PROPERTIES OF HYDROGEL MATERIALS USED FOR ENTRAPMENT OF MICROBIAL CELLS IN PRODUCTION OF FERMENTED BEVERAGES

Figures & data

Table 1. Macromolecular Characteristics of Commercial and Laboratory-Prepared Samples of Pectate Gel Bead Precursors Related to Mechanical Properties of Calcium Alginate Gel Beads

Pectate origin	Producer	α-D-galacturonic acid content (%)	Intrinsic viscosity η (cm ^3.g ^−1)	Molecular weight M W 1 ^c	Deformability of CPG (g.s.mm ^−1)
Apple	Fluka	79.6	67.0	29,800	–
Orange	Sigma	95.0	65.5	23,100	643
Apple	LS 2 ^a	78.8	104.0	52,800	693
Citrus	LS 3 ^b	85.9	125.2	33,250	548

^aLaboratory sample of apple pectate (APA), i.e., potassium pectate prepared from commercial apple pectin.[[15]], [[20]]

^bLaboratory sample of apple pectate (CPA) prepared from commercial citrus pectin.[[20]], [[31]]

^cDetermined by SE-HPLC.[[8]]

Table 2. Macromolecular Characteristics of Polysaccharide Gel Precursor

Polysaccharide 4 ^a	Origin	Symbol/Trademark	Content of uronic acid		Constant of stability log K	Intrinsic viscosity η (cm ^3.g ^−1)	Molecular weight M W
			(%)	(mmol/g)
Pectate	Apple	APE 5 ^b	69.5	3.34	4.10	212	136,500
	Citrus	CPE 5 ^b	88.5	4.13	4.30	232	114,800
Alginate	L. hyperborea	LF 10/60 6 ^c	70.0 7 ^d	4.25	3.88	529	138,400
	L. hyperborea	LF 20/60 6 ^c	70.0 7 ^d	4.42	3.85	720	112,800

^aPotassium salts of pectic acid and sodium salts of alginic acid were used.

^bFor supplier of apple and citrus pectins, see Materials and Methods.[[15]], [[20]], [[31]]

^cProtanal LF 10/60 and Protanal LF 20/60 are produced by Pronova, Drammen, Norway.

^dContent of α-L-guluronate units was determined by the producer, Pronova Biopolymer Co., Drammen, Norway.

Table 3. Macromolecular Characteristics of Polysaccharide Gel Precursor

Pectate origin 8 ^a	Symbol/Trademark	Content of uronic acid		Constant of stability log K	Intrinsic viscosity η (cm ^3.g ^−1)	Molecular weight M W
		(%)	(mmol/g)
Apple	APA	81.0	3.80	4.30	178	165,000
Citrus	CPA	86.4	4.03	4.12	166	164,000

APA, potassium pectate from apple pectin; CPA, potassium pectate from citrus pectin.

^aPotassium salts of pectic acid were used.

Figure 1. Viscosity curves as a function of the shear rate γ. The measurements were done at 25°C using the rotational viscometer VT550 (Haake, Germany). Last digit in legends expresses the gel concentration in % (w/w): A10–Protanal LF 10/60; A20–Protanal LF 20/60 Pronova, Drammen, Norway; FAL–pectinate type 1, Federal Agricultural Research Centre, Braunschweig, Germany; APA–pectate type 4, Slovak Academy of Sciences, Bratislava, Slovak Republic. ▪–A102, •–A103, ▴–A201, ▾–A202, ♦–A203, ◂–FAL5, ▸–FAL8, ⧫–APA5, *–APA8.

Table 4. Mechanical Characteristics of Calcium Polysaccharide (Polyuronate) Gel Beads Prepared by Single-Nozzle JetCutter Device (Prüße et al., 1988) and Measured by Device According to Washausen

Polysaccharide precursor	Symbol/Trademark	Polysaccharide concentration (w/w)	Deformability F/d (N.mm ^−1)
Pectate	APA	5.0	1.25
		10.0	2.25
	CPA	5.0	0.87
		10.0	1.24
Alginate	LF 20/60	2.5	0.27

APA, potassium pectate from apple pectin; CPA, potassium pectate from citrus pectin.

Table 5. Rheological Parameters K (Consistence Index) and n (Flow Index) Evaluated According to the Ostwald de Waele Model for Pseudoplastic Liquids− τs= Kγ ⁿ, Where τ is the Shear Stress and γ is the Shear Rate (Viscosity Measurements Were Done at 25°C (Temperature at Which Bead Preparation Is Done) and 35°C (Many Fermentations Are Done at This Temperature) Using Rotational Viscometer VT550 (Haake, Germany))

Polysaccharide precursor	Symbol	Polysaccharide conc. [%]	Index K (Pa.s ^n)		Index n		Deformation power F (N)
			25°C	35°C	25°C	35°C
Alginate	A102	2	0.087	0.058	0.955	0.982	0.07
	A103	3	0.366	0.242	0.873	0.904	0.17
	A201	1	0.062	0.045	0.931	0.945	0.02
	A202	2	0.646	0.427	0.784	0.820	0.11
	A203	3	3.070	2.062	0.683	0.723	0.21
Pectinate	FAL5	5	0.712	0.458	0.857	0.886	0.21
	FAL8	8	3.832	2.631	0.814	0.832	0.43
Pectate	APA5	5	0.054	0.039	0.987	1.000	0.46
	APA8	8	0.191	0.128	0.981	1.000	0.82

A10–Protanal LF 10/60; A20–Protanal LF 20/60 (Pronova, Drammen, Norway); FAL–pectinate type 1 (Federal Agricultural Research Centre, Braunschweig, Germany); APA–pectate type 4 (Slovak Academy of Sciences, Bratislava, Slovak Republic). Last digit in second column entries expresses the gel concentration in % (w/v).

Figure 2. Simple laboratory multi-nozzle device for gel bead production. The solution of potassium pectate containing the cell suspension is pushed through the needle and dropped into the CaCl ₂ solution.

Figure 3. Sophisticated “jet-cutting” system for production of gel immobilizates. The beam of potassium pectate solution containing the cell suspension running from the nozzle is cut by single- (Prüße et al., 1998) or multi-wire cutting rotary device.

Figure 4. Diagram of a two-column packed-bed bioreactor for primary fermentation process of mead using immobilised yeast two-stage reactor system. The volume of the reactor system was 1100 ml with an internal diameter of 4.6 cm.

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