Encapsulation of Brewers Yeast in Chitosan Coated Carrageenan Microspheres by Emulsification/Thermal Gelation

Figures & data

Figure 1. Viability of London yeast incubated for 15 min at increasing temperatures.

Figure 2. Gelation temperature of 2 (•) and 3% (▪) carrageenan solutions with different proportions of low gelation temperature carrageenan.

Figure 3. Size distribution of yeast-loaded carrageenan microspheres formed by emulsification/thermal gelation.

Figure 4. Growth of yeast in brewing medium (▪) and pH profile (•) during free cell culture.

Figure 5. Growth (squares) and pH profile (circles) during fermentation with yeast encapsulated in uncoated (solid symbols) and chitosan-coated (open symbols) carrageenan microspheres.

Figure 6. Free cells (circles) and total cell concentration (squares) over the course of fermentation with yeast-loaded uncoated (open symbols) and chitosan-coated (solid symbols) carrageenan microspheres.

Figure 7. Kinetics of free amino nitrogen uptake in fermentations with free cells (•), and cells entrapped in uncoated (▪) and chitosan-coated carrageenan microspheres (▴).

Table 1. Alcohol and ester content for fermentations with free and carrageenan entrapped cells. Determinations were carried out at the end of fermentation (75 h) and at the end of the maturation process

	Free cells		Carrageenan gel		Chitosan/carrageenan
Component (g L^−1)	Fermentation	Maturation	Fermentation	Maturation	Fermentation	Maturation
Acetaldehyde	0.224	0.229	0.196	0.225	0.181	0.203
Ethylacetate	nd	0.059	nd	nd	nd	nd
Methanol	1.6	1.5	1.2	1.3	1.2	1.1
Ethanol (%)	7.0	4.7	4.0	4.7	4.7	2.8
1-Propanol	0.054	0.024	0.003	0.020	0.014	0.005
Isobutanol	0.094	0.026	0.044	0.004	0.043	0.008
Isoamylacetate	0.084	0.024	0.039	0.003	0.038	0.007
Isoamylalcohol	0.111	0.070	0.066	0.081	0.076	0.049

nd: Not detected.