SOURCES OF PALM WINE

The sap for production of palm wine is mainly oil palm . Different palm species are tapped for sap. All the palms are tapped mainly at the base of immature male inflorescence of mature palm tree, and they all produce to a large extent6 some kind of sap, but with varying organololeptic quality. The sap obtained used the same principle irrespective of the occurence4 of various shape and sizes of the inflorescence occurring in the various palm species. However, the various species of palm wine and their variou8s locations are shown below.

Types of palm wine

Locations

A Raffia Sudanica

Africa

B Raffia vinfera

Africa

C Raffia Hookeri

Africa

D Elacis Quinensis

West Africa

NATURE AND COMPOSITION P OF PALM WINE.

Palm wine is a collection for a group of alcoholic beverages produced by fermentation of the sap of palms. It is drank in various part of the tropical world, including South America, Asia and Africa, the production of palm wine appears to have been known for several centuries, but the earliest record of it, comes from the chronicles of Europeans travelers recorded as early as is all (pigetetta and lopes, 1593). Other early chronicles of the beverages are to be form in Capelle (1641) de Rome (1648), and Da firenze (1820). The type of palm whose3 sap is fermente4d varies from one part of the world to another and includes the coconut palm, and the date palm. But the two main sources of palm wine in Migeria are oil palm (Elais buineansis) and the raffia (Raffia vinifera and R. hookeri). Accurate figures of the quantity of palm wine produced are not available, but in Nigeria, with a population of some 120 million, a rough estinate shows t6hat about 300 million trees frows in some 1,304 square mile with potentialproduction of 450 million fallons of palm wine annually (koleoso and oniwinde, 1978). Bassir (1968) suggested that these people serves some nutritional benefit6s from the approximately7 300 calories (from sugar and alcohol , 0.5 – 2.0fm), proteiro and large4 amounts of vitamins present in each litre. The consumption of the liquid howe4ver, is recognized not only as an inexpensive source of “joy” but also having a certain nutritional value because of its vit6amin content some3times referred to as “good for the eyes”. Palm wine, no matter the origin of the sap, is usually a whitest liquid, which is efferrscent because the micro-organisms causing the fermentation are alive. The palm wine obtained by tapping the young flowering spathe of the respective palm contains fermentable sugar in solution, but vary in composition with time of tapping.

To obtain palm wine that has not undergone fermentation with in the collecting vessel (CALABASH), such vessels are treated with a solution of freshly burnt hime or with sopdium metal- disulphate to contain about 0.1% in the volume of palm wine (Chinnarasa, 1968).

The sugars present in palm wine include3 not only sucrose but also maltose, raffinose, glucose, and fructose. What is certain is that the total sugar cont6ent usually7 has anb upper li8mit6 of about 12%. The organic acids present include mainly acetic aci8d, laqctic acid and tartaricacid. Other consttuent includes vitamins and alcohol. However, Chinnarasa in September 1968, obtained sap from palm which contains ferment5able sugars in solution. This palm wine was collecte4d in sterile vessel, and remained unfermented for a considerable time. The composition of this fresh sweet wine, according to Chi8nnarasa, analysis at the federal institute of industrial research, was follows:

Specific gravity at 30oc

1.057

Total solids

16.0%

Sucrose

13.0%

Ash

0.36%

Protein

0.30%

Vitamin C

10mg/100ml

Alcohol

Nil

The concentration of vitamin C in sweet do notr change during fermentation (Kolwoso and Oniwinde, 1978, Chinnarasa 1968).

MICRO- ORGANISM IN PALM WINE ITS EFFECT6S ON ALCOHOL PRODUCTION

The juice that escape from an incision palm free or its inflorescence is a sweet and colourless sap containing 4.29+1.4 percent glucose “0.038+0.015 percent NH3 and small amount6 of lactic acid and amino acids (Olumbe, Bassir, 1968). According to Bassir, this sap is inoculated naturally by yeast cells which accumulate in millions in sendates on the flower stalk. Futher more, the same source reveals that the fungi contained in the palm wine have been shown to be mostly Saccharomycess Cerevisiae and schizosaccharomyces pombe. Palm sap is contaminated with bacteria as it drops from the inasum, the bacteria most commonly found in fresh we are lactobacillus plantaum and leuconostoe mesenteroides, an unidentified micrococcus species. They frow and multiply rapidly in the presence of yeast, producing lactic and other acids.

Various dominant pairs have been isolated from fermented palm juice (Bassir, 1968).

A Saccharomyces cerevisiae and mesenterials

B Saccharomyces cerevisiae and micrococcus sp

C Pischia sp, and tactabacfillus plantarim

D Saccharomyces cerevisiae anmd comybacterum

Although different yeast may vary in detail, their fermentation patterns have general characters in common. Almost all can ferment glucose.

Nevertheless, the correct micro- organism most be used and of course the right nutrients must be applied. In addition to carbonhydrates, most organisms require specific inorganic compounds such as phosphate, as well as special growth promoting factors. Some micro- organism must have air, while other need none or may even be killed by exposure to it.

In aerotic fermentation oxygen from the gas phase must reaches the surface4 of the growing cells, which are present in the liquid. The crucial problem is to ensure an adequate oxygen supply for proper cellular respiratio9n and this requires maintaining the concentration of oxygen in the liquid above a particular critical minimum level. For this reason large gas liquid interfacial area are needed. It is also ge3nerally found that liquid film resistance controls (octave cevenspicl- chemical Engineering, page. 196-197)

FERMENTATION PROCESS

The term fermentation is applied to a group of chemical changes caused by living microorganisms acting on organic material.

Process involving bacterial, yeast, and would have been used for hundreds of years in the preparation of foods, beverages, textiles, and leather, but it was not until late nineteenth century that organic chemicals were manufactured by fermentation. Thus, fermentation is a process of microbial breakdown of carbon hydrates or other substrates in which no sectional electron acceptor is required; instead the carbon and energy source is broken down by a series of reaction which release energy by substrate level, phosphorylatum. It can be referred as a natural process and also forms a most important class of reaction in which alcohol and organic acids such as vinegar and lactic acid are formed from dissolved sugar in the absence of air. They are widely used by man to produce alcoholic beverages, antibiotics, vitamins, proteins, toxins, yeast and many foodstuffs and also to purify organic wastes such as sewage. These fermentation reaction results have been known used all over the world through out history.

Basically two-view point evolved to explain these processes

Biological theory and non- biological theory.

BIOLOGICAL THEORY OF FERMENTATION:

Thus, before 1800, the association of yeast or leaven with fermentation had been noted, but the natures of these apart were understood. This concept believes that a number of lowly simple plants which are not freen (lack chlorophyll) and hence non- photosynthesis, normally live by a kind of anaerobic respiration. The yeast plant is an important example of this kind of plant of and usually lives insolutio9n of plant juice, which contain sugar. The yeast get its energy for growth and reproduction by the process of fermentation. The experiment, (Caganiar Lacten,F.T kutzing and Theodore schwann in 1837), indicated that yeast is a living organism and is the cause of fermentation.

The biological concept became generally accepted as ye4ast fungi became widely applied in them beer and wine industry for fermenting sugar containing liguors into alcoholic mixtures from which the drinks are made.

Louis pasture also discovered the lactic acid and butyric acid fermentation and from his experiments concluded that specific micrbe conced each kind of fermentationm.

In non biological concepts leading chemists such as J. Vonciebig, fredricks Novel and Jons Jackas Berzelios opposed the biological concept of fermentation, they soughted a chemical rather than a biological explanation of the process. The concept then believes that not only the re3duction of pyruvate but lactic acid fermentation as a whole many may be considered as trans hydrogenation reaction in so far as in the splitting of glucose, two hydrogen atoms are transferred from carbon atom 3 and 4 to atom 1 and 6of the glucose. This transferred has been confirmed with isotopic tracers.

The chemical concept of fermentation holds on the view that during fermentation, organic matter is decomposed in the absence of air, hence there is always an accumulation of reduction products or incomplete oxidation products. Some of these products for be ample alcohol and lactic acid are signi9ficant important to man and fermentation has there been used for their manufacturer on an industrial scale.

THE FERMENTATION OF CARBONHYDRATE TO PRODUCE ETHANOL

The raw23 material is any foodstuff rich in carbohydrate, e.g. what, barely, cassava, grapes, yams, apples, corn, rice, bananas, and plantains. Carbohydrate are poly hydroxyl compounds, the mo0syt common sample of which are starch and t6he various types of sugar4s like glucose, sucrose and maltose.

The starch granules are first extracted by crushing and pressure cooking the material, which are letter treated with malt at 50oc to 600c for an hour. Malt is partially germinated bialy which contains the enzyme diastase. The starch is converted by this enzyme into maltose.

Hydrolysis

(C6H10O5)n + (n/2)H2O((n/2)C12H22O1165

( (diastase) (

Starch Maltose(a sugar)

Ye3ast is the added at room temperature. Yeast contains two enzymes namely: maltose, which converts the maltose top glucose and zymase which then converts the glucose into ethanol and carbon (iv) oxide.

Maltose

C12H22O11 +H2O ( 2C6H12O6

(

Maltose Glucose

Zymase

C6H12O6 ( 2C2H5OH + 2CO2

(

Glucose Ethanol

It is these enzyme which effect the conversion of starch or sugar4 into ethanol in over.

90% yield, the ethanol obtained from fermentation only has a maximum concentration. Further concentration and purification is done3 by fraction distillation.

The production of ethanol from glucose in this way is called alcohol fermentation; it is the basic of the beers, wines and spirits industry. Beers and wines are made by a process of fermentation o9nly, where as spirits require addition process of distillation.

The strength of alcohol beverages are often given as a number of degrees, proof spirits being taken as 100o, and corresponds to rough 57% pure alcoholic content (united kingdom standard). On is basis spirits like gin and whiskey marked 70cl proof contain 40% alcohol, liquid like brandy (87.5-100oproof) about 50-57% alcohol, wines and sherries (25-350 proof) 14-195 alcohol, ciders and beers (6-15o proof ) 3.5-9% alcohol. Palm wine and other locally brewed alcohol be4verages, sold under various names, are not yet marketed in standardized qualities. It is hope that this will be possible in due course.

FACTORS THAT AFFECT FERMENTATION OF PALM WINE.

There are certain factors, which affect the rate at which palm wine fermen. These factors include temperature, time, substrate/micro-organism concentration, oxidation/reduction potential and high alcohol concentration.

1. Temperature: The fermentation process itself is sensitive to temperature; therefore, temperature should be kept fairly constant, thus, at to low temperature, the kinetics of the reaction are severally retarded, which high temperature kill many strains of micro- organism thus affecting the yeast activety adversely and also the growth of the micro-organism. The optimal temperature range of fer4ment5atio9n of palm wine is 20-30oc and this temperature promotes the growth of micro-organism in palm wine.

Time: This is a very important fact6or in fermentation of palm wine. The micro organism do not start acting in the palm wine immediately. It takes about certain hours after tapped depending on the variety and quantity of water present.

Substrates concentration: This factor affects the fermentation of palm wine especially in the batch culture fermentation when an organism is growing, after the initial lag phase, it enter the lag phase of growth, this phase can be to go on for a very long time, if there is a continuous supply of nutrients. However, since in a batch culture nutrients are not continuously supplied, the growth rate declines ads the nutrients becomes exhausted. Thus saccharromyce4s cerevisiae (yeast) i.e. organism for fermentation of palm wine enter the stationary phase and from there to the decline phase. Therefore there is no further fermentation of palm wine.

Oxidation/Reduction Potential: This factor equally affects the fermentation process. When an organism which is sero9bic is growing in a giving medium in the presence of air, the growth can be impaired if suddenly air is stopped and he3nce there is decrease in oxidation/reduction potential. Conversely in a fermentation that is an aerobic, the process changes/ decline, the moment air is introduced. The introduction of air increase the oxidation/reduction potential of the medium. This is because the oxidation/reduction potential of the food is determine by the oxygen tension of the atmosphere about the food. Another factor that determine the3 oxidation/reduction potential of the beverages is the poisoning capacity i.e. the resistance to change in potential of the fermenting medium. Heating may reduce the poisoning power of the medium by destruction or atteratio9n of the reducing and oxidizing substance or because of changes in the physical structure of the medium.

High Alcohol Concentration: High alcohol concentration is another factor that also, inhibits yeast activity, which places a limitation on the initial sugar concentration that may be used. The ethanol obtained from 18% as yeast cells die above concentration.