Re: What ingredient in Molasses causes fermentation when combined with Yeast?

Date: Tue Nov 14 02:39:11 2006
Posted By: Devendra Dusane, Junior Research Fellow (BARC-UoP research programme)
Area of science: Microbiology
ID: 1161974473.Mi

Message:

The composition of molasses depends on the grade of molasses (A, B or C). A being more pure in terms of presence of more sugar concentration and so on. The typical composition of cane molasses-C is shown below. This shows presence of fermentable sugars which are readily utilized and other unfermentable sugars that cannot be utilized by the yeast as it do not possess the enzymes to convert the sugars into utilizable ones.

	Sr. no	Analytical Parameters	Units	Normally observed values
A. Chemical Analysis:
	1	Total solids	% by wt.	65 to 80
	2	Total Reducing Sugars	% by wt.	45 to 50
	3	Unfermentable Sugars	% by wt.	4 to 5
	4	Fermentable Sugars	% by wt.	40 to 46
	5	F/N ratio	-------	1 to 2.5
	6	Total inorganics	% by wt.	8 to 12
	7	Calcium as CaO	% by wt.	1.5 to 3.5
	8	Total settlable sludge at 4.5 pH	% by wt.	5 and below
	9	Specific gravity	-------	1.38 to 1.55
	10	Titrable volatile acidity in terms of acetic acid & acetate salts	M1 of 0.1 N NaOH	29 ml
	11	pH at 40o Bx dilution	----------	4.5 to 5.2
	12	Suspended particles >100 microns	% by wt.	Up to 0.05
	13	Color in terms of Optical Density (OD) at 375 nm with 0.01% w/v dilution	OD	0.15 to 0.4
	14	Soluble sulphates as SO4	--------	1.5 to 5
B. Microbiological:
	1	Total bacterial count	CFU/gm	10 exp 3 and below
	2	Wild yeast and fungal count	CFU/gm	10 exp 2 and below

(Adopted from Konchady, 2003)

The reaction for utilization of sugars and production of ethanol is given below.

C6H12O6	------------------>	C2H5OH	+ 2CO2	- 265kcal /kg cal
Glucose		ethyl alcohol	carbon dioxide

The yeast is able to utilize sugars depending on the fermentable sugars, also the pH is favorable for the yeast near to neutral. Moreover the presence of divalent ions such as Calcium present in molasses also favors the enzymatic reaction.

I suggest you check my article on managing wild yeast contamination in molasses based fermentation to know more about the same.
Check http://www.ch eresources.com/wild_yeast_contamination.shtml

Regards,
Devendra

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