Abstract:
The activity of sunflower
seeds lipase on its own substratum
(sunflower oil), and on other substrata,
belonging to seven plant species, searched
under certain conditions of temperature and
pH, was the purpose of this work. Dried
sunflower seeds (SMC =10%) – used as
lipase source, and refined oils from seeds of
eight plant species (sunflower, pumpkin,
soya bean, sesame, almond, maize, walnut
and peanut) – used as substratum for
enzyme, has represented the biological
material in this work. The lipase activity,
expressed as μm oleic acid/gram
product/min., was determined at 20ºC and
three pH values (5.5, 7.4 şi 9.5), by means of
titrating of fatty acids (released from oils by
enzyme, in a certain time interval) with a
solution of KOH. At pH 5.5, the highest
enzyme activity was registered on soya been
oil, followed, in order, by walnut, maize,
peanut and sunflower oils (very close values
for the last three ones). In this pH value, the
lowest lipase activities was on pumpkin,
almond and sesame oils (all very close
values). At pH 7.4, the gratest lipase activity
value was registered on walnut oil, followed
by peanut and maize oils, and the lowest
ones on soya bean and sunflower oils (close
values). At pH 9.5, the highest lipase
activities have been on sunflower oil,
followed by walnut, pumpkin, soya bean
and maize oils (close values), and the least
ones on sesame and almond oils (close
values). The analyse of the sunflower seeds
lipase activity on the eigth substrata
(sunflower, pumpkin, soya bean, sesame,
almond, maize, walnut and peanut oils) at
20ºC, has highlighted the highest values at
pH 5.5 and the lowest ones at pH 9.5.The
sunflower seeds lipase activity, at 20ºC, was
influenced both by pH values and
substratum nature.
