Friday, 30 November 2012

Science behind Paiwari Making by Indians

I wanted a place to store this great little article on Paiwari making and the science behind it. My appologies to the author for copying it without permission, but it is an obscure article and hard to locate. (The author may write me if he wants it removed.)/drf 
The Science Behind Paiwari Making by Indians
From Earliest Recorded Use of Biotechnology Procedures in Guyana by Seelochan Beharry PhD. and specifically,

The late Sir Everard F. im Thurn (MA. Oxon, b1852 - d1932) published (1883) a work entitled: “Among the Indians of Guiana: Being Sketches Chiefly Anthropologic from the Interior of British Guiana.” I have in my possession a copy of the Dover Publications Inc, New York, 1967 (Library of congress #66-30384). This Dover edition first published in 1967 is an unabridged and unaltered republication of the work originally published by Kegan, Paul, and Trenton Co, 1883.
There are detailed descriptions of how Cassava bread is made, with variations under different conditions when the cassava is scarce. However, we want to focus on the earliest recorded incidence of ‘Biotechnology’ procedures in British Guiana. (This is from my contemporary readings of our national historical documentation – I am of course subject to correction by evidence to the contrary by the experts in this field.)
On Page 263 of the abovementioned work (over a century ago), we read: “Much cassava, after being made into bread, is further transformed into paiwari, the chief Indian beverage. Astounding quantities of this are consumed at special drinking bouts, of which we shall hear more presently. But paiwari is also largely used at other times; and indeed as long as there is any cassava to be had, a stock of this liquor is always kept ready. Whenever the men return from hunting, and whenever a stranger comes into the house, it is drunk. And women and children – even the youngest babies – drink it.”
“Cassava bread which is to be transformed into paiwari, is made as that for other purposes; but it is thicker, and is baked, or rather burned, until it is quite black. It is then broken into smaller fragments, and is mixed with water in a large jar or pot. The larger fragments are picked out and chewed by the women, who do this while moving about and performing their usual household work; and the masses are again replaced in the jar. As soon as this jar is sufficiently filled, its contents, after being well stirred, are slightly boiled, and are then poured into the trough. More and more is added to the liquor in the trough. More and more is added to the liquor in the trough until it is full.”
“The mixture is then allowed to stand for some days, until it is sufficiently fermented – a process which is said to be much accelerated by the mastication of the bread. Sometimes a little juice of sugarcane is added to sweeten the liquor. The result is a brownish liquor –looking like coffee with a great deal of milk in it - with a sub-acid, but not unpleasant taste. Some of the True Caribs, it is said, and some of the Brazilian tribes, manage to prepare paiwari, and to procure a proper degree of fermentation, by simply boiling, without resorting to the very disagreeable but more orthodox chewing process; but paiwari produced in this way is said to be of very inferior flavour.”
“In some parts of the country, instead of paiwari, both for festivals and for ordinary occasions, a much pleasanter drink is used. This is casiri, which is made of sweetpotatoes and sugar-cane. A little cassava is sometimes added. Generally, though not always, it is prepared simply by boiling the ingredients, and allowing them to ferment. It has a pretty pink colour, due to the sweet potatoes; and when well made it tastes not unlike thin claret. ……”
For those who love to eat and have done some science, we would remember that digestion of food begins in the mouth – i.e. chewing breaks down the size of the food particles to smaller and smaller-sized ones. This chewing is necessary so that we can have the maximum surface area of the food exposed to the saliva – produced by the salivary glands in the mouth. This chewing therefore also maximises the efficiency of the catalytic process that occurs in the presence of saliva. The saliva produced in the mouth contains an enzyme called human salivary amylase also called ptyalin (among other chemicals) which is mainly called alpha amylase that breaks down a complex carbohydrate such as starch (polymer of glucose) into simple sugars (monosaccharide, disaccharide or trisaccharide e.g. such as glucose, maltose, maltotriose, respectively, and “limited dextrin”). The alpha amylase enzyme is present in very small amounts in the saliva. Usually, in any biological enzymatic process only a small amount of the catalyst is needed. The alpha amylase enzyme (like other enzymes) here works best at a particular pH (i.e. a measure of acidity or alkalinity) range (in this case slightly alkaline, 7.4). (Incidentally, the saliva also contains another enzyme called lysozyme that lyses (breaks down) bacteria, in addition to other anti-bacterial compounds.)
This saliva helps to sterilise any bacteria that would remain on any improperly washed or handled cassava. Hence the saliva destroys any bacteria present as well as breaking down starch to form glucose, maltose, maltotriose and “limited dextrin”- done by alpha amylase and lysozyme, respectively.
The stirring mentioned above also allows for maximum exposure to the enzymatic processes – thereby maximising the efficiency of the catalytic breakdown of starch into maltose. The heating to a slight boiling denatures (kills) the enzymes - thereby stopping the catalytic action of the enzyme (alpha amylase). This phase of the production process is over. The heating to a boiling also acts as sterilization step – since heat kills bacteria, viruses, and other living micro-organisms that may also be present.
The sterilised maltose is now ready for the next step - fermentation of simple sugar i.e. maltose into alcohol. (Incidentally, from cane sugar we extract the sucrose (a disaccharide) which is then fermented to give alcohol.). Unfortunately, I found no detailed record of how the fermentation process was/is initiated, controlled, and stopped. Maybe those with this knowledge or experience can kindly let us know.
We see from the above that the old making of paiwari is indeed complex science - and the participants involved intuitively must have some understanding of the biological chemistry or biochemistry involved. Today such a complex process would be in the realm of applied science i.e. biotechnology, since it involved the use of biological materials in a complex production process.
Next time, we see Amerindians I hope that we have more respect for their immense knowledge. If we look carefully without prejudice, we can learn a lot from them. They do have a lot to teach us – we just have to be open-minded.
I taught biochemistry at UG, regrettably I was not aware at time that there was a good local example of the application of early biotechnology in Guyana. I never learnt about this until I was doing some research about the ‘Rupununi Uprising.’ Who knows what other gems are there to be discovered and record before they are lost.
These liqueurs (paiwari and casiri) can probably be produced for commercial exploitation using alpha-amylase. Besides the use sweet potatoes in casiri, fruits such as ‘jamoon,’ goose-berry, tamarind, and/or other local fruits can be used to make flavoured liqueurs. This would provide an additional market for cassava–based products. This would be a good enterprise for DDL or some adventurous group of young entrepreneurs.
Hope that next time we can all celebrate Amerindian Heritage month with a new found respect for their contribution and knowledge – in addition to their knowledge in forestry, botany, zoology, and their environmental awareness.
Seelochan Beharry PhD.

also another article

Traditional cassava-based foods: Survey of processing techniques

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As an armed forces brat, we lived in Rockcliff (Ottawa), Namao (Edmonton), Southport (Portage La Prairie), Manitoba, and Dad retired to St. Margaret's Bay, NS.
Working with the Federal Govenment for 25 years, Canadian Hydrographic Service, mostly. Now married to Gail Kelly, with two grown children, Luke and Denyse. Retired to my woodlot at Stillwater Lake, NS, on the rainy days I study the life and work of A. Hyatt Verrill 1871-1954.