute a source to of the fermentable high Brix value sugars. of mso [15]. It was suggested that mso was a source of fermentable sugars.

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Figure 7. Stirring the mixture of germinated finger millet flour using a wooden rod. Figure 7. Stirring the mixture of germinated fingerfinger milletmillet flourflour usingusing aa woodenwooden rod.rod. Figure 7. Stirring the mixture of germinated finger millet flour using a wooden rod.

Figure 8. Change in the temperature of the germinated finger millet mixture during cooking. Figure 8. Change in the temperature of thethe germinatedgerminated fingerfinger milletmillet mixturemixture duringduring cooking.cooking. Figure 8. Change in the temperature of the germinated finger millet mixture during cooking.

FigureFigure 9.9. Mso.Mso. Figure 9. Mso. Figure 9. Mso. Finally,Finally, thethe freshlyfreshly preparedprepared nyalunyalu andand msomso werewere mixedmixed togethertogether inin aa woodenwooden barrel.barrel. AsAs shownshown Finally, the freshly prepared nyalu and mso were mixed together in a wooden barrel. As shown inin TableTable 2,2, thethe mixturemixture containedcontained onlyonly aa smallsmall amountamount ofof ethanolethanol (1.0%)(1.0%) rightright afterafter thethe mixingmixing in TableFinally, 2, the the mixture freshly prepared containednyalu onlyand a smallmso were amount mixed of together ethanol in(1.0%) a wooden right barrel.after the As mixing shown process.process. TheThe mixturemixture waswas calledcalled togwatogwa inin thisthis state.state. TogwaTogwa isis thethe namename ofof aa saccharifiedsaccharified beveragebeverage thatthat inprocess. Table 2The, the mixture mixture was contained called togwa only in a this small state. amount Togwa ofis the ethanol name (1.0%) of a saccharified right after beverage the mixing that isis widelywidely consumedconsumed inin TanzaniaTanzania [16].[16]. ItIt waswas aa sweetsweet andand slightlyslightly soursour beverage.beverage. AfterAfter 66 hh ofof process.is widely The consumed mixture in was Tanzania called togwa [16]. inIt thiswas state.a sweetTogwa andis slightly the name sour of abeverage. saccharified After beverage 6 h of fermentation,fermentation, thethe ethanolethanol concentrationconcentration ofof thethe mixturemixture increasedincreased toto 2.7%,2.7%, andand itsits BrixBrix valuevalue thatfermentation, is widely consumedthe ethanol in concentration Tanzania [16]. of It wasthe mixture a sweet andincreased slightly to sour 2.7%, beverage. and its AfterBrix 6value h of decreaseddecreased (Table(Table 2).2). ThisThis waswas mainlymainly thethe resultresult ofof spontaneousspontaneous alcoholicalcoholic fermentationfermentation byby yeastsyeasts inin decreased (Table 2). This was mainly the result of spontaneous alcoholic fermentation by yeasts in thethe nyalunyalu usingusing fermentablefermentable sugarssugars fromfrom thethe msomso.. AA yeastyeast ((SaccharomycesSaccharomyces cerevisiaecerevisiae)) andand lacticlactic acidacid the nyalu using fermentable sugars from the mso. A yeast (Saccharomyces cerevisiae) and lactic acid bacteriumbacterium ((LactobacillusLactobacillus plantarumplantarum)) areare thethe mainmain microorganismsmicroorganisms engagedengaged inin mbegembege productionproduction [10].[10]. bacterium (Lactobacillus plantarum) are the main microorganisms engaged in mbege production [10].

Beverages 2016, 2, 21 8 of 10 fermentation, the ethanol concentration of the mixture increased to 2.7%, and its Brix value decreased (Table2). This was mainly the result of spontaneous alcoholic fermentation by yeasts in the nyalu using fermentable sugars from the mso. A yeast (Saccharomyces cerevisiae) and lactic acid bacterium Beverages 2016, 2, 21 8 of 10 (Lactobacillus plantarum) are the main microorganisms engaged in mbege production [10]. Therefore, Therefore,lactic acid lactic bacteria acid might bacteria also might be engaged also be engaged in the spontaneous in the spontaneous fermentation fermentation in addition in addition to yeasts, to yeasts,and might and causemight the cause decrease the decrease of the pHof the of thepH mixture.of the mixture. The mixture The mixture was called was calledmbege mbegein this in state. this state.Mbege Mbegewas a was red-colored a red‐colored alcoholic alcoholic beverage beverage with a with slightly a slightly sour taste. sour Ataste. gourd A gourd cup was cup used was to used drink to drinkit (Figure it (Figure10). It was10). consumed It was consumed within one within or two one days. or Thetwo changes days. The of the changes ethanol of concentration, the ethanol concentration,Brix value, and Brix pH value, of the andmbege pHover of the the mbege course over of 48the h course of spontaneous of 48 h of spontaneous fermentation fermentation after mixing afterare shown mixing in are Table shown2. After in Table 48 h of 2. theAfter fermentation, 48 h of the fermentation, its ethanol concentration its ethanol concentration reached 4.0%, reached and its 4.0%,Brix value and its dropped Brix value to 6.0. dropped A similar to brewing6.0. A similar technique brewing involving technique a mixture involving of two a mixture different of types two differentof porridge types was of also porridge reported was in also southern reported Tanzania in southern [14]. InTanzania that region, [14]. germinatedIn that region, finger germinated millet is fingeralso used millet as anis also amylase used source,as an amylase and the source, brewing and technique the brewing to control technique the temperature to control the of temperature the mixture ofduring the mixture saccharification during saccharification exists [14]. The exists results [14]. of thisThe study results showed of this thatstudy there showed were that many there brewing were manytechniques brewing shared techniques between shared northeastern between and northeastern southern Tanzania. and southern Tanzania.

Table 2. togwa mbege Table 2. Ethanol concentration, Brix value, and pH of togwa and mbege..

EthanolEthanol Concentration (%)(%) BrixBrix pHpH TogwaTogwa (0(0 h) h) * * 1.01.0 9.09.0 4.64.6 MbegeMbege (6(6 h) h) 2.72.7 8.08.0 4.44.4 MbegeMbege (9(9 h) h) 3.03.0 8.58.5 4.44.4 MbegeMbege (12(12 h) h) 3.23.2 7.57.5 4.24.2 Mbege (24 h) 3.0 6.5 4.2 MbegeMbege (24(48 h) h) 4.03.0 6.06.5 4.24.2 Mbege (48* Length h) of time (hours) after4.0 mixing nyalu and mso6.0. 4.2 * Length of time (hours) after mixing nyalu and mso.

Figure 10. Mbege. Figure 10. Mbege. 3.3. The Effect of Msesewe on Mbege Production 3.3. The Effect of Msesewe on Mbege Production Under the direction of the local brewer, we prepared mbege with and without mesesewe, Under the direction of the local brewer, we prepared mbege with and without mesesewe, according to the brewing method shown in Figure 1. The ethanol concentration, Brix value and pH according to the brewing method shown in Figure1. The ethanol concentration, Brix value and of the nyalu and mbege after 12 h of spontaneous fermentation were measured in each batch. The pH of the nyalu and mbege after 12 h of spontaneous fermentation were measured in each batch. parameters of the samples are shown in Table 3. Our results showed that the ethanol concentration The parameters of the samples are shown in Table3. Our results showed that the ethanol concentration of the nyalu with msesewe was higher than that without msesewe. In contrast, the Brix value of the of the nyalu with msesewe was higher than that without msesewe. In contrast, the Brix value of the nyalu nyalu with msesewe was lower than that without msesewe. We also observed bubbling in the nyalu with msesewe was lower than that without msesewe. We also observed bubbling in the nyalu with msesewe with msesewe after five days of spontaneous fermentation, although it was not observed in that without msesewe. These facts suggested that the alcoholic fermentation had taken place much more actively in the nyalu with msesewe than in that without msesewe. It was reported that the stem bark of mangroves can suppress the growth of all microorganisms in palm except for yeasts [17]. This suppressive effect is due to the tannins in the bark. As msesewe also contains tannins, it was supposed that msesewe helped yeasts to become the dominant microorganism in nyalu [12]. Yeasts might be able to proliferate rapidly once they dominate the population of microorganisms in nyalu. Our

Beverages 2016, 2, 21 9 of 10 after five days of spontaneous fermentation, although it was not observed in that without msesewe. These facts suggested that the alcoholic fermentation had taken place much more actively in the nyalu with msesewe than in that without msesewe. It was reported that the stem bark of mangroves can suppress the growth of all microorganisms in except for yeasts [17]. This suppressive effect is due to the tannins in the bark. As msesewe also contains tannins, it was supposed that msesewe helped yeasts to become the dominant microorganism in nyalu [12]. Yeasts might be able to proliferate rapidly once they dominate the population of microorganisms in nyalu. Our observations were consistent with the traditional understanding that msesewe accelerated the fermentation process.

Table 3. Ethanol concentration, Brix value, and pH of nyalu and mbege with msesewe (A) and that without msesewe (B).

Ethanol Concentraion (%) Brix pH A. Mbege with mesesewe Nyalu 0.7 10.0 4.7 Mbege (12 h) * 4.2 9.0 4.7 B. Mbege without mesesewe Nyalu 0.2 15.0 4.6 Mbege (12 h) * 1.8 11.0 4.6 * Length of time (hours) after mixing nyalu and mso.

Similarly to the case of nyalu, the ethanol concentration of mbege with msesewe after 12 h of spontaneous fermentation was higher than that without msesewe, and their Brix values showed the opposite relationship (Table3). This result was also consistent with the traditional knowledge of brewers in this region, which stated that msesewe increased the ethanol concentration of mbege. It was supposed that the ethanol concentration of mbege with msesewe became higher than that without msesewe, because nyalu with msesewe contained a much larger population of yeasts capable of spontaneous alcoholic fermentation. In this on-site trial, we demonstrated the validity of the traditional understanding of the effect of msesewe on mbege production. However, an excess amount of msesewe may cause inefficient alcoholic fermentation and an unpalatable taste of mbege because of the effect of tannins [18]. Therefore, we must determine the adequate range of the quantity of msesewe to add for improving the quality of mbege in a future study.

4. Conclusions This study observed and recorded a detailed traditional brewing technique of mbege. Mbege was produced by mixing two different porridges, nyalu and mso. The nyalu was a fermented porridge made of ripened banana. It was the source of yeasts in mbege production. The other ingredient, mso, was a sweet porridge made of germinated finger millet. Its role was as a source of fermentable sugars. In the preparation of mso, we observed the technique to maintain the temperature of the mixture within a specific range for optimized saccharification. We found that the brewing techniques of mbege in northeastern Tanzania had similarities with the techniques of southern Tanzania. We also verified the effect of msesewe on mbege production. The on-site trial found that msesewe accelerated the fermentation of nyalu and increased the final ethanol concentration of mbege. These effects of msesewe were consistent with the traditional knowledge of this region. Therefore, we demonstrated the validity of this traditional knowledge in regards to the effect of msesewe through the on-site trial. Beverages 2016, 2, 21 10 of 10

Acknowledgments: We would like to thank the people in the Kilema kaskazini ward for their all kindness during our stay. We would also like to extend our appreciation to all the members of our research project, the International Network-hub for Future Earth: Research for Global Sustainability, for their encouragement to complete this study. This study was granted by the Program for Advancing Strategic International Networks to Accelerate the Circulation of Talented Researchers and promoted by the Japan Society for the Promotion of Science (JSPS). Author Contributions: In this study, Ryosuke Kubo conceived and designed the field research and experiments; Ryosuke Kubo and Method Kilasara conducted the field research together; Ryosuke Kubo performed the experiments in the field; Ryosuke Kubo wrote the paper under the supervision of Method Kilasara. Conflicts of Interest: The authors declare no conflict of interest.

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