foam-mat freeze drying of egg white and ... - McGill University

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owl has higher stability than those made using another kind of bowl. This claim indicates the effect of copper on the stability of foam (Sagis et al. 2001). Similarly different kinds of stabilizers are used in stabilizing foams and emulsions. Most of the stabilizers are high molecular polysaccharides in nature. Their hydrophobic nature prevents them from being absorbed at the plateau borders, this helps to strengthen bubble walls, which in turn helps to improve the stability of the foam (Papalamprou et al. 2005). Polysaccharides are more popular type of stabilizers than any other types (Baeza et al. 2004). Proteins can also be used as stabilizers. For a protein to be a good stabilizing agent it should be able to reduce the surface energy levels between the bubbles as they are continuously created during foaming (German & Phillips 1994). 3.4.1 Xanthan Gum Xanthan gum is one of the widely used polysaccharide in food processing industries. Xanthomonas campestris pv. campestris produces Xanthan, which is exopolysaccharide in nature. Polyelectrolyte nature of the Xanthan molecule makes it highly water soluble. The temperature of the water does not affect the solubility of Xanthan gum; this makes it highly adaptable for industrial applications regardless of the processing temperature (Becker et al. 1998). Xanthan Gum is one of the extensively researched food additives for its toxicological and safety properties. Laboratory tests at USDA on rats, showed no adverse effects such as toxicity and growth inhibition. Long term studies on rats and dogs also proved Xanthan gum produces no adverse effect (Kang & Pettitt 1993). United States Food and Drug Administration (FDA) approved Xanthan gum in 1969 as a food additive without any specific quantity limitations. In 1980 it got the European Commission (EC) 17
approval (Kang & Pettitt 1993; Katzbauer 1998; Garcia-Ochoa et al. 2000). It also got Canadian Governor-in-Council approval. The physical properties of Xanthan Gum are shown in Table 3.4 (Kang & Pettitt 1993). When Xanthan gum is added to any liquid it increases the viscosity of the liquid, due to this property it is widely used in food industry as a thickening agent as well as stabilizer. It can produce very high viscosity at lower concentration, for example at 1% level it can produce viscosity in the range of 1000 – 4300 mPa s. Viscosity of the solution is dependent on many factors such as temperature, pH, concentration of Xanthan gum and concentration of salts. The effect of heat and pH on affecting the performance of Xanthan Gum is usually minimal (Lachke 2004; Sahin & Ozdemir 2004). 3.4.2 Propylene Glycol Alginate Propylene glycol alginate (PGA) is a surface active ester obtained from alginic acid. It is a high molecular weight 1, 4 D-mannuronic acid and L-guluronic acid (Baeza et al. 2004). It increases the viscosity of the solution, which will help improving the stability of foam by reducing the drainage. Its cross linking ability was investigated in studies involving model foam. The experiments on thin film drainage by Wilde and Sarkar (1999) showed that PGA improved the stability of foam; but when the concentration level of PGA was increased fluid drainage increased. The increased drainage by PGA at higher concentration has not been properly explained. 3.4.3 Methyl Cellulose Methyl cellulose is another popular food additive, which is widely used in food processing industries. It is a cellulose derivative; cellulose ethers are produced by etherification of alkaline cellulose with methyl chloride. It produces a gel upon heating, 18
Page 1 and 2: FOAM-MAT FREEZE DRYING OF EGG WHITE
Page 3 and 4: RÉSUMÉ ARUN MUTHUKUMARAN M. Sc. G
Page 5 and 6: CONTRIBUTIONS OF AUTHORS The work r
Page 7 and 8: 3.6.1.2 Primary drying stage.......
Page 9 and 10: LIST OF TABLES Table 3.1 World egg
Page 11 and 12: Figure 5.3 Foam-mat freeze drying o
Page 13 and 14: Φ Concentration, mol m -3 ΔHs ΔH
Page 15 and 16: fermentation removes glucose from e
Page 17 and 18: focuses on determination of drying
Page 19 and 20: III. LITERATURE REVIEW 3.1 Overview
Page 21 and 22: 3.2 Structure and composition of eg
Page 23 and 24: Table 3.2 Nutrient Composition of e
Page 25 and 26: The transportation of protein occur
Page 27 and 28: 3.3.3.3 Sparging or Bubbling The me
Page 29: Protein based foams are relatively
Page 33 and 34: Table 3.4 Physical properties of co
Page 35 and 36: use is restricted only for high com
Page 37 and 38: wwater to achi ieve drying. The low
Page 39 and 40: ddrying stage, , all the freee wate
Page 41 and 42: structural collapse even before the
Page 43 and 44: widely used for modeling radiation
Page 45 and 46: 2 L ρms ( X 0 − X t = 8k ( T −
Page 47 and 48: x) The frozen region is homogenous
Page 49 and 50: Foam is a two phase system having a
Page 51 and 52: Figure 4.2 A typical foam volume pr
Page 53 and 54: configuration of the Buchner filter
Page 55 and 56: camera attached to the microscope w
Page 57 and 58: Drain, ml 70.00 0 60.00 0 50.00 0 4
Page 59 and 60: Fig 4.5 Egg white foam (with 0.125%
Page 61 and 62: 4.7 References Alleoni, A. and Antu
Page 63 and 64: CONNECTING TEXT The previous chapte
Page 65 and 66: Freeze drying has several advantage
Page 67 and 68: 5.4 Materials and methods 5.4.1 Exp
Page 69 and 70: 5.4.1.4 Determination of Moisture c
Page 71 and 72: middle layer during drying. The sam
Page 73 and 74: that the time taken for drying of e
Page 75 and 76: accurate in predicting the foam fre
Page 77 and 78: Moisture Ratio (X/X0) 1 0.9 0.8 0.7
Page 79 and 80: Moisture content, %(db) 450.00 400.
Page 81 and 82:
5.7 References Bala, B. K. (1997).
Page 83 and 84:
VI. GENERAL SUMMARY AND CONCLUSIONS
Page 85 and 86:
(2006). FAOSTAT DATA. REFERENCES
Page 87 and 88:
Foegeding, E. A., Luck, P. J. and D
Page 89 and 90:
Karim, A. A. and Wai, C. C. (1999).
Page 91 and 92:
Muthukumaran, A., Ratti, C. and Rag
Page 93:
Van Kalsbeek, H. K. A. I. and Prins
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