The effect of alginate concentration on the EEBD of oil in Caalginate
beads is shown in Fig. 1a. The EEBD was determined
immediately after the encapsulation process and before the drying
process. In this experiment, the oil loading used was 30 vol% of
the total volume of the alginate-oil emulsion. The EEBD, expressed
as the percentage of encapsulated oil relative to the total oil used,
increased with increasing alginate concentration. The EEBD was
found to increase significantly (from 60% for the 5 g/L alginate solution
to 90% for the 25 g/L solution). The EEBD was found to level off
and reach a maximum of 93% when the alginate concentration was
increased to 45 g/L. The alginate concentration was fixed at 25 g/L
in subsequent work because further increases in the concentration
did not cause significant increases in the EEBD.
The effects of alginate type and oil loading on the EEBD are shown
in Fig. 1b. The following two different types of alginate were used:
high in guluronic acid (high G) and high in mannuronic acid (high
M). The oil loading ranged from 10 to 60 vol%. In general, high G
alginate gave a higher EEBD for all oil loadings when compared to
the high M alginate. The EEBD using the high G alginate remained
relatively constant (at about 85–90%) for oil loading up to 50 vol%,
but it decreased drastically (to 30%) when oil loading was increased
to 60 vol%. On the other hand, the EEBD using the high M alginate
showed a different trend, decreasing gradually from 86% to 70%
for the oil loading from 10 to 30 vol%, respectively. Above the oil
loading of 30%, the EEBD decreased drastically; it was found to be
approximately 20% for an oil loading of 60 vol%.
We also determined the fraction of non-encapsulated oil found
in the gelation bath and on the surface of wet beads, and the results
are presented in Fig. 2. Generally, the fraction of non-encapsulated
oil found on the bead surface was in the range of 4–10% of total
oil used. Interestingly, the surface oil fraction at lower oil loading
was higher than that of higher oil loading. It is worth mentioning
that the amount of surface oil found in all samples was about the
same (i.e., 0.3–0.6 mL) despite the variation in oil loading. This is
logical because the number of beads and the bead size were found
to be relatively constant, and the amount of surface oil should be
dependent on the total surface area of the beads. Therefore, the
higher surface oil fraction obtained was a result of dividing the
value with a lower oil volume. The data verifies that the nonencapsulated
oil leaked into the gelation bath. The extent of leakage
depended on the oil loading as well as on the type of alginate
used
The effect of alginate concentration on the EEBD of oil in Caalginatebeads is shown in Fig. 1a. The EEBD was determinedimmediately after the encapsulation process and before the dryingprocess. In this experiment, the oil loading used was 30 vol% ofthe total volume of the alginate-oil emulsion. The EEBD, expressedas the percentage of encapsulated oil relative to the total oil used,increased with increasing alginate concentration. The EEBD wasfound to increase significantly (from 60% for the 5 g/L alginate solutionto 90% for the 25 g/L solution). The EEBD was found to level offand reach a maximum of 93% when the alginate concentration wasincreased to 45 g/L. The alginate concentration was fixed at 25 g/Lin subsequent work because further increases in the concentrationdid not cause significant increases in the EEBD.The effects of alginate type and oil loading on the EEBD are shownin Fig. 1b. The following two different types of alginate were used:high in guluronic acid (high G) and high in mannuronic acid (highM). The oil loading ranged from 10 to 60 vol%. In general, high Galginate gave a higher EEBD for all oil loadings when compared tothe high M alginate. The EEBD using the high G alginate remainedrelatively constant (at about 85–90%) for oil loading up to 50 vol%,but it decreased drastically (to 30%) when oil loading was increasedto 60 vol%. On the other hand, the EEBD using the high M alginateshowed a different trend, decreasing gradually from 86% to 70%for the oil loading from 10 to 30 vol%, respectively. Above the oilloading of 30%, the EEBD decreased drastically; it was found to beapproximately 20% for an oil loading of 60 vol%.We also determined the fraction of non-encapsulated oil foundin the gelation bath and on the surface of wet beads, and the resultsare presented in Fig. 2. Generally, the fraction of non-encapsulatedoil found on the bead surface was in the range of 4–10% of totaloil used. Interestingly, the surface oil fraction at lower oil loadingwas higher than that of higher oil loading. It is worth mentioningthat the amount of surface oil found in all samples was about thesame (i.e., 0.3–0.6 mL) despite the variation in oil loading. This islogical because the number of beads and the bead size were foundto be relatively constant, and the amount of surface oil should bedependent on the total surface area of the beads. Therefore, thehigher surface oil fraction obtained was a result of dividing thevalue with a lower oil volume. The data verifies that the nonencapsulatedoil leaked into the gelation bath. The extent of leakagedepended on the oil loading as well as on the type of alginateused
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