Abstract:
Mahuwa (Madhuca longifolia) flowers and murcha samples from Gadhawa Gaunpalika,
Ward No. 08 (followed by a brief survey) were screened for fermentative yeast to study the
effect of different yeasts and pH levels on the chemical and sensory quality of mahuwa wine.
Yeasts were screened by culturing on MYPG and molasses agar media at 30°C for 2-3 days.
The isolates that could ferment molasses broth at a low pH were utilized for must
fermentation, while the others were rejected. Yeast isolates were characterized based on
colony morphology, microscopic characteristics, fermentative capacity. Furthermore,
mahuwa juice was subjected to a 21-day of the fermentation period at room temperature
(25±2°C), nine (9) treatment combinations were used, each including three varieties of
yeasts, viz., Fy1 (mahuwa flower yeast), My2 (murcha yeast), and Wy3 (commercial wine
yeast) at three pH values (3, 3.5, and 4). Fermentation kinetics for total soluble solids (TSS),
titratable acidity and yeast growth were also studied. The quality of wines prepared using
Fy1, My2, Wy3 were assessed and compared by chemical analyses (ethanol, higher alcohols,
esters, aldehydes, total phenolic content, and acidity) and sensory evaluation (7-point
hedonic rating for the attributes appearance, odor, mouthfeel, finish, and overall acceptance).
The survey showed engagement of 53% of the households of Gadhawa Gaunpalika, Ward
No. 08 in mahuwa spirit production, with an annual income of ~ NRs 40000.0 per household.
Variations in yeast strain and pH of mahuwa must had a considerable (p ≤ 5%) effect on
wine quality and fermentation kinetics. After 21 days of fermentation of mahuwa flower
juice, sample E (fermented using isolated murcha yeast at pH 3.5) wine was found to have
the best sensory quality. Upon physicochemical analysis, the best sample had the following
characteristics: ethanol (12.13±0.23% abv), total titratable acidity (0.97±0.07% as lactic
acid), volatile acidity (0.083±0.006% as acetic acid), fixed acidity (0.84±0.08% as lactic
acid), total phenolic content (250.7±5.3 mg GAE/L) of wine), esters (236±6.7 g ethyl
acetate/100 L), aldehyde (148.8±4.3 g aldehyde /100 L) and higher alcohol 181.7±6.6 mg/L.
It can be concluded that all fermentative yeast types can be used to prepare mahuwa wine,
but a pH of 3.5 appears to be the best condition. Further, the physicochemical properties
(ethanol, methanol, esters, aldehydes, etc., in particular) either do not necessarily relate or
are too complex to relate to the sensory quality of mahuwa wines.
Description:
A dissertation submitted to the Department of Food Technology, Central Campus of
Technology, Tribhuvan University, in partial fulfillment of the requirements for the
degree of B. Tech. in Food Technology