Spray drying of starch submicron particles prepared by high pressure homogenization and mini-emulsion cross-linking
- Authors: Shi, Aimin , Li, Dong , Wang, Li-jun , Zhou, Yuguang , Adhikari, Benu
- Date: 2012
- Type: Text , Journal article
- Relation: Journal of Food Engineering Vol. 113, no. 3 (2012), p. 399-407
- Full Text: false
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- Description: The suspensions containing starch submicron particles prepared through a novel high pressure homogenization and mini-emulsion cross-linking technology were spray dried to obtain cross-linked starch submicron particles. Dryer inlet temperature and feed flow rate were varied to investigate their effect on moisture content, glass transition temperature (T g), morphology of the starch submicron particles. The residual moisture content of the particles was below 10% (w/w) and particle had collapsed morphology. The T g of these submicron particles varied between 54 and 57°C corresponding to moisture contents of 9.78% and 8.31%, respectively and the cross-linking and the high hydrogen bond density in these submicron particles strongly affected the moisture dependence in their T g. The X-ray diffraction and FT-IR experiments revealed that these starch submicron particles were in amorphous glassy state, fully cross-linked and had very high extent of hydrogen bonding. © 2012 Elsevier Ltd. All rights reserved.
Effect of addition of proteins on the production of amorphous sucrose powder through spray drying
- Authors: Adhikari, Benu , Howes, Tony , Bhandari, Bhesh , Langrish, Tim
- Date: 2009
- Type: Text , Journal article
- Relation: Journal of Food Engineering Vol. 94, no. 2 (2009), p. 144 -153
- Full Text:
- Reviewed:
- Description: Spray drying trials were carried out to produce amorphous sucrose powder. Firstly, pure sucrose solutions were prepared and spray dried at inlet and outlet temperatures of 160 °C and 70 °C, respectively. No amorphous powder was obtained and only 18% of the feed solids were recovered in a crystalline form, with the remaining solids lost as wall deposits. Secondly, sodium caseinate (Na-C) and hydrolyzed whey protein isolate (WPI) were added in sucrose:protein solid ratios of (99.5:0.5) and (99.0:1.0) and drying trials were conducted maintaining the initial drying conditions. In both these cases, greater than 80% of the feed solids were recovered in an amorphous form. The increase in protein concentration from 0.5% to 1% on dry solid basis did not further improve the recovery. The remarkable increase in recovery from a small addition of protein is attributed to preferential migration of protein molecules to the droplet-air interface, and the subsequent transformation of the thin, protein-rich film into a non-sticky glassy state upon drying. This film overcomes both the particle-to-particle and particle-to-wall stickiness. The measured bulk glass rubber transition temperature (Tg-r) values of the bulk mixtures at various moisture contents were very close to the corresponding mean glass transition temperature (Tg) of the pure sucrose indicating that surface layer Tg rather than the bulk Tg is responsible for this. Electron spectroscopy for chemical analysis (ESCA) studies revealed that the particle surface was covered by 50-58% (by mass) proteins. The calculated glass transition temperature of the surface layer (Tg,surface layer), based on the surface elemental compositions, showed that the Tg,surface layer has increased to the extent that it remained within the safe drying envelope of spray drying. © 2009 Elsevier Ltd. All rights reserved.