Active emulsions based on alginate and lemongrass/citral essential oils: effect of encapsulating agents on physical and antimicrobial properties

Figures & data

Table 1. Mean values and standard deviation of average droplet size and polydispersity index for active emulsions with different encapsulating agents and active compound:encapsulating agent ratios (AC:EA). Abbreviations: CIT: Citral; LEM: Lemongrass essential oil; CAP: Capsul®; MD: Maltodextrin

Samples	AC:EA*	Average droplet size (d32)	Polydispersity index
CIT-CAP	1:1	0.87 ± 0.02 (59.9%) ^a	0.24 ± 0.10 ^a
	1:2	0.88 ± 0.05 (77.3%) ^a	0.28 ± 0.12 ^a
	1:3	0.86 ± 0.01 (59.4%) ^a	0.51 ± 0.06 ^a
	1:4	1.15 ± 0.05 (84.5%) ^a	0.29 ± 0.02 ^a
LEM- CAP	1:1	0.87 ± 0.01 (60.3%) ^a	0.11 ± 0.01 ^a
	1:2	0.74 ± 0.01 (63.7%) ^a	0.20 ± 0.01 ^a
	1:3	0.75 ± 0.02 (54.7%) ^a	0.51 ± 0.22 ^a
	1:4	0.79 ± 0.04 (67.8%) ^a	0.32 ± 0.03 ^a
CIT-MD	1:1	1.11 ± 0.27 (50.3%) ^a	0.98 ± 0.67 ^a
	1:2	1.11 ± 0.30 (54.6%) ^a	0.54 ± 0.01 ^a
	1:3	1.09 ± 0.14 (45.5%) ^a	0.84 ± 0.48 ^a
	1:4	0.99 ± 0.26 (51.6%) ^a	0.85 ± 0.49 ^a
LEM-MD	1:1	0.95 ± 0.34 (41.4%) ^a	0.96 ± 0.61 ^a
	1:2	0.92 ± 0.07 (52.3%) ^a	0.41 ± 0.19 ^a
	1:3	0.95 ± 0.11 (56.6%) ^a	0.44 ± 0.02 ^a
	1:4	0.95 ± 0.11 (50.9%) ^a	0.38 ± 0.06 ^a
Control CIT		1.02 ± 0.16 (45.9%) ^a	0.95 ± 0.58 ^a
Control LEM		1.04 ± 0.17 (53%) ^a	0.45 ± 0.11 ^a

* Relation active compound (AC):encapsulating agent (EA).

** Average size for the population drop in greater proportion. The percentage for this population is reported in parentheses.

^a,bDifferent letters in the same file indicate significant differences (p < 0.05).

Figure 1. Changes in backscattering profiles as function of tube length at different storage time at 4°C and relation active compound:encapsulating AC:AE agent 1:4 for: (a) CIT-CAP; (b) LEM-CAP; (c) CIT-MD; (d) LEM-MD; (e) Control CIT and (f) Control LEM. Abbreviations: CIT: Citral; LEM: Lemongrass essential oil; CAP: Capsul®; MD: Maltodextrin (

0 h,

2 h,

5 h,

19 h,

24 h,

28 h,

44 h,

48 h)

Figure 2. Physical instability kinetics measured as %Backscattering normalized at initial time during storage time at 4°C for samples containing citral (CIT) at a concentration rate of 1:4 oil:encapsulating agent (CAP: Capsul® or MD: maltodextrin); (a) clarification, (b) floculation/coalescence and (c) creaming mechanisms. Bars indicate standard deviation of triplicate means. Lines indicate zero-order kinetics rate fitting and their corresponding equation

(

CIT:CAP;

CIT:MD).

Figure 3. Color difference (ΔE₂₀₀₀) of active emulsions with lemongrass essential oil (LEM) or citral (CIT), as active compounds, and maltodextrin (MD) or Capsul® (CAP), as encapsulating agents, using alginate as reference. Bars indicate standard deviation of mean from triplicates

^a,bDifferent letters indicate significant differences (p < .05) between samples and between ratios (

Control CIT,

CIT:CAP,

CIT:MD,

Control LEM,

LEM:CAP,

LEM:MD).

Table 2. Mean values and standard deviation of flow parameters of active emulsions with different encapsulating agents and active compound:encapsulating agent ratios (AC:EA). Abbreviations: CIT: Citral; LEM: Lemongrass essential oil; CAP: Capsul®; MD: Maltodextrin

	Relation AC:EA**	n	K (Pa s^n)	r^2	Viscosity (mPa s)
CIT-CAP	1:1	0.97 ± 0.02 ^a	0.11 ± 0.01 ^a	0.99 ± 0.01	89.9 ± 1.1^a
	1:2	0.99 ± 0.05 ^a	0.10 ± 0.05 ^a	0.99 ± 0.01	73.3 ± 1.3^b
	1:3	0.98 ± 0.08 ^a	0.08 ± 0.03 ^a	0.99 ± 0.01	71.9 ± 1.9^b
	1:4	1.04 ± 0.02 ^a	0.06 ± 0.01 ^a	0.99 ± 0.01	65.5 ± 1.3^c
LEM-CAP	1:1	0.97 ± 0.05 ^a	0.09 ± 0.03 ^a	0.99 ± 0.01	81.4 ± 1.5^d
	1:2	0.98 ± 0.02 ^a	0.09 ± 0.01 ^a	0.99 ± 0.01	83.0 ± 0.9^d
	1:3	1.00 ± 0.05 ^a	0.08 ± 0.02 ^a	0.99 ± 0.01	85.7 ± 0.2^d
	1:4	1.01 ± 0.05 ^a	0.08 ± 0.03 ^a	0.99 ± 0.01	81.2 ± 1.9^d
CIT-MD	1:1	0.92 ± 0.06 ^a	0.17 ± 0.09 ^a	0.99 ± 0.01	151.8 ± 1.9^f
	1:2	0.95 ± 0.03 ^a	0.13 ± 0.02 ^a	0.99 ± 0.01	106.9 ± 1.2^gh
	1:3	0.93 ± 0.04 ^a	0.14 ± 0.03 ^a	0.99 ± 0.01	110.3 ± 1.6^h
	1:4	0.96 ± 0.03 ^a	0.13 ± 0.02 ^a	0.99 ± 0.01	105.3 ± 0.5^g
LEM-MD	1:1	0.97 ± 0.03 ^a	0.10 ± 0.01 ^a	0.99 ± 0.01	107.3 ± 1.5^gh
	1:2	0.95 ± 0.04 ^a	0.12 ± 0.02 ^a	0.99 ± 0.01	105.6 ± 1.5^g
	1:3	0.94 ± 0.04 ^a	0.14 ± 0.03 ^a	0.99 ± 0.01	109.8 ± 1.1^gh
	1:4	0.95 ± 0.06 ^a	0.16 ± 0.06 ^a	0.99 ± 0.01	122.2 ± 0.7^i
Control alginate		0.96 ± 0.06 ^a	0.12 ± 0.03 ^a	0.99 ± 0.01	106.1 ± 0,9^g
Control CIT		0.95 ± 0.06 ^a	0.13 ± 0.04 ^a	0.99 ± 0.01	103.2 ± 1.7^g
Control LEM		0.98 ± 0.03 ^a	0.11 ± 0.01 ^a	0.99 ± 0.01	92.9 ± 1.5^a

* K = consistency index, n = flow index.

**Relation active compound (AC): encapsulating agent (EA).

^a,bDifferent letters in the same file indicate significant differences (p < 0.05).

Figure 4. Induction time or induction period of emulsions with lemongrass essential oil (LEM), and maltodextrin (MD) or Capsul® (CAP), as encapsulating agents, using LEM as reference. Bars indicate standard deviation of triplicates

^a,bDifferent letters indicate significant differences (p < .05) between samples and between ratios (

LEM:CAP,

LEM:MD,

LEM,

ALG:LEM).